D Plants for food Unit guide - Physicslocker 3/Unit D.pdfD Plants for food Unit guide Where this unit fits in Prior learning This unit builds on:unit 8D Ecological relationships and

Sheet 1 of 1© Harcourt Education Ltd 2004 Catalyst 3This worksheet may have been altered from the original on the CD-ROM.

D Unit guidePlants for food

Where this unit fits in Prior learningThis unit builds on: unit 8D Ecological relationships and unit 9C Plants and photosynthesis.With some pupils, teachers may wish to consolidate the earlier work, to concentrate on some of the new topics,extending activities, and with others, to spend more time on revision of previous work.There are opportunities for links with citizenship in the teaching of food production issues.

The concepts in this unit are: how humans are part of a complex food web, factors affecting plant growth, the effect of food production onanimal and plant populations and the environment.

This unit leads onto: further work in key stage 4 on the impact of humans on the environment, the managementof food-production systems and the importance of sustainable development, for which it provides the foundation.This unit relates to: unit 8E(i) Producing batches (food) and unit 9A(i) Selecting materials (food) in the designand technology scheme of work, and to unit 14 Can the Earth cope? in the geography scheme of work. It alsorelates to unit 9A Inheritance and selection, and to unit 9G Environmental chemistry.

To make good progress, pupilsstarting this unit need tounderstand:• about some of the life processes

common to living things, e.g.movement, growth,reproduction, nutrition.

Framework yearly teaching objectives – Cells and Interdependence • Describe relationships of organisms in a food web and use this to explain: why photosynthesis is important to humans; why maximising human

food production can significantly affect other animals and plants; how the abundance and distribution of organisms may be affected by pesticides,weedkillers and the accumulation of toxins; how pyramids of numbers represent feeding relationships in a habitat.

• Explain that habitats change in response to changes in physical, chemical and biological factors.• Begin to describe a model for the whole environment that recognises how the materials that make up all living organisms are recycled, and that

energy from sunlight flows through the system; use this to explain the need for sustainable development.

Expectations from the QCA Scheme of Work At the end of this unit …

… most pupils will … … some pupils will not have made somuch progress and will …

… some pupils will haveprogressed further and will …

in terms of scientific enquiry NC Programme of Study Sc1 1c, 2c, d, e, f, g, i, j, k, m

• decide on an appropriate approach to investigating a questionabout the effects of fertiliser, identifying relevant variables andchoosing an appropriate sample size

• present results in tables and graphs which show features effectively• draw conclusions that are consistent with the evidence,

identifying shortcomings where appropriate, and relate them toscientific knowledge and understanding.

• suggest how to control variables identifiedfor them

• present results in tables and graphs andpoint out patterns in these

• draw conclusions, relating these to scientificknowledge and understanding, and suggestsome improvements to their work.

• consider critically tables ofresults and graphs and explainhow additional data wouldenable them to have moreconfidence in theirconclusions.

in terms of life processes and living things NC Programme of Study Sc2 2a, 3a, c, e, 5c, d, e, f; Sc4 5b

• name the products of photosynthesis and some of the nutrientssupplied by fertilisers

• identify conditions in which crops will grow well• describe how the abundance and distribution of organisms may be

affected by pesticides or weedkillers, relating this to knowledgeof food webs

• describe how other plants compete with food crops, and otheranimals compete with humans for the food crops, and that thereare ways of achieving a balance between communities.

• name the products of photosynthesis andsome of the nutrients provided byfertilisers

• identify factors which affect the growth ofcrops and identify some organisms whichcompete for resources where crops aregrown.

• relate crop production topyramids of numbers andexplain some ways of achievinga balance between the demandsof different communities withinan environment

• explain how toxic materialscan accumulate in a foodchain.

Suggested lesson allocation (see individual lesson planning guides)Direct route

D1Storing food

D2Make them grow

D3Competing plants

D4What a pest!

D5How many? – Thinkabout sampling

Booster 2Focus on interdependence –Interconnections

Extra lessons (not in Pupil book)

D2 Make them grow Extralesson for Activity D2a.

D5 How many? Extralesson for Activity D5a.

Review and assess progress(distributed appropriately)

MisconceptionsPupils think that plants store food ‘for’ human consumption, and that food chains exist to provide humans with food. Pupils fail to recognise wherecompetition can occur in food webs because they concentrate on linear food chains, rather than realising that food chains have members incommon. Pupils find it easier to understand competition between animals (where the competition appears active) rather than between plants.

Health and safety (see activity notes to inform risk assessment)Risk assessments are required for any hazardous activity. In this unit pupils use fertilisers, which may contain hazardous substances. They also planand carry out their own investigation and carry out work outside the school.

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D1Lesson planning

guideStoring food

Suggested alternative starter activities (5–10 minutes)

Introduce the unit

Unit map for Plants forfood.

Learning objectivesi What happens to the products of photosynthesis?ii Plants respire.iii Different parts of plants (e.g. stem, leaf, seed) store food, often as starch.iv Use ideas about feeding relationships including humans.

Scientific enquiryv Use chemical tests to identify different nutrients safely.

Learning outcomes

Share learningobjectives

• Describe what happens tothe products ofphotosynthesis.

• Recognise that humans arepart of some food chains.

• Use chemical tests toidentify different nutrientssafely. (Sc1)

Word game

True/false quiz to recap unit 9C.

Brainstorming

In turn, pupils add to astory based on the pictureof a lion in its habitat.

Capture interest

Show pupils a picture of amicroscope slide of starchgrains. Catalyst InteractivePresentations 3

Suggested alternative plenary activities (5–10 minutes)

Review learning

Play ‘What am I?’ aboutparticular food storageorgans in plants (e.g.carrots, onions).

Sharing responses

Collate results andconclusions from Activity D1b.

Group feedback

In groups, pupils suggestways to expand the foodwebs from Activity D1a toproduce a larger food web.

Word game

Pupils write their ownquestions about the lesson’skey topics.

Looking ahead

Pupils consider how plantsmake more biomass.

Suggested alternative main activitiesActivity

Textbook D1

Activity D1a Paper

Activity D1b Practical

Activity D1cCatalyst InteractivePresentations 3

Learningobjectivessee above

i, ii, iii andiv

i and ii

i, ii, iii, ivand v

i, ii and iv

Description

Teacher-led explanation and questioning OR Pupils work individually,in pairs or in small groups through the in-text questions and thenonto the end-of-spread questions if time allows.

Making food webs Pupils use a restaurant menu to write food webs.

Where is starch stored? Pupils identify parts of plants as stem,roots and leaves, test them for starch (Core) and examine slides ofstarch grains (Extension).

Drag and drop exercise to create food chains.

Approx. timing

30 min

10 min

45 min

10 min

Target group

C H E S

R/G G R S

✔ ✔

✔ ✔

✔

Key wordsNone

Out-of-lesson learningHomework D1Textbook D1 end-of-spread questionsRead about issues relating to plant breeding in newspapers and periodicals

Most pupils will …

• construct a food web showing feedingrelationships of humans

• explain why plants store food• identify, from experimental results, starch

stores in some plants• name some materials produced by a plant

from glucose.

Some pupils, making less progress will …

• construct some food chains showing feedingrelationships of humans

• identify which part of a plant is a food store.

Some pupils, making more progress will …

• understand why humans do not eat every partof a plant

• explain how the balance betweenphotosynthesis and respiration ratesdetermines whether food will be stored.



D2Lesson planning

guideMake them grow


Recap last lesson

Pupils do thetrue/false quiz basedon statements aboutthe last lesson.

Learning objectivesi Environmental factors influence plant growth.ii Growing crops in a controlled environment has advantages and disadvantages.iii Plants require a range of nutrients for healthy growth.iv Fertilisers supply nutrients to crop plants.

Scientific enquiryv Understand the need to control variables. (Framework YTO Sc1 9b)vi Draw conclusions from results and explain their significance. (Framework YTO Sc1 9f)

Learning outcomes

Share learning objectives

• Recognise what plants need tostay healthy and that fertiliserssupply plants with extra nutrients.

• Use a simulation to investigatephotosynthesis. (Sc1)

Problem solving

Pupils ring the differencesbetween pairs of plants(with different deficiencysymptoms).

Word game

Wordsearch about what aplant needs to makebiomass.

Brainstorming

In groups, pupils make alist of what a plant needsto be healthy.


Review learning

Pupils play bingo to checkunderstanding.

Sharing responses

Pupils compare anddiscuss their predictionsfor Activity D2a.

Group feedback

In groups, pupils look ateach other’s advertisingposters for fertiliser fromActivity D2b and evaluatethem.

Word game

Pupils play Pelmanismgame to matchnutrients withdeficiency symptoms.

Looking ahead

Show pupils a photo of the edge ofsome woodland. Pupils try to explainwhy the understorey plants are somuch higher outside the woodland.Catalyst Interactive Presentations 3


Textbook D2

Activity D2a Practical

Activity D2b Paper

Activity D2cCatalyst InteractivePresentations 3


i, ii, iii and iv

iii, iv, v andvi

i, ii, iii and iv

i, ii, iii, ivand v

Description


What does fertiliser do? Carry out an investigation into the effectsof fertiliser on duckweed.

What is in fertiliser? Use fertiliser packaging to make an advert toencourage gardeners to use fertiliser. It should contain informationabout the constituents of fertiliser and their functions in a plant.

Pupils use a simulation to run a virtual greenhouse with a view tomaximising yield.

Approx. timing

20 min

50 min

25 min

20 min

Target group

C H E S

R/G G R S

✔ ✔

✔

✔

Key wordsfertiliser, red only: application rate

Out-of-lesson learningHomework D2Textbook D2 end-of-spread questionsDesign the ideal greenhouse for growing cropsWatch television programmes which deal with issues relating to intensive crop productionGo fruit-picking or grow fruit to gain first-hand experience of food production and harvestingPupils find leaflets from garden centres about fertilisers


• be able to describe the best conditions for plant growth• identify the effect of fertilisers on plants• plan an investigation, and make a prediction, about the

effect of nutrients on growth rate in duckweed,identifying relevant confounding variables (e.g.concentration of nitrate, mass of fertiliser).


• find information about fertilisers and plantnutrients

• use a simulation to investigate the effectof nutrients and other variables onphotosynthesis and growth rate.


• explain how fertilisers supply crop plantswith nutrients.



D3Lesson planning

guideCompeting plants


Recap last lesson

Pupils list four thingsthat affect plant growth.

Learning objectivesi Organisms living in a habitat compete with each other for resources from the environment.ii Treating fields with selective weedkillers affects food webs.

Scientific enquiryiii Use scientific knowledge to make predictions. (Framework YTO Sc1 9f)iv Present quantitative data using graphs and charts, and use the data to make conclusions. (Framework YTO Sc1 9f, g)

Learning outcomes


• Describe how plants competewith each other for resources.

• Recognise that weedkillers affectfood webs.

• Use scientific knowledge to makepredictions. (Sc1)

Word game

Play a game of ‘Hangman’with the whole class tointroduce vocabulary andspelling of the lesson’skey words.

Problem solving

Pupils list their ideasof the differencesbetween organic andnon-organic food.

Capture interest

Show pupils photos of ahealthy plant and one that hasbeen sprayed with weedkiller.Catalyst InteractivePresentations 3


Review learning

Show and discuss the pictures ofthe wood in spring and summer.Catalyst Interactive Presentations 3

Sharing responses

Collate results ofcalculations and conclusionsfrom Activity D3a.

Group feedback

In groups, pupilscompare answers toquestions in ActivityD3b.

Word game

Play ‘What am I?’ about thekey words in the lesson.


Textbook D3

Activity D3a Paper

Activity D3b Paper


i and ii

i, ii and iii

i, ii, iii andiv

Description


Should farmers control weeds? Pupils analyse data about yield ofcrops, comparing situations in which farmers do and do not controltheir weeds.

Competition in duckweed Core: Pupils interpret a graph of resultsfrom a study of a duckweed population. Help: Pupils examinecompetition in two simple pond scenarios.

Approx. timing

20 min

25 min

25 min

Target group

C H E S

R/G G R S

✔

✔ ✔


• describe how weeds compete with food crops• explain how animals are affected by the

removal of a particular plant by a selectiveweedkiller

• collect data about the population anddistribution of weeds in the school grounds.

• write a report for a landowner, presentingfindings in a suitable format such as graphsand charts, and making a conclusion.


• know that weeds need the same resources ascrop plants

• follow a given plan to collect data about thepopulation and distribution of weeds

• produce tables and graphs to present data anduse them to make a conclusion.


• explain how the distribution and abundanceof organisms within a food web may beaffected by weedkillers

• suggest how a high crop yield may bemaintained alongside preservation of ananimal’s food supply.

Looking ahead

Pupils list five otherspecies that competewith humans for farmers’crops.

Key wordsweed, weedkiller, compete, yield, selective,organic

Out-of-lesson learningHomework D3Textbook D3 end-of-spread questionsWatch television programmes which deal with issues relating to intensive crop productionVisit a rural or city farm to gain first-hand experience of farm practiceGo fruit-picking or grow fruit to gain experience of food production and harvesting



D4Lesson planning

guideWhat a pest!


Recap last lesson

Pupils complete thewordsearch on the pupilsheet.

Learning objectivesi Organisms living in a habitat compete with each other, e.g. for food resources.ii Represent feeding relationships using pyramids of number.iii The numbers of a population of predators influence the numbers of prey.iv Toxins enter a food chain when plants take them in and build up in animals that feed on them.

Scientific enquiryv To evaluate conflicting evidence to arrive at a considered viewpoint. (Framework YTO Sc1 9g)

Learning outcomes


• Describe how organisms compete witheach other.

• Identify what pests are and how theyare dealt with.

• Recognise that poisons can build up ina food chain and affect all the organisms.

• Evaluate conflicting evidence frompeople with differing perspectives. (Sc1)

Brainstorming

Play ‘Tip of my tongue’,asking pupils to predictwhat you are going tosay next.

Problem solving

In groups, pupils use thefood web to list animalsthat eat the same foodas humans.

Capture interest

Show a photo or videoclip of a huge plague oflocusts. Catalyst InteractivePresentations 3


Review learning

Pupils match words to theirdefinitions.

Sharing responses

Share and collate responsesto Activity D4a by votingon the debate.

Group feedback

In groups, pupils sequence aset of cards to describe howbioaccumulation happens.

Word game

Pupils play ‘Taboo’ toreview learning.

Looking back

Pupils revise andconsolidate knowledgefrom the unit.


Textbook D4

Activity D4a Discussion

Activity D4b Paper

Activity D4c Catalyst Interactive Presentations 3


i, ii, iiiand iv

i, ii, iv and v

iv

i, ii and iii

Description


Are pesticides a problem? Pupils debate the issue from differingperspectives.

Trace the poison Pupils answer questions about bioaccumulation.

Animation where pupils can change the numbers of species in a foodweb to see the effect on other members of the food web.

Approx. timing

20 min

40 min

20 min

10 min

Target group

C H E S

R/G G R S

✔ ✔

✔

✔

Key wordspests, pesticide, insecticide, selective, non-selective,red only: toxin

Out-of-lesson learningHomework D4Textbook D4 end-of-spread questionsWatch television programmes which deal with issues relating to intensivecrop productionVisit a rural or city farm to gain first-hand experience of farm practice


• identify some common pests which feed on crops and explainhow they compete with humans for these resources

• explain how elimination of pests will affect the populationsof predator animals such as birds

• describe how the distribution and abundance of organismsmay be affected by pesticides, relating this to knowledge offood webs

• describe how a toxic material passes up the food chain• extract the key points about build-up of toxins from

conflicting evidence from people with different perspectives.


• identify some common pests which feedon crops

• describe how elimination of pests canaffect other animals in a food chain

• describe how a toxic material may bepassed between members of a food chain

• use a simulation model to see the effecton a food web of changing one species’numbers.

Some pupils, making moreprogress will …

• explain how elimination of pestswill affect the populations ofpredator animals such as birds,relating explanations to pyramids ofnumbers

• explain how toxic materials canaccumulate within a food chain

• relate food production to pyramidsof numbers



D5Lesson planning

guideHow many? – Think aboutsampling


Bridging to the unit

Ask pupils to write and discussnewspaper headlines about aweedkiller that has killed anendangered species of plant.

Learning objectivesi Deforestation can have a range of local and global effects on ecosystems.The structure of this lesson is based around the CASE approach. The starter activities give concrete preparation. The main activities move away from theconcrete towards a challenging situation, where pupils need to think. The extended plenary gives pupils time to discuss what they have learnt, tonegotiate a method to commit to paper and express their ideas verbally to the rest of the class.

Scientific enquiryii Consider issues of environmental protection from several perspectives.iii Consider how to sample populations to estimate population sizes. (Framework YTO Sc1 9b)iv Consider how to use population data to highlight problems caused by human intervention in ecosystems.

Learning outcomes

Setting the context

Pupils identify the evidence they wouldneed to prove whether the headline storyis true or false.

Concrete preparation (1)

In groups, pupils discuss theproblems with trying to countevery member of a rare species.Summarise as a class.


Using the map of rare species,discuss why it is necessary tochoose sampling points atrandom within a habitat.


Group feedback

Pupils discuss their conclusions and evaluations of Activity D5a.

Bridging to other topics

Pupils brainstorm three different professions that use sampling in their everyday jobs.


Textbook D5

Activity D5a Practical


i, ii, iii and iv

iii and iv

Description


Looking after grassland Pupils investigate whether wild flowersgrow better in long grass or mown grass.

Approx. timing

30 min

50 min

Target group

C H E S

R/G G R S

✔ ✔

Key wordssample, estimate, population

Out-of-lesson learningTextbook D5 end-of-spread questionsRead about forest clearance and the consequent loss of biodiversity


• analyse data from a study sampling grassland• write a report highlighting issues of environmental protection

from several perspectives.


• complete a report highlighting issues ofenvironmental protection from differentperspectives.

Some pupils, making moreprogress will …

• evaluate sampling methods,highlighting problems which maylead to inaccurate estimation ofpopulation sizes.


D Unit mapPlants for food


Copy the unit map and use these words to help you complete it.You may add words of your own too.

application rate Rbiomasscompeteestimatefertiliserfood chainfood webinsecticidenon-selectiveorganic

pesticidepestsphotosynthesispopulationsampleselectivetoxin Rweedweedkilleryield

Plants for food

Plantsstoring food

Sampling

Competition with animals

Competitionbetween plants

Plantnutrients

Unitmaps.qxd 18-Jun-04 11:36 AM Page 4


D1 StartersStoring food

Introduce the unit� Either draw the outline of the unit map on the board

then ask pupils to give you words to add, saying where toadd them. Suggest some words yourself when necessaryto keep pupils on the right track.

� Or give out the unit map and ask pupils to work ingroups, deciding how to add the listed words to thediagram. Then go through the map on the board as eachgroup gives suggestions.

Share learning objectives� Ask pupils to write a list of FAQs they would put on a

website telling people about food stores in plants. Collectsuggestions as a whole-class activity, steering pupilstowards those related to the objectives. Conclude byhighlighting the questions you want them to be able toanswer at the end of the lesson.

Word game� Make a set of cards for each pupil: true, false and unsure.

(You could use a different colour card for each word.)

� Read out the statements on the separate teacher sheet.Pupils hold up their cards for each answer.

� Explain the answers. If many pupils get an answer wrong,repeat the statement later.

Brainstorming� Begin a story based on the picture of a lion in its habitat.

� Pupils in turn suggest what the lion does next, based onthe picture.

� Use pupils’ responses to introduce the idea of foodchains.

Capture interest� Show pupils a microscope slide of starch grains, either via

a data projector or by them looking at slides under themicroscope.

➔ Unit map

➔ Teacher sheet

➔ Pupil sheet

➔ Catalyst Interactive Presentations 3


Introduce the unit

Unit map for Plantsfor food


• Describe what happens to theproducts of photosynthesis.

• Recognise that humans are partof some food chains.

• Use chemical tests to identifydifferent nutrients safely. (Sc1)

Word game

True/false quiz to recapUnit 9C.

Brainstorming

In turn, pupils add to astory based on the pictureof a lion in its habitat.

Capture interest

Show pupils a picture of amicroscope slide of starchgrains.Catalyst InteractivePresentations 3

D-Starters.qxd 17-Jun-04 8:42 PM Page 1

D1 StartersStoring food


Word gameTeacher sheet1 Plants get all their food through their roots. [False]

2 Photosynthesis needs light energy to happen. [True]

3 Plants produce glucose and carbon dioxide in photosynthesis. [False]

4 Leaves have green chlorophyll to trap light energy. [True]

5 Veins carry gases around a plant. [False]

6 Plants can convert glucose into other substances like starch. [True]

7 Plants respire and photosynthesise. [True]

8 Plants respire only at night and photosynthesise only during the day. [False]

Display the words below in large type for pupils to hold up for you to see.Make them into 2 × 4 = 8 cards to a sheet.

True TrueTrue TrueTrue TrueTrue True


False FalseFalse FalseFalse FalseFalse False


Unsure UnsureUnsure UnsureUnsure UnsureUnsure Unsure


D1 Starters

Sheet 1 of 1

Sheet 1 of 1

© Harcourt Education Ltd 2004 Catalyst 3This worksheet may have been altered from the original on the CD-ROM.

StartersD1 Storing food


Storing food

Brainstorming

Brainstorming



D2 StartersMake them grow

Recap last lesson� Pupils do the true/false quiz based on statements about

last lesson.

� Go through the answers as a class.


website telling people about the conditions needed forplant growth. Collect suggestions as a whole-classactivity, steering pupils towards those related to theobjectives. Conclude by highlighting the questions youwant them to be able to answer at the end of the lesson.

Problem solving� Pupils identify two differences between the plants in

each pair (which have different deficiency symptoms)on the pupil sheet.

� Pupils can write down or ring the differences on one ofthe pictures.

� Go through the differences using the pupil sheet as anOHT.

Word game� Ask pupils to complete the wordsearch on the pupil

sheet.

� Ring the words on a copy of the pupil sheet and show itas an OHT for pupils to check their answers. Use thewords to introduce the lesson.

Brainstorming� In groups, pupils make a list of what a plant needs to be

healthy.

� Collate each group’s list into a ‘master’ list on the board.

➔ Pupil sheet

Answers1 true; 2 false; 3 true; 4 false; 5 false; 6 false;7 true; 8 true; 9 true

➔ Pupil sheet

Answers1 Floppy leaves and stem; 2 Tall stem butfew small leaves; 3 Dark leaves but shortstem and roots; 4 Short stem but very smallpale leaves

➔ Pupil sheet


Recap last lesson

Pupils do the true/falsequiz based on statementsabout the last lesson.


• Recognise what plants need tostay healthy and thatfertilisers supply plants withextra nutrients.

• Use a simulation to investigatephotosynthesis. (Sc1)

Problem solving

Pupils ring thedifferences between pairsof plants (with differentdeficiency symptoms).

Word game

Wordsearch about what aplant needs to makebiomass.

Brainstorming

In groups, pupils make alist of what a plant needsto be healthy.



Recap last lesson

Decide if the following statements are true or false.

1 Carrots store food in their roots. true/false

2 Plants only store food in their seeds so animals can eat them. true/false

3 Energy in the food chain originally comes from the Sun. true/false

4 All the energy in food chains originally comes from the soil. true/false

5 A carnivore is an animal that only eats plants. true/false

6 Producers must eat other living things to get food. true/false

7 Plants store food to help them survive the winter. true/false

8 Lots of food chains drawn together make a food web. true/false

9 Plants store glucose as starch. true/false

Sheet 1 of 1

Sheet 1 of 1


StartersD2 Make them grow

Recap last lesson

Decide if the following statements are true or false.

1 Carrots store food in their roots. true/false

2 Plants only store food in their seeds so animals can eat them. true/false

3 Energy in the food chain originally comes from the Sun. true/false

4 All the energy in food chains originally comes from the soil. true/false

5 A carnivore is an animal that only eats plants. true/false

6 Producers must eat other living things to get food. true/false

7 Plants store food to help them survive the winter. true/false

8 Lots of food chains drawn together make a food web. true/false

9 Plants store glucose as starch. true/false



D1 Starters

Sheet 1 of 1

Sheet 1 of 1


StartersD2 Make them grow


D2 Make them grow

Problem solving

Look at the pairs of plants below. For each pair, write down twodifferences between the plants in the space below the pictures.

1 2

healthy healthywaterdeficient

lightdeficient

3

healthy phosphorusdeficient

4

healthy nitrogendeficient

Problem solving

Look at the pairs of plants below. For each pair, write down twodifferences between the plants in the space below the pictures.

1 2

healthy healthywaterdeficient

lightdeficient

3

healthy phosphorusdeficient

4

healthy nitrogendeficient



Word game

All the words below are connected with plant growth. See howmany of them you can find in the wordsearch.


greenhouse light warmth photosynthesis

nutrients soil fertilisercarbon dioxide

water nitrogen magnesium phosphorus

Q E D I X O I D N O B R A C

S D F R E S I L I T R E F E

P H O T O S Y N T H E S I S

U L Y S T N E I R T U N W R

W I T O T U I O O R E T A W

D G F I G H H J G J K L R P

A H A L M A G N E S I U M S

M T N B V C X I N Z A S T D

Q W E O S U R O H P S O H P

G R E E N H O U S E B V C X



D3 StartersCompeting plants

Recap last lesson� Pupils list four things that affect plant growth.

� Begin to discuss with pupils their preconceptions abouthow these factors affect growth.


website telling people about competition and weedkillers.Collect suggestions as a whole-class activity, steeringpupils towards those related to the objectives. Concludeby highlighting the questions you want them to be ableto answer at the end of the lesson.

Word game� Play a game of ‘Hangman’ with the whole class to

introduce vocabulary and spelling of the lesson’s keywords.

Problem solving� Pupils list their ideas of the differences between organic

and non-organic food.

� Take a vote on who thinks organic food is better forthem. Ask voters to give reasons to the class.

Capture interest� Show pupils photographs of a healthy plant and one that

has been sprayed with weedkiller.

� Tell pupils to look at the leaves and stem, and ask themto describe what they look like.

Answerslight; water; carbon dioxide; temperature

Wordscompete; organic; selective; weed;weedkiller; yield



Recap last lesson

Pupils list four things thataffect plant growth.

Share learningobjectives

• Describe how plantscompete with each otherfor resources.

• Recognise that weedkillersaffect food webs.

• Use scientific knowledgeto make predictions. (Sc1)

Word game

Play a game of ‘Hangman’with the whole class tointroduce vocabulary andspelling of the lesson’s keywords.

Problem solving

Pupils list their ideas of thedifferences between organicand non-organic food.

Capture interest

Show pupils photographs of a healthy plant and onethat has been sprayed with weedkiller. Catalyst InteractivePresentations 3



D4 StartersWhat a pest!

Recap last lesson� Ask pupils to complete the wordsearch on the pupil sheet.

� Ring the words on a copy of the pupil sheet and show it as an OHT for pupils to check their answers. Use the words tointroduce the lesson.


website telling people about pests. Collect suggestions as a whole-class activity, steering pupils towards those related to the objectives. Conclude by highlighting the questions you want them to be able to answer at the end of the lesson.

Brainstorming� Write on the board the first part of the sentence shown on

the right.

� Ask pupils to write down how they would finish the sentence.

� Ask for suggestions and write them on the board. Discuss any problem areas.

Problem solving� In groups, pupils use the food web to list animals that eat

the same food as humans.

� Use their answers to point out that these can be considered pests and how to identify them from their position in the food web.

Capture interest� Show a photograph or video footage of a plague of locusts.

� Discuss the effect of such a plague on farmers’ crops.

➔ Pupil sheet

SentenceA pest is ...

➔ Pupil sheet

Answersinsects; rabbits; foxes



Recap last lesson

Pupils complete thewordsearch on thepupil sheet.


• Describe how organisms compete with each other.• Identify what pests are and how they are dealt with.• Recognise that poisons can build up in a food chain

and affect all the organisms.• Evaluate conflicting evidence from people with

differing perspectives. (Sc1)

Brainstorming

Play ‘Tip of mytongue’, askingpupils to predictwhat you aregoing to say next.

Problem solving

In groups, pupilsuse the food web tolist animals that eatthe same food ashumans.

Capture interest

Show a photograph orvideo footage of aplague of locusts.Catalyst InteractivePresentations 3



Recap last lesson

All the words below are connected with weeds and competition.See how many of them you can find in the wordsearch.


weed compete roots weedkiller

water organic food

W E T R T Y U I O P L K J

H E N H G F D S A Z A X S

C D E C D V F R B G N H M

N J I D E T E P M O C E R

F T R E K T T Y J U K I K

I L T E A I O I L S Z A X

D C U W S E L E C T I V E

F C N G B H N L H O N J M

K L P K I J U H E O Y G T

D O O F C I N A G R O T F

nutrient selective



Problem solving

Look at the food web. Write down a list of animals that eat thesame animals and plants as humans.


Duck

Insects Squirrel

Oak tree

Rabbit Cow

Pondweed

Lettuce

HumanFox

Grass

Sheet 1 of 1

StartersD4 What a pest!

Problem solving

Look at the food web. Write down a list of animals that eat thesame animals and plants as humans.


Duck

Insects Squirrel

Oak tree

Rabbit Cow

Pondweed

Lettuce

HumanFox

Grass



D5 StartersHow many? – Think about

Bridging to the unit� Explain to pupils that a weedkiller is suspected to have

killed off a rare, endangered species of plant. Ask the classto pretend to be journalists. Ask them to write emotivenewspaper headlines that criticise the manufacturers andspell out environmental disasters.

� Collate some of the headlines on the board. Discuss howscientists can respond to such journalism. Use thediscussion to move on to Setting the context.

Setting the context� In groups, pupils should suggest two pieces of evidence

they would need to prove whether a story about aweedkiller affecting an endangered species of plant is trueor false.

� Collate ideas as a class.

Concrete preparation (1)� In groups, pupils discuss the problems with trying to

count every member of a rare species.

� Summarise the problems as a class. If there is time, askpupils for solutions.

Concrete preparation (2)� Using the map of rare species on the teacher sheet as an

OHT, recap why it is necessary to choose sampling pointsat random within a habitat.

➔ Teacher sheet


Bridging to the unit

Ask pupils to write and discussnewspaper headlines about aweedkiller that has killed anendangered species of plant.

Setting the context

Pupils identify the evidence theywould need to prove whether thestory is true or false.


In groups, pupils discuss theproblems with trying to count everymember of a rare species.Summarise as a class.


Using the map of rare species,discuss why it is necessary tochoose sampling points at randomwithin a habitat.


D5 StartersHow many?




D1aTeacher

activity notesMaking food webs

Running the activityCore: Pupils should create food webs from the information given, eventuallycombining each food web into a larger one.

Help: Pupils fill in the gaps on the food web template provided.

Expected outcomesBoth core and help pupils produce a food web.

PitfallsSome pupils will draw the arrows in the wrong direction in the food web. Theyshould be in the direction of energy flow.

ICT opportunitiesPupils could use a branching database program to create their food web.

AnswersCore:

1


Type Purpose DifferentiationPaper Pupils construct food webs from given information about animal feeding. Core, Help

Human

CowChicken

Grass Broccoli Beans PeppersGrain Carrots Potatoes

Humans

Blue tit

Caterpillar

GoosePheasant

Oak leaves

Help:

1

D-Teachers.qxd 07-Jun-04 12:35 PM Page 1

D1aActivity

CoreMaking food webs

Humans are part of lots of different food chains, which arelinked together as a food web.

1 Look at the meals onthe menu.

1 Make up a food webthat includes all thedifferent foods listed. (Hint: chickens eatgrain; cows eat grass.)

Sheet 1 of 1

Sheet 1 of 1


ActivityCoreD1a Making food webs


1 Look at the meals onthe menu.

1 Make up a food webthat includes all thedifferent foods listed. (Hint: chickens eatgrain; cows eat grass.)


Restaurant MenuRoast chicken

with potatoes, carrots and broccoli

Stir-fried beef with potatoes and beans

Peppers stuffed withminced beef, beans and broccoli

Restaurant MenuRoast chicken

with potatoes, carrots and broccoli

Stir-fried beef with potatoes and beans

Peppers stuffed withminced beef, beans and broccoli

D-Activities.qxd 07-Jun-04 12:32 PM Page 1

D1aActivity

HelpMaking food webs


1 Fill in the gaps in the food web based on what you can seehappening in the picture.


Humans

Oak leaves

Goose

Blue titPheasant

Caterpillar



D1bTeacher

activity notesWhere is starch stored?

Running the activityCore: Pupils test a range of food samples to see which contain starch. They should be aware thatstarch is the form in which glucose, a product of photosynthesis, is stored and is the basis formany other plant foods that we consume. Pupils need only small pieces of food and these can beprepared beforehand. The reaction of iodine with starch is rapid and gives an immediate blue-black colour if starch is present in the food. Warn pupils that iodine stains skin brown, and is verydifficult to wash off.

Extension: Pupils look at starch grains under the microscope, and draw a group of cells. Before theystart, explain the need for a sharp pencil, a large drawing, and a scale line or magnification. Somepupils may need reminding how to use the microscope properly. If the microscopes allow theobjectives to rack below the level of the slide, instruct pupils on their correct use so that they donot focus down and crack the slide.

EquipmentFor each group: � prepared slides of potato cells showing starch grains

� microscope

Other relevant materialSkill sheet 1: Using a microscope Skill sheet 9: Safety in the labSkill sheet 2: Magnification Skill sheet 10: Hazard symbols

Expected outcomesCore: Pupils will produce a table of results showing which of the sample foods contain starch.

Extension: Pupils will produce drawings showing the location of the starch grains.

PitfallsPupils may not put enough iodine on the food samples to see a visible colour change.

Safety notesWarn pupils not to taste anything in the lab. Ensure they take care using the scalpel or knife, andreplace the guard between uses. Tell pupils that iodine solution is harmful and will stain handsand clothing, and that they should wear eye protection. Ensure pupils carry microscopes with twohands, and that they do not use the microscope where direct sunlight may strike the mirror.

AnswersCore:

1 Contain starch: potato, carrot, turnip. Unlikely to contain starch: cabbage, celery, apple, grapefruit, onion.

2 If plants have surplus food, they may store it as starch for when they need it for respiration.They may also store food in seeds to help their offspring to grow.

3 As sugar or fat.

Extension:

1 If plants have surplus food, they may store it as starch for when they need it for respiration.They may also store food in seeds to help their offspring to grow.

2 Through the veins in the leaves and stem.

3 To attract animals to eat their fruit.

Type Purpose DifferentiationPractical Pupils identify parts of plants as stem, roots and leaves, test them for starch (core) and

examine slides of starch grains (extension)Core, Extension


D1bActivity

CoreWhere is starch stored?

In this activity, you are going to use iodine to test differentplants to find out which of them store starch.

Equipment

• samples of food: potato, celery, carrot, turnip, apple, grapefruit,cabbage, onion

• iodine solution and dropper• sharp scalpel or knife with guard• white tile

Obtaining evidence

1 Draw a table to record your results. It should have threecolumns, headed: ‘Food’, ‘Stem, root or leaf’ and ‘Starchpresent or absent’.

2 Place a sample of food on your white tile and chop it up intotiny pieces.

3 Carefully add one or two drops of iodine solution and note theresult in your table.

4 Repeat steps 2 and 3 for each of the samples of food.

Considering the evidence

1 Make two lists, showing those plant samples that do containstarch, and those samples that do not contain starch.

2 Why do some plants store starch?3 Some plants do not store food as starch. Suggest how these

plants may store their food.


The test for starch is to add iodine solution. If the food turnsblue/black, it contains starch.

Wear eyeprotection.

Do not tasteanything in the lab.

Take care using thescalpel or knife. Replacethe guard between uses.

Iodine solution isharmful and will stainyour hands and clothing.


D1bActivity

ExtensionWhere is starch stored?

You are going to look at prepared slides showing starch grainsinside cells.

Equipment

• prepared slides of potato cells showing starch grains• microscope

Obtaining evidence

1 Put the prepared slide of potato cells on the microscope stage.Use low power to focus on a group of cells.

2 Rotate the objective lenses to medium power and re-focususing the fine focusing knob.

3 Observe any areas that are stained blue–black with iodinesolution. Draw and label a group of three cells.

1 Give two reasons why plants store starch.2 Think about where food is made in the potato plant.

How does it get to the potato itself?3 Suggest one reason why some plants store food as sugar.


Do not use amicroscope

where direct sunlight may strikethe mirror.


D2aTeacher

activity notesWhat does fertiliser do?

Running the activityThe activity will take two weeks and should be revisited each lesson. The fertiliser solution should beprepared in advance. Decant 80 cm3 into 100 cm3 beakers before the first lesson. The beakers of duckweedshould be kept in a propagator to ensure constant growing conditions. Pupils set up the apparatus andthen record the number of duckweed plants every few days for the next two weeks.

Other relevant materialSkill sheet 5: Drawing charts and graphsSkill sheet 6: Interpreting graphsSkill sheet 9: Safety in the labSkill sheet 26: Designing a spreadsheetSkill sheet 27: Graphs with a spreadsheet

Expected outcomesCore: Pupils predict how fertiliser will affect growth rate, comparing a population of duckweed growing infertiliser with a control population. After two weeks, they will draw and interpret graphs to compare therate of change of population size.Help: Pupils predict how fertiliser will affect growth rate in the same way as core pupils, but choosing froma list of given predictions. They also monitor their populations over a period of two weeks, although theirconclusions will be based on the total numbers of duckweed plants at the end of the experiment, ratherthan drawing and interpreting graphs about growth rate.

PitfallsIf pupils do not monitor their populations often enough, their graphs of population change will bedifficult to interpret.

Safety notesWarn pupils to wear eye protection.The fertilisers should only be available as a solution for pupils to use.Nitrates may cause combustible materials to ignite, so avoid putting waste nitrates into the waste bins with paper towels or other combustible material.

ICT opportunitiesCore pupils could record their data and plot graphs using a spreadsheet program.

AnswersCore:

1 The population of duckweed will grow faster with fertiliser.2 The beaker with fertiliser.3 As a control to check that the fertiliser was actually having an effect.4 Growth would happen more quickly.

Help:

1 a Bb Fertiliser makes plants grow more quickly. Plants without fertiliser would probably grow a little anyway.

2 To let gases in and out (e.g. oxygen and carbon dioxide).3 As a control to check that the fertiliser was actually having an effect.4 Individual answers.5 There would have been more duckweed plants at the end of the experiment.


Type Purpose DifferentiationPractical Pupils look at the effect of fertiliser on the growth of duckweed. Core, Help


D2aTechnician

activity notesWhat does fertiliser do?

Other relevant materialSkill sheet 5: Drawing charts and graphs Skill sheet 26: Designing a spreadsheetSkill sheet 6: Interpreting graphs Skill sheet 27: Graphs with a spreadsheetSkill sheet 9: Safety in the lab

EquipmentFor each group:� 100 cm3 beaker containing 80 cm3 of fertiliser solution (see below) � 10 duckweed plants� 100 cm3 beaker containing 80 cm3 of deionised water (distilled � cling film

water can be used if deionised water is unavailable) � marker pen

For the class:� access to propagator

Duckweed can be obtained from most ponds and slow-moving streams, but it would be sensible tomaintain a stock of growing plants in the prep. room. You can use commercial fertiliser (make it upaccording to the manufacturer’s instructions) or you can make your own as follows.

Dissolve each of the solids below in 200 cm3 distilled water.

Ca(NO3)2.4H2O 4.00 g NaHCO3 3.18 gKH2PO4 2.48 g Na2HPO4.12H2O 7.20 gMgSO4.7H2O 10.00 g NaNO3 16.00 g

Mix together 1 cm3 of each solution in a 1 dm3 beaker.Make up to 1 dm3 with distilled water.

For your informationRunning the activityThe activity will take two weeks and should be revisited each lesson. The fertiliser solution should beprepared in advance. Decant 80 cm3 into 100 cm3 beakers before the first lesson. The beakers of duckweedshould be kept in a propagator to ensure constant growing conditions. Pupils set up the apparatus andthen record the number of duckweed plants every few days for the next two weeks.

Expected outcomesCore: Pupils predict how fertiliser will affect growth rate, comparing a population of duckweed growing infertiliser with a control population. After two weeks, they will draw and interpret graphs to compare therate of change of population size.

Help: Pupils predict how fertiliser will affect growth rate in the same way as core pupils, but choosing froma list of given predictions. They also monitor their populations over a period of two weeks, although theirconclusions will be based on the total numbers of duckweed plants at the end of the experiment, ratherthan drawing and interpreting graphs about growth rate.

PitfallsIf pupils do not monitor their populations often enough, their graphs of population change will bedifficult to interpret.

Safety notesWarn pupils to wear eye protection.The fertilisers should only be available as a solution for pupils to use.Nitrates may cause combustible materials to ignite, so avoid putting waste nitratesinto the waste bins with paper towels or other combustible material.Technicians should avoid skin contact with fertilisers, whether commercial or DIY andshould avoid raising or inhaling dust.


Type Purpose DifferentiationPractical Pupils look at the effect of fertiliser on the growth of duckweed. Core, Help

D-Technician.qxd 07-Jun-04 12:35 PM Page 1

D2aActivity

CoreWhat does fertiliser do?

Fertiliser is used to increase growth in plants. Duckweed is a smallplant that floats on the surface of ponds. It grows by dividing intotwo. In this activity you will investigate the effect of fertiliser on the growth of duckweed.

Equipment

• beaker of fertiliser solution • cling film• beaker of deionised water • marker pen• 10 duckweed plants • access to propagator

Predicting

1 Predict what you think will happen to the growth of duckweed with fertiliser compared with the growth of duckweed without fertiliser.

Obtaining evidence

1 Your teacher will give you a beaker containing fertiliser solution. Label the beaker with the date, what is in it, and the names of the people in your group.

2 Add five duckweed plants to the beaker.3 Cover the beaker with cling film. Make five small holes in the cling film with

the tip of your pen or pencil.4 Repeat steps 1–3 with another beaker containing deionised water instead of fertiliser.5 Place the beakers in a propagator.6 Every few days count the number of duckweed plants in each beaker. Record

your results in a table like this.

Presenting the results

7 After two weeks, use the data to draw two graphs showing how the population of duckweed changes in each beaker.


2 In which beaker did duckweed grow more quickly?3 Why did you grow duckweed in deionised water as well as in fertiliser?4 What do you think would happen if you increased the amount of fertiliser

dissolved in the beaker of water?


Time (days) Number of plants in Number of plants in fertiliser solution deionised water

Wear eyeprotection.

Wash yourhands afterhandling the

duckweed and thefertiliser solution.


D2aActivity

HelpWhat does fertiliser do?

Fertiliser is used to help plants grow. Duckweed is a smallplant that floats on the surface of ponds. It grows by dividinginto two. In this activity, you are going to look at how fertiliseraffects the growth of duckweed.

Equipment

• beaker of fertiliser solution• beaker of deionised water• 10 duckweed plants• cling film• marker pen• access to propagator

Predicting

You are going to grow some duckweed in a beaker of water withfertiliser and in a beaker of deionised water (without fertiliser).

1 Look at the three predictions (A–C) below and answerquestions a and b.

A The number of plants in the fertiliser will stay the same. Thenumber of plants in the water will increase.

B The number of plants in the fertiliser will increase very quickly.The number of plants in the water will increase very slowly.

C The number of plants in the fertiliser will increase. The numberof plants in the water will stay the same.

a My prediction is (write A, B or C) .

b I made this prediction because

.

Obtaining evidence

1 Your teacher will give you a beaker containing fertiliser solution.Label the beaker with the date, what is in it, and the names ofthe people in your group.

2 Add five duckweed plants to the beaker.3 Cover the beaker with cling film, and make five small holes in

the cling film with the tip of your pen or pencil.4 Repeat steps 1–3 with another beaker containing deionised

water instead of fertiliser.


Wear eyeprotection.

Wash yourhands afterhandling the

duckweed and thefertiliser solution.


D2aActivity

HelpWhat does fertiliser do? (continued)

5 Place the beakers in a propagator.6 Every few days count the number of duckweed plants in each

beaker. Record your results in the table below.


2 Why did you put holes in the cling film?

3 Why did you grow some duckweed without fertiliser?

4 Was your prediction correct?

5 What do you think would have happened to the number ofduckweed plants if you had put more fertiliser into thefertiliser beaker?


Time (days) Number of plants Number of plants in in fertilser solution deionised water


D2bTeacher

activity notesWhat is in fertiliser?

Running the activityYou will need to find some labels from fertilisers that provide a list ofconstituents, and the function of each nutrient in the plant. Fertiliser advertsthat list the deficiency symptoms for each nutrient would also be useful. If youhave trouble finding enough fertiliser labels, pupils could search on theInternet for information about fertilisers.

Other relevant materialSkill sheet 4: Web searches

PitfallsAvoid letting pupils spend an excessive amount of time on presentation.

Safety notesAll containers should be empty and free of fertiliser traces. Plastic containersshould be well rinsed.

ICT opportunitiesPupils could search the Internet for information about fertiliser.


Type Purpose DifferentiationPaper Pupils make an advert to encourage gardeners to use fertiliser. Core


D1aActivity

Core

Sheet 1 of 1

Sheet 1 of 1


ActivityCoreD2b What is in fertiliser?

You are going to make an advert to encourage gardeners to use fertiliser.

Equipment

• fertiliser labels

What to do

1 Look at the fertiliser labels and information you have been given.2 Decide on a name for your fertiliser.3 Design your advert to include:

a information about the nutrients in the fertiliserb an explanation of why nutrients are important to plant growthc information on how gardeners can work out which nutrients

their plants are lackingd instructions for using the fertiliser.


D2b What is in fertiliser?

You are going to make an advert to encourage gardeners to use fertiliser.

Equipment

• fertiliser labels

What to do

1 Look at the fertiliser labels and information you have been given.2 Decide on a name for your fertiliser.3 Design your advert to include:

a information about the nutrients in the fertiliserb an explanation of why nutrients are important to plant growthc information on how gardeners can work out which nutrients

their plants are lackingd instructions for using the fertiliser.


D3aTeacher

activity notesShould farmers control weeds?

Running the activityThe activity looks at the effect of weedkiller on reducing competition with cropplants. You may need to provide extra support for the calculations.

ICT opportunitiesA spreadsheet could be set up for the results and subsequent calculations.

AnswersCore:

1 Field A: 10 tonnes per hectare; Field B: 2 tonnes per hectare

2 Field A

3 a £14 000b £3500

4 She could employ people to dig up the weeds.

5 a 100 litresb £120

6 £10 500 (without allowing for cost of weedkiller)

7 Yes, because the weedkiller only cost her £120, whereas she made £10 500extra.


Type Purpose DifferentiationPaper Pupils analyse data about yield of crops, comparing situations in which farmers do and

do not control their weeds.Core


D3aActivity

CoreShould farmers control weeds?

Farmers need to balance the growth of crops against the cost of using weedkillers to control competition from weeds. You are going to look in more detail at the decisions a farmer must make when she uses weed killer.

Weedkillers are expensive, so Mary wants to check that using weedkiller is cost-effective. This means she wants to check that the money she spends on weedkiller is less than the extra money she may make from a bigger crop.

To test this idea, she decided to use weedkiller on one field of wheat (field A) but not on the other (field B). She measuredthe crop yield from each field. You can seethe results on her notepad.

1 Calculate the crop yield per hectare foreach field.

2 Did Mary get a better crop yield fromfield A or field B?

3 a How much money will Mary receivewhen she sells the wheat from field A?

b How much money will Mary receivewhen she sells the wheat from field B?

4 If she still did not want to useweedkillers, suggest another way thatMary could get rid of competition fromthe weeds.

5 a How many litres of weedkiller did Mary have to use on field A?b How much did this volume of weedkiller cost?

6 How much extra money did Mary make when you compare field A and field B?7 Is it cost-effective for Mary to use weedkiller? Explain why.


Kill those weeds!

SODIUM CHLORATEWeedkiller

Application rate:5 litres per hectare

Cut price!£ 1.20 per litre

doff

WWeeeeddkkiilllleerr eexxppeerriimmeenntt

Yield from field A = 200 tonnes

Yield from field B = 50 tonnes

Area of field A = 20 hectares

Area of field B = 25 hectares

Selling price of wheat = £70 pertonne


D3bTeacher

activity notesCompetition in duckweed

Running the activityCore: Pupils analyse a graph from a study of a duckweed population. Theyshould recognise the importance of quantitative data when they describe andexplain patterns of change within an ecosystem.

Help: Pupils look at two different pond scenarios and fill in a results table foreach, based on the time taken for the duckweed population to double in size.Pupils suggest and explain reasons for differential plant growth in two differentponds.

Other relevant materialSkill sheet 6: Interpreting graphsSkill sheet 18: Reading from graphs

ICT opportunitiesPupils could search the Internet for information about duckweed.

AnswersCore:

1 About 20 days

2 a Space to grow, light for photosynthesis, nutrients for healthy growth.Plants are NOT competing for water because there is plenty of it.

b Space, because they only have a limited surface area available to them.c They have plenty of space available, but may be competing with each

other and with the oak tree for light, water and minerals.

3 Because they are competing with each other for resources, there are notenough resources to keep any more plants alive.

4 Named herbivore

5 The population wouldn’t be able to grow much bigger because of the spaceconstraint. Some plants may die because of lack of resources.

Help:

1

2

3 Peter’s pond

4 A

5 Carbon dioxide, light, nutrients (not water because there is plenty in thepond)


Type Purpose DifferentiationPaper Core: Pupils interpret a graph of the results from a study of a duckweed population.

Help: Pupils examine competition in two simple pond scenarios.Core, Help

Number of plants in Peter’s pond

Start 5 days 10 days 15 days 20 days 25 days 30 days 35 days 40 days

10 20 40 80 160 320 640 1280 2560

Number of plants in Jane’s pond

Start 10 days 20 days 30 days 40 days

10 20 40 80 160


D3bActivity

CoreCompetition in duckweed

Adrian and Heather decided to study a population ofduckweed. They set up a beaker of pond water. At the start oftheir experiment, there was one duckweed plant on thesurface of the water. They counted the number of duckweedplants each day for 24 days.

1 Look at the graph. How long did it take for theduckweed population to reach its maximum size?

2 a List the resources for which the duckweed plantswere competing with each other.

b Which resource do you think the duckweed plantswere competing for the most? Explain your answer.

c Explain why your answer might have been differentfor a population of daisies growing under an oaktree.

3 Explain why the duckweed population reaches amaximum size, and does not carry on getting biggerand bigger.

4 What consumer do you think might also affect thesize of the duckweed population in a pond?

5 What might Adrian and Heather have seen if they hadcontinued the experiment for more than 24 days? Explainyour answer.


70

60

50

40

30

20

10

00 10 20 305 15 25

Num

ber

of p

lant

s

Time in days


Peter and Jane both have ponds. They are going to study how competition affects the growth of duckweed in each oftheir ponds.

Peter has just built his pond. He put 10 duckweed plants in thepond just after building it. There were no other plants in thepond. Duckweed grows very quickly. The number of plantsdoubles every five days.

1 Fill in the boxes to show how many plants Peter would haveafter 40 days. The first two have been done for you.

Jane has had a pond in her garden for two years. It alreadycontains lots of plants. Jane puts 10 duckweed plants into herpond. The duckweed grows more slowly. The number doublesevery 10 days.

2 Fill in the boxes to show how many plants Jane would haveafter 40 days. The first one has been done for you.

3 Which pond has more plants after 40 days?4 Which of these conclusions best explains the results?

A The plants in Jane’s pond had more competition forresources.

B The plants in Peter’s pond had more competition forresources.

C There is no difference in competition between the twoponds.

5 What are the ‘resources’ referred to in question 4?

Number of plants in Peter’s pond

Start 5 10 15 20 25 30 35 40 days days days days days days days days

10 20 40

D3bActivity

HelpCompetition in duckweed


Number of plants in Jane’s pond

Start 10 days 20 days 30 days 40 days

10 20


D4aTeacher

activity notesAre pesticides a problem?

Running the activityDivide the class into three groups: red, blue and green. Ensure there is a mix ofability in each group. Help the groups to identify two speakers and a secretary.It may be sensible to ensure each group has two outgoing individuals whowould be happy to speak in front of the class. You can give pupils the Resourcesheet or the Help sheet to help them prepare their ideas. If you use the Resourcesheet, ensure pupils also have access to the textbook.

Other relevant materialD4a ResourceSkill sheet 22: Writing frame: Debate

PitfallsYou may want to set quite definite time limits, and engineer your group sizes toensure that everyone participates. You may have more than one red, blue andgreen group.

ICT opportunitiesPupils could search the Internet for information on organic farming as a followup to the debate.


Type Purpose DifferentiationDiscussion Pupils take part in a debate about whether farmers should use pesticides to grow crops. Core, Help

Resource


D4aActivity

CoreAre pesticides a problem?

In this activity, you are going to look at what different peoplethink about using pesticides. You will be given a role to take ina debate with other members of the class. By the end of theactivity you should have your own opinion on whether weshould use pesticides to help grow crops.

What to do

Your teacher will put you into one of three groups.

• Red group: you will take the role of a worried shopper whodoesn’t want to eat food that might contain pesticides.

• Blue group: you will take the role of a farmer who wants touse pesticides to increase the amount of crops she can grow.

• Green group: you will take the role of an organic farmer whodoes not want to use pesticides on his farm.

Preparing for the debate

1 Look at the Resource sheet. Make a list of the arguments thatwould be taken by the person whose role you are going to play.

2 Using your list of arguments, and the textbook to help youexplain the science, prepare a short speech to make at thestart of the debate.

3 Choose two pupils to speak for your group in the debate.Choose someone as a secretary to make notes about thespeeches made by the other groups.

The debate

4 Your teacher will invite the first person from each group topresent their case. Your group’s secretary should make notesabout what the other groups say.

5 After each group has given their first speech, you will have fiveminutes to consider their arguments and to prepare a speechfor your second speaker. This should deal with and try tocounter the arguments made by the other groups. You can usethe Resource sheet again to help you clarify the points youneed to argue against.

6 The second speaker from each group will then give theirspeeches.



D4aActivity

HelpAre pesticides a problem?

This sheet provides more information to help preparethe speeches in the debate.

The sheet should be cut up and the parts given to the relevant group only.

Red group

You do your family’s weekly food shopping. You are worried that your fruit andvegetables may contain pesticides.

You know that pesticides are poisonous to insects, and you are worried that if you eatthem, even in small amounts, they may harm you and your family.

You don’t trust farmers because you feel they will tell you anything to make more moneyfrom their crops.

Although you want cheap food, you don’t want to eat poisons. You want to know howthe farmer can guarantee that pesticides are safe.

Blue group

You are a farmer who uses pesticides. You know they help you produce a big crop, sothat you make more money.

The food you produce also looks better as it does not have any signs of damage byinsects. You know that people like to buy nice-looking food.

Pesticides let you grow more crops in a field without worrying about attack from pests.

You only know what the chemical companies tell you about the pesticides. You think theyare safe. You have used them for years and you personally do not seem to have come toany harm. You would like to keep using them.

Green group

You are an organic farmer and you do not use any pesticides. Your crops do not alwayslook as good as the ones from farmers who use pesticides.

You know that pesticides kill useful insects as well as pests. You want to keep these usefulinsects on your farm. However, you have to grow your crops in small fields to stop pestsspreading.

You also know that pesticides can build up as you go up the food chain, and that thepesticides can often poison the animals at the top of the food chain.

Your crops will cost more because you need to hire more people to look after them.However, some people will pay more for your food because it does not contain pesticides.



D4aActivityResourceAre pesticides a problem?

Arguments

Decide which of these arguments you can use when preparing your speech for the debate.

• Pesticides are thought to be safe in very small amounts.• Some scientists think there is no safe level for pesticides.• Pesticides kill harmful insects.• Pesticides kill useful insects.• Pesticides may cause brain and nerve damage in humans.• Without the use of pesticides, food will be more expensive.• Pesticides are broken down very slowly and stay in our bodies for a long time.• Food produced without using pesticides does not look as nice.• Pesticides build up as you go up the food chain.• Without pesticides, farmers need to employ more labourers.• Organic farms have more birds, butterflies and other wildlife than farms

that use pesticides.• Pesticides let farmers produce more food so that few people will die of starvation.

Sheet 1 of 1

Sheet 1 of 1


ActivityResourceD4a Are pesticides a problem?


Arguments

Decide which of these arguments you can use when preparing your speech for the debate.

• Pesticides are thought to be safe in very small amounts.• Some scientists think there is no safe level for pesticides.• Pesticides kill harmful insects.• Pesticides kill useful insects.• Pesticides may cause brain and nerve damage in humans.• Without the use of pesticides, food will be more expensive.• Pesticides are broken down very slowly and stay in our bodies for a long time.• Food produced without using pesticides does not look as nice.• Pesticides build up as you go up the food chain.• Without pesticides, farmers need to employ more labourers.• Organic farms have more birds, butterflies and other wildlife than farms

that use pesticides.• Pesticides let farmers produce more food so that few people will die of starvation.


D4bTeacher

activity notesTrace the poison

Running the activityPupils should work individually on the activity.

Expected outcomesPupils should put one dot in each aphid, six dots in each blue tit and 18 dots inthe owl.

Answers1 owl

2 May be poisoned/become ill/die.

3 It was passed on through food chains and built up. Wildlife was beingendangered. It could have passed to humans, with toxic effects.

4 Natural pest control methods such as using ladybirds to eat the greenfly.


Type Purpose DifferentiationPaper Pupils use a pictorial representation to draw a conclusion. They use dots to show how

DDT passes through a food chain and appreciate that it accumulates.Core


D4bActivity

CoreTrace the poison

DDT is an insecticide. In the past, it was used to kill pests likeaphids on rose bushes. Small birds like blue tits ate the aphids,and birds of prey ate the blue tits. DDT is now banned inBritain. You are going to find out why.

The 18 black dots on the leaves in this diagram represent thenumber of DDT particles in the rosebush leaves.

1 Copy the food chain diagram above. Include the 18 dots.2 Divide the number of black dots by the number of aphids.

Draw the black dots on the aphids to show how much DDT ispassed on to each aphid.

3 Do the same with the blue tits and the owl.

1 Which organism has the most DDT in its body?2 What do you think might happen to the owl?3 Why do you think that DDT has been banned in Britain?4 Suggest a different way to control the aphids on rosebush

leaves.


The three blue tits areeaten by one owl.

All the aphids are eatenby three blue tits.

Lots of aphids feed onthe rosebush leaves.


D5aTeacher

activity notesLooking after grassland

Running the activityBegin with a class discussion on the management of wild flower meadows, and how to encourage the growthof different species. Pupils should work in groups of two or three, depending on the number of quadratsavailable. There is a Resource sheet to help with identification of the most common wild flowering plants.Core: Pupils count the wild flower plant species in two grassy areas. They are given instructions on theactivity sheet and some help with the results table.Extension: Pupils decide whether to measure diversity or quantity of wild flowers in two grassy areas. Theyhave to plan their investigation and devise their own table for recording their results.

Equipment

For each group:� 1 m2 quadrat � additional wild flower identification � clipboard sheets or books (optional)

Other relevant materialD5a ResourceWild flower reference booksSkill sheet 4: Web searches

Expected outcomesPupils follow instructions (core) or plan an investigation (extension) to measure the population of wildflowers in mown and unmown grassland.

PitfallsFinding suitable areas and identification of wild flowers might be a problem. There may be a meadownearby that can be visited, or perhaps one could be created in the school grounds.The mown and unmown areas should be fairly close to each other to ensure a fair test.Extension pupils will have difficulty counting some species and may need a rule for estimating (e.g. rare = 1plant in the quadrat; common = 2–6 plants in the quadrat; abundant = more than 6 plants in the quadrat).More able pupils might be prompted to estimate percentage cover, so they can apply a more quantitativeanalysis of their results.

Safety notesFollow the LEA and/or school policy on taking pupils out of school. Ensure adequate supervision. Visit thearea before the lesson to do a risk assessment.Allow hayfever sufferers to withdraw from the activity if necessary.Beware of nettle stings, insect bites and pupils handling poisonous plants, e.g. buttercup.Show pupils how to throw a quadrat safely.

ICT opportunitiesSearch the Internet using key words: wild flowers, meadows.

AnswersCore:

1 – 7 Individual responses

Extension:

1 – 7 Individual responses


Type Purpose DifferentiationPractical Pupils investigate whether wild flowers grow better in long grass or mown grass. Core, Extension

Resource


D5aActivity

CoreLooking after grassland

In this activity you are going to investigate whether wild flowers grow better in long grass or mown grass.

Predicting

1 Before you start, think about these ideas.

• Long healthy grass competes with the wild flower plants, so fewer wild plants will grow and they are less likely to flower.

• Mown grass is cut so often that the wild plants are cut down and will not flower.

1 Which of these ideas do you agree with?

Obtaining evidence

2 Take your 1 m2 quadrat to the area of long grass.3 Throw your quadrat randomly (so that it lands anywhere)

in the grass.4 Identify the plant types. Some of the plants may not be in

flower, so you will have to look carefully for the different leafshapes (see Resource sheet).

5 Count how many types of wild flower are growing inside thequadrat. Record your results in a table like this.

6 Repeat steps 2 to 5 until you have thrown the quadrat 10 times.7 Repeat the investigation in a similar sized area of nearby mown grass.


2 Which area had the most different types of wild flower?3 Use your results to explain whether your prediction was right or wrong.

Evaluating

4 Was your sample large enough to support your conclusion?5 What problems did you have with your investigation?6 Were the two areas of grass similar enough to compare?7 Are there any other key factors you should have taken into account

in your planning?


Take carewhenthrowing

your quadrat. Wash your handsafter completingthis activity.

Habitat type Quadrat number (1–10) Number of types(long or of wild flower short grass) plants


D5aActivity

ExtensionLooking after grassland

The success of wild flowers in grassy areas can be measured in two ways – the number of different types of wild flower plantsin an area (diversity) or how well they grow (quantity). In thisactivity you are going to investigate the success of wild flowersin long grass or mown grass.

Planning and predicting

1 Before you start, think about these ideas.

• Long healthy grass competes with the wild flower plants, sofewer wild plants will grow and they are less likely to flower.

• Mown grass is cut so often that the wild plants are cut downand will not flower.

1 Which of these ideas do you agree with?

2 Choose two suitable areas for your investigation.3 Select your apparatus and equipment. A 1 m2 quadrat is essential.4 Decide how many times you need to throw your quadrat to

sample each area.5 Decide what you are going to count in each quadrat. You may

want to count the number of wild flowers, the number of wild flower species or the number of grass plants.

6 Decide how you will record your results.7 Use the Resource sheet to help you identify the wild flowers.

You may need to look carefully at the leaves if the plant is not in flower.

Obtaining evidence

8 Ask your teacher to approve your plan, then carry out your investigation.9 Present your results in a suitable table.


2 Compare your results with your prediction.3 Write a conclusion based on your results. Decide which is the best

way to manage grassland for wild flowers.

Evaluating

4 Was your sample large enough to support your conclusion?5 What problems did you have with your investigation?6 Were the two areas of grass similar enough to compare?7 Are there any other key factors you should have taken into

account in your planning?


Take carewhenthrowing

your quadrat. Wash your handsafter completingthis activity.


D5aActivityResourceLooking after grassland

Common wild flowering plants




D1 PlenariesStoring food

Review learning� Ask ‘What am I?’ about particular food storage organs.

� Remind pupils they can only ask closed questions thatcan be answered yes or no.

� They have to determine the answer with as few questionsas possible.

Sharing responses� As a class, collate results and conclusions from

Activity D1b.

� Make sure pupils are clear which parts of plants storestarch.

Group feedback� In groups, pupils suggest ways to expand the food web

from Activity D1a to draw a larger food web.

Word game� Pupils write their own questions about the lesson’s key

topics to elicit specified answers.

� Give pupils the list of answers. Ask them to work in pairsto devise a question that would result in each of theanswers.

Looking ahead� Set the questions for individuals to consider and suggest

answers to.

� Then ask them to share their responses with other pupils.

� Make it clear that they may not know the answer andneed to suggest their ideas and predictions.

� Pupils can summarise the suggestions and record them intheir books, to reconsider after the next lesson.

Answers1 glucose; 2 water; 3 consumer;4 carnivore; 5 stem; 6 starch;7 lettuce → rabbit → human

Questions1 How do plants make more biomass?

2 Why do people grow plants ingreenhouses?

3 Why do gardeners use fertiliser?


Review learning

Play ‘What am I?’ aboutparticular food storageorgans in plants (e.g.carrots, onions).

Sharing responses

Collate results and conclusionsfrom Activity D1b.

Group feedback

In groups, pupils suggestways to expand the foodwebs from Activity D1a toproduce a larger food web.

Word game

Pupils write their ownquestions about the lesson’skey topics.

Looking ahead

Pupils consider how plantsmake more biomass.

D-Plenaries.qxd 18-Jun-04 11:56 AM Page 1


D2 PlenariesMake them grow

Review learning� Pupils select nine words from the list to write into their

bingo grid.

� Read out definitions from the teacher sheet in anyorder. Pupils match these to their chosen words. Thegame is over when a pupil can strike out a line.

� The ‘winning’ pupil has to recall the definitions of thewords as they read each one in the winning line to theclass.

Sharing responses� Pupils compare and discuss their predictions for Activity

D2a.

Group feedback� In groups, pupils look at each other’s adverts for

fertiliser, and evaluate them according to the criteriaopposite.

Word game� Pupils play ‘Pelmanism’ game to match nutrients with

deficiency symptoms.

� Pupils work in pairs. They place all the cards face down.They then take turns to turn two cards face up and lookat them. If they match (i.e. a nutrient and its deficiencysymptom), they keep the cards. If not, they turn themface down again in their original positions.

� Pupils need to remember where the cards are so thatthey can turn up a pair of a nutrient and its deficiencysymptom together later. The person with the mostcorrect pairs wins.

Looking ahead� Show pupils a photograph of the edge of woodland. As

a class, try to explain why the understorey plants are somuch taller outside of the woodland.

➔ Pupil sheet

➔ Teacher sheet

CriteriaDo they give information about nutrientsin fertiliser?Do they explain what the nutrients do?Do they explain the symptoms of nutrientdeficiencies?Do they contain instructions on how to usethe fertiliser?

➔ Pupil sheet

Correct matchesNitrogen – Grows slowly and has

small pale leavesPhosphorous – Purple leaves and

short roots and stemMagnesium – Yellow/brown leaves

and cannotphotosynthesise

Potassium – Leaf edges turnbrown; few flowersproduced

Water – Leaves start to wiltCarbon dioxide – Leaves start to fall offLight – Turns pale and grows

tall and spindly.



Review learning

Pupils play ‘Bingo’ tocheck understanding.

Sharing responses

Pupils compare anddiscuss their predictionsfor Activity D2a.

Group feedback

In groups, pupils lookat each other’s advertsfor fertiliser fromActivity D2b andevaluate them.

Word game

Pupils play ‘Pelmanism’game to match nutrientswith deficiency symptoms.

Looking ahead

Show pupils a photograph of the edge ofa woodland. Pupils try to explain whythe understorey plants are so muchhigher outside of the woodland. Catalyst Interactive Presentations 3



Review learning

Choose nine words from the list below and write them in the empty grid.

Cross out each word when you hear the teacher read out its definition. Shout bingo! when youhave crossed out a line of three words on the grid. The line can be across, down or diagonal.

Sheet 1 of 1

Sheet 1 of 1


PlenariesD2 Make them grow


application rate

deficiency symptomfertiliser

expensive

photosynthesis

nitrogen light

warm

carbon dioxidewilt

Review learning

Choose nine words from the list below and write them in the empty grid.

Cross out each word when you hear the teacher read out its definition. Shout bingo! when youhave crossed out a line of three words on the grid. The line can be across, down or diagonal.

application rate

deficiency symptomfertiliser

expensive

photosynthesis

nitrogen light

warm

carbon dioxidewilt




Review learningTeacher sheetRead out the definitions below in any order.

1 Why some farmers do not use fertiliser, but use manure instead. [expensive]

2 The amount of fertiliser to use. [application rate]

3 This gives plants extra nutrients. [fertiliser]

4 The process by which plants make their own food. [photosynthesis]

5 Indications that a plant is missing out on particular nutrients. [deficiency symptom]

6 What happens when a plant does not get enough water. [wilt]

7 If plants don’t get enough of this, they cannot make protein. [nitrogen]

8 If plants don’t get enough of this, they turn pale and grow tall and spindly. [light]

9 If plants don’t get enough of this, their leaves start to fall off. [carbon dioxide]

10 People close the windows of greenhouses at night to keep plants ... [warm]



Word game

Working with your partner, place all the cards face down.

Take turns to turn two cards face up and look at them. If they are a pair, which means that you have a nutrient and its deficiency symptom, you keep the cards. If they do not match, turn the cards face down again in the same position.

Remember where the cards are so that you can turn up a pair of cards with a nutrient and what happens if a plant does not get enough of it. The person with the most correct pairs wins.


NitrogenYellow/brown leaves and cannotphotosynthesise

Leaf edges turn brown; few flowersproduced

Grows slowly and has small paleleaves

Purple leaves and short roots andstem

Turns pale and grows tall and spindly

Leaves start to fall off

Leaves start to wilt

Phosphorous

Magnesium

Potassium

Water

Carbon dioxide

Light



D3 PlenariesCompeting plants

Review learning� Show and discuss pictures of a wood in spring and

summer. In the spring, the bluebells are in flower,whereas in the summer the canopy is full and the forestfloor is very bare.

� Ask pupils to explain the differences between the twopictures.

Sharing responses� As a class, check calculations and conclusions from

Activity D3a.

� Discuss with pupils how using fertiliser is cost-effective(in terms of money), but not necessarily in terms of theenvironment.

Group feedback� In groups (core and help), compare answers to questions

in Activity D3b.

� Discuss why the increase in growth of duckweedgradually tails off, by talking about competition forresource availability.

Word game� Ask ‘What am I?’ using the key words in the lesson.

� Remind pupils they can only ask closed questions thatcan be answered yes or no.

� They have to determine the answer with as fewquestions as possible.

Looking ahead� Ask pupils to list five species that they think compete

with humans for farmers’ crops.


Wordsweed; weedkiller; compete; yield; selective;organic; toxin

Answersrabbit; duck; goose; slug; snail; caterpillar;hare; pheasant; chicken


Review learning

Show and discuss the pictures of thewood in spring and summer. Catalyst Interactive Presentations 3.

Sharing responses

Collate results ofcalculations and conclusionsfrom Activity D3a.

Group feedback

In groups, pupils compareanswers to questions inActivity D3b.

Word game

Play ‘What am I?’about the key wordsin the lesson.

Looking ahead

Pupils list five otherspecies that compete withhumans for farmers’ crops.



D4 PlenariesWhat a pest!

Review learning� Pupils match words to their definitions, and descriptions to

explanations using the pupil sheet.

Sharing responses� As a class, share and collate responses to Activity D4a.

� After all the speeches, each pupil should decide which ofthe speakers they agree with: the shopper, the farmer or theorganic farmer.

� Take a show of hands to see which argument has won theday.

Group feedback� In groups, pupils sequence the cards, describing how toxins

build up in a food chain.

Word game� Pupils play ‘Taboo’ using cards cut out from the pupil sheet.

� Give one pupil a card with a mystery word on it. The pupiloffers clues to the class to allow them to identify themystery word, but is not allowed to use the given ‘taboo’words in their clues.

� You can adjust the level of challenge by banning the use ofjust the first word in the taboo list, or the first and secondwords, and then increase the number later.

Looking back� Pupils revise and consolidate knowledge from the unit.

They can use the Unit map, the Pupil checklist or theTest yourself questions.

➔ Pupil sheet

Answers1 Pest = Animal that competes with

humans for foodPesticide = Chemical that kills pestsInsecticide = Chemical that killsinsectsNon-selective insecticide = Aninsecticide that kills all insects

2 One species died out after usingweedkiller because it depended onweeds for food.

One animal population increased innumber after using a pesticidebecause the pests were no longercompeting for the animal’s food.

Farmers are paid to plant hedges togive nesting sites for birds.

➔ Pupil sheet

Answer2, 4, 1, 6, 3, 5

➔ Pupil sheet

➔ Unit map

➔ Pupil checklist

➔ Test yourself


Review learning

Pupils match words to theirdefinitions.

Sharing responses

Share and collate responsesto Activity D4a by votingon the debate.

Group feedback

In groups, pupils sequencethe cards, describing howbioaccumulation happens.

Word game

Pupils play ‘Taboo’ to reviewlearning.

Looking back

Pupils revise andconsolidate knowledge fromthe unit.



Review learning

1 Match each word to its definition.

2 Match each description to its explanation.


Pesticide

Pest

Insecticide

Non-selective insecticide

Chemical that kills insects

Animal that competes withhumans for food

An insecticide that kills all insects

Chemical that kills pests

One species died out after�

using weedkiller

One animal populationincreased in number after �

using a pesticide

Farmers are paid to plant �

hedges

�Because the pests were no longercompeting for the animal’s food

�To give nesting sites for birds

�Because it depended on the weeds for food




Group feedback

Cut up the sentences and put them in the correct order to explainhow toxins build up in a food chain.

11 The insecticide can’t be broken down, and is stored in the greenflies’bodies.

22 A gardener sprays his roses to get rid of greenfly.

33 Owls eat lots of blue tits, getting thousands of tiny doses ofinsecticide.

44 Most of the greenfly die, but some only absorb a little insecticide, and survive.

55 There are only a few owls at the top of the pyramid of numbers. Each owl gets many doses of insecticide. The build up of insecticidepoisons and kills the owl.

66 Blue tits eat a lot of greenfly, getting a tiny dose of insecticide fromeach one.


C1 Plenaries

Sheet 1 of 1

Sheet 1 of 1


PlenariesD4 What a pest!


D4 What a pest!

Word game

Pest

� insect� pesticide� mouse

TabooInsecticide

� insect� pesticide� weedkiller

Taboo

Toxin

� poison� accumulate� build up

TabooSelective Insecticide

� insect� pesticide� species

Taboo

Word game

Pest

� insect� pesticide� mouse

TabooInsecticide

� insect� pesticide� weedkiller

Taboo

Toxin

� poison� accumulate� build up

TabooSelective Insecticide

� insect� pesticide� species

Taboo



D5 PlenariesHow many? – Think about

Group feedback� Pupils feedback their conclusions about whether wild

flowers grow better in mown or unmown grass.

� Discuss pupils’ answers to the evaluation questions inthe activity, focussing particularly on whether thesample size was large enough to support theirconclusions.

Bridging to other topics� Pupils brainstorm three different professions that use

sampling in their everyday jobs.Ideasecologist; food quality control;microbiologist


Group feedback

Pupils discuss their conclusions andevaluations of Activity D5a.

Bridging to other topics

Pupils brainstorm three different professions that usesampling in their everyday jobs.


D1 SpecialsStoring food

1 Use words from the list to fill in the gaps. You mayneed to use each word once, more than once,or not at all.

a Plants make a food called . They

can turn it into which they can

store away.

b Plants store in their roots,

, leaves, and seeds.

c Plants store food to help them survive

and to help their grow.

2 Chickens eat seeds. Humans eat chickens.Write the names in this food chain.

3 Snails eat rotting leaves. Hedgehogs eat snails.Foxes eat hedgehogs. Complete this food chain.

rotting leaves →→ →→ →→

4 Slugs eat lettuces. Birds eat slugs. Cats eat birds.Complete this food chain.

→→ →→ birds →→


consumersstarch fruits glucose seeds

producers stems summer winter

D-Specials.qxd 07-Jun-04 1:54 PM Page 1

D1 SpecialsStoring food (continued)

5 Draw lines to match the words to descriptions.


Lots of food chains drawn together.

An animal that eatsplants or other animals.

An animal that eatsother animals.

consumer

carnivore

herbivore

Shows who eats who. The arrows show the

energy transfer.

An animal that eats only plants.

A plant that makes its ownfood by photosynthesis.

food chain

food web

producer


D2 SpecialsMake them grow

1 Look at this list of words.

a What do plants need for photosynthesis? Colourthem green.

b What gives a plant extra nutrients? Colour itblue.

c Which nutrient deficiency makes the leaves smalland yellow? Colour it yellow.

d What is an alternative to fertilizer? Colour it red.

2 Read through these sentences about thegreenhouse.

a Which are advantages about using a greenhouseto grow crops? Colour them green.

b Which are disadvantages about using agreenhouse to grow crops? Colour them red.


nitrogenfertilizer water oxygen manure

carbon dioxide glucose light potassium

Greenhouses areexpensive to

build and run.

Vegetables grownin greenhouseshave no flavour.

Equipment cango wrong.

Plants can begrown out of season,

e.g. strawberries in thewinter. The carbon dioxide,

light and water levelscan be kept just right.

Fruit and vegetablesgrown in them aremore expensive.

The temperature canbe kept just right

all year round.


D3 SpecialsCompeting plants

1 Here are some sentences about weeds.Draw lines to match the beginnings and endings.


Weeds are ...

Weedscompete with ...

Selectiveweedkillers kill ...

Organic farmersdon’t use ...

Killing one weed species in a food web can affect ...

... crops for water, light and nutrients.

... the rest of the food web.

... weeds not crops.

... artificial chemicals to kill weeds.

... plants that grow whereyou don’t want them.

2 Look at this listof features of plants.

a Colour the featuresthat help weedscompete for light inyellow.

b Colour the featuresthat help weedscompete for waterand nutrients in blue. long roots

short roots

roots spread out

roots notspread out

tall stem

short stem

nice smell

nice smell

bright flowers

green flowers

big leaves

small leaves

weed

crop plant

short rootsspread out roots tall stembig leaves

nice smell

long roots bright flowersshort stem

small leaves roots not

spread out


D4 SpecialsWhat a pest!

1 Draw lines to match the words to the descriptions.


pest

pesticide

A chemical that kills pests.

A chemical that kills any insect.

Any organism that feeds on crops.

A chemical that kills one kind of insect.

selectiveinsecticide

non-selectiveinsecticide

2 Write true or false for each sentence.

a Poisons build up in food chains and can kill organisms

at the top.

b Killing pests doesn’t harm the rest of the food web.

c Pests compete with humans for food when they eat

the crop. 3 Look at this food chain. The dots represent the amount

of pesticide inside the organism.

a Name the pest in this food chain.

b What organism is at the top of the food chain?

Underline the correct word to complete the sentences.

c The amount of pesticide in the organisms at the top of the foodchain is less than / the same as / more than at the bottom.

d If all the greenfly are killed, the number of ladybirds willgo down / go up / stay the same.

rose greenfly ladybird small bird large bird cat


D5 SpecialsHow many?

1 Look at this table. It shows the fish populations intwo sites. In site 1 there is an oil platform. In site 2there is no oil platform.


Estimated fish population

Site Oil 1988 1990 1992 1994 1996 platform?

1 yes 10 000 4000 2000 1500 1000

2 no 10 000 10 000 10 000 10 000 10 000

a Show this information as abar graph. The first barshave been drawn for you.

b Has the oil platform affected the fish population?

Underline the correct word tocomplete the sentences.

c I think this because the fishpopulation has gone down / gone up / stayed the same.

d The fish population in site 2 has gone down / gone up / stayed the same.

e What things could have affected the fishpopulation in site 1? Draw a circle round themin the list below.

0

1988 1990 1992Year

Estim

ated

fish

pop

ulat

ion

1994 1996site 1 site 2 site 1 site 2 site 1 site 2 site 1 site 2 site 1 site 2

1000

2000

3000

4000

5000

6000

7000

8000

9000

10 000

more foodmore predators

pollution killing them

fewer predators

more fish born

less food

fewer fish born


D1 Storing food1 a glucose, starch

b starch, fruits, stemsc winter, seeds

2 Order of words – seeds, chickens, humans.3 Order of words – rotting leaves, snails,

hedgehogs, foxes.4 Order of words – lettuces, slugs, birds, cats.5 food chain – Shows who eats who. The arrows

show the energy transfer.food web – Lots of food chains drawn together.producer – A plant that makes its own food byphotosynthesis.consumer – An animal that eats plants or otheranimals.carnivore – An animal that eats other animals.herbivore – An animal that eats only plants.

D2 Make them grow1 a Coloured green – water, carbon dioxide,

light.b Coloured blue – fertilizer.c Coloured yellow – nitrogen.d Coloured red – manure.

2 a Coloured green – Plants can be grown out ofseason, e.g. strawberries in the winter. Thecarbon dioxide, light and water levels can bekept just right. The temperature can be keptjust right all year round.

b Coloured red – Greenhouses are expensive tobuild and run. Vegetables grown ingreenhouses have no flavour. Equipment cango wrong. Fruit and vegetables grown inthem are more expensive.

D3 Competing plants1 Weeds are … plants that grow where you don’t

want them.Weeds compete with … crops for water, lightand nutrients.Selective weedkillers kill … weeds not crops.Organic farmers don’t use … artificial chemicalsto kill weeds.Killing one weed species in a food web canaffect … the rest of the food web.

2 a Coloured yellow – tall stem, big leaves.b Coloured in blue – spread out roots,

long roots.

D4 What a pest!1 pest – Any organism that feeds on crops.

pesticide – A chemical that kills pests.selective insecticide – A chemical that kills onekind of insect.non-selective insecticide – A chemical that killsany insect.

2 a trueb falsec true

3 a greenflyb catc more thand go down

D5 How many?1 a

b yesc gone downd stayed the samee Circled – pollution killing them, less fish

born, less food, more predators.

0

1988 1990 1992

Year

Estim

ated

fish

pop

ulat

ion

1994 1996Site 1 Site 2 Site 1 Site 2 Site 1 Site 2 Site 1 Site 2 Site 1 Site 2

1000

2000

3000

4000

5000

6000

7000

8000

9000

10 000

D Specials answersPlants for food


Spe Answers.qxd 6/23/2004 9:19 AM Page 4

D1 HomeworkStoring food

HELP

1 Plants can store chemical energy which humans often eat. Whereis the main energy store in each of the plants named below?

a tomato b parsnip c potato

2 Look at the drawing of the food web.

a Name two producers in the food web.

b Name two carnivores in the food web.

c Where did all the energy that transfers through the food weboriginally come from?

CORE

3 Eddy put some iodine solution onto different plants. The tableshows the results from Eddy’s tests.


Cabbage

Cabbage whitecaterpillar

Great titBlue tit

Peregrinefalcon

Garden pea

Pea weevil

Woodpigeon

Buzzard

Part of the plant Colour of the iodinesolution on the plant

Slice of potato Lots of blue-black

Cabbage leaf All pale brown

Carrot A little blue-black in patches

Piece of apple All pale brown

Inside of a piece of tomato All pale brown

D-Homework.qxd 07-Jun-04 2:01 PM Page 1

D1 HomeworkStoring food (continued)

a Which plants contain starch?

b i Which plant part, in the table, can photosynthesise?

ii What substance is made during the photosynthesis?

c Eddy leaves a potato in his shed, on the windowsill, andforgets about it for three months. When he checks it again ithas grown shoots and leaves. The potato has become smalland wrinkly. Suggest why it has become small and wrinkly.

d Potato leaves are poisonous to many animals, includinghumans. Why is this an advantage to the potato plant?

e Maize is an important food. It is used to feed chickens and tomake bread. Both humans and foxes eat chickens. Draw afood chain that contains maize, chickens, humans and foxes.

EXTENSION

4 Rhubarb grows in the spring and summer. In late autumn theleaves die and the large stems collapse. There is no sign of therhubarb plant, above ground, in the winter.

a i What two processes are happening in the rhubarb plant,during the summer?

ii Write a symbol equation for the process that is producingfood for the plant.

iii Rhubarb has very thick, long stems. Explain why it mustalso have very wide leaves.

b George grows rhubarb in a pot. He left some in his darkgarage for a week.

i What happens to the amount of glucose in the rhubarbstem, after a week in George’s garage?

ii Explain why this happens.



D2 HomeworkMake them grow

HELP

1 The boxes contain the names of things that plants need to grow well.

Match each word in the boxes to the function it has in the plant.

a Needed to make glucose during photosynthesis.

b Needed to make chlorophyll.

c The more there is the faster photosynthesis happens.

d Lack of this means the plant has small, weak roots.

e Without this the plant wilts and goes yellow.

2 Japanese Bonsai trees are specially grown to stay very small. They are put intosmall, shallow pots with very little soil. Their branches are pruned every fewweeks and their roots are cut back every two years. A full sized bonsai treemay only be 50 cm tall. Bonsai trees need to be in very good light and mustbe watered at least twice each week.

Copy and complete the following sentences.

a Bonsai trees must be watered more often than normal trees because … .

b Bonsai trees must get very good light because … .

c Growers must add fertiliser to bonsai tree pots regularly because … .

CORE

3 Tong’s Dad wants to plant some carrots in a patch of ground in their garden.The patch is under some trees, where it is quite dry and shaded. Tong hasnoticed that the plants in his garden grow better in some places than inothers. The ones under the trees are small and pale. Those in the flowerbedsin the middle of the lawn are taller and greener. Tong thinks that the plantsunder the trees do not do well because they are shaded and lack light. HisDad says that it will be fine if he waters them regularly. Tong tells his Dad thathe will do some experiments to see who is right.


carbon dioxide

phosphoruswater light

magnesiumnitrogen


D2 HomeworkMake them grow (continued)

a First Tong sets up an experiment to find out if light is important.

i Give two variables that Tong should control to make his experiment afair test.

ii Suggest one thing that Tong could measure.

iii Tong used just two plants in his experiment. Suggest what he shoulddo to improve the reliability of his results.

iv Why will this improve the reliability of his results?

b Next Tong investigates the need for water. He has two plants and watersthem both every day. He keeps everything else the same. They are awayfrom the light.

i Name the variable that Tong must change this time.

ii How much light should each plant get to make it a fair test?

iii One of Tong’s plants is nearer to the window than the other. Explainhow this will affect Tong’s plants.

c Neither of Tong’s sets of plants grow well. Say whether his Dad’s idea thatthe carrots will only need watering is a good idea or not and explain why.

EXTENSION

4 a Explain the following statements.

i Plants in greenhouses can be destroyed by disease faster than plantsgrown outdoors.

ii Plants grown in greenhouses are ready for harvesting before thosegrown outside.

iii Carbon dioxide is often pumped into greenhouses.

iv The soil in greenhouses needs more fertiliser than the soil outside.

b Farmer Green spreads fertiliser onto his grass. The fertiliser costs £2.50 perkilo and is usually applied at a rate of 10 kg per 100 square metres.

i How much will it cost Farmer Green to fertilise his 750 square metrefield? Show how you arrive at your answer.

ii Farmer Green also has a 400 square metre field that is in very poorcondition. He wants to double the amount of fertiliser that he spreads.How much will it cost him to do this?



D3 HomeworkCompeting plants

HELP

4 Weeds usually seem to grow faster than garden vegetables.The diagram shows some typical weeds and one vegetable.

Tom is trying to grow some carrots in his vegetable patch. Carrotsgrow best when they are about 10 cm apart.

a i Which weeds have roots that will compete most with the carrots?

ii Why will the carrots be affected by these weeds?

b i Which weeds have leaves that will compete most with the carrots?

ii Why will the carrots be affected by these weeds?

c i Suggest two ways in which Tom could control the weeds.

ii Which method will be cheapest for Tom?

CORE

2 The diagram shows part of a food web based ona field of cabbages, next to a wood.

a i Why would the farmer want to get rid ofthe grass and groundsel?

ii Suggest the quickest way that he coulddo this.


dandelion

10 cm

couch grass

15cm

15cm

A Bdaisy

5cm

C

carrot2cm

Dbuttercup

E

Cabbage

Caterpillar

Thrush

Groundsel

Starling Skylark

Grass

Sparrowhawk


D3 HomeworkCompeting plants (continued)

b i What would happen to the number of starlings andskylarks if both weeds were removed?

ii Why would this happen?

iii Why and how would this affect the number of thrushes?

iv Why would this affect the cabbages?

c An organic farmer might leave an unploughed strip all roundthe edge of the field. Explain why this might help to maintainthe food web in its original state.

EXTENSION

4 In some USA states the main agriculture is growing grain. This isdone in huge fields often up to a kilometre square. All the hedgeshave been ploughed up to create these fields. Vast amounts ofweedkiller are used to improve the grain yields. Vast amounts offertiliser are spread onto the soil every year. These farms are in apart of the USA that experiences high winds in most years.

a Explain why these USA farms do not use an organic farmingmethod to remove weeds.

b Why is artificial fertiliser so important for these fields?

c i Suggest what has happened to the number and range ofbird species in these parts of the USA, since such largefields were created.

ii Why has this happened?

iii The number of small, seed-eating rodents such as fieldmice has increased during the same period. Suggest whythis has happened.

d Since the large fields were created there has been a major lossof fertile topsoil in most years.

i Suggest a reason why this has occurred.

ii What will the farmers have to do now to prevent all thetopsoil from being removed?



D4 HomeworkWhat a pest!

HELP

1 The food chain shown below can be found in an orchard.

apple greenfly robin sparrowhawk

a i Which of the animals is a pest?

ii How can this pest be removed from the food chain?

iii How will the number of sparrowhawks be affected, if the pest is removed?

iv Why will this happen?

b Another way to remove the pest would be to add lots of ladybirds to the orchard.

i What do ladybirds eat?

ii If ladybirds are added the number of robins stays the same. What does this tell you about the diet of a robin?

c Organic fruit growers prefer to use ladybirds to control greenfly. Why do they prefer natural control to chemicals?

CORE

2 Slugs are a major pest in flower and vegetable gardens. They eat the leaves of many plants. Uncontrolled slugs can destroy whole crops overnight.

The food chain below happens in many vegetable gardens.

lettuces slugs hedgehogs

a Slugs can be prevented from reaching plants by spreading fire ash round the baseof the plants. The slugs cannot get a grip on the ash, so cannot reach the plants.

i What effect will using fire ash have on the plants in your own garden?

ii Your next door neighbours do not use any slug control in their garden. What is likely to happen to their plants, if you use fire ash in your garden?

iii Why is this likely to happen?

b Slugs can also be controlled by spreading ‘slug pellets’ around the garden. Slugs eat them and die. Slug pellets are toxic to hedgehogs.

i What will happen to the level of slug pellet chemical, inside hedgehogs, over a period of several months?

ii How will this affect the hedgehog population?



D4 HomeworkWhat a pest! (continued)

c A newer way to control slugs is to release a special worm, called a nematode, into the soil. The worm burrows into slugs and kills them but it does not affect hedgehogs.

Explain why using nematode worms to control slugs is better than using slug pellets.

EXTENSION

3 A food web found in many gardens is drawn below.

A non-selective insecticide is sprayed over the whole garden.

a i What will happen to thepopulation of swallows?

ii Explain why this wouldhappen.

b i How would using theinsecticide affect thepopulation of hedgehogs?

ii Explain your reasoning.

c Two pyramids of numbersthat can be found in thegarden are shown below.

Which pyramid of numbers was measured after the garden had been sprayed with a non-selective insecticide?

d i How will the population of thrushes be affected by the use of the insecticide?

ii How, if at all, will the insecticide build up in the bodies of the hawks?


Rose Lettuce

Slug

ThrushHedgehog

Greenfly

Ladybird Hoverfly

Swallow

Hawk

A B


D1Homework

mark schemeStoring food


HELPQuestion Answer Mark

1 a In the tomato/fruit. 1

b In the parsnip/root. 1

c In the potato/tuber. 1

2 a Cabbage; garden pea. 1 mark each. 2

b Two from: buzzard; peregrine falcon; great tit; blue tit. 2

c The Sun. 1

Total for Help 8

COREQuestion Answer Mark

3 a Potato; carrot. 1 mark each. 2

b i The cabbage leaf. 1

ii Glucose/oxygen. 1

c The starch stored in the potato has been used up 1by the shoots and leaves 1to grow/make new cells. 1

d It helps to stop animals eating the plant’s leaves, which are neededfor photosynthesis. 1

e Either: maize chickens foxesor: maize chickens humansor: bread chickens humansor: bread chickens foxesor: bread humans 2Award 1 mark if chain starts with a producer; award the second mark for a correct, complete food chain.

Total for Core 10

EXTENSIONQuestion Answer Mark

4 a i Photosynthesis; respiration. 2

ii 6CO2 + 6H2O C6H12O6 + 6O2 2Award 1 mark for correct formulae and 1 mark for correct balancing,whatever the formulae.

iii The stems contain a large food store 1so the leaves must be large to do the photosynthesis needed tomake the food store. 1

b i It decreases. 1

ii There is no light on the leaves so they cannot photosynthesise. 1

Total for Extension 8


D2Homework

mark schemeMake them grow



1 a Carbon dioxide and water. 1

b Magnesium 1

c Light 1

d Phosphorus 1

e Water 1

2 a Bonsai trees must be watered more often than normal trees because theirroots do not spread out over a large area of soil. 1Underscore is pupil response. Accept equivalent responses.

b Bonsai trees must get very good light because they do not have so manyleaves/such large leaves for photosynthesis as normal trees. 1Underscore is pupil response. Accept equivalent responses.

c Growers must add fertiliser to bonsai tree pots regularly because there isnot much soil so the nutrients are used up quickly. 1Underscore is pupil response. Accept equivalent responses.

Total for Help 8


3 a i Two points from: The amount of water; the amount of nutrients;temperature; draughts; amount of soil. 2

ii Height of the plant/biomass. 1

iii Use lots of plants. 1

iv It removes the possibility that a mistake in one plant will makethe conclusions wrong. Accept equivalent responses but not ‘It makes 1the results more accurate’.

b i The amount of water given to each plant. 1

ii The same amount for each plant. 1

iii It will get more light/grow faster/do more photosynthesis. 1

c Not a good idea because plants need both light and water to grow 1well/there will not be enough light/watering them regularly will notsolve all the problems. 1

Total for Core 10


4 a i They are much closer together; so disease is spread more easily. 1 + 1

ii It is warmer/they are specially treated so they grow faster. 1

iii It increases the rate of photosynthesis. 1

iv The plants are closer together so they remove the nutrients faster. 1

b i 750/100 × (2.50 × 10) 1= £187.50 1

ii 400/100 × (2.50 × 10 × 2) = £200.00 1



D3Homework

mark schemeCompeting plants



1 a i B and E. 2

ii Their roots spread over a large area of soil. 1

b i A, B and E. 3 correct = 2 marks; 1 or 2 correct = 1 mark. 2

ii The leaves will block out the light over a large area. 1

c i He could pull them out; he could use a weedkiller. 1

ii Pulling them out. 1

Total for Help 8


2 a i To stop it from competing with his cabbage plants. 1

ii Use a weedkiller. 1

b i Numbers would decrease. 1

ii There would be less/nothing for them to eat. 1

iii The sparrowhawks would eat more thrushes 1so the number of thrushes would decrease. 1

iv They would be eaten by more caterpillars. 1

c It would allow the weeds to grow 1so there would be food for the starlings and skylarks 1and the sparrowhawks would not have to eat so many thrushes/sothere would more thrushes to eat the caterpillars/so the cabbageswould not be so damaged. Accept similar correct statements. 1

Total for Core 10


4 a It would take too long/need too many people/cost too much. 1

b The crops are removing nutrients very quickly/the same nutrientsare being removed all the time. 1

c i They have decreased. 1

ii The availability of a range of food types 1has decreased. 1

iii There is plenty of grain for them to eat/they are not being caught by hawks. 1

d i It has been blown away by the wind. 1

ii Plant windbreaks/hedges. 1



D4Homework

mark schemeWhat a pest!



1 a i The greenfly. 1

ii By using an insecticide. 1

iii It would decrease. 1

iv There would be fewer robins to eat. 1

b i Greenfly 1

ii They also eat ladybirds. 1

c It prevents damage to the crops 1but does not put chemicals/poisons/toxins into the food chain. 1

Total for Help 8


2 a i They will be healthier/stronger/taller/more leafy 1because they will not be eaten by slugs. 1

ii They will be eaten by slugs more. 1

iii The slugs will have to go next door for food. 1

b i It will increase. 1

ii It will reduce it/some of them will die. 1

c It controls the pest 1but does not affect the rest of the food chain 1because it does not use toxic chemicals 1which can concentrate in other parts of the chain. 1

Total for Core 10


3 a i It will decrease. 1

ii There will be fewer insects for the swallows to eat. 1

b i It would not affect it. 1

ii The insecticide does not enter the hedgehog’s part of the food web. 1

c Pyramid B. 1

d i They will not be affected. 1

ii At first it will increase, as swallows are eaten. 1Then it will stop increasing/stay the same as the hawks have to eatthrushes instead. 1



D Test yourselfPlants for food

1 In the following list, cross out those substances that are not produced by photosynthesis.

oxygen glucosecarbon dioxide nitrateswater

2 Complete these sentences by crossing out the words that are wrong.

a A plant is an example of a producer/consumer.

b Animals that eat plants are called herbivores/carnivores.

c Starch turns green/black when iodine solution is added.

d Animals that eat other animals are called predators/prey.

3 a Complete the following food web by adding arrows to show the transfer of energy within the web.

b Write down two organisms in the food web that are competing with each other.


grass

cowrabbit

human milk

Test-Qust.qxd 6/25/2004 10:32 AM Page 11

D Test yourselfPlants for food (continued)


a Plant growth increases in the light/dark.

b Plant growth increases in the cold/warmth.

c Plant growth needs/does not need carbon dioxide.

d Plant growth needs/does not need nutrients.

e Plants growth needs/does not need water.

5 Plants need various nutrients to be healthy and grow well. Draw lines to match each nutrient with its function.

Nutrient Function

potassium � � helps to make roots

nitrogen � � helps to make protein

phosphorus � � helps to make chlorophyll

magnesium � � helps to make flowers

6 Complete the following sentences. Choose from the words below to fill the gaps. You may use each word once, more than once, or not at all.

Fertilisers are used by farmers to the yield of

their crops. Although fertilisers are for the farmer

to buy, the increase in yield will more than pay for the cost of the fertiliser.

Farmers need to know how much to use.

Too little will not increase the , and too much

will just be .

7 Draw in lines to match each process with the correct explanation.

Process Explanation

organic farming � � kills insects that use the crop for food

use of pesticide � � provides the crop with nutrients

use of weedkiller � � produces crops without using artificial chemicals

use of fertiliser � � kills plants that compete with the crop for resources


expensive fertiliser increase wasted yield


D Test yourselfPlants for food (continued)

8 Reshma is out walking. She finds a dead kestrel. It has been killed by pesticides. Which of the following statements is most likely to be correct?

A The kestrel ate some pesticide found on a farm.

B The kestrel was sprayed with insecticide by a farmer.

C The kestrel ate lots of small mammals that each contained a small amount of pesticide.

The correct answer is .

9 Richard and Jade are farmers. They know that the yield depends on how they plant the crops. Complete the paragraph by crossing out the wrong words.

Plants compete with each other for nutrients/soil that they need for growth. They also remove oxygen/carbon dioxide from the air. If Richard and Jade plant their crop too close together, the smaller plants will not be able to get enough light/sound and will not grow as well. In dry/wet weather, Richard and Jade must water/hoe their crop to ensure a good yield.

10 Look at the diagram of a farm food web.

The farmer decides to spray the crop with apesticide. Underline any statements belowthat are true.

� The number of carrot fly will increase.

� The number of small birds will increase.

� The number of rabbits will increase.

� The number of falcons will increase.


small bird

carrots

carrot fly

falcon

rabbit


DTest yourself

AnswersPlants for food

1 In the following list, cross out those substances that are not produced by photosynthesis.

oxygen glucosecarbon dioxide nitrateswater


a A plant is an example of a producer/consumer.

b Animals that eat plants are called herbivores/carnivores.

c Starch turns green/black when iodine solution is added.

d Animals that eat other animals are called predators/prey.

3 a Complete the following food web by adding arrows to show the transfer of energy within the web.

b Write down two organisms in the food web that are competing with each other.

rabbit and cow


grass

cowrabbit

human milk

Test-Ans.qxd 16-Jun-04 2:55 PM Page 11

DTest yourself

AnswersPlants for food (continued)


a Plant growth increases in the light/dark.

b Plant growth increases in the cold/warmth.

c Plant growth needs/does not need carbon dioxide.

d Plant growth needs/does not need nutrients.

e Plants growth needs/does not need water.

5 Plants need various nutrients to be healthy and grow well. Draw lines to match each nutrient with its function.

Nutrient Function

potassium � � helps to make roots

nitrogen � � helps to make protein

phosphorus � � helps to make chlorophyll

magnesium � � helps to make flowers

6 Complete the following sentences. Choose from the words below to fill the gaps. You may use each word once, more than once, or not at all.

Fertilisers are used by farmers to the yield of

their crops. Although fertilisers are for the farmer

to buy, the increase in yield will more than pay for the cost of the fertiliser.

Farmers need to know how much to use.

Too little will not increase the , and too much

will just be .

7 Draw in lines to match each process with the correct explanation.

Process Explanation

organic farming � � kills insects that use the crop for food

use of pesticide � � provides the crop with nutrients

use of weedkiller � � produces crops without using artificial chemicals

use of fertiliser � � kills plants that compete with the crop for resources

wasted

yield

fertiliser

expensive

increase


expensive fertiliser increase wasted yield


DTest yourself

AnswersPlants for food (continued)

8 Reshma is out walking. She finds a dead kestrel. It has been killed by pesticides. Which of the following statements is most likely to be correct?

A The kestrel ate some pesticide found on a farm.

B The kestrel was sprayed with insecticide by a farmer.

C The kestrel ate lots of small mammals that each contained a small amount of pesticide.

The correct answer is .

9 Richard and Jade are farmers. They know that the yield depends on how they plant the crops. Complete the paragraph by crossing out the wrong words.

Plants compete with each other for nutrients/soil that they need for growth. They also remove oxygen/carbon dioxide from the air. If Richard and Jade plant their crop too close together, the smaller plants will not be able to get enough light/sound and will not grow as well. In dry/wet weather, Richard and Jade must water/hoe their crop to ensure a good yield.

10 Look at the diagram of a farm food web.

The farmer decides to spray the crop with apesticide. Underline any statements belowthat are true.

� The number of carrot fly will increase.

� The number of small birds will increase.

� The number of rabbits will increase.

� The number of falcons will increase.

C


small bird

carrots

carrot fly

falcon

rabbit


DEnd of unit test

GreenPlants for food


1 Look at the list below. Which two conditions does a plant need to grow? 2 marks

A to be close to other plants D to be sprayed with pesticide

B enough sunlight E nutrients in the soil

C to be sprayed with weedkiller

2 Look at the list below. Which two of the following are nutrients obtainedfrom fertilisers? 2 marks

A carbon D soil

B nitrate E water

C phosphate

3 Jane is a farmer who grows wheat. Look at the food web for her farm.

a Identify two organisms that are competing withthe wheat for nutrients. 2 marks

b Name an organism that is a predator in the food web. 1 mark

c Name an organism that is prey in the food web. 1 mark

4 Complete these sentences:

Plants make their own food. They are

Animals cannot make food themselves. They are 2 marks

kestrel

small bird

wheat

mouse

dandelion

grass

D-F-EUTest.qxd 18-Jun-04 1:43 PM Page 1

DEnd of unit test

GreenPlants for food (continued)

5 Peter used fertilizer on some plants in his greenhouse.

He noticed this label on the bottle of fertiliser.

a Name one other mineral that plantsneed which is not mentioned on thisfertiliser label. 1 mark

b Give two reasons why Peter’s plants need nutrients. 2 marks

6 A farmer sprays his crop with a pesticide. The diagram shows a food webincluding the farmer’s crop.

a Explain how spraying with pesticide will increase the farmer’s crop yield. 1 mark

b After some months, the farmer notices that there are fewer finches flyingaround his farm. Suggest two reasons why this might be. 2 marks

c Greenfly reproduce much quicker than ladybirds. Suggest why there wasa massive increase in greenfly the following year. 1 mark

d The farmer decides to grow even more lettuce. Suggest what effect thiswill have on the population of foxes. 1 mark

7 A farmer sprays her crop with weedkiller.

a Give one resource for which the weeds compete with the crop plants. 1 mark

b Weedkiller can have unwanted effects on food webs. How else can weeds becontrolled so the balance between organisms is not destroyed? 1 mark


falcon

finch

fox

grass lettucerabbit

greenfly

ladybird

GROWALOT

Contains: nitrogen, phosphorus.


DEnd of unit test

GreenPlants for food (continued)

8 Daphnia are tiny water creatures, measuring 1 or 2 mm across. They can be kept incontainers of water, and will breed rapidly if fed.

Two daphnia were put into each of threebeakers of water. They were kept in thelaboratory and counted each week.

These are the results:

a i What factor (variable) is being changed in the experiment? 1 markii Name one other factor (variable) that should be kept constant

during the experiment. 1 markiii Which factor could be changed in Beaker A to increase the number

of daphnia? 1 mark

b Andrew predicted that more food would mean more daphnia. Do theresults in the table support his conclusion? Give a reason. 1 mark

c Describe the pattern of the population growth in Beaker A. 1 mark


Time in weeks Numbers of daphnia

Beaker A, 1 drop Beaker B, 2 drops Beaker C, 4 drops of food per week of food per week of food per week

0 2 2 2

1 4 5 7

2 7 16 28

3 12 29 102

4 12 51 0

5 12 59 0


DEnd of unit test

RedPlants for food


1 Complete these sentences:

Plants make their own food. They are

Animals cannot make food themselves. They are 2 marks

2 Peter used fertilizer on some plants in his greenhouse.

He noticed this label on the bottle of fertiliser.

a Name one other mineral that plantsneed which is not mentioned on thisfertiliser label. 1 mark

b Give two reasons why Peter’s plants need nutrients. 2 marks

3 A farmer sprays his crop with a pesticide. The diagram shows a food webincluding the farmer’s crop.

a Explain how spraying withpesticide will increase thefarmer’s crop yield. 1 mark

b After some months, the farmernotices that there are fewerfinches flying around his farm.Suggest two reasons why thismight be. 2 marks

c Greenfly reproduce muchquicker than ladybirds.Suggest why there was amassive increase in greenflythe following year. 1 mark

d The farmer decides to grow evenmore lettuce. Suggest what effect thiswill have on the population of foxes. 1 mark

e After several years of spraying, the farmer starts to find dead kestrels onhis farm. Explain why the pesticide has killed the kestrels even thoughit does not come into direct contact with them. 2 marks

GROWALOT

Contains: nitrogen, phosphorus.

falcon

finch

fox

grass lettucerabbit

greenfly

ladybird


DEnd of unit test

RedPlants for food (continued)

4 Look at the followingpyramids of numbers for organisms foundon a farm.

a Explain why there are fewer kestrels than wheat plants. 1 mark

b Explain why there are more greenfly than wheat plants. 1 mark

c Suggest why in poor countries, it would be better to grow wheat forfood, rather than feeding the wheat do chickens and eating them. 2 marks

5 An organic farmer grows lettuces on his farm. Each year, some of his cropof lettuces is eaten by caterpillars.

He decides to plant more hedgerows to encourage more wildlife.

After several years he notices that the hedgerow has provided a habitat formore birds and also more rabbit burrows.

Using the example given above, suggest why farmers often find it difficult toachieve a balance between the demands of different animal and plantcommunities within an environment such as a farm. 2 marks

6 Predicting what will happen in an environment isn’t alwaysstraightforward. Look at the food web for question 3. The farmersprays his crop of lettuces with pesticide to kill greenfly.

John said there would be no change in the number of foxes as a result ofthe spraying. Jane said there would be more foxes as a result of the spraying.

a Give a reason why John could be right. 1 mark

b Give a reason why Jane could be right. 1 mark

7 Daphnia are tiny water creatures, measuring 1 or 2 mm across. They can be kept incontainers of water, and will breed rapidly if fed.


kestrelmicewheat

finchgreenflywheat


DEnd of unit test

RedPlants for food (continued)

Two daphnia were put into each of three beakers of water.

They were kept in the laboratory and counted each week.

These are the results:

a i Andrew predicted that more food would mean more daphnia.Do the results in the table support his conclusion? Give a reason. 1 mark

ii What might have caused the pattern of population growth inBeaker C? 1 mark

b i Describe the pattern of the population growth in Beaker A. 1 markii What might have caused the pattern of population growth

in Beaker A? 1 markiii What experiment could be done to test whether this might

be true? 1 mark


Time in weeks Numbers of daphnia

Beaker A, 1 drop Beaker B, 2 drops Beaker C, 4 drops of food per week of food per week of food per week

0 2 2 2

1 4 5 7

2 7 16 28

3 12 29 102

4 12 51 0

5 12 59 0


DEnd of unit test

mark schemePlants for food


Green (NC Tier 3–6)Question Answer Mark Level

1 B or enough sunlight. 1 3E or nutrients in the soil. 1 3

2 B or nitrate. 1 4C or phosphate. 1 4

3 a Dandelion, grass. 1,1 4

b Kestrel 1 4

c Mouse 1 4

4 Producers 1 5Consumers 1 5

5 a Potassium or magnesium or correct alternative. 1 5

b Any two from: for growth; to make chlorophyll; to make protein;to make flowers; for roots. 2 5

6 a There will be fewer greenfly so more lettuce. 1 6

b There are fewer greenfly for finches to eat. 1 6There is more lettuce, so less grass grows for finches to eat. 1 6

c Ladybirds were killed by the pesticide and cannot reproduce fastenough to eat the greenfly. 1 6

d More food for rabbits so more food for foxes, so the number offoxes will increase. 1 6

7 a Any one from: light; nutrients; water; space. 1 5

b Hoeing or hand weeding. 1 5

8 a i Amount of food. 1 4ii Amount of water or temperature. 1 5iii More food or increase temperature. 1 5

b No, beaker C with most food drops to zero after 3 weeks. 1 6

c Increases and then levels off after 3 weeks. 1 6

Scores in the range of: NC Level

4–6 3

7–11 4

12–16 5

17–25 6


DEnd of unit test

mark schemePlants for food


Red (NC Tier 5–7*)Question Answer Mark Level

1 Producers 1 5Consumers 1 5

2 a Potassium or magnesium or correct alternative. 1 5

b Any two from: for growth; to make chlorophyll; tomake protein; to make flowers; for roots. 2 5

3 a There will be fewer greenfly so more lettuce. 1 6

b There are fewer greenfly for finches to eat. 1 6There is more lettuce, so less grass grows for finches to eat. 1 6

c Ladybirds were killed by the pesticide and cannotreproduce fast enough to eat the greenfly. 1 6

d More food for rabbits so more food for foxes,so the number of foxes will increase. 1 6

e Kestrels eat finches, which eat contaminated pests. 1 7Kestrels eat many finches so the pesticide builds up to lethal level. 1 7

4 a Not all the energy is transferred as you move up a food chain. 1 6

b Greenfly are smaller or have smaller biomass than wheat plants. 1 6

c Energy is lost when chickens eat wheat, so there 1 7is more energy in the wheat than in the chickens. 1 7

5 The farmer grows a hedgerow to encourage birds,which eat caterpillars. 1 7However, this also encourages rabbits,which eat the lettuce. 1 7

6 a Could be no change because rabbits and foxes do noteat greenfly. 1 7*

b Could be more foxes because more lettuce feed morerabbits which are eaten by foxes. 1 7*

7 a i No, Beaker C with most food drops to zero after three weeks. 1 6ii Any one from: overcrowding; disease;

lack of oxygen; pollution of water. 1 6

b i Increases and then levels off after three weeks. 1 6ii Enough food for 12 daphnia but no more. 1 7iii Add more food and see if numbers increase. 1 7

Scores in the range of: NC Level

5–9 5

10–14 6

15–18 7

19–25 7*


D Pupil checklistPlants for food


Learning outcomes I can do I can do I need to this very this quite do more well well work on this

I can describe how other animals compete with humans for their food crops.

I can use chemical tests to identify nutrients safely.

I can identify food storage organs in plants.

I can name some of the nutrients supplied by fertilisers.

I can identify conditions in which plants grow well.

I can identify factors that affect plant growth.

I can plan and carry out an investigation about growth, understanding the need to control variables, and select an appropriate sample size.

I can describe how weeds compete with crop plants.

I can explain why farmers use weedkillers.

I can describe how pesticides can affect animals in a food chain.

I can explain how toxic materials can build up in a food chain.

I can draw pyramids of number.

I can describe how energy is lost from a food chain at each feeding level.

I can describe how the population size of predators and prey can affect each other.

I can identify some animals that compete for crop plants with humans.

I can plan and carry out an investigation involving sampling.

I can present results using a variety of charts and graphs, and draw conclusions from them using scientific knowledge.

I can consider and evaluate conflicting evidence from different sources.

Pupil-Checklist.qxd 17-Jun-04 8:00 PM Page 4

D GlossaryPlants for food


Word

application rate R

compete

deficiency symptoms R

estimate

insecticide

non-selective

organic

pesticide

pests

selective

toxins R

weedkiller

weeds

Definition

Noticeable features of poor health or disease caused by a lack of certain nutrients. R

The amount of substance you need to apply to a given area. R

Plants that grow where you don’t want them to grow.

Try to get the same food sources or other resources as otherorganisms.

A chemical substance applied to weeds, that kills them.

Affecting some things and not others.

Not involving the use of manufactured chemicals.

Destructive insects or other animals that attack crops, food or livestock.

A chemical used on crops to kill insects or other pests.

A type of pesticide that kills insects.

Affecting everything. Non-selective insecticides kill all insects,not just the pests.

Poisonous substances that may cause death or serious injury. R

An informed guess, usually applied to numbers.

Glossary.qxd 18-Jun-04 11:33 AM Page 5

D Key wordsPlants for food

application rate R

compete


estimate

insecticide

non-selective

organic

pesticide

pests

selective

toxins R

weedkiller

weeds

Sheet 1 of 1

Sheet 1 of 1


Key wordsD Plants for food

application rate R

compete


estimate

insecticide

non-selective

organic

pesticide

pests

selective

toxins R

weedkiller

weeds


Keywords.qxd 18-Jun-04 11:35 AM Page 4


D Book answersPlants for food

D1 Storing foodGreena Biomass is the total mass of plant or animal

material, not including water.b Roots, stem, fruit, seeds.c Any of: humans, lions, tigers, cats, dogs, fish, or

any other carnivore.d Any of: cows, sheep, rabbits, chickens, ducks or

any other herbivore.1 Food web – you get this when you draw lots of

food chains together.Producer – this is a plant that catches lightenergy from the Sun.Consumer – this is an animal that eats otherliving things.Energy flow – the arrows in a food chain show this.

2 cereal plants → (any one of: cows, rabbits,chickens, pheasants, fish or ducks) → humansgrass → cows → humans water plants → (either fish or ducks) → humans

3 a Any three from: roots, stem, fruit or seeds.b They store food to use it at a later time when

they need it, to make the plants grow in thenext season and to make fruit taste nice.

Reda i potatoes

ii carrotsiii applesiv beans

b The winning vegetable may have had the largestmass because it contained more water, but waterdoes not make up biomass.

c Plants store food in their seeds so that the tinyplant inside has food when it starts to grow inspring. They store food in their fruit as sugar tomake it taste nice to animals. If an animal eatsthe fruit, it may carry the seeds inside to an areawith good conditions for growth.

d potatoes → humans; grass → cows → humans;cereal plants → humans

e rice, beans, potatoes, flour, carrots →humans ← cow ← grass

f The Sun is the energy source for the food web.1 a Any three from: roots, stems, fruit, seeds.

b They store food to use it at a later time whenthey need it, to make the plants grow in thenext season and to make fruit taste nice.

2 Why we save money Why plants store foodto keep spare money store extra food for usefor when it is needed in winterto bring up children store food in seed for

new plant in springsave money in bank surround stem of plantto keep it safe from with poisonous leavesrobbers

3 weeds → tadpoles → water beetles → pike; weeds → tadpoles → pike;

weeds → tadpoles → perch → pike; weeds →minnows → pike;weeds → minnows → perch → pike; weeds →minnows → water beetles → pike

D2 Make them growGreena photosynthesisb i The leaves fall off.

ii The plant wilts and dries out.c Crops grow for a longer season. Crops look good

and healthy. Fewer weeds grow to compete withthe crop. Fewer people are needed to look afterthe crop.

d Some people think the crops grown in agreenhouse don’t taste as good. It is expensiveto buy the greenhouse and the equipment.Because all plants are close together disease canspread easily.

e Nitrogen, phosphorus, potassium andmagnesium.

f The plant grows slowly and has small pale leaves.g The plant looks yellow or brown and cannot

photosynthesise well.1 Fertiliser – provides a plant with extra nutrients.

Nitrogen – helps a plant to grow.Light – needed for photosynthesis.Carbon dioxide – needed for photosynthesis.

2 a The plant is spindly with few leaves.b The stem and roots are short and the leaves

look purple.3 Individual answers.

Reda To photosynthesise and grow well, plants need the

right amount of light, water and carbon dioxide.b i The leaves fall off.

ii The plant is spindly with few leaves.iii The plant wilts and dries out.iv The plant dies.

c i Phosphorus helps make roots.ii Potassium is used to make flowers.

d i The plant grows slowly and has small paleleaves.

ii The plant looks yellow or brown and cannotphotosynthesise well.

e £8001 a To photosynthesise, to carry nutrients around

the plant and to keep the plant upright.b Magnesium helps to make chlorophyll.c Light is needed to photosynthesise.2 Plants need carbon dioxide to get into the

greenhouse for the plants to photosynthesiseand for oxygen to get into the greenhouse atnight for respiration.

3 Individual answers.

Book Answers.qxd 18-Jun-04 12:44 PM Page 9


D Book answersPlants for food (continued)

D3 Competing plantsGreena Weeds are plants that grow where you don’t

want them to grow.b Weeds grow tall to catch the light before it

reaches the plants below.c Long and widely spread roots help the weeds get

water before other plants can.d Weeds reduce the amount of crops produced.e It would take too many people and be too

expensive to weed by hand.f The fat hen plants would be killed.g They would decrease.h Sugar beet plants.1 Weedkiller is good because it gets rid of weeds.

Weedkillers are selective otherwise they wouldkill the crop as well.Weedkiller gets rid of plants that compete forlight and resources.Weedkiller can affect food webs in anunexpected way.

2 a They reduce the amount of weeds andincrease the amount of crop.

b They can affect food webs in ways that areharmful to some birds and animals.

3 If a weedkiller kills weeds that an animal feedson, the numbers of these kind of animals willdecrease.

Reda They grow tall to catch the light and they grow

very long roots to reach water and nutrientsbefore other plants can.

b garden – wheatfarm – wild oats

c It would take too many people and be tooexpensive to weed by hand.

d The fat hen plants would be killed.e They would decrease.f Sugar beet plants.g They would decrease.1 a They grow taller and have longer root systems.

b They get more sunshine having broader leaves.2 a Advantages are that it doesn’t upset food

webs and rotating crops provides habitats formore different animals.

b Disadvantages are that more people areemployed on an organic farm to make thefarm run properly and the produce becomesmore expensive.

3 Individual answers.

D4 What a pest!Greena Field mice and sparrows.b A pesticide will kill all pests. An insecticide will

kill only pests which are insects.

c The numbers of insects would decrease.d cats1 a sawflies

b There was less food for the pheasants, sosome of them died.

c The pheasants that humans eat have eatenmany sawflies, each containing a smallamount of insecticide. Also, when humanseat barley, they eat much more in quantitythan would a sawfly.

2 A selective insecticide only kills insects whichare pests. A non-selective insecticide will kill allinsects, whether they are pests or not.

Reda Field mice and sparrows.b A non-selective insecticide.c It would decrease.d There is less food for the bluetits so some will die.e Encourage ladybirds into the garden.1 a Any organisms that feed on farmers’ crops

are called pests.b They feed on farmers’ crops and compete

directly with humans for food.c Food webs can be affected.

2 A selective insecticide will only kill insects thatare pests. A non-selective insecticide will kill allinsects whether they are pests or not.

3 a The concentration of a toxin increases as yougo along the food chain.

b Toxins are dangerous in food webs becausethey build up in food chains and poisonorganisms at the top of the food chain.

D5 How many?Greena 100b 50c 1:10d 50e 500f Site 1:1988 – 10000; 1990 – 2170; 1992 – 1390;

1994 – 1040; 1996 – 1000.Site 2: 1988 – 10000; 1990 – 10000; 1992 –10000; 1994 –10000; 1996 – 10000.

g

h Yes.

Year

Site 112000

14000

10000

8000

6000

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01988 1990 1992 1994 1996

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Year

Site 212000

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01988 1990 1992 1994 1996

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D Book answersPlants for food (continued)

1 To make it a fair test.2 Any two from: a change in the amount of

fishing that went on; the amount of foodavailable for the fish changing; disease amongstthe fish.

Reda 1:10b 50:500c i 5:50

ii 50:500iii 500

d Site 1: 1988 – 10000; 1990 – 2170; 1992 – 1390;1994 – 1040; 1996 – 1000.Site 2: 1988 – 10000; 1990 – 10000; 1992 –10000; 1994 –10000; 1996 – 10000.

e

Year

Site 112000

14000

10000

8000

6000

4000

2000

01988 1990 1992 1994 1996

Estim

ated

pop

ulat

ion

of fi

sh

Year

Site 212000

14000

10000

8000

6000

4000

2000

01988 1990 1992 1994 1996

Estim

ated

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sh

f In order of bullet points in the diary: it wouldhave made fewer marked snails recovered; thenumber of snails recovered would be fewer; thesmaller shape of the trap would catch fewersnails; the recovery of painted snails would beincreased if they hadn’t mixed thoroughly withall of the others; the difference in distribution ofwhere snails go could have increased ordecreased the number recovered.

1 To make it a fair test.2 Any two from: a change in the amount of

fishing that went on; the amount of foodavailable for the fish changing; disease amongstthe fish.

3 They should take samples of water at each sitevisit and measure and record the pH of thewater.


Documents

D Plants for food Unit guide - Physicslocker 3/Unit D.pdfD Plants for food Unit guide Where this unit fits in Prior learning This unit builds on:unit 8D Ecological relationships and