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Life Processes 1

What you should know by the end of this unit:

Life Processes

The 4 basic needs of animals are nutrition, water, air and shelter.

The 4 basic needs of plants are nutrition, water, air and light.

Respiration

Living things (organisms) require energy for heat, movement, growth and

chemical reactions.

This energy comes from a process called respiration.

Energy is measured in units called kilojoules.

Fats and oils contain more chemical energy per gram than carbohydrates or

proteins.

Cells need oxygen to release energy from food during aerobic respiration.

The waste products from this reaction are carbon dioxide and water.

Aerobic respiration produces a lot of chemical energy.

This energy can be converted by cells into heat or movement energy.

The rate of aerobic respiration can be affected by factors such as availability of

glucose, oxygen and temperature.

Photosynthesis

Photosynthesis is the process by which green plants make their own food in the

form of sugar and starch.

Carbon dioxide and water are converted using energy from the sun into sugar

and oxygen.

Certain environmental conditions such as light intensity, carbon dioxide

concentration and temperature affect the rate of photosynthesis.

These environmental conditions are known as limiting factors.

Life Processes 2

The Carbon Cycle

The Carbon Cycle is a complex series of processes through which all of the

carbon atoms in existence cycle between living organisms and their

surroundings.

Carbon dioxide from the atmosphere is taken in by plants during photosynthesis

and made into plant tissue.

Plant tissue is then eaten by animals and broken down to release energy during

respiration.

Carbon dioxide is then released back into the atmosphere from respiration and

decay.

Burning fossil fuels release carbon dioxide into the atmosphere.

Skills that you should be able to carry out by the end of this unit are:

Burn food to determine how much energy it contains.

Design an experiment to investigate aerobic respiration.

Observe and form conclusions from demonstration experiments.

Be able to test leaves for starch.

Interpret and draw graphs.

Calculate averages and percentages.

Extract information from different sources.

Write up experiments with an aim, method, results and conclusion.

Understand the importance of variables in an experiment to ensure it is a fair

test.

Understand the importance of repeating an experiment to improve the

reliability of the results.

Work as part of a group and take responsibility to support the work of the

group.

Life Processes 3

Basic Needs of Living Things

Living things (organisms) have basic needs for survival.

Animals need:

water

air

nutrition

shelter.

Plants need:

water

air

nutrition

light.

All plants and animals are made up of CELLS. All cells use energy converted from

stores of fat and carbohydrate for a large number of processes.

For example:

Cells divide to produce new cells which may be used for growth or to replace cells

which have died or been damaged. The production of new cells requires energy.

Warm-blooded animals lose heat to their surroundings so they must convert the

chemical energy from their food into heat energy to keep their body temperature

constant.

In animals, muscle cells do mechanical work to produce movement. Chemical

energy from food must be converted to kinetic (movement) energy for this to occur.

Some chemical reactions that take place within cells require some energy to get

them started.

This energy is released from food through a process called respiration.

Life Processes 4

? Key Questions (Answer in sentences)

1. List FOUR uses of energy in living things.

2. Give TWO energy conversions which occur in living things.

Heat Movement

Growth

Chemical

reactions

Life Processes 5

Experiment 1: Burning Food

Living things obtain the energy they need from food. Energy is measured

in units called kilojoules. The food eaten by animals contains various

amounts of carbohydrates, protein and fat/oil. We can measure the

energy in different foodstuffs by carrying out the following experiment.

Firstly, your teacher will demonstrate the experiment showing you how to

burn oil.

This experiment should be written up by completing the ’Burning

Food’ resource sheet provided.

Thermometer Wear safety

goggles

Test tube of water

Deflagrating

Spoon Burning food

Life Processes 6

Collect:

clamp stand

deflagrating spoon

boiling tube

thermometer

safety goggles

Bunsen burner and heat mat

measuring cylinder

2 different foodstuffs

balance

Method:

1. Measure 20ml of water using a measuring cylinder and pour into a

boiling tube. Note the starting temperature on the resource sheet.

2. Use a deflagrating spoon to collect a sample of each foodstuff.

3. Heat one of the samples of foodstuff in the deflagrating spoon in the

Bunsen burner flame until it catches fire. You must wear safety

goggles and hold the deflagrating spoon at an angle.

4. Hold the burning foodstuff underneath the test tube of water until it

has burned out completely. Note the final temperature of the water.

Life Processes 7

Respiration is a process carried out by all living things. It is a series of

chemical reactions that occurs in all living cells to release energy from

food.

Respiration usually occurs in the presence of oxygen, this is called

aerobic respiration. Fuel, in the form of glucose (sugar), combines with

oxygen. Carbon dioxide and water are produced; these are waste

products and are released from all living cells as they respire. Aerobic

respiration produces a lot of energy from food. The information described

above can be summarised as a word equation:

Glucose + Oxygen Carbon dioxide + Water +

The rate at which a cell respires depends upon:

the availability of oxygen

the availability of glucose

temperature

? Key Questions (Answer in sentences)

1. What is aerobic respiration?

2. What do living cells need in order to respire?

3. What are the waste products of this reaction?

4. Write the word equation for aerobic respiration.

5. Suggest three factors which will affect how quickly a cell will respire.

ENERGY

Life Processes 8

Experiment 2: The Use of Oxygen in Aerobic Respiration

Experiments can confirm that respiring cells do indeed use up oxygen,

release carbon dioxide and energy in the process of aerobic respiration.

You are going to carry out and observe some of these experiments.

1. Write the heading ‘The Use of Oxygen in Aerobic Respiration’ into

your jotter. This experiment will be carried out over 2 days.

2. Copy the aim into your jotter:

The aim of this investigation is to confirm that oxygen is used up

during the process of aerobic respiration.

3. Day 1

Collect:

2 boiling tubes

live peas

boiled (dead) peas

Method:

1. Label boiling tubes with your initials. Label one ‘live peas’ and

one ‘boiled peas’.

2. Put 10 live peas into one boiling tube and insert a stopper.

3. Put the 10 boiled peas into the other boiling tube and insert a

stopper.

4. Leave both boiling tubes overnight.

Life Processes 9

4.

Day 2

Collect:

boiling tube containing living peas

boiling tube containing boiled peas

Bunsen burner and heat mat

wooden splint

Method:

1. Remove stoppers from boiling tubes one at a time and

plunge a glowing splint into each boiling tube.

2. Record your results.

5.

Results:

Copy and complete the results table below:

Result

Live Peas

The splint …………………{goes out quickly/slowly}

Dead Peas

The splint …………………{goes out quickly/slowly}

6. Conclusion:

Copy and complete the following conclusion into your jotter using

the word bank below to help you:

energy oxygen less take in give out more

The jar containing the living peas contains ..............oxygen than

the jar with the dead peas. Living peas therefore, ..............

.............. oxygen. .............. is taken in by living cells to release

.............. from food in a process called aerobic respiration.

Life Processes 10 Demonstration – Investigating Aerobic Respiration and Carbon

Dioxide Production

Bicarbonate indicator can be used to test for the presence of carbon

dioxide. The following table illustrates the colour change that will take

place depending on the level of carbon dioxide present.

Carbon dioxide level Colour of bicarbonate indicator

High Yellow

Medium Red

Low Purple

1.

Write the heading ‘Investigating Aerobic Respiration and Carbon Dioxide

Production’ into your jotter.

2.

Copy the aim into your jotter:

The aim of this investigation is to find out if plants carry out aerobic

respiration

3.

Your teacher will demonstrate the experiment illustrated below:

Collect a copy of the diagram of the above experiment and paste it into

your jotter. Note on your diagram the final colour of the bicarbonate

indicator.

Life Processes 11

?

Key Questions (Answer in sentences)

1. Why is the plant in the dark?

2. What is the purpose of flask 1?

3. What does the final colour of flask 3 tell you?

4.

5.

6.

Name another chemical used to test for the presence of carbon

dioxide.

What colour change occurs with this chemical?

Copy and complete the following conclusion:

In the dark, a green plant carrying out respiration releases

……………… …………………… .

Life Processes 12

Investigation: Proving That Carbon Dioxide Is Given off by

Respiring Cells

Suppose that you are provided with 4 boiling tubes containing 10ml of

bicarbonate indicator, stoppers, a live mealworm (or a woodlouse), peas,

a mushroom and sponge platforms.

Using whatever other materials you think are necessary, copy and

complete the diagrams below to show how you would set up an

experiment to demonstrate that each of these organisms produces

carbon dioxide. (10ml bicarbonate indicator in each test tube has already

been done for you).

Think/Pair/Share

To ensure your results are valid you must only change one variable, in

this case it is the organism used. Write in your jotter three variables

you will have to keep the same in this investigation to ensure the

experiment is a fair one.

What do you expect will be the result of this investigation?

10ml

Bicarbonate

Indicator

Life Processes 13

The Release of Energy as Heat

Some of the chemical energy produced by aerobic respiration will be

converted into heat energy.

This can be seen by the following demonstration.

Collect a copy of the above diagram and paste it into your jotter. On

the diagram, record the temperature of both flasks.

Write a sentence explaining what this experiment tells us about living

germinating peas.

Life Processes 14

Experimental Controls

An experimental control is a copy of the experiment in which all the factors

are kept the same except the one being investigated in the original

experiment.

When the results are compared any difference must be due to that one

factor.

How would a control experiment differ from the set up you were

shown?

Observe the following demonstration.

? Key Questions (Answer in sentences)

1. What happens to the liquid level in the U-tube?

2. Explain why the liquid moves.

3. Copy and complete the conclusion into your jotter:

From the two experiments it can be concluded that living plants

and animals release some energy in the form of ………….

Life Processes 15

Comparing Aerobic Respiration and Burning

Aerobic respiration can be compared to burning (combustion). Both reactions

release energy from fuel and both use oxygen and release carbon dioxide.

Glucose/Fuel + Oxygen Carbon dioxide + Water +

The main difference between aerobic respiration and burning is the rate at which

they release energy. Aerobic respiration releases energy more slowly than burning

and its rate can be controlled. It is very important that the release of energy is slow

and controlled with aerobic respiration as a sudden and uncontrolled release of

energy may cause damage to the cells.

The following graph shows the energy release from both processes against time.

? Key Questions (Answer in sentences)

1. What is the main difference between aerobic respiration and

burning?

2. What affect would a sudden release of energy have on living cells?

ENERGY

Life Processes 16

Photosynthesis is the process by which green plants make their own food using

energy from the sun.

Read the background information on page 18. Select 5 important points

and write them into your jotter under the heading ‘Photosynthesis’.

Life Processes 17

The word "photo" means light. "Synthesis" means putting together.

The word photosynthesis means putting together with light.

Plants contain a green coloured pigment called chlorophyll. Plants take in water

and minerals from the soil through tiny hairs on the roots. The water and minerals

are transported through the root hairs to the roots, and then are drawn up the stem

through tubes that are arranged in bundles. These tubes are called xylem and they

transport the water up the stem to the leaves where it is used for photosynthesis.

There is a layer of cells found just below the top surface of a leaf. These cells

contain chloroplasts. Chlorophyll is found in the chloroplasts. When sunlight shines

on the top of a leaf the light energy is trapped by the chlorophyll. This energy is

stored for later use.

Air passes in through tiny holes on the bottom surface of the

leaf. Molecules of carbon dioxide from the air reach the

cells where chlorophyll has trapped energy from sunlight.

This trapped energy turns the carbon dioxide into a variety

of sugars and oxygen.

The information describe above can be summarised as a word equation:

Water + Carbon dioxide Sugar + Oxygen

There are three fates of the sugar produced during photosynthesis:

1. some of the sugar produced will be used in respiration to provide energy

2. some of the sugar will be used to make plant cell walls

3. some of the sugar will be converted to starch and stored in the leaves.

Background Information - Photosynthesis

Light energy

chlorophyll

Life Processes 18

Experiment 3: Testing Leaves for Starch - 1

You are now going to carry out an experiment to prove that plants do

make and store food (in the form of starch).

Collect:

tripod stand

Bunsen burner

heat mat

green leaf

forceps

beaker

safety goggles

iodine solution

dropper

white tile

ethanol (alcohol) from

your teacher.

Method:

1. Place leaf into a beaker of water.

2. Boil the leaf in a beaker of water.

3. Switch the Bunsen burner OFF.

4. Place the leaf into a boiling tube of ethanol

and put the boiling tube into the freshly

boiled water.

5. Remove the leaf from the boiling tube using

forceps, rinse in the beaker of water. Spread

the leaf out over a white tile and test it for

starch using iodine solution.

Wear safety goggles

Life Processes 19

Factors That Affect the Rate of Photosynthesis

Certain environmental factors slow down the rate of photosynthesis if they are in

short supply.

Look at the word equation for photosynthesis again:

Water + Carbon dioxide Sugar + Oxygen

Think/Pair/Share

Can you think of the environmental factors that may slow down the rate of

photosynthesis?

Share and discuss with your partner.

Limiting Factors

The factors you have been discussing are called LIMITING FACTORS as they LIMIT

(slow down) the rate of photosynthesis if they are in short supply.

Experiment 4: Testing Leaves for Starch - 2

You are now going to carry out an experiment using leaves from plants

that have been exposed to different conditions.

Before the experiment all the plants are destarched by keeping them in

the dark for 3 days, this uses up all their stores of starch. The plants are

then exposed to new conditions for 24 hours. If any starch is present it

must have been made under the new conditions.

Chlorophyll

Light energy

Life Processes 20

Plant 1 has been deprived light.

Plant 2 has been deprived carbon dioxide.

Plant 3 has had light and carbon dioxide BUT the leaves from plant 3 are

variegated this means that there is only chlorophyll in some parts of

the leaf.

You are going to use the same procedure from ‘Testing Leaves for

Starch - 1’ on page 18 using a leaf from each of these three plants.

Collect a results resource sheet and add your results and a conclusion.

Plant 3 Destarched

variegated plant

Plant 1 Destarched plant

kept in the dark

for 24 hours

Plant 2 Destarched plant

deprived of carbon

dioxide for 24 hours

Chemical which

removes carbon

dioxide

Green part contains

chlorophyll

White part does not contain chlorophyll

Life Processes 21

Respiration vs. Photosynthesis

As we have learned, plants need to take in carbon dioxide in order to

photosynthesise. As they are photosynthesising, plants release oxygen into the

atmosphere. This can be summarised by the following word equation.

Water + Carbon dioxide Sugar + Oxygen

Plant cells also carry out respiration which releases energy from the glucose that

was produced by the plant during photosynthesis. For this they need to take in

oxygen and give out carbon dioxide. This can be summarised by the following word

equation.

Glucose + Oxygen Carbon dioxide + Water +

If you look carefully you will see that the two equations are very much the opposite

of one another, but otherwise the same. It is important to remember that in plants,

these two equations are connected.

Photosynthesis is one of the most important chemical reactions on Earth. It is the

way that energy from sunlight is trapped to make food and the way in which oxygen

that is used up by respiration gets replaced in the atmosphere.

Both photosynthesis and respiration are important for the recycling of carbon which

is represented by the Carbon Cycle.

Photosynthesis

Light energy

Chlorophyll

Respiration

ENERGY

Life Processes 22

Collect a set of card sorts.

Arrange the cards to show the word equation for both aerobic respiration

and photosynthesis. Get your teacher to check that you have the two

equations correct. Copy both equations into your jotter.

Life Processes 23

Life Processes 24

Process Description

Photosynthesis

The process by which the dead

remains of plants, animals and

other organisms are preserved.

Respiration

The termination of the biological

functions that sustain a living

organism.

Combustion Process by which energy is

released from food.

Death

Process by which green plants

use light energy to produce their

own food.

Fossilisation The burning of a fuel to produce

heat.

The following tables show various processes and descriptions associated with the

Carbon Cycle but not correctly matched. Match the descriptions to the correct

processes.

Life Processes 25

The Carbon Cycle

The following diagram shows the Carbon Cycle. The Carbon Cycle shows how carbon

is recycled in nature. The diagram below has various processes involved with the

Carbon Cycle which are numbered 1 - 5.

Collect a copy of the diagram above and paste it into your jotter.

Using the information on pages 23 and 24 identify the processes numbered

1 – 5 in the diagram.

1

2

3

4

2

5

4

Life Processes 26

The Carbon Cycle Game

You are now going to imagine that you are a carbon atom being recycled in

nature. You will work in your collaborative groups for this activity.

1. Collect:

The Carbon Cycle game board

Play cards

A Dice

Game pieces

An instruction card

2.

Follow the instructions given on the instruction card

Life Processes 27

Working in groups your teacher will give you a task sheet. In each group

there will be:

A Chairperson

Role: Overall responsibility for the group and ensures that all group

members participate fully, complete their task and carry out their role

within the group.

A Clarifier

Role: Ensures that everyone understands their given task and asks

for help from the teacher if needed.

A Resource Manager

Role: Ensures that all materials required for each task are available

for all members of the team.

A Time Manager

Role: Ensures that the group is working to schedule and that all tasks

are completed on time.

You will be given two periods to complete your task. The third period will

be used for presenting the information back to the rest of the class.

C The Carbon Cycle Collaborative Lesson

Life Processes 28

Aerobic Respiration process by which energy is released in living cells

from food in the presence of oxygen

Basic Needs requirements that all living things need to survive

Carbon Cycle complex series of processes through which all of the

carbon atoms in existence cycle between living

organisms and their surroundings

Combustion the process of burning

Energy the ability to do work. It exists in many forms e.g.

kinetic, heat, chemical etc

Fossil Fuels coal, oil and gas derived from the dead remains of

plants and animals over millions of years

Kilojoules a unit of energy

Limiting Factor refers to any condition that is required by a species

which becomes insufficient or absent in a habitat

Organism a living thing

Photosynthesis process by which green plants form carbohydrates

such as sugar, from water and carbon dioxide, using

light as an energy source

Respiration process by which energy is released from food in

living cells