Curriculum for Excellence - Larbert High School1438]Unit_2_Homework_Booklet.pdf · Curriculum for Excellence Higher Biology ... Catechol oxidase is an enzyme found in apple ... The

Curriculum for Excellence Higher Biology

Name: _________________________

Key Area Feedback Mark

2.1. Metabolism pathways and their control

2.2. Cellular respiration

2.3. Metabolic rate

2.4. Metabolism in conformers and regulators

2.5. Metabolism and adverse conditions

2.6. Environmental control of metabolism

2.7. Genetic control of metabolism

CfE Higher Biology Unit 2 Metabolism & Survival Homework

2

Key Area 2.1 1. In the condition phenylketonuria (PKU), the human body is unable to

A synthesise phenylalanine from tyrosine B secrete phenylalanine from cells C absorb phenylalanine into the bloodstream D convert phenylalanine to tyrosine.

2. 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/carbohydrates) and has a (fibrous/porous) nature. As a result, the membrane is (fully/selectively) permeable.

3. Membranes can form small compartments within cells. Small compartments have A high surface to volume ratios and allow low concentrations of substrates

inside B high surface to volume ratios and allow high concentrations of substrates

inside C low surface to volume ratios and allow low concentrations of substrates

inside D low surface to volume ratios and allow high concentrations of substrates

inside.

4. The sodium–potassium pump spans the plasma membrane. Various processes involved in the active transport of sodium and potassium ions take place either inside the cell (intracellular) or outside the cell (extracellular).

Which line in the table correctly applies to the transport of potassium ions?


3

5. The graph below shows the effect of substrate concentration on the rate of an enzyme-catalysed reaction.

At which substrate concentration is the reaction rate equal to 75% of the maximum rate? A 5 units B 8 units C 12 units D 15 units

6. The reaction below is part of a metabolic pathway in cells.

amino acids polypeptide Which line in the table below correctly identifies the type of reaction and whether it releases or takes up energy?


4

7. The graph below shows the mass of product resulting from an enzyme controlled reaction.

What is the initial rate of reaction? A 0·53 mg s−1 B 0·63 mg s−1 C 0·89 mg s−1 D 1·60 mg s−1

8. The table below shows the results of an investigation into the effects of varying substrate concentration on the activity of the enzyme phosphatase in the presence of inhibitors. The greater the absorbance the more active the enzyme. What valid conclusion can be drawn from the results?

A An increase in substrate concentration reduces the effect of all three

inhibitors. B All three inhibitors are competitive inhibitors. C Inhibitor Z has least effect on enzyme activity. D Inhibitor Y has least effect on enzyme activity.


5

9. Which of the following is responsible for cell-cell recognition?

A Glycoprotein B Phospholipid C Hormones D Peptidoglycan

10. The diagram below shows the distribution of protein molecules in a cell membrane.

Which line in the table below correctly identifies a peripheral and an integral membrane protein?

11. An inhibitor of an enzyme-catalysed reaction can be described as competitive if

A its effect is decreased by raising substrate concentrations B it is the final product in a metabolic pathway C it switches off the gene encoding the enzyme D it permanently changes the shape of the active site.


6

12. Liver tissue contains an enzyme which breaks down alcohol. The graph below shows the effect of different concentrations of copper ions on the breakdown of alcohol by this enzyme over a 30 minute period.

Which of the following conclusions can be drawn from the graph?

A 4·5 mM copper has no effect on enzyme activity. B 2·5 mM copper halves the enzyme activity. C 0·5 mM copper completely inhibits enzyme activity. D Enzyme activity increases when copper concentration is increased from 1 mM

to 2 mM.

13. The diagram below shows a metabolic pathway that is controlled by end product inhibition.

For Substance 4 to bring about end product inhibition, which of the following will it interact with?

A Substance 1 B Substance 3 C Enzyme 1 D Enzyme 3


7

14. The diagram below shows an enzyme-catalysed reaction.

Which of the following correctly identifies molecule P? A Substrate B Activator C Competitive inhibitor D Non-competitive inhibitor


8

15. Phenylalanine and tyrosine are amino acids produced from the digestion of protein in the human diet. Once absorbed, they are involved in the metabolic pathway shown below.

The condition phenylketonuria (PKU) can be caused by the absence of enzyme 1. (a) Describe what leads to the absence of enzyme 1 in this condition. _________________________________________________________________________ _________________________________________________________________________ (b) Explain why individuals with PKU still develop some pigment in their skin. _________________________________________________________________________ _________________________________________________________________________ (c) State the role of thyroxine in the human body. _________________________________________________________________________ _________________________________________________________________________

16. The diagram below shows a section of plasma membrane with proteins labelled A to E.

(a) Identify which of the proteins A to E are integral membrane proteins.

__________________________________________________________________________________________________________________________________________

(b) Which type of signalling molecule requires a receptor protein at the cell surface? __________________________________________________________________________________________________________________________________________


9

17. Catechol oxidase is an enzyme found in apple tissue. It is involved in the reaction which produces the brown pigment that forms in cut or damaged apples.

The effect of the concentration of lead ethanoate on this reaction was investigated.

10 g of apple tissue was cut up, added to 10cm3 of distilled water and then liquidised and filtered. This produced an extract containing both catechol and catechol oxidase.

Test tubes were set up as described in Table 1 and kept at 20 ºC in a water bath.

Every 10 minutes, the tubes were placed in a colorimeter which measured how much brown pigment was present.

The more brown pigment present the higher the colorimeter reading.

The results are shown in Table 2.


10

(a) (i) Identify two variables not already mentioned that would have to be kept constant. 1 ____________________________________________________________________

2 ____________________________________________________________________

(ii) Describe how tube A acts as a control in this investigation. _____________________________________________________________________ _____________________________________________________________________

(b) Explain why the initial colorimeter readings were not 0.0 units. _____________________________________________________________________ _____________________________________________________________________

(c) The results for the extract with 0.1% lead ethanoate are shown in the graph below.

Use information from Table 2 to complete the graph by:

(i) adding the scale and label to each axis;

(ii) presenting the results for the extract + 0.01% lead ethanoate solution and labelling the line.

(d) State the effect of the concentration of lead ethanoate solution on the activity of catechol oxidase. _____________________________________________________________________ _____________________________________________________________________

(e) The experiment was repeated with the 0.1% lead ethanoate solution at 60 °C. Predict the colorimeter reading at 10 minutes and justify your answer. Prediction _____________ units

Justification _________________________________________________________

_____________________________________________________________________


11

18. Cholesterol is an important component of cell membranes and a starter molecule in the formation of steroid hormones. (a) Give one role of cholesterol in cell membranes.

__________________________________________________________________________________________________________________________________________

(b) When cholesterol accumulates in the wall of an artery, the plaque that forms reduces the internal diameter of the vessel.

Plaque formation (atherosclerosis) is a major cause of heart disease. Statins are taken to reduce blood cholesterol and are one of the most commonly prescribed medications.

Cholesterol is synthesised by cells in a sequence of steps starting with acetyl-CoA from the Krebs cycle.

The step that limits the rate of production is near the start and is catalysed by the enzyme HMG-CoA reductase, as illustrated below.

(i) In this pathway, a form of end-product inhibition occurs in which increasing cholesterol promotes the destruction of HMG-CoA reductase.

Describe how end-product inhibition would be achieved if the enzyme was allosteric.

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

(ii) Statins are competitive inhibitors of HMG-CoA reductase.

Explain how they would reduce cholesterol formation.

______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


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(iii) The graph below shows results of an experiment done in 1976 on three forms of a substance, ML-236, extracted from a fungal culture.

The experiment was assessing how well these substances inhibit cholesterol formation, the key requirement for a potential statin.

Use data for 50% inhibition to compare the effectiveness of the three molecules as potential statins.

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

19. Describe the control of enzyme activity by competitive and non-competitive inhibitors. ___________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


13

20. Enzyme kinetics is the study of the rate of enzyme-catalysed reactions.

The graph below shows the rates of the reaction for the enzyme penicillinase over a range of substrate concentrations. The substrate is penicillin.

The Michaelis constant (Km) of an enzyme is the substrate concentration at which the reaction rate is half its maximum rate.

(a) Calculate the Km of penicillinase assuming the graph shows that the maximum rate has been reached. ________________________________________________________________________________________________________________________________________

(b) Explain why the Km of an enzyme increases when a competitive inhibitor is present. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

(c) The turnover number of an enzyme is the number of substrate molecules converted into product by an enzyme in one second when an enzyme is working at its maximum rate. The turnover number for penicillinase is 2000 per second.

Calculate the time taken to catalyse the breakdown of one penicillin molecule. ________________________________________________________________________________________________________________________________________


14

21. Write notes on:

(a) structure of the plasma membrane;

(b) function of the plasma membrane in active transport;

(c) structure and function of the cell wall.

___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


15

22. Give an account of proteins in the following contexts:

(a) membranes;

(b) cell signalling;

(c) cytoskeleton.

___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


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23. Give an account of enzyme action and enzyme inhibition. ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


17

Key Area 2.2 1. Which of the following must be present in a living cell for glycolysis to occur?

A Glucose and ATP B Pyruvic acid and oxygen C Glucose and oxygen D Pyruvic acid and ATP

2. Which of the following chemical changes in cells results in the synthesis of most ATP?

A Glucose to pyruvic acid B Pyruvic acid to lactic acid C Pyruvic acid to acetyl group D Pyruvic acid to carbon dioxide and water

3. The processes in the list below occur in living cells.

1 NADP acts as a hydrogen acceptor. 2 ATP is synthesised. 3 Oxygen acts as a hydrogen acceptor. 4 Carbon dioxide enters a cycle of reactions.

Which line of the table below matches each process with the set of reactions in which it

occurs?


18

4. The statements in the list below refer to respiration.

1 Carbon dioxide is released. 2 Occurs during aerobic respiration. 3 The end product is pyruvic acid. 4 The end product is lactic acid.

Which statements describe glycolysis?

A 1 and 4 B 1 and 3 C 2 and 3 D 2 and 4

5. The diagram below represents a summary of respiration in a mammalian muscle cell.

Which box represents ATP?

6. Which line in the table below correctly shows the two chemical reactions which occur in

the grana of a chloroplast following the absorption of light energy by chlorophyll?


19

7. Which line in the table below correctly shows the number of molecules of ATP used and

produced when one molecule of glucose undergoes glycolysis?

8. Which of the following produces water?

A Krebs cycle B Glycolysis C Photolysis D Cytochrome system

9. The table below refers to processes in cellular respiration.

Which line in the table below correctly identifies processes X, Y and Z?


20

10. The diagram below shows energy transfer within a cell.

Which line in the table below identifies correctly compounds X and Y?

11. Which line in the table below shows correctly the sites of stages in aerobic respiration?


21

12. The diagram below shows the regeneration of ATP in a cell.

The following statements relate to this diagram.

1 Reaction X releases energy for anabolic pathways. 2 Reaction Y releases energy for anabolic pathways. 3 Reaction X is catalysed by ATP synthase. 4 Reaction Y is catalysed by ATP synthase.

Which statements are correct?

A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

13. An investigation was carried out into the uptake of sodium ions by animal cells.

The graph below shows the rates of sodium ion uptake and breakdown of glucose at different concentrations of oxygen.

How many units of sodium ions are taken up over a 5 minute period when the concentration of oxygen in solution is 2%?

A 80 B 100 C 400 D 500


22

14. The energy content of a glucose molecule is 2900 kilojoules. A glucose molecule

entering aerobic respiration transfers 1160 kilojoules of the energy to ATP.

What percentage of energy in glucose is transferred to ATP?

A 40 B 60 C 150 D 250

15. The final electron acceptor in the electron transport chain of respiration is

A NADH B water C ATP D oxygen


23

16. In an investigation into the effect of lead ion concentration on respiration in yeast, two flasks were set up as described below.

The flasks were placed in a water bath at 20 °C for 10 minutes. After this time 2·5 cm3 of yeast suspension was added to each and oxygen sensors fitted as shown in the diagram below.

The flasks were left for a further 10 minutes and then oxygen concentration was measured in each flask every 20 seconds for 2 minutes. The results are shown in the table below.

(a) (i) Identify the independent variable in this investigation. ____________________________________________________________________ (ii) Identify one variable, not already mentioned, which would have to be kept constant so that valid conclusions could be drawn. ____________________________________________________________________


24

(ii) Explain why the flasks were left for 10 minutes before the yeast suspension was added. ____________________________________________________________________________________________________________________________________________________________________________________________________________ (iii) Explain why the flasks were left for a further 10 minutes after the yeast suspensions were added before measurement of oxygen concentrations were taken. ____________________________________________________________________________________________________________________________________________________________________________________________________________

(b) On the grid provided, draw a line graph to show the oxygen concentration in Flask A against time. Use an appropriate scale to fill most of the grid.

(c) Using information from the table, state the effect of increasing lead ion concentration on the aerobic respiration of yeast. ________________________________________________________________________________________________________________________________________


25

(d) Bubbles of gas appeared in both flasks throughout the investigation. (i) Name this gas.

______________________________________________________________________________________________________________________________

(ii) Explain why this gas continued to be produced in Flask A at 120s.

______________________________________________________________________________________________________________________________

17. Cyanide is a poison that inhibits enzymes involved in aerobic respiration.

The graph below shows how cyanide concentration affects the uptake of chloride ions by beetroot cells.

The rates of chloride ion uptake are given as percentages of those obtained in a control experiment with no cyanide.


26

(a) Predict the cyanide concentration at which chloride ion uptake would stop.

______________ units

(b) The rate of chloride ion uptake by beetroot at 30 units of cyanide was 200 μg per hour.

Calculate the rate of uptake in the control experiment.

Space for calculation

___________________ μg per hour

(c) The uptake of chloride ions occurs by active transport.

Explain how the information given supports this statement. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

18. The diagram below shows an outline of respiration in yeast cells.

(a) State the location of glycolysis in yeast cells. _______________________________________________________________________


27

(b) Name one substance, other than glucose, which must be present for glycolysis to occur.

_______________________________________________________________________

(c) Name compounds R and S.

R __________________________________________________________________

S __________________________________________________________________

(d) Explain why the further stages of respiration cannot occur in anaerobic conditions. ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

19. In an investigation, yeast was grown in a glucose solution for 160 minutes in a sterilised

fermenter. Temperature was kept constant and anaerobic conditions were maintained.

The graph below shows the changes in concentration of ethanol in the fermenter during

the period.

(a) (i) Calculate the increase in concentration of ethanol between 60 and 140 minutes.

___________ grams per litre


28

(ii) Calculate the average increase in ethanol concentration per minute during the first 40 minutes.

___________ grams per litre per minute

(b) (i) At point A on the graph, the ethanol concentration stopped increasing when air temporarily leaked into the fermenter.

Explain this result.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

(ii) Assuming no further air leaks, explain why the ethanol concentration stopped increasing at point B.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

20. The diagram below shows some of the steps in respiration.


29

(a) Complete the table below by naming substances W, X and Y.

(b) State the number of carbon atoms present in a molecule of substance Z.

_______________________________________________________________________

21. Yeast cells were grown in both aerobic and anaerobic conditions and the volume of

carbon dioxide produced was measured.

The results are shown in the graph below.

(a) At which time is there the greatest difference between the volumes of carbon

dioxide produced in aerobic and anaerobic conditions?

Tick (✓) the correct box.


30

(b) Calculate the average rate of carbon dioxide production per hour over the first 6

hours in aerobic conditions.


__________ cm3 per hour

22. The diagram below shows parts of two stages in the aerobic respiration of glucose.

(a) Name stages X and Y.

X __________________________________________________________________

Y __________________________________________________________________


31

(b) Name compounds P and Q.

P __________________________________________________________________

Q __________________________________________________________________

(c) Describe the role of the dehydrogenase enzymes in stages X and Y.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

(d) The diagram below shows part of the electron transport chain attached to the inner

membrane of a mitochondrion.

(i) In this system, hydrogen ions are pumped across the inner mitochondrial membrane as shown in the diagram.

Describe the source of energy required for this process.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

(ii) The return flow of hydrogen ions drives enzyme X which results in the production

of ATP.

Name enzyme X.

___________________________________________________________________

(iii) State the role of oxygen in the electron transport chain.

___________________________________________________________________

___________________________________________________________________


32

23. Give an account of the structure of a mitochondrion and the role of the cytochrome system in respiration.

___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


33

24. Give an account of glycolysis and the citric acid cycle in cells. ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


34

Key Area 2.3 1. The graphs below show the results of an experiment into the effect of aerobic and

anaerobic conditions on the uptake of calcium and magnesium ions by pond algae.

Which of the following is a valid conclusion that can be drawn from the results?

A At 120 minutes in aerobic conditions the uptake of calcium ions is greater than that of magnesium ions.

B At 60 minutes in anaerobic conditions there was a greater uptake of calcium ions compared with magnesium ions.

C Over the 120 minutes in aerobic conditions the average rate of uptake of calcium ions is greater than that of magnesium ions.

D At 60 minutes in anaerobic conditions there was a greater uptake of magnesium ions compared with calcium ions.

2. The table below shows the mass of water gained and lost by a small mammal over a 24-

hour period.

What percentage of water gained comes from metabolic water?

A 9% B 45% C 54% D 90%


35

3. The graph below shows the effect of the carbon dioxide concentration of inhaled air on

the breathing rate of an individual.

If the volume of one breath is 0·5 litre, what volume of air will be breathed in one minute

when the CO2 concentration is 4%?

A 6 litres B 9 litres C 18 litres D 36 litres

4. An investigation was carried out into the uptake of sodium ions by animal cells. The

graph below shows the rates of sodium ion uptake and breakdown of glucose at different

concentrations of oxygen.


36

How many units of sodium ions are taken up over a 5 minute period when the

concentration of oxygen in solution is 2%?

A 80 B 100 C 400 D 500

5. The graph below shows the effect of air temperature on the metabolic rate of two

different animals.

Which line in the table below identifies correctly the temperatures at which oxygen

consumption will be greatest in the tissues of each animal?


37

6. In an investigation into the metabolic rate of a snail at rest, its oxygen uptake was

measured using the apparatus shown in the diagram below.

The apparatus was kept at 10 °C with the tap open for 15 minutes. To start the

experiment, the tap was closed and the reading on the scale recorded.

Every 2 minutes for 10 minutes, the oxygen uptake was recorded by taking readings from

the scale.

The results are shown in the table below.

(a) Explain why the apparatus was left for 15 minutes with the tap open before readings

were taken.

_____________________________________________________________________

_____________________________________________________________________


38

(b) Describe a suitable control for this investigation.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

(c) Identify the dependent variable in this investigation.

_____________________________________________________________________

_____________________________________________________________________

(d) To increase the reliability of results, the experiment was repeated several times.

Identify one variable, not already mentioned, that would have to be kept the same

each time to ensure that the procedure was valid.

_____________________________________________________________________

_____________________________________________________________________

(e) On the grid below, draw a line graph to show the reading on the scale against time,

choosing appropriate scales so that the graph fills most of the grid.


39

(f) The mass of the snail was 5·0 g.

Use results in the table to calculate the rate of oxygen uptake by the snail over the

10 minute period.

________________ cm3 oxygen per minute per gram of snail

(g) Predict the effect of an increase in temperature to 15 °C on the oxygen uptake by

the snail and justify your answer.

Prediction _________________________________________________________

_____________________________________________________________________

Justification _________________________________________________________

_____________________________________________________________________

(h) Explain how the respiration of the snail and the presence of the solution in the test

tube results in the movement of the coloured liquid on the scale.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

7. The following diagrams represent the structures of fish, mammal and amphibian hearts.


40

(a) Complete the table below by inserting the correct letters, animal group and type of

circulation.

Heart Animal Group

Type of circulation

(single, incomplete double

or complete double)

single

mammal

S

(b) Add arrows in the vessels X, Y and Z on the diagrams to indicate the direction of flow

of blood within them.

(c) Explain how heart R is better adapted than heart S to allow a high metabolic rate in

the cells which it supplies with blood.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

8. The graph shows the rate of potassium ion uptake by human liver cells in different

oxygen concentrations at 30 °C.


41

(a) When the oxygen concentration is 1%, how many units of potassium would a cell

take up in one hour?

________________ units per hour

(b) Suggest a reason why the graph levels off at oxygen concentrations above 3·5%.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

(c) When the experiment was repeated at 20 °C, the potassium ion uptake decreased.

Explain this observation.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________


42

Key Area 2.4 and 2.5

1. The drinking rate and concentrations of sodium and chloride ions in blood were

measured over a six hour period after a salmon was transferred from freshwater to

sea water.

The results are shown in the graph below.

Which line in the table correctly shows the results after three hours?


43

2. Which line in the table below shows features likely to be found in a plant and in a

small mammal both adapted to life in hot desert conditions?

3. The statements below describe methods of maintaining a water balance in fish.

1 Salts actively absorbed by chloride secretory cells

2 Salts actively secreted by chloride secretory cells

3 Low rate of kidney filtration

4 High rate of kidney filtration

Which of these are used by freshwater bony fish?

A 1 and 3 only

B 2 and 4 only

C 1 and 4 only

D 2 and 3 only

4. Which line in the table below shows correctly the main source of body heat and the

method of controlling body temperature in an ectotherm?


44

5. The graph below shows the relationship between air temperature and the body

temperature of two animal species X and Y.

Which line in the table below correctly describes species X and Y?

6. The figure below shows the general relationships between the internal environment

and variation in the external environment of four animals.

Which animal could occupy the widest range of habitats?


45

7. The graphs below show how environmental changes can affect the internal

conditions in aquatic organisms W, X, Y and Z.

Which line in the table correctly identifies the osmoconformer and the

homeotherm?

8. Animals may interact with their environment by conformation or regulation. Each

statement below applies to one of these interactions.

1 A wide range of habitats can be occupied

2 A restricted range of habitats can be occupied

3 There is a high energy cost

4 There is no energy cost

Which statements apply to conformation?

A 1 and 4

B 1 and 3

C 2 and 4

D 2 and 3


46

9. The diagram below shows a section through the skin of a mammal.

Which line in the table below correctly identifies the state of the erector muscle and

the change in blood flow in the capillary which would be expected if the skin was

exposed to low temperature?

10. Which graph below best illustrates the effect of increasing temperature on oxygen

consumption in a conformer and a regulator?


47

11. In an investigation, 50 salmon were kept in a tank of fresh water for four days, then

transferred to a tank of salt water for a further six days.

Each day, their gills were examined and the average diameter of chloride secretory

cells was recorded.


(a) In the following sentence, underline one alternative in each pair to make the

sentence correct.

On day 3 the salmon are (hypertonic / hypotonic) to their

surroundings and their chloride secretory cells actively transport salts

(into / out of) the salmon.

(b) Describe the effect of salt water on the average diameter of the chloride

secretory cells between day 5 and day 10.

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

(c) Following the investigation, the fish were returned to fresh water. In the table

below, tick one box in each row to show how this change affects kidney

function.


48

12. The diagram shows an outline of the control of body temperature in a mammal.

(a) (i) State the exact location of the temperature monitoring centre.

__________________________________________________________________

__________________________________________________________________

(ii) The skin has effectors which are involved in corrective mechanisms A and B.

State how messages are sent from the temperature monitoring centre to the

skin.

__________________________________________________________________

__________________________________________________________________

(iii) Give one example of a corrective mechanism B and explain how it would

return the body temperature to normal.

Example ___________________________________________________

Explanation ___________________________________________________

___________________________________________________

___________________________________________________

(iv) Explain why maintaining body temperature within tolerable limits is important

to the metabolism of mammals.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

(b) Mammals obtain most of their heat from their metabolism.

Give the term which describes animals that obtain most of their body heat from

their surroundings.

__________________________________________________________________

__________________________________________________________________


49

13. The list below shows conditions which must be maintained within tolerable limits in

the human body.

A blood glucose concentration

B blood water concentration

C body temperature

(a) Use all the letters from the list to complete the table below to show where each

condition is monitored.

(b) The liver contains a reservoir of stored carbohydrate.

Name two hormones which can cause the breakdown of this carbohydrate to

increase the concentration of glucose in the blood.

1 _______________________________________________________________

2 _______________________________________________________________

(c) An increase in blood water concentration causes a reduction in the level of ADH

in the bloodstream.

Describe the effect of this reduction on the kidney tubules.

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

(d) (i) When body temperature falls below normal, the blood vessels in the skin

respond.

State how the blood vessels in the skin respond and explain how this helps return

body temperature to normal.

Blood vessel response _____________________________________________

_____________________________________________

Explanation _____________________________________________

_____________________________________________

_____________________________________________

(ii) What term is used to describe animals which derive most of their body heat

from their own metabolism?

__________________________________________________________________

__________________________________________________________________


50

14. Animals that live under polar sea-ice benefit from adaptations that allow them to

survive changes in the salinity of their immediate environment as the ice freezes and

thaws. The crustacean Gammarus wilkitzkii is a dominant species of the Arctic ice

community.

During the summer, as sea-ice melts, this species experiences low salinity and during

sea‑ice growth in the winter it is exposed to high salinity.

Figure 1 shows the rate of oxygen consumption of this animal when transferred to

water of varying salinity. Figure 2 shows ion concentrations in its body fluids at the

higher salinities.

(a) Refer to Figure 1. Explain how the data suggest that Gammarus wilkitzkii is a

regulator in salinities up to 2·5%.

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

(b) Refer to Figure 2.

(i) What term is used to describe an organism that shows this type of

physiological response?

_______________________________________________________________


51

(ii) Increasing concentrations of ions in body fluids lower the temperature at

which these fluids will freeze. Suggest how the response shown in Figure 2

would aid the survival of G. wilkitzkii during winter.

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

(c) Another crustacean, Parathemisto libellula, is unable to tolerate or resist salinity

variations. How would this affect the habitat range that it could occupy?

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

15. The table below refers to environmental problems that salt water bony fish and

desert rats have in osmoregulation and adaptations that these animals use to

maintain their water balance.

Complete the table by giving an environmental problem faced by salt water bony fish

and adding one adaptation to each empty box.


52

16. The diagram below represents a section through the skin of a mammal.

(a) Select one structure labelled in the diagram and explain how it responds to a

decrease in temperature to bring about a correction in body temperature.

Structure ___________________________________________________

Explanation ___________________________________________________

___________________________________________________

___________________________________________________

(b) (i) Explain the importance of thermoregulation to mammals.

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

(ii) Reptiles have behavioural adaptations to help them to thermoregulate.

Give one example of this.

__________________________________________________________________

__________________________________________________________________

(c) Name one external abiotic factor, other than temperature, which can affect the

ability of an organism to maintain its metabolic rate.

__________________________________________________________________

__________________________________________________________________


53

17. Write notes on maintaining a water balance under the following headings:

(a) osmoregulation in salt water bony fish;

(b) water conservation in the desert rat.

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18. Write notes on the following :

(a) endotherms and ectotherms;

(b) temperature regulation in mammals.

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Key Area 2.6 1. The diagram below shows an image of a bacterial cell that has been magnified 1500

times.

What is the actual length of the cell in micrometres (μm)?

A 0·003

B 3·000

C 6750

D 6·750

2. The graph below shows a typical growth pattern for micro-organisms in culture.

At which point on the graph are most enzymes being induced to metabolise available

substrates?

3. Which line in the table below correctly represents the organelles in a prokaryotic

cell?


56

4. The following diagram shows a bacterial cell.

The length of this cell in millimetres (mm) is

A 800

B 80

C 0·008

D 0·0008

5. Complete the following sentences by underlining one of the alternatives in each pair.

Regeneration involves development of cells with specialised functions

from (differentiated / undifferentiated) cells through the switching on

or off of particular (hormones / genes). Mammals have (limited /

extensive) powers of regeneration.


57

6. A growth curve in a culture of bacteria is shown in the diagram below.

(a) In culturing bacteria it is important to control the pH of the culture medium.

Describe how the pH of a culture medium can be controlled.

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(b) (i) Name each of the phases of growth indicated by letters on the graph.

W _________________________________________________________

X _________________________________________________________

Y _________________________________________________________

Z _________________________________________________________

(ii) Give the letter which indicates a region of the graph in which most enzymes

are being induced to metabolise the available substrate.

Letter _________________________________________________________

(iii) Give one reason for the decrease in number of cells at phase Z.

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7. Many enzymes used in biotechnology are produced industrially by fermentation

using naturally occurring micro-organisms.

(a) Name one industrially produced enzyme and the micro-organism used in the

fermentation.

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(b) (i) Describe two conditions that need to be controlled during the fermentation

process used to produce enzymes.

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(ii) Give one method used in the recovery of enzymes from the fermentation

culture.

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(c) Explain what is meant when an industrial enzyme is described as a secondary

metabolite.

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8. To make yoghurt, milk is pasteurised and then inoculated with bacteria that allow

fermentation to occur. Two species commonly used together in the inoculum are

Lactobacillus bulgaricus and Streptococcus thermophilus.

(a) What is the purpose of pasteurisation?

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(b) The fermentation is a two-stage process.

(i) State the chemical conversion taking place in the first stage.

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(ii) What is the role of the second stage?

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(c) The graph shows the growth of L. bulgaricus and S. thermophilus in both pure and

mixed culture.

(i) Calculate the reduction in growth of L. bulgaricus at 8 hours as a result of being

in the mixed culture.

(ii) Scientists have suggested that S. thermophilus receives a growth promoting

substance in this mixed culture. How do the data support that conclusion?

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9. Describe how the growth rate constant of a bacterial culture can be determined.

What is its relevance when culturing bacteria for enzyme production?

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61

Key Area 2.7 1. The following steps are involved in the process of genetic engineering.

1 Insertion of a plasmid into a bacterial host cell.

2 Use of an enzyme to cut out the desired gene from a chromosome.

3 Insertion of the desired gene into the bacterial plasmid.

4 Use of an enzyme to open a bacterial plasmid.

What is the correct sequence of these steps?

A 4 1 2 3

B 2 4 3 1

C 4 3 1 2

D 2 3 4 1

2. The table below contains descriptions of terms used to illustrate the control of

lactose metabolism in the bacterium Esherichia coli.

Which line in the table contains terms which correctly match the descriptions given?

3. According to the Jacob-Monod hypothesis, a regulator gene is responsible for

A coding for the production of an inducer molecule

B switching on an operator

C coding for the production of a repressor molecule

D switching on a structural gene.


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4. The flow chart below represents the programming of E. coli bacteria to produce

human insulin.

Which line in the table below identifies correctly the stages at which an

endonuclease and a ligase are used?

5. Using recombinant DNA technology, the bacterium E. coli can be modified so that it

can produce human insulin. The following steps are involved.

1 Culture large quantities of E. coli in nutrient medium.

2 Insert human insulin gene into E. coli plasmid DNA.

3 Cut insulin gene from human chromosome using enzymes.

4 Extract insulin from culture medium.

The correct order of these steps is

A 3, 2, 1, 4

B 3, 1, 2, 4

C 1, 4, 3, 2

D 1, 2, 3, 4.


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6. The gene encoding a protein was removed from the human genome and transferred

into two different recipient cells by different methods as shown in the table below.

The protein was functional only when produced in yeast cells.

The most likely reason for this was because the

A bacterial plasmids did not contain marker genes

B protein produced in bacteria had an incorrect amino acid sequence

C bacterial plasmids did not contain self-replication genes

D protein produced in bacteria was not folded correctly.

7. The diagram below shows the restriction enzyme sites in a plasmid that carries the

genes for resistance to the antibiotics ampicillin and tetracycline.

Which line in the table below identifies correctly the antibiotic resistance that would

remain when a gene is inserted at these restriction enzyme sites?


64

8. Diagram A shows a bacterial plasmid containing genes for resistance to the

antibiotics tetracycline and ampicillin.

Diagram B shows this plasmid after it had been genetically engineered by inserting a

human blood-clotting gene.

(a) Give a technique which could be used to locate the position of the blood-clotting

gene on a human chromosome.

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(b) Two different enzymes are used to produce the genetically engineered plasmid.

Complete the table to show the function of each enzyme.

(c) The genetically engineered plasmids were inserted into bacteria. Using information

from the diagrams, explain why these bacteria were not resistant to tetracycline.

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9. In an experiment to investigate the Jacob-Monod hypothesis of lactose metabolism

in E. coli, flasks were set up as shown in the diagram below.

E. coli breaks down lactose using the enzyme β–galactosidase as shown.

(a) (i) β –galactosidase was produced in Flask 1.

Describe events which led to the production of this enzyme.

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(ii) β –galactosidase was not produced in Flask 2.

Explain the advantage to E. coli of not producing the enzyme in this case.

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(b) ONPG is a colourless substance which is converted to a yellow product by β –

galactosidase.

Use this information to describe how ONPG could be used to show that E. coli

only produced β –galactosidase in the presence of lactose.

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10. In the control of lactose metabolism in Escherichia coli (E. coli), lactose acts as an

inducer of the enzyme β-galactosidase.

The graph shows changes in concentrations of lactose and β-galactosidase after

lactose was added to an E. coli culture growing in a container.

(a) Describe how the graph supports the statement that β-galactosidase breaks

down lactose.

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(b) The statements in the table refer to times X, Y and Z on the graph.

Complete the table by writing true or false in each of the spaces provided.


67

11. Diagram 1 below shows a plasmid that contains two genes for antibiotic resistance.

Diagram 2 shows the same plasmid after modification by the insertion of a gene

from another organism.

(a) Two different enzymes are required to produce the modified plasmid.

Complete the table below by:

(i) naming the enzyme which cuts plasmids at specific restriction sites;

(ii) naming the second enzyme required to modify plasmids;

(iii) describing the function of the second enzyme.

(b) Bacteria took up the modified plasmids.

Explain why these bacteria will not have resistance to antibiotic Y.

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12. Escherichia coli is a species of bacteria found in the lower intestines of humans.

Sections of the DNA of two strains of E. coli are shown below.

Gene B codes for a protein known as Shiga toxin which can cause serious food

poisoning in humans.

(a) The gene for Shiga toxin has been acquired by E. coli 0157H7.

Give two methods by which the bacterial strain could have acquired this gene.

1 _______________________________________________________________

2 _______________________________________________________________

(b) E. coli K12 is routinely used in recombinant DNA technology. Explain why E. coli

K12 is used whereas E. coli 0157H7 is not.

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(c) Bacteria are used in recombinant DNA technology.

Explain why animal DNA which has been transferred to bacteria may produce

proteins which are not functional.

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13. Transgenic plants can be produced using genetically engineered plasmids. The

plasmids are obtained from bacteria that naturally infect plant cells. A modified

plasmid is shown in the diagram below.

Bacterial cells containing the modified plasmid are incubated with plant cells. The

plant cells are then cultured in a growth medium containing kanamycin.

(a) What is meant by the term transgenic?

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(b) Name the bacterial source of these plasmids.

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(c) Explain the role of kanamycin in the production of transgenic plants.

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(d) Give one example of the use of this transgenic technology

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70

14. The Jacob-Monod hypothesis describes lactose metabolism in the bacterium

Escherichia coli. Lactose acts as an inducer of the enzyme β-galactosidase in the

bacterium. This enzyme breaks down lactose as shown.

An investigation of this reaction in E. coli at 25 °C was carried out as described

below.

• 100cm3 of gel beads coated with E. coli were placed into each of seven identical funnels fitted with outlet taps.

• 100cm3 of solution containing 2 grams of lactose was poured into each funnel.

• At each time shown in the table, the solution from one of the funnels was collected.

• The mass of lactose in each solution was measured.


(a) Identify one variable, not already mentioned, that should have been controlled

to ensure that the experimental procedure was valid.

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(b) A control experiment would be needed for each funnel.

Describe such a control and explain its purpose in the investigation.

Description ________________________________________________________

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Purpose _________________________________________________________

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(c) On the grid provided below, draw a line graph to show the mass of lactose in the

solution collected against time.

Use an appropriate scale to fill most of the grid.

(d) Calculate the average mass of lactose broken down per minute in funnel 5.


____________ g per minute


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(e) Use the information given to explain why E. coli had not broken down any lactose

in the first 10 minutes.

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(f) State one advantage to E. coli of controlling lactose metabolism as described by

the Jacob-Monod hypothesis.

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15. The diagram below shows information relating to the Jacob–Monod hypothesis of

the control of gene action in the bacterium Escherichia coli.

(a) Name gene 1

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(b) Name the substance which acts as the inducer.

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(c) Describe the sequence of events that occurs in the absence of the inducer.

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(d) Explain why it is important for E. coli to control gene action.

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