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National 5 Cell Biology Homework Booklet

This booklet contains homework questions for the cell biology unit. Do not write in the booklets. If you have to copy a diagram then do it carefully in your jotter. If you have to draw a graph then make sure the teacher remembers to give you graph paper. Answer questions in sentences. Please ask your parent or guardian to sign your homework.

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Section 1.1 Cell Structure

The diagram shows some of the structures found in a typical plant cell.

1. (a) Tick the boxes to show the structures that are also found in a typical animal cell. 2

(b) Why are cells often stained before being viewed under a microscope?

________________________________________________________________ 1

(c) The diagram shows some plant cells as they appear when viewed under a microscope.

Calculate the average length of the cells.

Space for calculation

____________ micrometres 1

2. The diagrams below show three different cells, not drawn to scale.

Field of view = 600 micrometres

3

(a) Select information from the diagrams above to complete the table below.

The information on the onion cell has been completed for you.

= Present and = absent

Part of cell Human cheek cell Onion cell Leaf cell

Nucleus

Cell membrane

Cell wall

Chloroplast

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3. The diagram below shows a cell from the pancreas.

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(a) What feature of this cell shows that is involved in aerobic respiration?

______________________________________________________________ 1

4. The diagram below shows Paramecium, a unicellular organism found in fresh water.

(a) Identify organelles P and Q

P _____________________________

Q _____________________________ 2

5. Decide if each of the following statements is True or False and tick the appropraite box.

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If the statement is False write the correct word in the Correction box to replace the word(s)

underlined in the statement.

Statement True False Correction

Iodine is a common stain used for looking at cells under the microscope.

The cell wall can be found in both plant and animal cells.

The cytoplasm controls the cell activities.

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Section 1.2 : Transport across the cell membrane

1. Active transport is a way for molecules to move across the cell membrane. When

active transport is used to move molecules, what is required?

A. Concentration gradient

B. Very small molecules

C. Energy that the cell provides

D. Osmosis 1

2. Where does the energy molecule ATP that drives active transport come from?

A. Aerobic respiration

B. Diffusion

C. Anaerobic respiration

D. Active transport 1

3. The diagram below refers to the cell membrane of an animal cell.

X Y

A Active transport Diffusion

B Diffusion Active transport

C Respiration Diffusion

D Active transport Respiration

1

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4. (a) The diagram below shows a single-celled organism that lives in ponds.

(i) Complete the table below.

Letter Structure Function

A Controls the work of the cell

B Cell membrane

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(ii) State one difference in structure between this cell and a plant cell.

___________________________________________________________________ 1

(b) The diagram below shows area X magnified.

The concentration of oxygen is shown by the number of dots.

(i) Draw an arrow on the diagram to show the overall direction of movement of oxygen. 1

(ii) Name the term used to describe this type of movement.

____________________________________________________ 1

(c) (i) Complete the following sentence to give a definition of the process of diffusion.

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Diffusion is the movement of a substance

from an area of _______________________________________________________

to an area of ________________________________________________________ 1

(ii ) The list below names three substances which diffuse into and out of living cells.

List dissolved food carbon dioxide oxygen

Complete the diagram to show correctly the movement of each named substance into or out

of the cell.

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(iii) Which part of the cell controls the passage of substances into or out of the cell?

_______________________________

5. (a) The diagram represents the transfer of oxygen from the atmosphere to muscle cells.

From the diagram, state where the highest and lowest concentrations of oxygen are found.

Highest concentration ______________________________

Lowest concentration ______________________________ 1

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6. (a) The following sentences give information about the plasma membrane of beetroot cells.

Underline one alternative in each pair to make the sentences correct.

The plasma membrane contains {cellulose / protein} and {phospholipids / carbohydrate} and

has a {fibrous / porous} nature. As a result, the membrane is {fully / selectively} permeable.

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7. The diagram shows a human liver cell and a magnified section of its plasma membrane.

(a) (i) Identify molecules S and T

S _______________________ 1

T _______________________ 1

(ii) Name a molecule which would diffuse OUT of the plasma membrane

__________________________ 1

(iii)What evidence in the diagram suggests that this cell produces large quantities of ATP?

____________________________________________________ 1

8. (a) The process of diffusion is important to organisms.

From the list below, select a substance which is involved in diffusion and answer the questions

which follow.

List Oxygen glucose carbon dioxide

Substance selected ______________________________

(i) Explain why its diffusion is important.

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_________________________________________________________

_________________________________________________________

(ii) Where does its diffusion take place?

_________________________________________________________

_________________________________________________________

(b) Cells from the same plant tissue were placed in three different liquids, left for 20 minutes

and then examined using a microscope.

The following diagrams represent cells from each liquid.

Which cell is most likely to have been placed in pure water?

Give a reason for your answer.

Cell __________

Reason ____________________________________________________________

__________________________________________________________________

__________________________________________________________________ 2

(ii)What name is given to the special case of the movement of water into and out of cells?

_______________________ 1

9.(a) State the definition of active transport.

________________________________________________________

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________________________________________________________ 2

(b) Give an example of a molecule which is transported in or out of a cell by active

transport.

_____________________________________ 1

10.The diagram below shows Paramecium, a single-celled organism which lives in water.

(a) The water concentration outside the cell is higher that the water concentration of

the cytoplasm. This causes water to enter the cell constantly.

(i) What is the name for this movement of water?

_________________________ 1

(ii) From the information given, state whether Paramecium is likely to live in

fresh water or salt water.

_________________________ 1

(b) Paramecium must get rid of excess water. Pure water is collected in the vacuoles by

removing it from the cytoplasm. The vacuoles are emptied to the surrounding water

as soon as they are full.

(i) What would happen to the Paramecium cell if the vacuoles stopped working

properly?

______________________________________________ 1

(ii) The vacuoles are not filled by the diffusion of water. What evidence is there to

support this statement?

__________________________________________________________

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__________________________________________________________ 1

(c) (i) Name two chemical components of the cell membrane

1 ________________________

2 ________________________ 1

(ii) Give a property of the cell membrane which is related to its role in osmosis.

______________________________________________________ 1

11. The diagrams below represent red blood cells in different solutions as they would

appear under a microscope.

(a) Use the information in the diagrams to predict the percentage solute

concentration of human blood. Explain your answer.

Solute concentration _________ %

Explanation ________________________________________________

__________________________________________________________

__________________________________________________________

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(b) What has happened to the cells in diagram B? Explain the change in terms of

water concentrations.

Description ________________________________________________

Explanation ________________________________________________

__________________________________________________________ 2

12. An investigation was carried out into the effect of water concentration on the rate of

osmosis.

Details of the apparatus, method used and results are given below.

Apparatus

Method

1. A thistle funnel containing 50cm3 of 0.5% sugar solution was covered with

selectively permeable membrane.

2. The funnel was placed in a beaker of pure water.

3. The scale was positioned with the sugar solution at zero on the scale.

4. The position of the sugar solution was recorded after 30 minutes.

5. The procedure was repeated using 1.0%, 2.0% and 3.0% sugar solution.

Results

Concentration of sugar solution (%)

Distance moved by sugar solution in 30 minutes (mm)

0.5 4.5

1.0 9.0

2.0 18.0

3.0 27.0

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(a) Identify two variables not already mentioned that should be kept constant when

setting up the investigation.

1 _______________________________________________________

2 _______________________________________________________ 2

(b) Explain the movement of the sugar solution in terms of water concentrations.

_________________________________________________________

_________________________________________________________ 1

(c) From the results, predict the distance moved by a 3.5% sugar solution in 30 minutes

and justify your prediction.

Prediction ___________ mm

Justification _______________________________________________

_________________________________________________________ 1

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Section 1.3 : Cell Division

1. What structure is responsible for pulling apart the chromatids?

A. Nuclear membrane

B. Equator

C. Spindle fibres

D. Cell membrane

2. Which of these is not what cell division is required for?

A. Growth

B. Repair

C. Asexual reproduction

D. Osmosis

3. What does diploid mean?

A. Two matching sets of chromosomes

B. Separating chromosomes

C. Half a set of chromosomes

D. 23 chromosomes

4. (a) The following diagrams show two stages in cell division.

Draw one line from each of the stages named below to its correct description.

Stage Description of stage

Chromosomes become visible in the nucleus

Chromosomes line up at the equator

Nuclear membrane breaks down

Cytoplasm divides

Stage X

Stage Y

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(b) Underline one option in each of the brackets to make the following sentences

correct.

Cell division is controlled by the {membrane / nucleus / cytoplasm}.

The number of chromosomes in the daughter cells is {greater than / less than / the

same as} the original cell. 2

5. (a)The diagrams below show two stages of mitosis in cells. Draw one straight line

from each diagram to its correct description.

2

(b) How does mitosis ensure that the daughter cells will be able to function

properly?

______________________________________________________________

______________________________________________________________ 1

Chromosomes shorten and thicken

Chromosomes line up at the centre of the cell

Chromatids are pulled to opposite ends of the cell

Nuclear membrane reforms

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6. The drawing represents part of a root tip as seen under high magnification.

(a) (i) What name is given to the type of cell division that can be seen in some of the

cells?

___________________________ 1

(ii) Describe what is happening in cells Y and Z.

Cell Y ____________________________________________________

____________________________________________________ 1

Cell Z ____________________________________________________

____________________________________________________ 1

(iii) Daughter chromosomes produced by this type of cell division contain the

same number of chromosomes as their parent cell.

Explain the importance of this.

_______________________________________________________

_______________________________________________________ 1

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7. A piece of onion skin was examined using a microscope and the lengths of 50 cells

were measured.

The bar chart below shows the number of cells of different lengths which were

found.

(a) Which range of cell lengths contained the most cells?

From _______________ to _______________ micrometres 1

(b) What percentage of cells had a length of 350 micrometres or more?

Space for calculation

_____________ % 1

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8. The diagram below shows stages in the division of an animal cell.

The stages are shown in the correct order.

(a) What name is given to the process of division of the nucleus shown in the

diagram?

___________________________ 1

(b) Describe what is happening at stage D.

_________________________________________________________

_________________________________________________________ 1

(c) New cells have exactly the same number of chromosomes as the original cell.

Explain why this is important.

_________________________________________________________

_________________________________________________________

_________________________________________________________ 1

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9. The diagram below represents a cell in an early stage of mitosis.

Which of the following diagrams represents the chromosomes you would expect to find in

the nuclei of the daughter cells at the end of mitosis?

Tick the correct box.

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Section 1.4 : DNA Structure and Proteins

1. The diagram below shows a molecule of DNA. Which bases are represented by

the numbers 1 and 2. (1)

2. A section of DNA contains 90 A bases. How many T bases does this DNA

molecule contain? (1)

3. DNA controls the activities of a cell by coding for the production of..? (1)

A. Proteins

B. Carbohydrates

C. Amino acids

D. Bases

4. A DNA molecule contains 8000 bases. 20% are A and 30% are G.

Calculate the number of A bases and the number of G bases in this strand of

DNA. (1)

5. A fragment of DNA was found to have 60 G bases and 30 A bases. What is the

total number of bases in this fragment? (1)

6. a) Proteins are made up of sub-units called (1)

A. amylase

B. amino acids

C. glycerol

D. glucose

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b) The sub-units of protein are joined together to form what type of chain? (1)

7. Decide if each of the following statements is True or False and tick () the

appropriate box.

If the statement is False, write the correct word in the Correction box to

replace the word underlined in the statement. (3)

True or False Correction

The protein sequence

determines the amino

acid sequence.

DNA is double-stranded.

Base C pairs with base T.

8. A muscle cell divides every 20 minutes. How many cells would there be after 3

hours? (1)

9. In an experiment lumps of potato were placed in a salt solution. The mass of

potato lost was measured. The results are shown in the table below. (3)

Time (minutes) 0 1 2 3 4 5

Mass lost (mg) 0 32 50 60 66 67

Draw a line graph of these results

b) Using your graph, predict the mass lost at 3 ½ minutes. (1)

10. a) State the function of mRNA (1)

b) Where does protein synthesis take place? (1)

11. Describe the structure of DNA and base pairing. (3)

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Section 1.5 Proteins and Enzymes

1. Use the word-bank below to complete the following paragraph and fill in the missing words.

Enzymes function as ___________________ __________________ and are made by

______________ ______________. They speed up cellular reactions and are

___________________ in the process. The shape of the ____________ ___________ of

enzyme molecules is complementary to a specific _______________.

A change in ____________________ or ______ will affect the rate of reaction and may

result in _______________________.

2. Phosphorylase is an enzyme extracted from potatoes. Drops of phosphorylase, glucose-1-

phosphate and water were added to a dimple tile as show.

A drop of iodine solution was added to one dimple in each row at three-minute intervals. If

starch is present, a black colour forms.

Active site biological catalysts unchanged

Temperature denaturing substrate

Living cells pH

Row A phosphorylase + glucose-1-phosphate

Row B phosphorylase + water

Row C glucose-1-phosphate + water

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The results are shown below.

a) In which row has starch been synthesised?

Row _______ 1

b) The experiment was carried out at 25°C. How would the results in Row A differ if the

experiment had been carried out at a lower temperature?

_____________________________________________________________ 1

c) Rows B and C are control experiments.

(i) What conclusion can be drawn from Row B?

_________________________________________________________________ 1

(ii) What conclusion can be drawn from Row C?

________________________________________________________________ 1

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3. Liver contains the enzyme catalase which breaks down hydrogen peroxide. The diagram

shows that results of an experiment on the effect of temperature on catalase activity.

a) (i) Complete the following table to show the results of the experiment.

Temperature (°C)

Height of froth (cm)

20

30 2

40

50

60

(ii) From the results, identify the optimum temperature for catalase activity.

___________ °C 1

(iii) Predict the height of froth if another tube had been included at 10°C, and give a reason

for your answer.

Predicted result ___________ cm 1

Reason _______________________________________________

_____________________________________________________ 1

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4. (i) The process of cell division is controlled by many specific enzymes. Explain the term

specific as used in this context.

_____________________________________________________________

_____________________________________________________________ 1

(ii) Enzymes have an optimum temperature and pH. Explain the meaning of the word

optimum.

_____________________________________________________________

_____________________________________________________________ 1

5. The graph shows the activity of enzymes A, B and C at different pH values.

a) Pepsin is made in the stomach.

Which enzyme could be pepsin?

Enzyme _______ 1

b) Over what pH range would enzymes B and C both be able to work?

Between pH _______ and pH _______ 1

c) Describe the changes in the activity of enzyme B as the pH changes from pH 5 to pH 9.

_________________________________________________________

______________________________________________________________ 2

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6. To investigate the effect of temperature on the activity of the enzyme pepsin, five test tubes

were set up as shown below.

Each tube was placed in a water bath at a different temperature.

After 12 hours, the following results were obtained.

Test tube Temperature (°C)

Length of egg white after 12 hours (mm)

A 5 19

B 20 17

C 35 13

D 45 15

E 60 20

a) At which temperature did the greatest digestion of egg white take place?

______ °C 1

b) Describe the effect of increasing the temperature on the activity of the pepsin over each of

the temperature ranges below.

Between 5°C and 35°C __________________________________________________ 1

Between 35°C and 60°C _________________________________________________ 1

c) If the experiment had been repeated at pH7, which of the following would be the most likely

result for the length of egg white in test tube B?

Tick the correct box

19mm 17mm

15mm 13mm

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Section 1.6. Genetic Engineering

1. In 1997 the USA planted 8.2 million hectares of land with genetically engineered crops. By 1998, this had increased to 20.5 million hectares.

What was the percentage increase in the area sown between 1997 and 1998?

A 12.3%

B 66%

C 150%

D 166.7% 1

2. Genetic engineering can be used to alter bacterial cells in order to produce human insulin.

The stages in the process are:

1. insulin gene extracted from a human cell 2. bacteria divide and produce large quantities of human insulin

3. plasmid is removed from bacterial cell and ‘cut’ open 4. insulin gene is inserted into bacterial plasmid.

The correct sequence of these stages is

A 1, 3, 4, 2

B 1, 3, 2, 4 1

C 3, 4, 2, 1

D 3, 1, 2, 4

3. The table below shows the relationship between planting

density and the mass of seed harvested for a trial cereal crop.

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The reason a low mass of seed was harvested when the planting density was 128 plants per square metre was

A less disease at high planting densities

B more nutrients available

C more competition for light and nutrients

D less space for weeds

4. The table below shows the relationship between planting density and the mass of seed harvested for a cereal crop trial.

Planting density

(number of plants per square metre

Mass of seed

harvested

(grams per

square metre)

4 60

8 86

16 104

32 77

128 22

Planting density

(number of plants per square metre)

Mass of seed Harvested (grams per square metre)

4 60

8 86

15 105

32 77

128 21

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What is the percentage increase in mass of seed harvested as planting density increases from 4 to 14 plants per square metre?

A 45%

B 75%

C 90%

D 105%

5. a) Arrange the following stages of genetic engineering in the correct order.

Stage number Description of stage

1 Bacterial cell produces insulin 2 Insulin gene inserted into plasmid 3 Plasmid removed from bacterial cell 4 Plasmid inserted into bacterial cell 5 Insulin gene removed from human chromosome

b) Give one advantage of genetic engineering.

6. Labelled diagrams may be included where appropriate.

Genetic engineering uses bacteria to produce human insulin. Describe the stages involved in this process. 3

Items 7 and 8 refer to the accompanying diagram which shows the genetic material of a bacterium.

7. Which structure is the chromosome?

A 1

B 2

C 4 1

D 6

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8. Which structure is a plasmid?

A 2

B 3

C 4 1

D 7

9. Other than insulin, name another product made through genetic engineering. 1

Items 11, 12 and 13 refer to the following list of procedural steps employed during a genetic engineering experiment.

1 host cell allowed to multiply 2 required DNA fragment cut out of appropriate chromosome 3 duplicate plasmids formed which express ‘foreign’ gene 4 plasmid extracted from bacterium and opened up 5 altered plasmid inserted into bacterial host cell 6 DNA fragment sealed into plasmid

10. The correct order in which these steps would be carried out is

A 2,4,6,5,1,3

B 2,4,5,6,3,1

C 4,6,2,5,3,1 1

D 4,6,2,5,1,3

11. A special enzyme that acts as biochemical ‘scissors’ would be used

during steps

A 2 and 4

B 2 and 6

C 4 and 5 1

D 4 and 6

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12. A special enzyme that acts as biochemical ‘glue’ would be used

at stage

A 2 1

B 4

C 5

D 6

13. Insulin produced by genetic engineering is given to people who would otherwise suffer

A haemophilia

B reduced growth 1

C diabetes mellitus

D internal blood clotting

14. The first of the accompanying diagrams shows two preparatory

stages carried out during the process of genetic engineering.

Which part of the second diagram shows a later stage in the process?

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Section 1.7: Respiration

1. The energy yield per glucose molecule during aerobic respiration is

A. 2 molecules of ATP

B. 18 molecules of ATP

C. 36 molecules of ATP

D. 38 molecules of ATP

2. The following are statements about respiration.

1 ATP is produced

2 Lactic acid is produced

3 Carbon dioxide is produced

4 Ethanol is produced

3. Which of the following stages in respiration would result in the production of 38 molecules

of ATP?

A. Glucose to pyruvic acid

B. Pyruvic acid to lactic acid

C. Pyruvic acid to carbon dioxide and water

D. Glucose to carbon dioxide and water

4. After running a race an athlete experienced muscle fatigue.

Which of the following had increased in the muscles?

A. Glucose

B. Oxygen

C. ATP

D. Lactic acid

5. The diagram below shows energy transfer within a cell

Which line of the table below identifies correctly compounds X and Y

X Y

A Glucose ATP

B Glucose ADP

C ADP ATP

D ATP Glucose

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6. The process of aerobic respiration in a muscle cell is outlined below.

Glucose

Product Y

Carbon dioxide

+ water

a) (i) Name Stage 1

_____________________________ 1

(ii) Name product Y from Stage 1

_____________________________ 1

(iii) What other substance must be present for Stage 2 to occur?

______________________________ 1

b) ATP is formed during respiration and broken down for uses in cells.

(i) How many molecules of ATP are formed from each glucose molecule during

Both Stage 1 and 2? _________ 1

(ii) What two molecules are produced when ATP is broken down?

______________ and ____________ 1

(iii) State one use of the energy released when ATP is broken down.

__________________________________________________________ 1

Stage 1

Stage 2

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7. An investigation was carried out into the effect of temperature on the rate of respiration by

yeast.

Details of the apparatus , method used and results are given below.

Apparatus

Method

1 Water baths were set up over a range of temperatures.

2 100cm3 of glucose solution and 50cm3 of yeast suspension were allowed to reach the

same temperature as the water bath.

3 The glucose solution and the yeast suspension were mixed in the reaction flask.

5 After 1 hour, the volume of gas in the measuring cylinder was measured.

Results

Temperature (°C) 10 20 30 40 50

Volume of gas produced in 1 hour (cm3 ) 9 18 36 48 5

a) Ethanol was formed in the reaction flask.

What cell process produced this?

____________________________________________________ 1

b) Describe the relationship between the temperature and the volume of gas produced in one

hour.

______________________________________________________________

______________________________________________________________ 2

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c) Predict the volume of gas which would be collected in one hour if the investigation was

repeated at 60°C. Give an explanation for your answer.

Prediction ___________cm3 1

Explanation -_______________________________________________________

__________________________________________________________________ 1

d) Describe the control flasks that would be set up to show that the gas was produced due to

activity of the yeast and to no other factor.

_____________________________________________________________________

_____________________________________________________________________ 2

e) Use the results to complete a line graph to show the volumes of gas produced in one hour

over the range of temperatures. 2

Section 1.8: Photosynthesis

1. Fill in the blanks to complete the word equation for photosynthesis.

Light energy

Carbon dioxide + water _______________ + oxygen

__________________ _ 2

2. What is the first stage of photosynthesis called?

A. Carbon fixation

B. Photolysis

C. The light dependent stage

D. Mitosis 1

3. Name one useful product that a plant can use glucose for once it has been produced.

__________________________________ 1

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4. What chemical can absorb light energy and convert this into chemical energy?

___________________________________ 1

5. State the three environmental limiting factors that can affect the rate of photosynthesis.

1. __________________________________

2. __________________________________

3. __________________________________ 3

6. What are the limiting factors at point A and B?

A: __________________________________________

B: ___________________________________________ 2

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7. Decide if each of the following statements is True or False and tick () the appropriate box.

If the statement is False, write the correct word in the Correction box to replace the word

underlined in the statement.

True or False Correction

Excess carbon dioxide diffuses from the cell.

Light energy is converted into chemical energy in the form of ATP.

8. a) Fill in the blanks to complete the diagram of the first stage of photosynthesis.

A: ____________________________

B: ____________________________ 2

b) What is the name of the above process?

______________________________________ 1

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c) What controls the different stages involved in photosynthesis?

______________________________________ 1

9. The diagrams below show four experiments used in an investigation into the conditions

needed for photosynthesis.

The results from which two experiments should be compared to show that light is needed for

photosynthesis?

A. 1 and 2

B. 1 and 4

C. 2 and 3

D. 3 and 4 1

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10. The graph below show the effects of two different environmental factors on the rate of

photosynthesis.

a) What are the limiting factors at points X and Y?

X _______________________________________ 1

Y _______________________________________ 1

11. Suggest one way that the rate of photosynthesis can be measured?

___________________________________________________________________

___________________________________________________________________ 1

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12. The following diagram shows a stage of photosynthesis.

a) What are molecules A and B?

A ___________________________________

B___________________________________ 1

b) What is this stage of photosynthesis called?

___________________________________________ 1

c) Name the two products produced in the first stage of photosynthesis that are required for

the second stage of photosynthesis.

____________________________________

____________________________________ 1

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13. The diagram below shows the green water plant Elodea used in an experiment to investigate

photosynthesis.

Describe how the requirements for photosynthesis shown in the diagram are used in

photolysis and carbon fixation to produce oxygen and starch.

_______________________________________________________________________

_______________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________ 5

14. The grid below contains compounds which contain carbon and are found in plants.

Use the letters to complete the flow diagram below.

Place one letter in each box to name the carbon compound present at each stage.

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15. In an investigation into the rate of photosynthesis, a piece of Elodea (pondweed) was placed

in a beaker of water and a bright light shone on it.

Bubbles of oxygen given off from the Elodea were counted. This was repeated with the

lamp at different distances from the Elodea.

A graph of the results is shown below.

a) (i) What was the rate of bubbling when the lamp was at a distance of 200mm from the

Elodea?

_______ bubbles per minute 1

(ii) What distance between the lamp and the Elodea would give a rate of bubbling of 5

bubbles per minute?

__________ mm 1

(iii) What would happen to the rate of bubbling if the container with the Elodea was

placed in the dark?

_______________________________________________________ 1

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b) (i) At which distances between the lamp and the Elodea did light act as a limiting factor

on the rate of photosynthesis?

Tick the correct box.

50 – 150 mm

150 – 400 mm

400 – 500 mm 1

(ii) Name one other factor which could limit the rate of photosynthesis.

____________________________________________________________ 1

c) The investigation was carried out several times and the average results were used to

plot the graph. Why was this good experimental technique?

____________________________________________________________ 1

16. The graphs below show the effect of increasing light intensity on the rate of photosynthesis

of plant at two different temperatures. All other conditions were kept constant.

a) Use the information in the graph to identify the limiting factors at points X and Y.

At point X the limiting factor is ________________________________________

At point Y the limiting factor is ________________________________________ 2

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b) Name another factor, not indicated in the graph, which could affect the rate of

photosynthesis.

_________________________________________________________________ 1

c) What measurement is used to indicate the rate of photosynthesis?

__________________________________________________________________ 1