10489 9c p092 127 - Wikispacesmnwikiks3yr3.wikispaces.com/file/view/Plants+and+photosynthesis... · An experiment was done to see how the amount of starch in some leaves changed during

92 © Pearson Education Limited 2002Exploring Science for QCA Copymaster File 9

Page 1 of 2

9Ca

1 Where does photosynthesis occur in a rose bush?

A in all the parts

B in parts R and S only

C in part R only

D in part Q only

2 Plants often turn some of the food theymake into another substance for storage.The name of this substance is:

A glucose. B starch.

C fibre. D pasta.

3 Which of these shows the correct wordequation for photosynthesis?

A glucose + carbon dioxide → water + oxygen (+ energy)

B glucose (+ energy) → oxygen + glycerol

C water + carbon dioxide (+ energy) → glucose + oxygen

D chlorophyll + carbon dioxide → water + glycogen

4 Aerobic respiration is a process which:

A stores chemical energy in food.

B makes food for plants living underwater.

C does not happen in plants but only inhumans when they exercise hard.

D releases energy from food.

9Cb

1 Leaves are often wide so that they can:

A absorb as much sunlight as possible.

B catch as much rain as possible.

C provide shelter for animals livingunder them.

D float to the ground when they drop in autumn.

On your answer sheet, write in or circle the correct letter for each question.

9

C

9C Quick Quiz

2 Gases get into and out of a leaf by:

A diffusion. B absorption.

C conduction. D convection.

3 Look at this list of substances.

glucose fat cellulose protein

Which of these substances can plants make?

A glucose and cellulose only

B glucose, cellulose and fat

C glucose, cellulose and protein

D all of them

4 Plants need cellulose to:

A store energy.

B repair damaged cells.

C make cell walls.

D make cell surface membranes.

9Cc

1 The picture shows a cell from a root. What is it called?

A xylem cell B root cortex cell

C root palisade cell D root hair cell

2 If plants do not get enough water theystart to:

A shrink.

B grow towards the light.

C grow bigger roots.

D wilt.

3 One important type of mineral salt is:

A nitrate. B sodium chloride.

C clay. D loam.

4 Water is carried up a plant in xylem tubes.What else do xylem tubes carry?

A glucose B fibre

C mineral salts D pollen

P

RS

Q

Page 2 of 2


9C Quick Quiz (continued)

9

C

9Cd

1 The atmosphere is about:

A 80% oxygen and 20% nitrogen.

B 80% nitrogen and 20% oxygen.

C 80% carbon dioxide and 20% oxygen.

D 80% oxygen and 20% carbon dioxide.

2 Look at these chemical processes.

photosynthesis respirationburning fuels

Which of these processes add carbondioxide to the air?

A respiration and burning

B respiration only

C photosynthesis and respiration

D burning only

3 Plants are important in keeping theatmosphere in balance because:

A they use up oxygen.

B they use up carbon dioxide.

C they provide food for animals andhumans.

D they use water.

4 Which of these would not be adisadvantage of cutting down forests?

A Logging companies could make moreprofits.

B There would be fewer trees to keep theatmosphere in balance.

C Some species might become extinct.

D Floods might wash away the soil.


9C Target Sheet

Topic Targets Before the unit I have learned this I have revised this9Ca 1 Know where photosynthesis occurs.

2 Know how plants store the food they make.

3 Know the word equation for photosynthesis.

4 Know what aerobic respiration is and where it occurs

9Cb 1 Know how leaves are adapted to the job they do.

2 Know how gases get into and out of leaves.

3 Know what the products of photosynthesis are used to make.

4 Know why plants need the different substances they make from glucose.

9Cc 1 Know how roots are adapted to the job they do.

2 Know why plants need water.

3 Know some of the mineral salts needed by plants.

4 Know how substances are transported around a plant.

9Cd 1 Know which gases form the atmosphere.

2 Know which processes add carbon dioxide to the atmosphere.

3 Know why plants are important in keeping the atmosphere in balance.

4 Understand some consequences of clearing forests.

9

C

Name Class

Page 1 of 2


9C Word Sheets

9

C

Word sheets that include new words from the ‘Focus on:’ pages are available on theExploring Science website.

Word Pronunciation Meaning

aerobic respiration air-O-bick Chemical reaction that releases energy from glucose. It uses up oxygen and produces res-per-ay-shun carbon dioxide and water.

biomass The mass of material (except water) that makes up an organism.

chlorophyll klor-O-fill Green substance found inside chloroplasts. It absorbs light.

glucose Type of sugar made during photosynthesis.

photosynthesis foto-sinth-e-sis Chemical reaction that plants use to make their own food. It needs light to work.Carbon dioxide and water are the reactants and glucose and oxygen are the products.

raw material Something used up in a chemical reaction. Also called a reactant.

reactant Something used up in a chemical reaction. Also called a raw material.

phloem tube flow-em Tube made from chains of living phloem cells. Carries glucose and other solublesubstances up and down the plant.

product Something made in a chemical reaction.

starch Insoluble carbohydrate made from glucose and used as a storage material in plants.

word equation Simple way of showing what happens in a chemical reaction.

9Ca – A light reaction/Plants respire too


adapted When something has a particular shape to help it do a function (job). A root hair cellhas a shape that helps it absorb water and is said to be ‘adapted to its function’.

amino acids am-mee-no ass-ids The building blocks of proteins.

biomass The mass of material (except water) that makes up an organism.

cellulose A substance used to make cell walls.

chlorophyll klor-O-fill Green substance found inside chloroplasts. It absorbs light.

chloroplast klor-O-plast Green disc containing chlorophyll. Found in plant cells. Where glucose is made by photosynthesis.

diffusion dif-few-shun The random movement of particles from where there are a lot of them to where thereare fewer of them.

fat Substance needed by living things to make cell membranes. Our bodies also use fats asa store of energy and to keep warm.

function Something’s job.

guard cells Cells which open and close the stomata.

mineral salt Chemical found in soil that plants need to grow healthily.

nitrate night-rate Mineral salt that plants need to make proteins.

oil Liquid fat, often found in nuts and seeds.

palisade cells pall-iss-aid Cells found in leaves, containing many chloroplasts.

protein A substance made from amino acids. Proteins are needed for growth and repair.

starch Insoluble carbohydrate made from glucose and used as a storage material in plants.

stoma stO-ma Singular of stomata.

stomata stom-mart-a Small holes on the underside of leaves which let gases into and out of the leaf.

9Cb – Leafy adaptations/Sugary food


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9

C

9C Word Sheets (continued)


global warming The process of the Earth’s atmosphere warming up. It is partly caused by an increase incarbon dioxide in the air.

methane The gas that is ‘natural gas’. Also formed in large amounts in the digestive systems of cows. Methane absorbs heat and so helps global warming.

9Cd – A changing atmosphere


absorb Soak up.

function Something’s job.

mineral salt Chemical found in soil that plants need for healthy growth.

nitrate night-rate Mineral salt that plants need to make proteins.

phloem tube flow-em Tube made from chains of living phloem cells. Carries glucose and other solublesubstances up and down the plant.

root hair cell Cell found in roots. The root hair has a large surface area to help the cell absorb waterquickly.

wilting When a plant does not have enough water and droops.

xylem tubes zy-lem Tube made from chains of dead, hollow xylem cells. Carries water and dissolvedmineral salts up a plant.

9Cc – The root of the matter

Page 1 of 3


9C End of Unit Test

Name Class

9

C

1 The drawing shows a bean seedling.

a Why is the plant not growing straight up?

[1 mark]

b The roots have a number of functions. Tick the two functions of roots.

Absorb carbon dioxide from the air.

Absorb glucose from soil.

Make food for the plant.

Absorb water and mineral salts from the soil.

Hold the plant in the soil.

Make seeds for new plants to grow.

[1 mark]

c What are the names of the parts marked ‘X’ in the drawing?

[1 mark]

d Explain how these parts help the root to work efficiently.

[1 mark]

2 Here is a diagram of a palisade cell.

a Where, in a leaf, would you expect to find palisade cells?

[1 mark]

b What is the name of the part where photosynthesis occurs?

[1 mark]

c What substance does this part contain?

[1 mark]

X

LIGHT

3 Complete the word equation for photosynthesis:

+ water (+ energy) → glucose + .

[2 marks]

4 The drawing shows Marimo weed. This organism forms into a ball which fills with a gas during the day and floats in the water.

a What gas produced by the plant fills the weed balls?

[1 mark]

b On some days the weed balls float higher in the water. On other days they are

lower in the water. What makes the balls float?

[1 mark]

c Explain why the weed balls float higher on a sunny day.

[2 marks]

5 This experiment was set up.

Hydrogencarbonate indicator is red in tap water. It becomes purple if the waterloses carbon dioxide. It becomes yellow if the water gains more carbon dioxide.

a What colour would you expect the indicator to be in Tube A after two days?

[1 mark]

b Explain your answer to part a.

[2 marks]

Elodea pondweed

water containing hydrogencarbonate indicator

Tube A kept in darkness.

Tube B kept in the light.


Page 2 of 3

9C End of Unit Test (continued)

9

C

6 Glucose can be turnedinto starch in the leavesand stored. When it isneeded, the starch isturned back intoglucose. An experimentwas done to see howthe amount of starch insome leaves changedduring a week. Theresults are shown in thegraph. 0 1 noonnoon noon noon

Day

Am

ou

nt

of

star

chco

nta

ined

in

lea

ves

noon noon noon2 43 5 6 7

a Explain why the amount of starch in the leaves increases and then decreases,every 24 hours.

[1 mark]

b Glucose can also be used to make proteins. Which substance is also needed tomake proteins? Tick the correct box.

potassium salts phosphates calcium salts nitrates

[1 mark]

c Apart from starch and proteins, name one other substance that a plant can makefrom glucose.

[1 mark]

7 a What is the name of the process that releases energy from food?

[1 mark]

b Where does this process happen in plants and other living organisms?

[1 mark]

c In plants, at which times of day does this process happen?

[1 mark]

d Complete the word equation for this process.

+ oxygen → + water (+ energy)

[2 marks]

Page 3 of 3


9C End of Unit Test (continued)

9

C


Page 1 of 2

9C Summary Sheets

9

C

PhotosynthesisThis is a chemical reaction and so can be written as a word equation:

Light energy and chlorophyll are needed for photosynthesis to happen. The lightenergy is changed into chemical energy which is stored in the glucose that is made.

Getting the waterWater is taken out of the soil bythe roots. Roots are branched andspread out to help them absorbwater from a large volume of soil.They also have root hair cellswhich are adapted to theirfunction – they have a largesurface area to help them absorbwater quickly. The water flows upxylem tubes (made of hollowcells) to the leaf.

Water is also needed because mineral salts are dissolved in it, which are needed tokeep plants healthy. Water also stops plants wilting and can keep their leaves cool.

Getting the carbon dioxideAir, containing carbon dioxide,diffuses into leaves through small holes called stomata. Leaves are thin so that the carbon dioxide does not need to go very far before reaching the cells that need it.Photosynthesis can often bespeeded up by increasing theamount of carbon dioxide around a plant.

soil

Many root hair cellsgrouped together formroot hair tissue.

roothair

xylem tube

water and minerals

water + carbon dioxide (+ light energy) glucose + oxygen

reactants (light is not a substance productsand so is not a reactant)

cuticle guard cellstoma

spongy cells

lower epidermis

phloem tubes carry food

xylem tubes carry water

palisade cell

upper epidermis

chloroplast

cuticle

vein

Plants and photosynthesis

Getting the lightMany leaves are wide so that they have a big surface area to trap as much sunlight aspossible. Most photosynthesis happens in the palisade cells which are found near theupper surface of leaves. Palisade cells are packed with chloroplasts. Chloroplastscontain chlorophyll which absorbs light energy. Photosynthesis can often be speededup by increasing the amount of light.

RespirationPlant cells release the energy stored in glucose using aerobic respiration (another chemical reaction):

glucose + oxygen carbon dioxide + water (+ energy)

All living cells need energy and so all living cells respire. Respiration happens all thetime but photosynthesis can only happen when there is light.

Uses of glucoseGlucose is a type of sugar. It is used for three things:

� respiration� making other substances that act as stores of energy (eg starch)� making new materials for growth.

Glucose is turned into cellulose (for cell walls), fats and proteins. To make proteins,mineral salts called nitrates are needed.

New substances made by a plant are carried around the plant in phloem tubes. Newsubstances help to build up a plant’s biomass (the mass of all the materials in theplant except water).

Page 2 of 2


9C Summary Sheets (continued)

9

C

Question Level Answers Mark scheme

1 3 a Plant shoots grow towards light. 1 mark

3 b Absorb water and mineral salts from the soil; hold 1 mark – �� mark for each.the plant in the soil.

4 c root hairs/root hair cells 1 mark7 d They have a large surface area to help absorb 1 mark

water.

2 6 a upper part of leaves 1 mark6 b chloroplast 1 mark7 c chlorophyll 1 mark

3 5 carbon dioxide; oxygen 2 marks

4 5 a oxygen 1 mark6 b more gas in the balls 1 mark6 c Higher temperature/more light increases the 2 marks – 1 mark for each point. Accept higher temperature

speed of photosynthesis; so more oxygen is causes the gases in the balls to expand.produced.

5 5 a yellow 1 mark6 b The weed is respiring which gives out 2 marks – 1 mark for each point

carbon dioxide; it is not photosynthesising which would use up carbon dioxide.

6 7 a Starch is made during daylight from glucose 2 marks – 1 mark for each pointby photosynthesis; it is used up at night by respiration.

EP b nitrates 1 mark8 c fats/cellulose/sucrose 1 mark

7 5 a respiration 1 mark6 b in all cells 1 mark6 c at all times 1 mark6 d glucose, carbon dioxide 2 marks – 1 mark for each substance

End of Unit Test marks

9C

53Exploring Science for QCA Teacher’s Guide 9 © Pearson Education Limited 2003

9C Mark schemes

Question Answers Marks

Topic 1 2 3 4

9Ca C B C D 4

9Cb A A D C 4

9Cc D D A C 4

9Cd B A B A 4

Quick Quiz

Level Marks Cumulative Suggested available total threshold for

achieving level

3 2 2 2

4 1 3 3

5 5 8 6

6 11 19 14

7 4 23 21

8 1 24 Insufficient marks to justify level

EP 1 25 Insufficient marks to justify level

Matching End of Unit Test marks to NC levels


Page 1 of 2

9Ca/1 Measuring photosynthesis 1

Name Class

9

C

a

You are going to try to find out how light affects the amount of photosynthesis.

PredictionRead the instructions and then complete the sentence below.

I think the gas will collect fastest when the light is

(further away from the beaker/closest to the beaker).

Method

1 Measure 1 cm from the end of the funnel and make a mark.

2 Set up the apparatus but do not put the bung in yet. Make sure the waterlevel is above the top of the funnel.

3 Place the lamp 10 cm away from the beaker. Wait for two minutes and then put in the bung and start the stopclock.

4 Stop the stopclock when the gas bubbles have filled the end of the funnel down to your mark. Write down how long this took in seconds.

5 Repeat steps 2 and 3 at various distances between the lamp and the beaker. Write down which distances you choose.

PApparatus� Elodea pondweed � Glass funnel � Lamp� Large beaker � Marker pen � Narrow bung� Pondwater � Ruler � Stopclock

bungmark, 1 cm from the end

bubble of gas

water

funnel

pondweed

Recording your resultsFill in this table with your results.

Distance between lamp and beaker (cm) Time it took for end of funnel to fill with gas (s)

Page 2 of 2



(continued)

9

C

a

Considering your results/conclusionsDraw a line graph to show your results.

What gas collected in the

syringe?

What was the relationshipbetween the distance of the lamp (to the beaker) and the amount of time it took to fill the end of the funnel?

The closer the lamp was to

the beaker,

EvaluationThere is a problem with this experiment. The lamp will give out heat which may heatup the water and give you a false result.

How do you think having hotter water affects the results?

Why do you think this?

Try to think of a way of stopping the lamp heating up the water.

Distance between lamp and beaker (cm)

Tim

e it

took f

or

end

of

fun

nel

to

fil

l w

ith

gas

(s)

planning, observing, considering, evaluatingS



9

C

a

You need to try to find out how different variables (or factors) affect the amount ofphotosynthesis in some pondweed.

Planning

1 Variables: what could you change that might affect how fast photosynthesis occurs?

� The amount of light (light intensity) can be altered using a lamp.� Extra carbon dioxide can be put into the water by adding sodium

hydrogencarbonate.� Water baths can be set to different temperatures.

2 Choose one or two variables to test. � How will you change them? How many times will you change them?� What will you measure? Can you find a way of measuring how much gas is

produced by the pondweed?� How long will you run the experiment for?� What apparatus will you need and how will you set it up?

3 Fair test: you should only change one variable at a time. Write down all thevariables you will keep the same.

4 Prediction: write down what you think will happen. Use your scientific knowledgeto explain why you think this will happen. You will need to know aboutphotosynthesis.

5 How will you make this a safe investigation?

6 Show your plan to your teacher before you begin.

planningS


9Ca/3 Leaves and photosynthesis

9

C

a

test tubeof ethanol

hot water

beaker

gauze

tripod

leaves

beaker

waterleaves

gauze

tripod

Bunsen burner

Is light needed for photosynthesis? – Instruction Sheet

Method

1 Take two leaves, one which has been in the light and one which has been inthe dark. Cut the end off the one that has been in the dark, so you canremember which is which.

2 Place both leaves in a beaker of boilingwater for one minute.

3 Turn off the Bunsen burner. Wait until youare told to continue.

4 Half fill a boiling tube with ethanol. Placethe two leaves in it using forceps. Placethe test tube in the beaker of hot waterand leave it for five minutes.

5 Take the leaves out of the test tube andwash them with tap water.

P

6 Place the leaves on a Petri dish and add 5drops of iodine solution to each leaf. If ablue-black colour appears, then there isstarch in the leaf. Starch is only made in aleaf when photosynthesis has happened.

�• Ethanol catches fire very

easily. Do not put itanywhere near a lightedBunsen burner.

• Take care with the Bunsenburner, the beaker and thewater. They get very hot.

• Take care when boilingwater. Wear eye protection.

Apparatus� Leaves for testing – one that has been in the light and one that has been in

the dark� Iodine solution � Pipette � Scissors� Bunsen burner � Ethanol � Tripod� Large beaker � Gauze � Boiling tube� Heatproof mat � Test tube holder � Eye protection� Forceps � Petri dish


9Ca/4 Leaves for photosynthesis 1

9

C

a

Name Class

Is light needed for photosynthesis?

You will need the instruction sheet 9Ca/3 Leaves and photosynthesis.

PredictionTick the box next to the sentence that says what you think will happen.

Both leaves will go blue-black because both leaves have been photosynthesising.

Only the leaf that had been in the dark will go blue-black because photosynthesishappens in the dark.Only the leaf that had been in the light will go blue-black because photosynthesishappens in the light.

Recording your resultsDescribe in your own words what happened.

Considering your results/conclusion

What substance goes blue-black when iodine is added to it?

What process makes this substance?

What colour did the leaf that had been in the dark go when iodine solution was

added?

What colour did the leaf that had been in the light go when iodine solution was

added?

Which of these sentences is true? Tick the right one.

Starch is made in leaves that are photosynthesising. Photosynthesis only happensin the light.Starch is made in leaves that are photosynthesising. Photosynthesis only happensin the dark.Starch is made in leaves that are not photosynthesising. Photosynthesis only happens in the light.Starch is made in leaves that are not photosynthesising. Photosynthesis only happens in the dark.

knowledge, observing, consideringS


9Ca/5 Leaves for photosynthesis 2

9

C

a

Is light needed for photosynthesis? Is chlorophyll needed forphotosynthesis?

knowledge, observing, consideringS

You will need the instruction sheet 9Ca/3 Leaves and photosynthesis.

Prediction

1 Which leaf do you think will have starch in it? Explain why you think this.

Recording your results

2 Write down what happened. What colours did each leaf go when iodine solutionwas added? Did all of the parts of the leaves change colour?

Considering your results/conclusions

3 If you add iodine solution and a blue-black colour appears, what substance is present?

4 What process produces this substance?

5 Which parts of which leaf do you think had been photosynthesising? Why do you think this?

6 Write down whether you think light is needed for photosynthesis and why youthink this.

7 If you have used a variegated leaf write down whether you think chlorophyll isneeded for photosynthesis and why you think this.


9Ca/6 Respiration andphotosynthesis 1

9

C

a

knowledgeS

1 Copy and complete these word equations.

a Photosynthesis:

carbon dioxide + (+ light energy) → + glucose

b Aerobic respiration:

oxygen + → + water (+ )

2 Scientists can find out aboutphotosynthesis by measuring theconcentration of different gasesnear plants. This graph shows theconcentration of carbon dioxide inthe air around an oak tree during aday in May.

a Which process in a plant uses up carbon dioxide?

b When do you think carbon dioxide was being used up by the tree?

c At which times of the day do you think that the light was brightest?Explain your answer.

d What does this tell you about the process that uses up carbon dioxide?

3 It is known that photosynthesisgets faster if there is more light.It is also known thatphotosynthesis gets faster ifthere is more carbon dioxide.This experiment was set up tosee if this was also true forplants that grow under water.

a What gas did the bubbles contain?

Write down whether each of the following changes would make the numberof bubbles go up or down. Explain your reasoning.

b The light bulb was moved further away.

c Why do you think this?

d Extra carbon dioxide was dissolved in the water.

e Why do you think this?

?

0 2 4 6 8 10 12 14 16 18 20 22 24

Time of day (hours)

noon

Am

ou

nt

of

carb

on

dio

xid

e

bubbles of gas

pondweed


9Ca/7 Respiration andphotosynthesis 2

9

C

a

Scientists can find out about photosynthesisby measuring the concentration of differentgases near plants. This graph shows theconcentration of carbon dioxide in the airaround an oak tree during a day in May.

Joseph Priestley (1733–1804) did some experiments similar to these to show that airwas changed by plants and animals. Some bell jars are set up with plants inside. Aftera week the air from the bell jars is used to see if a candle will burn for more or lesstime than in a bell jar of normal air.

knowledgeS

soda lime

1 For each bell jar (A–E) write down whether a lighted candle would burn formore or less time than in a bell jar of normal air. Explain your reasoning ineach case.

2 The air inside one of the bell jars allows a candle to burn for longer than theothers. Which one? Explain your reasoning.

3 A leaf was taken from each plant, boiled with ethanol and tested with iodine solution.

a What is being tested for?

b Describe what you would see when iodine solution was added to eachleaf. In each case explain why you think this would happen.

?

This bell jar was placedunder a lamp for a week.



This bell jar was placed inthe dark for a week.


A B C D E

0 2 4 6 8 10 12 14 16 18 20 22 24

Time of day (hours)

noon

Am

ou

nt

of

carb

on

dio

xid

e

4 a Which process in a plant uses up carbon dioxide?

b Write a word equation for this process.

c Explain why the concentration of carbon dioxide varies as shown in thegraph.

d Make a copy of the graph, and add another line to show how you thinkthe concentration of oxygen in the air around the tree would change overthe same time. Explain the shape of your line.

?


9Ca/8 Biological symbolequations

9

C

a

Every chemical can be represented by a chemical formula which uses symbols andnumbers. The symbols show the different atoms and the numbers show how manyatoms there are. For example, water has two hydrogen atoms and one oxygen atomand so its formula is H2O. These formulae can be used to write symbol equations.The reaction between hydrogen and oxygen to make water can be shown like this:

However, the symbol equation needs to have the same number of each type of atomon each side. At the moment there is only one oxygen atom on the right but two onthe left. We add numbers at the start of each chemical formula to balance the numberof atoms on each side of the equation.

This is now a balanced symbol equation which shows that two molecules ofhydrogen react with one molecule of oxygen to form two molecules of water.

H2 + O2 → H2O

We need to have these as H2 and O2because they exist as molecules of two

atoms joined to each other.

2H2 + O2 → 2H2O

1 a Write down the formula for carbon dioxide.

b How many carbon atoms are there in a molecule of carbon dioxide?

c How many oxygen atoms are there?

d How many oxygen atoms are there in a molecule of water?

2 a Write down the word equation for photosynthesis (leave out the ‘energy’ bit).

b The formula for glucose is C6H12O6. Write down a balanced symbolequation for photosynthesis. (Hint: Don’t put a number in front of theglucose formula.)

3 The formula for starch is (C6H12O6)n, where ‘n’ means a large number. Theformula in the brackets tells you what sort of molecules there are a largenumber of.

a What molecules are there a large number of in starch?

b Write down a balanced symbol equation for how starch is made.

4 Starch is usually broken down again into small molecules which are used torelease energy in cells.

a What process releases energy in cells?

b Write down its word equation (leave out the ‘energy’ bit).

c Write down its balanced symbol equation.

?

literacy, knowledgeS


9Ca/9 Gas exchange in anoak tree

9

C

a

An experiment was done to measure the amount of carbon dioxide diffusing into anoak tree on a partially cloudy day in May. The experiment was done over 18 hoursand the results are shown in the graph below.

knowledge, considering, numeracyS

1 The units for the amount of carbon dioxide that diffuses into the leaves isgiven as cm3/m2/min – that is cm3 of carbon dioxide per m2 of leaf area perminute. How much carbon dioxide was diffusing into the plant at:

a 14:00 hrs b 09:00 hrs?

2 a The line is below 0 cm3/m2/min for the first part of the day. Explain whatthis tells you.

b What process causes this to happen?

c What time do you think dawn was? Explain your answer.

3 a The time at which there is no overall diffusion of carbon dioxide into orout of the tree is called the compensation point. At what time did thecompensation point occur?

4 For each part of this question, explain your answer. How would the time ofthe compensation point change if:

a the skies were clear b it was partially cloudy but colder

c it was the middle of winter? (Be careful!)

5 a What was the maximum rate of diffusion of carbon dioxide into the leaf?

b The whole tree had leaves with a total surface area of 50 m2. How muchcarbon dioxide would have diffused into the tree in 12 hours if the diffusionstayed at its maximum rate? Show your working. Give your answer in cm3.

c There are 1000 cm3 in 1 litre. Write down the answer to part b in litres.

d One litre of carbon dioxide has a mass of 1.8 g. Write down your answer topart c in kilograms of carbon dioxide.

6 Sketch a graph to show what you would expect to find if the amount ofdiffusion of oxygen into the leaves had been measured instead.

?

Time of day

Am

ou

nt

of

carb

on

dio

xid

e d

iffu

sin

g in

to t

he

oak

tre

e (c

m3/m

2/m

in)

00:0

0

0

5

10

15

20

25

30

–5

–10

01

:00

02

:00

03

:00

04

:00

05

:00

06

:00

07

:00

08

:00

09

:00

10:0

0

11

:00

12

:00

13

:00

14

:00

15

:00

16

:00

17

:00

18

:00


9Cb/1 Leafy matters 1

Name Class

9

C

b

knowledge, literacyS

1 This diagram shows part of a leaf.

Fill in the labels on the diagram using words from the box.?

spongy cell

stoma

air space cuticle guard cell palisade cell

carbon dioxide cells chloroplasts heat holes large

light losing night oxygen small stomata waterproof

2 Fill in the gaps in these sentences using words from the box. You may needeach word once, more than once, or not at all.

The cuticle is a layer that stops the leaf too

much water. The palisade cells have lots of to

absorb energy to make photosynthesis happen. Leaves have

a surface area so they can absorb a lot of energy.

Cells in the leaf need to absorb from the air. Air gets

into the leaf through in the bottom surface called .

Guard can close the stomata at to stop the leaf

water.

3 Some of the glucose made in photosynthesis is used to make new materials forthe plant. Match up the materials with their uses.

Amino acids A store of energy in some seeds and special organs likepotatoes.

Cellulose Energy stores found in some nuts.

Fats Used to make proteins.

Oils Used to make cell walls.

Starch Used in cell surface membranes.


9Cb/2 Leafy matters 2

9

C

b

1. The drawing shows a slice through a leaf. ?


D

GC

A

E

B F

P

Q

a What are the names of the parts labelled A–G? Use these words to help you:air space, chloroplast, cuticle, guard cell, palisade cell, spongy cell, stoma.

b Water vapour is lost from leaves. Arrow P shows water vapour leaving thecells. What is the name of this process?

c Arrow Q shows the water vapour escaping from the leaf. What is the nameof this process?

2 a In which cells does most photosynthesis happen?

b How are these cells adapted to carry out photosynthesis?

c Where are these cells located in a leaf?

d Why do you think they are in this position?

3 Suggest a reason for each of these observations:

a Leaves have a large surface area.

b Leaves are thin.

c Leaves often grow in such a way that they do not shade one another.

d Stomata are shut at night.

4 a Name three types of substance that a plant makes using glucose.

b What is each type of substance used for?


Page 1 of 2

9Cb/3 Discovering photosynthesis

9

C

b

In the 17th century it was believed that everything was made up of four elements –earth, fire, water and air. Plants were believed to be made from fire and earth. Jean-Baptiste van Helmont (1579–1644) did an experiment to show that this was wrong.

Van Helmont said that his experiment showed that a plant could not be made fromearth because the mass of the soil decreased only a little bit but the mass of the willowtree increased a lot. He said that the extra mass of the tree must be made from water.

In 1771, Joseph Priestley did an experiment which showed that plants produced a gas inwhich a candle would burn. He called this ‘dephlogisticated air’ (dee-floj-jiss-tick-ay-ted).

Priestley said that after a while the candle hadproduced so much ‘fixed air’ that it went out.

The candle could now burn again. Priestley saidthis was because the plant had changed the ‘fixedair’ into ‘dephlogisticated’ air during the week

one week later→

In 1754, Charles Bonnet had shown that bubbles were produced by leaves placedunderwater. He said that this was due to dissolved air in the water sticking to theleaves. However, in 1779, Jan Ingenhousz showed that leaves placed underwaterproduced bubbles of ‘dephlogisticated air’ but only when the Sun was shining. He alsoshowed that only the green parts of plants would do this.

Later in 1782, Jean Senebier showed that ‘fixed air’ contained carbon dioxide and that itwas used up by the plant. During this time the idea that mass was conserved in reactionswas put forward. In 1804, Theodore de Saussure found that the mass of carbon dioxideused up by a plant was not enough to account for the increase in mass of the plant.Since the only other thing needed to keep the plant alive was water, he suggested thatboth carbon dioxide and water were changed by the plant into new material.

willow tree(mass = 76.74 kg)

mass of pot + dry soil = 90.66 kg

mass of pot + dry soil = 90.72 kg

small willow tree(mass = 2.27 kg)

5 years

watered regularly

Page 2 of 2


9Cb/3 Discovering photosynthesis

(continued)

9

C

b

1 a Write down the word equation for photosynthesis.

b Which substances are the reactants?

c Which scientist showed that light was needed for photosynthesis to happen?

d What observation led him to develop this theory?

2 a What is the modern word for the gas produced by the candle to make‘fixed air’?

b What is the modern word for the gas produced by the plant to make‘dephlogisticated air’?

3 a Suggest how Ingenhousz may have collected a sample of ‘dephlogisticatedair’.

b How do you think he showed that this was ‘dephlogisticated’ and not‘fixed’ air?

4 a Do you think van Helmont was successful in what he set out to prove?Explain your answer.

b Explain why van Helmont’s conclusion was only half right.

c Van Helmont’s tree had a mass of 76.74 kg after five years. Why do youthink that the total mass of material produced by the plant was actuallygreater than this?

?



9Cb/4 Transpiration

9

C

b

The loss of water by a plant is called transpiration. There are two processes involvedin this. First, there is evaporation of water from the surfaces of the cells into the airspaces in a leaf. Second, the water vapour diffuses out of the leaf.

An experiment was set up to investigate transpiration. The same amount of soil wasput into two identical pots and a plant was put into each. One plant had all its leavesremoved. Both were given the same amount of water at the start of the experiment.

knowledge, presenting, consideringS

The pots were left outside and the masses measured at the end of each day for one week.

1 Why were the pots covered in plastic bags?

2 What was being lost to make the plants lose mass?

3 What percentage of the original mass of pot 1 was left after one week?

4 Draw a line graph to show both these results. Plot both sets of results on thesame graph.

5 On which day did pot 1 lose most mass?

6 Explain why pot 1 lost more mass than pot 2.

7 Suggest an experiment you could do to find out whether there are morestomata on the lower surface of a leaf than the upper surface. (Hint: Vaselinewill block stomata; or cobalt chloride paper could be used.)

8 a What general conclusion can you make about the amount of mass lost andthe weather?

b Explain how the weather affects the loss of water by transpiration. Use thewords ‘evaporation’ and ‘diffusion’ in your answer.

9 Look at the leaves on the plant in pot 1. They are arranged so that they donot overlap each other. This arrangement is called a leaf mosaic. Suggestwhat the advantage of this arrangement is.

?

Day 0 1 2 3 4 5 6 7

Weather Cloudy Sunny Cloudy Cloudy Wet Sunny & Sunny Sunny

windy

Mass of pot 1 (g) 48 41 39 37 37 28 21 18

Mass of pot 2 (g) 41 41 40.5 40.5 40.5 39.5 39 38.5

pot 1

pots containingdamp soil

clear, colourlessplastic bags

pot 2


9Cc/1 Adaptations forphotosynthesis

9

C

c

Name Class

The organs of plants are shaped so that they can carry out their jobs well. They aresaid to be adapted to their jobs (or functions).

Water is needed to fill up the cells and help a plant stand up straight. If it does not getenough water, it wilts. Water is also needed for photosynthesis. The water is taken inby the roots which are spread through the soil. The many branches of roots also meanthat they hold the plant firmly in the ground. The stem helps to support the leavesand contains many hollow tubes to carry the water to the leaves. Leaves have smallholes called stomata and gases move in and out of the leaf through these (e.g. carbondioxide). Light is also needed for photosynthesis and so most leaves have a largesurface area to collect lots of light.


1 Name two uses of water in a plant.

a

b

2 Name two jobs that roots do.

a

b

3 Name two jobs that stems do.

a

b

4 List the three plant organs named in the passage.

a b c

5 In the passage, underline the phrases which are about how an organ is adapted.

6 In the passage, circle the names of the chemical substances needed for photosynthesis.

7 Plants use water for photosynthesis. They also lose quite a lot of it.

a Where do you think this water loss happens?

b Why do you think this?


9Cc/2 Plants and water

9

C

c

knowledgeS

1 Water and mineral salts are taken in through a plant’s roots. The drawing shows part of a root.

a What is a cell like the one labelled ‘X’ called?

b What is its function?

c How is it adapted to its function?

d What is the function of xylem tubes?

2 Which of these processes happens in roots?

photosynthesis combustion respiration neutralisation

3 Explain why the roots of plants usually look white, rather than green.

4 Phloem tubes carry sugar and other substances around plants. Explain whyroots have phloem tubes as well as xylem tubes.

5 Sam kept a plant in a pot in her bedroom. She watered the plant every day,but it died. Suggest why the plant might have died.

6 Dipesh’s garden has some plants growing in flower beds, and some plantsgrowing in pots.

?

X xylem tube

Dipesh’s family went away for two weeks in the summer, when the weatherwas very hot and dry. When they got back they found that the plants in thecontainers had died, but the ones in the flower bed were still growing.

Suggest why this might have happened.


9Cc/3 Carnivorous plantsThere are a few species of plant that trap and digest insects. These plants obtain all theirenergy through photosynthesis, so they do not need the insects to provide energy. Manyspecies of carnivorous plants grow in habitats where the soil does not contain many ofthe nutrients they need, and they use the insects they trap to provide nutrients.

Sundews are carnivorous plants that grow in bogs where nitrates are in short supply.Their leaves are covered with little stalks with glands on the end. If an insect lands onthe leaf it is trapped by a sticky liquid produced by the glands. The little stalks thengradually curl towards the centre of the leaf, and start to release digestive enzymes.

The diagram shows the results of an experiment to find out if sundews need insects tosupply nutrients.

9

C

c

considering, researchS

1 Suggest why the sundew plants were grown in sand.

2 This table shows the results of the experiment. Copy the table, and fill in theright-hand columns by putting ticks or crosses. One row has been done for you.

?

Watered with nutrientsolution including nitrates.

Watered with nutrientsolution including nitrates.

Watered with nutrientsolution without nitrates.

Watered with nutrientsolution without nitrates.

sand

A B C D

Plant Mass increase (%) Nitrates available via roots? Nitrates available via leaves?

A 100

B 65 � ✗

C 145

D 50

3 Will sundews grow without a supply of nitrates? Explain your reasoning.

4 Can sundews absorb nitrates through their roots? Explain your answer.

5 Do sundews absorb nitrates best through their roots or through their leaves?Explain your answer.

6 Why do sundew plants need nitrates?

7 Owen wants to keep a sundew plant in his house, but he does not wantinsects in his house. Explain why adding plant food to the soil will not helpthe plant to grow as well as it should.

8 Describe an experiment that you could carry out to find out if sundew plantsget phosphates mainly through their roots or their leaves.

9 Find out how Venus flytraps and pitcher plants trap insects.


Page 1 of 2

9Cd/1 Saving the forests

In many places in South America and Asia, large areas of forest are being cut down tosell the wood, or so that minerals can be extracted, or to clear land for farming.Environmental organisations are very concerned about this, and try to getgovernments and large companies to help keep the forests.

If a campaign to save the forests is to be successful, campaigners first need to find outwhy different people want to cut the trees down, and then find ways to help thosepeople live or earn a living in a different way.

All these people have different ideas or reasons for clearing the forests, or for wantingto save them.

9

C

d

1 For each person, decide if they want to cut down trees or want to stoppeople doing it. Explain why they have these opinions.

2 For the people who want to cut down trees, suggest how they could live orearn their living in a different way that did not involve cutting down trees.

?

Tropical hardwoods like mahogany and teak arevaluable because they are long lasting and lookgood when they are made into furniture. Ourlogging company employs many people who wouldbe out of work if we were not allowed to cut downtrees. We try to cut down only the trees we wantand leave the rest of the forest – this is calledselective logging.

We live in the forest. We hunt and fish, and gatherfruit and nuts for food and wood for fuel. Ourtraditional way of life will be destroyed if theforests disappear.

It is all very well you rich countries saying we mustnot cut down our forests, but we have very poorpeople here who need the land to farm, and oureconomy needs to make money by selling wood,and we need the land for crops like sugar andcocoa, or for mining. Many of your own companieshave cleared large areas of forest to convert tograssland, just so you can have cheap beef!

Tropical rainforests may contain up to 30 millionspecies of animals and plants. Many of theseplants could be useful as medicines, but if theforests disappear we might never know! Manyspecies will become extinct.

A

CD

B

Page 2 of 2


9Cd/1 Saving the forests (continued)

9

C

d


I have to grow food. I cut down a small area of theforest and burn the wood, then grow food for meand my family. After a few years the crops do notgrow as well any more, and I need to clear a newpatch of forest.

After a patch of forest has been farmed it can take20 years or more before the trees grow back. Thereare more people on the land now, so the land doesnot usually get time to recover properly. There areways of growing trees in combination with cropsthat would help to avoid this problem, but the poorfarmers would have to be taught how to use them.

EF

Selective logging takes only the most valuabletrees, but damages a lot more of the forest. Thereare different ways of managing the forest so thatnot too much damage is done, but timber can stillbe harvested.

Trees return a lot of water to the air – thisincreases local rainfall and makes sure there isplenty of water for the people living nearby. Thetrees also stop rainfall running away too quickly. Ifthe trees are cut down, there may be more floodsand the soil could also be washed away.

G H

The world needs metals and other minerals thatwe mine from the forest areas. I know it causesdamage, but the trees will grow back!

We can try to use up less fossil fuels, but thatwon’t help if there are no trees left! We will stillneed lots of trees to use up the carbon dioxide thatpeople and animals make.

IJ


Page 1 of 2

9Cd/2 Plants and photosynthesis

9

C

d

Use the phrases and diagrams below to make a poster showing the important factsabout plants and photosynthesis. Add your own labels and drawings if you need to.Your poster should include information on:

• which substances plants use to produce biomass• what source of energy is needed for photosynthesis• what happens in leaves, and how they are adapted to their function• what happens in roots, and how they are adapted to their function.

revisionS✄

DO NOT MAKE A DOUBLE SIDED PHOTOCOPY OF THIS WORKSHEET

Roots take in water andmineral salts from the soil.

Water and mineral salts pass up through the stem of the plant

in xylem tubes.Light is needed for photosynthesis.

Leaves have a large surface area. Palisade cells have a lot of chloroplasts.

carbon dioxide + water (+ light energy) → glucose + oxygen

Root hair cells have alarge surface area to help

them absorb water.

Carbon dioxide diffusesinto leaves through the

stomata.

Page 2 of 2


9Cd/2 Plants and photosynthesis

(continued)

9

C

d

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d

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9Cd/4 Amazon rainforest

This article about deforestation in the Amazon rainforest was published on the NewScientist website in 2001.

9

C

d


1 How was the information about deforestation obtained?

2 a How much of the Brazilian Amazon rainforest was cut down in 2000?

b Is the amount cut down each year increasing or decreasing?

3 Who is doing most of the logging?

4 a How is the Environment Ministry in Brazil planning to control the logging?

b Will this reduce the area of rainforest cut down each year? Explain your answer.

5 Why is it important to control logging in the Amazon rainforest?

6 If you lived in Brazil, would you want the government to allow logging or totry to reduce the amount of logging? Write a letter to the EnvironmentMinistry to explain your opinion. You may need a copy of Worksheet 9Cd/1to help you.

?

Trees toppled

12:30 16 May 01

Deforestation of the Brazilian Amazon during2000 hit the highest levels since 1995, satelliteimages have revealed.

Data from Brazil’s National Institute forSpace Research (INPE) show 0.56 per cent ofthe rainforest was cut down in 2000. Over12 250 square kilometres were logged,compared with 10 660 in 1999.

‘The beginning of the new millenniumcould not have been worse for the Amazon.The figures are worrying if we look to thefuture,’ says the World Wildlife Fund.

The rise was mostly down to increasedlogging by small-scale farmers, says INPE. Inresponse, Brazil’s environment ministryannounced plans to introduce a logginglicensing system, which will allow onlyholders of ‘environmental licences’ to cutdown trees.

‘At first we will concentrate our work in theworst-affected areas, but the demand forlicences on rural properties will apply for all of

Amazonia,’ Mary Allegretti, Brazil’s secretaryof co-ordination for the Amazon, told Reuters.

Put to the vote

Official figures had showed a gradualreduction in logging since 1995, when 0.8 percent of the forest in Brazil was destroyed.

However, a government bill that wouldallow Brazilian farmers to legally log largerareas of the Amazon is due to be put to thevote on 30 May. Environmentalists arecampaigning against any change to thelogging laws.

Most of the Amazon, which stretches overan area larger than western Europe, is inBrazil. The Amazon represents 40 per cent ofthe world’s rainforest and is an important sinkfor the greenhouse gas, carbon dioxide.

Related story: Amazon rainforest couldsuffer huge damage from road building(19/01/01).

Emma Young


9Cd/5 Plants kriss-kross

9

C

d

Name Class

Answer the clues below and then use the answers to fill in the grid. There areno clue numbers so you will need to find a way of getting all the answers tofit in the grid properly. Use a pencil in case you make a mistake.

A green chemical needed to allow photosynthesis to happen.

A green disc found in palisade cells.

A plant does this if it does not get enough water.

A product of photosynthesis which is a gas.

A product of photosynthesis which is a solid.

A reactant in photosynthesis which is a liquid.

A substance which a plant can make as a store of energy.

An important mineral salt needed to make proteins in plants.

Holes in leaves surrounded by guard cells.

Hollow cell through which water travels.

Photosynthesis turns light energy into this sort of energy.

Plant organ that takes water from the ground.

Plant organ where photosynthesis happens.

Process in which molecules move from an area where there are a lot of them

to an area where there are fewer of them.

The mass of material that makes up a plant.

The source of energy for photosynthesis.

?



9Cd/6 Seasonal changes

Scientists and governments aregetting increasingly worriedabout rising levels of carbondioxide in the atmosphere, andthe possibility that increasedcarbon dioxide will lead to themean (average) temperature ofthe Earth increasing – an effectknown as global warming.

Monitoring stations have beenset up all over the world torecord the concentrations ofdifferent gases in theatmosphere. The graph showshow the concentration of carbon dioxide in the atmosphere changed over four years in the northern and southern hemispheres.

9

C

d

knowledge, numeracyS

Year 1

60°N

Co

nce

ntr

atio

n o

f C

O2

Year 2 Year 3 Year 4

60°S

Seasonal changes in atmospheric CO2.

1 Which natural processes produce carbon dioxide?

2 Which natural processes remove carbon dioxide from the air?

3 How are human activities adding to the amount of carbon dioxide in the air?

4 Look carefully at the line showing carbon dioxide concentrations in thenorthern hemisphere.

a At which time of year do the high concentrations occur?

b What do you think causes the highs and lows in this line? (Hint: Thinkabout when most plant growth occurs.)

5 Look at the line for the southern hemisphere. Why are the highs and lowson this line in different places to the ones for the northern hemisphere?

6 What overall trend do both lines show?

7 Sketch a graph showing how you would expect the concentration of oxygenin the atmosphere to change over this four-year period. You should includelines for the northern and southern hemispheres.

8 If you look at an atlas you will see that there is a lot more land in the northernhemisphere than in the southern hemisphere, and the southern hemispherehas a lot more ocean. Does most photosynthesis happen in land plants or inwater plants in the oceans? Explain how you arrived at your answer.

?

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10489 9c p092 127 - Wikispacesmnwikiks3yr3.wikispaces.com/file/view/Plants+and+photosynthesis... · An experiment was done to see how the amount of starch in some leaves changed during