Topic 4 - Exchange and Transport – Animals

Q1. 

Blood contains a variety of cells, plasma and clotting factors.

Smoking can increase the risk of blood clot formation.

An investigation was carried out to determine the effects of smoking on the contents of blood plasma.

In the first part of the investigation, blood samples were taken from male smokers and non-smokers aged between 35 and 50. All males were matched for health status, body mass and diet.

The concentration of fibrinogen in their blood plasma was measured.

The results are shown in the table.

In the second part of the investigation, blood samples were taken from men aged between 35 and 50 just after waking.

Another blood sample was taken just after the men had smoked their first cigarette.

The concentration of thrombin present in both blood samples was measured.

The concentration of thrombin present in the blood of the non-smokers was also measured.

The results are shown in the table.

Analyse the data to explain why smoking can increase the risk of blood clot formation.

(4)

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(Total for question = 4 marks) 

Q2. 

Scientists also investigated the effect of temperature on the percentage saturation of haemoglobin with oxygen, using blood from an Asian elephant.

The oxygen dissociation curves are shown in the graph.

(i)   In the alveolar capillaries, the partial pressure of oxygen is 12 kPa at a temperature of 38 °C and haemoglobin is fully saturated with oxygen.

In active muscle tissue, the partial pressure of oxygen is 2 kPa at a temperature of 43 °C.Use the graph to determine the percentage saturation of haemoglobin in active muscle tissue.

(1)

Answer ........................................................... %

(ii)  When 1g of haemoglobin is fully saturated it carries 1.3 cm3 of oxygen.

Calculate the volume of oxygen released by 1 g of haemoglobin to this active muscle tissue.Show your working.

(2)

Answer ...........................................................

(iii)  Scientists extracted the genes for mammoth haemoglobin and used them to produce mammoth haemoglobin.

The oxygen dissociation curve for mammoth haemoglobin at 38 °C was found to be the same as for the Asian elephant at 38 °C.Lowering the temperature did not shift the oxygen dissociation curve.Explain how these observations show that this haemoglobin enabled mammoths to be adapted for life in cold Arctic regions.

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(Total for question = 6 marks) 

Q3. 

Gills are the site of gas exchange in fish.

The table shows some information for five species of fish.

(i)   The comparison of surface area to mass of mullet is

(1)   A    1010 cm2 g–1

   B    10.10 cm2 g–1

   C    1.01 cm2 g–1

   D    0.99 cm2 g–1

(ii)  Analyse the data to explain the difference in the activity levels of these fish species.

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(Total for question = 4 marks) 

Q4. 

Water is the major component of tissue fluid in mammals.

In humans, left side heart failure can cause symptoms such as breathlessness, palpitations and a rapid pulse.

The table shows the mean blood pressure in the lung capillaries of patients with left side heart failure compared with healthy individuals.

(i)  Calculate the percentage increase in the mean blood pressure in the lung capillaries due to left side heart failure.

(1)

Answer ........................................................... %

(ii)  This increased blood pressure in the capillary will cause more tissue fluid to be formed.

Analyse this information to explain the symptom of breathlessness.

(2).............................................................................................................................................

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(iii)  In healthy individuals, only 80% of excess tissue fluid is reabsorbed directly into the blood stream.

Describe how the remaining 20% is reabsorbed.

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Q5. 

A student planned to keep two species of fish in an aquarium.

One species of fish should be kept at a minimum temperature of 25 °C. The other species requires a minimum concentration of oxygen of 7.5 mg dm−3 water.

Explain why the student chose to keep these two species of fish in an aquarium at 30 °C.

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(Total for question = 4 marks) 

Q6. 

Cholera is a disease caused by a bacterial infection that affects the absorption of water in the small intestine.

The bacteria that cause cholera release a toxin.

This toxin affects the CFTR protein found in the membrane of intestinal epithelium cells.

The toxin causes the CFTR protein to pump more chloride ions out of these cells into the intestine. This causes a lot of water to be lost in the faeces.

Explain how the toxin causes this water loss.

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(Total for question = 3 marks) 

Q7. 

There are many disorders that affect the health of people.

The graph shows the number of people in the world who die each year from different health disorders.

The graph shows that atherosclerosis kills more people than any of the other disorders.

This is mainly due to its development in the coronary arteries.

(i)  State the number of deaths caused by atherosclerosis.

Give your answer in standard form.(1)

Answer ...........................................................

(ii)  Describe how atherosclerosis develops in the coronary arteries.

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(Total for question = 4 marks) 

Q8. 

Some snakes bite their prey and inject venom. The venom is sometimes lethal.

A man was bitten by a snake. The snake venom circulated in his blood.

(i)  Which of the following shows the flow of blood through his heart?

(1)

   A    left atrium → bicuspid valve → left ventricle

   B    left atrium → tricuspid valve → right ventricle

   C    left ventricle → bicuspid valve → left atrium

   D    left ventricle → tricuspid valve → left atrium

(ii)  The snake venom circulated in the man's blood by mass transport.

Explain why this is more effective at killing prey than diffusion.(3)

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Q9. 

The pancreas is an organ that secretes digestive enzymes.

The electron micrograph shows part of a secretory cell from a human pancreas.

Calcium ions are needed for the secretion of enzymes from pancreatic cells.

The graph shows the effect of increasing calcium ion concentration on the uptake of calcium ions by pancreatic cells.

Explain the effects of calcium ion concentration on the rate of uptake of calcium ions through the pancreatic cell membrane.

(3)

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(Total for question = 3 marks) 

Q10. 

Amoeba proteus is a single-celled organism that lives in pond water.

Amoeba has a structure called a contractile vacuole that removes excess water from the cell.

Water that moves into the cytoplasm is transported into the contractile vacuole. When full, the contractile vacuole moves to the surface of the cell and fuses with the cell membrane. This allows the water it contains to be removed from the cell.

The diagram shows Amoeba with a contractile vacuole.

The actual diameter of the contractile vacuole shown in this diagram is 20 μm.

Calculate the magnification of this Amoeba.

(2)

Answer ...........................................................

 

(Total for question = 2 marks) 

Q11. 

The Northern elephant seal is a mammal found in the Eastern Pacific Ocean.

In the nineteenth century, Northern elephant seals were hunted and this reduced the population to about 20 seals.

The seals were listed as an Appendix II species when CITES was established in the 1970s.

The population has now recovered to over 100 000 individuals.

The seals in this population have developed health problems, including a high mortality rate for newborn pups, deformities and weak immune systems.

Northern elephant seals are able to dive to great depths and hold their breath for up to two hours.

The tables show data for four diving mammals.

(i)  Calculate the total mass of haemoglobin in a Northern elephant seal.

(3)

Answer ...........................................................

* (ii) Analyse the data to explain how marine mammals are adapted for diving.

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(Total for question = 9 marks) 

Q12. 

A student was interested to find out how his heart rate would vary throughout the day.

He wore a heart rate monitor from the time he woke up until the time he went to bed.

The graph shows the data collected and some of the student's activities during the day.

Calculate the rate of increase in the student's heart rate between 6 am and 8 am.

(2)

Answer ...........................................................

 

Q13. 

ATP is involved in a wide variety of biological processes such as active transport and muscle contraction.

A typical adult human body has a mass of 62 kg.

It contains approximately 250 g of ATP and has approximately 3.7 × 1013 cells.

(i)  Calculate the mean mass of ATP in one cell of a typical human.

Express your answer in standard form.(2)

Answer ........................................................... g

(ii)  Explain why this calculation does not give an accurate estimate of the mass of ATP in a nerve cell.

(2).............................................................................................................................................

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Q14. 

Each individual cell in an insect's body is supplied with oxygen from a tracheole.

The diagram shows the appearance of tracheoles in a resting insect.

The diameter of a tracheole is 1μm.

Calculate the magnification of the tracheoles in this diagram.

(2)

Answer ...........................................................

 

Q15.

 

Scientists have calculated that a typical person synthesises their own body mass in ATP every 24 hours.

(i)  Calculate the mean rate of ATP production in grams per second in a person with a body mass of 62 kg.

(2)

Answer ...........................................................

(ii)  Explain why people do not double their body mass in 24 hours due to ATP production.

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Q16. 

The venom from some species of snake contains enzymes that affect the blood clotting process.

Factor Xa is a clotting factor present in human blood.

The table shows the effect of different masses of Factor Xa and snake venom on the time taken for blood to clot.

Describe the effect of snake venom on the time taken for the blood to clot.

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(Total for question = 2 marks) 

Q17. 

A student was interested to find out how his heart rate would vary throughout the day.

He wore a heart rate monitor from the time he woke up until the time he went to bed.

The graph shows the data collected and some of the student's activities during the day.

Explain why the student's heart rate changed at the time of his maths test.

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Q18. 

Some snakes bite their prey and inject venom. The venom is sometimes lethal.

In an investigation, scientists estimated the toxicity of venom from different species of snake. They did this by measuring the dose that can kill 50% of mice after injection with the venom.

This dose is called the LD50.

Two scientists, P and Q, investigated the LD50 values for the venom produced by each snake.

Their results are shown in the table.

Scientist P measured the toxicity in mg kg−1 and scientist Q measured the toxicity in μg kg−1.

(i)  Name the species with the most toxic venom.

(1).............................................................................................................................................

(ii)  The venom of one species of snake can kill a human by activating a substance called factor X. This causes prothrombin in the plasma to change to its active form.

Explain why this venom can be lethal.(4)

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Q19. 

During the cardiac cycle, there are pressure changes in the left atrium, left ventricle and aorta.

The graph shows these pressure changes.

(a)  (i)  Which of the following statements is correct?

(1)   A    the pressure in the left ventricle is always higher than in the aorta   B    the highest pressure in the left atrium causes an increase in pressure in the aorta   C    the time taken for the pressure to change from its lowest value to its highest value is greatest

in the left ventricle   D    the increase in pressure in the left atrium at 0.24 s causes the increase in pressure in the left

ventricle

(ii)  Which of the following is occurring in the heart at 1.0 s on the graph?(1)

(iii)  Use the information in the graph to calculate the heart rate of this person.(2)

Answer ........................................................... beats per minute

(b)  When the heart valves close, they make a sound. Doctors listen to this sound using a stethoscope.

(i)  State a time from the graph when the sound of a semilunar valve closing would be heard.(1)

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(ii)  Explain why the semilunar valves close.(2)

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(Total for question = 7 marks) 

Q20. 

The CFTR protein is also found in the membrane of epithelial cells in the lungs.

Cystic fibrosis is a recessive genetic condition caused by mutations of the allele for the CFTR protein.

This can result in the production of thick, highly viscous mucus in the bronchioles and bronchi.

Explain why the blood of people with cystic fibrosis has a low oxygen concentration.

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(Total for question = 2 marks) 

Q21. 

An investigation was carried out to study the effect of dietary salt on systolic blood pressure.

A group of people had the salt content of their diet changed during a 12-week period.

The people had a diet containing 8 g day−1 of salt for four weeks. Their blood pressure was then measured.

The diet was then changed to 6 g day−1 of salt for four weeks. Their blood pressure was measured again.

Finally, the diet was changed to 4 g day−1 of salt for four weeks. Their blood pressure was measured again.

The table shows the results of this investigation.

(a)  Which of the following is the best explanation of the data in the table?

(1)

   A    less salt decreases the water potential of plasma

   B    less salt increases the water potential of plasma

   C    less salt decreases the water potential of erythrocytes

   D    less salt increases the water potential of erythrocytes

(b)  Explain how an increase in dietary salt can lead to the development of atherosclerosis.

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Q22. 

Materials are transported into and out of a cell through the surface membrane.

(a)  (i)  Proteins are transported out of a cell by

(1)   A    active transport and diffusion   B    active transport and exocytosis   C    active transport and endocytosis   D    diffusion and exocytosis

*(ii)  Cigarette smoke contains molecules called free radicals that damage the structure of cell membranes.

Explain the effect that cigarette smoke could have on the movement of molecules into and out of a cell.

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(b)  The content of blood needs to be monitored when being stored for later use. In an investigation, samples of blood were stored at 4 °C for 5 days.

The concentration of potassium ions in the plasma and in the erythrocytes was measured at the beginning and end of storage.The results are shown in the table.

Calculate the percentage change in the concentration of potassium ions in erythrocytes during this storage at 4 °C for 5 days.

(2)

Answer ...........................................................

In another investigation, two blood samples, A and B, were stored at 4 °C for 5 days.

Sample A was then stored at 37 °C for 24 hours.

Glucose was added to sample B, which was stored at 37 °C for 24 hours.

The potassium ion concentration in the erythrocytes was recorded.

The results are shown in the graph.

(c)  Analyse the data to explain the results of this investigation.

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(Total for question = 13 marks)

Q23. 

Each individual cell in an insect's body is supplied with oxygen from a tracheole.

The diagram shows the appearance of tracheoles in a resting insect.

The concentration of lactic acid in the cytoplasm of the cells is higher when the insect is active.

This can change the volume of fluid in the ends of the tracheoles.

Explain how an increase in the concentration of lactic acid will affect gas exchange between the tracheoles and the cells in an active insect.

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Q24. 

Malaria causes serious problems for pregnant women. They often suffer from a condition known as anaemia in which the ability of the blood to carry oxygen is significantly reduced.

Explain how malaria causes anaemia.

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(Total for question = 2 marks)

Q25. 

Gills are the site of gas exchange in fish.

Water polluted with heavy metal ions can cause the death of fish.

The photographs show cross-sections of the lamellae from a fish caught in unpolluted water and from a fish caught in water polluted with heavy metal ions.

Use the photographs to explain why fish die in water polluted with heavy metal ions.

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(Total for question = 2 marks) 

Q26. 

Xylem and phloem are involved in transport in plants.

The graph shows the effect of pressure gradient on the velocity of flow within three xylem vessels.

(i)  Describe the effect of pressure gradient and radius on the velocity of flow within the xylem vessels.

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(ii)  Calculate the percentage increase in the velocity of water flowing through a xylem vessel of radius 20

μm and a xylem vessel of radius 100 μm, at a pressure gradient of 17.5 kPa m–1.

(2)

Answer ...........................................................

 

(Total for question = 4 marks) 

Q27. 

* During the cardiac cycle, muscles in the walls of the atria and ventricles contract and relax.

The graph below shows the changes in pressure that occur in the left side of the mammalian heart during one cardiac cycle.

* During this cardiac cycle, the changes in pressure that occur in the left atrium and in the left ventricle are different.

Using the information in the graph and your own knowledge, explain these differences.

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Q28. 

A human heart can work effectively for over a hundred years but many people throughout the world have heart problems.

Explain how the sinoatrial node (SAN) ensures that oxygenated blood enters the aorta.

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Q29. 

The photograph below shows Daphnia (a water flea). Daphnia can be used to investigate the effect of chemicals on heart rate.

Explain why many small animals, such as Daphnia, have a heart.

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Q30. 

Cystic fibrosis is an inherited condition.

Explain why people with cystic fibrosis can have breathing difficulties.

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Q31. 

Insects such as locusts do not breathe through the mouth.

The gas exchange system of a locust includes air sacs, tracheae and tracheoles.

The diagram shows a locust before dissection.

Locusts have a complex gas exchange system because they are multicellular organisms.

Explain why single-celled organisms do not have a gas exchange system.

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(Total for question = 2 marks) 

Q32. 

Body size can affect gas exchange in insects.

The photograph shows a great green bush cricket, Tettigonia viridissima.

This animal is 4.5cm long and is the largest insect found in the UK.

A student investigated the effect of oxygen and carbon dioxide on the breathing rate of an insect.

The insect was placed in either atmospheric air, exhaled human air, pure oxygen or a gas mixture. Its breathing rate was then measured.

The table shows the results of this investigation.

(i) The data suggests that the breathing rate in this insect is increased by

(1)

   A    carbon dioxide

   B    oxygen

   C    carbon dioxide and oxygen

   D    neither carbon dioxide nor oxygen

(ii)  Describe how the student should treat this insect in an ethical manner during this investigation.

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Q33. 

Scientists are developing ways of using stem cells to replace heart cells that have been damaged as a result of heart disease.

The table shows the results of a survey of the incidence of heart disease.

Analyse the data to explain the factors affecting the incidence of heart disease.

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(Total for question = 2 marks) 

Q34. 

Platelets are tiny fragments of cells that, together with plasma proteins, are involved in the blood clotting process.

(a)  (i)  During the blood clotting process

(1)   A    prothrombin is changed to thromboplastin   B    prothrombin is changed to thrombin   C    thrombin is changed to thromboplastin   D    thromboplastin is changed to thrombin

(ii)  When blood clots a mesh is produced because(1)

   A    prothrombin is changed to thromboplastin   B    prothrombin is changed to thrombin   C    thrombin is changed to thromboplastin   D    thromboplastin is changed to thrombin

(b)  Several of the plasma proteins involved in making blood clot quickly are enzymes.

Explain how the properties of enzymes help to make blood clot quickly.(2)

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(Total for question = 4 marks)

Q35. 

The diagram below shows some of the cells found in blood.

Describe the function of a neutrophil in defence.

(2) .............................................................................................................................................

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(Total for question = 2 marks) 

Q36. 

The photograph shows an insect.

Explain how the gas exchange system of an insect is adapted for the efficient uptake of oxygen.

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(Total for question = 4 marks) 

Q37. 

Deer mice, Peromyscus maniculations, are small mammals.

The photograph shows a deer mouse.

Red blood cells in deer mice contain haemoglobin to transport oxygen in the blood.

(i)  Describe the structure of haemoglobin.

(2).............................................................................................................................................

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*(ii)  Deer mice can live at high altitude or at low altitude.

The graph shows the oxygen dissociation curves for haemoglobin in deer mice that live at high altitude and for deer mice that live at low altitude.

Compare and contrast the shape of these oxygen haemoglobin dissociation curves.(6)

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Q38. 

Body size can affect gas exchange in insects.

The photograph shows a great green bush cricket, Tettigonia viridissima.

This animal is 4.5cm long and is the largest insect found in the UK.

Explain why the gas exchange system in insects limits their maximum body size.

(2).............................................................................................................................................

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Q39. 

The graph shows the oxygen dissociation curves of haemoglobin from four species of mammal.

Explain why the dissociation curve for mouse haemoglobin is to the right-hand side of the dissociation curve for elephant haemoglobin.

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(Total for question = 3 marks) 

Q40. 

The graph below shows the oxygen haemoglobin dissociation curves for a blood sample from an elephant and a mouse.

(a)  Use the information in the graph to determine the difference in percentage saturation between elephant haemoglobin and mouse haemoglobin at a partial pressure of oxygen of 4 kPa.

(1)

Answer ...........................................................

*(b)  Explain the effect that body size has on the metabolic rate of these two mammals.

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(Total for question = 7 marks)

Q41. 

The graph shows the pressure changes in the left side of the heart during one cardiac cycle.

(i)  Calculate the heart rate.

(1)

Answer ...........................................................

(ii)  During which time period does blood leave the left ventricle?

(1)   A    0.10 s to 0.13 s   B    0.10 s to 0.37 s   C    0.13 s to 0.37 s   D    0.13 s to 0.43 s

(iii)  At which time does the valve between the atrium and the ventricle close?

(1)   A    0.10 s   B    0.13 s   C    0.37 s   C    0.43 s

 

(Total for question = 3 marks) 

Q42. 

The brain is involved in many homeostatic mechanisms.

The autonomic nervous system plays a role in regulating heart rate.

The diagram shows an ECG trace from a student before and during exercise.

(i)  Calculate the heart rate of this student during exercise.

(1)

Answer ...........................................................

(ii)  Describe how exercise results in an increased heart rate.

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(Total for question = 5 marks) 

Q43. 

Phagocytosis requires a source of energy in the form of ATP.

The diagram below shows the relationship between ATP and ADP.

Place a cross in the box next to the name of reaction A and reaction B.

(2)

 

Q44. 

The drawings show two single-celled organisms that live in ponds, Paramecium and a bacterium.

(i)  Many living organisms need a gas exchange system.

The drawing shows a locust.

Explain why a locust has a gas exchange system whereas a Paramecium does not.(2)

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(ii)  A student placed a locust inside a transparent syringe and observed the movement of the abdomen.

The student recorded the number of times the abdomen pumped in 30 seconds. This was carried out three times.The syringe was then flushed with atmospheric air and the procedur repeated first with air exhaled by a human, then pure oxygen and then a mixture of 5% carbon dioxide and 95% oxygen.The syringe was flushed with atmospheric air in between each treatment.The results are shown in the graph on page 14.

* Analyse the data to assess the effect of oxygen and carbon dioxide on locust abdominal pumping.(6)

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Q45. 

A student was interested to find out how his heart rate would vary throughout the day.

He wore a heart rate monitor from the time he woke up until the time he went to bed.

The graph shows the data collected and some of the student's activities during the day.

The student noticed that the graph showed a change in his heart rate while he was playing computer games.

He designed an investigation to find out how different computer games affect heart rate.

The student played one computer game and recorded the increase in his heart rate.

He then played four other different computer games and again recorded the increase in his heart rate.

He repeated this on six different occasions throughout the week.

(i)  Explain how the design of the student's investigation could be improved.

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(ii)  Sketch a suitable graph that the student could use to present the results of his investigation.

(2)

 

Q46. 

The graph shows the pressure changes in the left side of the heart during one cardiac cycle.

Describe how myogenic stimulation brings about contraction of the atria and the ventricles.

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(Total for question = 5 marks) 

Q47. 

The drawings show two single-celled organisms that live in ponds, Paramecium and a bacterium.

Structure A is a contractile vacuole. This removes water from the Paramecium.

Explain why the Paramecium needs to remove water.

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Q48. 

The graph shows the oxygen dissociation curves of haemoglobin from four species of mammal.

Calculate how much more oxygen is released as the partial pressure falls from 10 kPa to 5 kPa in the mouse than in the cat.

(3)

Answer ...........................................................

 

(Total for question = 3 marks) 

Q49. 

The development of atherosclerosis can affect life expectancy.

Cigarette smoke is another factor that increases the risk of developing atherosclerosis.

A study investigated the effect of cigarette smoking on the life expectancy of 35 year old males.

The percentage survival of 17000 male smokers and 17000 male non-smokers was measured for a period of 65 years.

The graph shows the results of this study.

(i)  The probability of death for non-smokers before the age of 70 is 1 in 5.

Calculate the probability of death before the age of 70 for smokers.(2)

Answer ...........................................................

(ii)  It was concluded from this study that smoking decreases life expectancy.

Criticise the validity of this conclusion.(4)

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Q50. 

Stroke volume is the volume of blood that leaves the left ventricle of the heart in each beat.

Cardiac output is the volume of blood that leaves the left ventricle each minute.

The table shows the relationship between heart rate, stroke volume and cardiac output in a person.

Analyse the data to explain the relationship between heart rate and cardiac output.

(2) .............................................................................................................................................

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(Total for question = 2 marks) 

Q51. 

Insects such as locusts do not breathe through the mouth.

The gas exchange system of a locust includes air sacs, tracheae and tracheoles.

The diagram shows a locust before dissection.

Explain the role of air sacs in the gas exchange system of locusts.

(2) .............................................................................................................................................

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(Total for question = 2 marks) 

Q52. 

The graph shows the oxygen dissociation curves of haemoglobin from four species of mammal.

Explain the shape of the haemoglobin dissociation curve.

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(Total for question = 3 marks) 

Q53. 

A student investigating the factors affecting the heart rate of humans carried out a trial to find out the most reliable method of counting the number of heartbeats in one minute.

She counted the number of pulses in one minute of a single subject in identical conditions using two different methods.

Method A – she counted the number of pulses for 15 seconds and multiplied the result by 4.

Method B – she counted the number of pulses continuously for one minute.

The table below shows the results of six trials for each method.

(a)  The student calculated the standard deviation for method A using the following formula:

Calculate the standard deviation for method B.(3)

Answer ...........................................................

(b)  Explain why standard deviation is used for analysing the data.

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(c)  Explain why both methods A and B can lead to inaccuracies.

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(Total for question = 9 marks)

Q54. 

A student planned to keep two species of fish in an aquarium.

One species of fish should be kept at a minimum temperature of 25 °C. The other species requires a minimum concentration of oxygen of 7.5 mg dm−3 water.

The student investigated the effect of water temperature on the solubility of oxygen in water.

The table shows the results of this investigation.

The student used a statistical test on these data.

(i)  Which is the correct statistical test to use on these data?

(1)

   A    Chi squared test

   B    correlation coefficient

   C    standard deviation

   D    Student's t test

(ii)  The student analysed the data using the formula:

The student calculated to be 108. Use the formula to calculate rs.

(3)

Answer ...........................................................

(iii)  Explain how the student should use the rs value calculated in part (ii) to find the strength of the relationship between these two variables.

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(Total for question = 6 marks) 

Q55. 

Stroke volume is the volume of blood that leaves the left ventricle of the heart in each beat.

Cardiac output is the volume of blood that leaves the left ventricle each minute.

The table shows the relationship between heart rate, stroke volume and cardiac output in a person.

(i)  Explain how electrical events during the cardiac cycle can lead to an increase in stroke volume.

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(ii)  Explain why Olympic athletes who train for long distance events often have low resting heart rates.

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(Total for question = 7 marks) 

Q56. 

The diagram shows the structure of a cell membrane.

Explain how the structure of the membrane controls the transport of polar molecules.

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(Total for question = 4 marks) 

Q57. 

The velocity of the conduction of nerve impulses along an axon can be studied.

Describe the structure of the cell surface membrane of an axon.

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(Total for question = 4 marks)

Q58. 

The photograph shows an adult mayfly.

Mayfly eggs hatch into immature insects called nymphs. The nymphs live in the water and develop to form adult mayflies.

The photograph shows a mayfly nymph.

Compare and contrast the structure of the gas exchange system of the mayfly nymph with the adult mayfly.

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(Total for question = 3 marks) 

Q59. 

A student investigated the effect of the shape of a potato chip on the rate of absorption of water.

Different shaped chips, A, B and C, were used.

Calculate the surface area to volume ratio of potato chip B.

(3)

Answer ...........................................................

 

(Total for question = 3 marks) 

Q60. 

Amoeba proteus is a single-celled organism that lives in pond water.

Amoeba has a structure called a contractile vacuole that removes excess water from the cell.

Water that moves into the cytoplasm is transported into the contractile vacuole. When full, the contractile vacuole moves to the surface of the cell and fuses with the cell membrane. This allows the water it contains to be removed from the cell.

The diagram shows Amoeba with a contractile vacuole.

(i)  The water leaves the contractile vacuole by

(1)

   A    endocytosis

   B    exocytosis

   C    osmosis

   D    facilitated diffusion

(ii)  A student investigated the effect of mineral ions in pond water on the rate at which the contractile vacuole emptied.

The student placed different specimens of Amoeba in different concentrations of mineral ion solution on microscope slides.The student recorded the rate at which the contractile vacuole emptied.The results are shown in the table.

Analyse the data to explain the change in the rate at which the contractile vacuole emptied.(2)

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(Total for question = 3 marks) 

Q61. 

The insect Dytiscus marginalis is a beetle that can dive underwater to feed.

Before diving underwater, the beetle traps an air bubble underneath its wings.

The air bubble is connected to its spiracles.

The diagram shows a beetle with an air bubble attached to its body.

Warm weather increases the temperature of the water.

This affects the time a beetle can stay underwater.

Devise an investigation to show the effect of water temperature on the time a beetle can stay underwater.

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(Total for question = 5 marks) 

Q62. 

During the cardiac cycle, muscles in the walls of the atria and ventricles contract and relax.

The graph below shows the changes in pressure that occur in the left side of the mammalian heart during one cardiac cycle.

Using the information in the graph, describe the pressure changes that take place in the left ventricle during each stage of this cardiac cycle.

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Q63. 

Blood taken from a patient had an unusually high proportion of eosinophils.

Explain why this patient had an unusually high proportion of eosinophils.

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(Total for question = 2 marks) 

Q64. 

In mammals, the mother and fetus have separate circulatory systems. Materials are exchanged between the two circulatory systems in the placenta.

The graph shows the oxygen dissociation curves for adult and fetal haemoglobin.

(i)  Calculate the percentage increase in oxygen saturation between adult haemoglobin and fetal haemoglobin at an oxygen concentration of 4 kPa.

(2)

Answer ...........................................................

(ii)  Explain why fetal haemoglobin ensures the transfer of oxygen from the maternal to the fetal circulation.

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The oxygen dissociation curve for myoglobin is different from that for adult haemoglobin.

(iii)  Draw a line on the graph to show the dissociation curve for myoglobin.(1)

(iv)  The table shows the results of an investigation to measure the myoglobin content in the muscle tissue of two different mammals.

Explain why the difference in myoglobin concentration affects the time mammals can spend underwater.

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(Total for question = 8 marks)

Q65. 

The production of tissue fluid is vital for cells in the human body.

In some parts of the world, mosquito bites can infect people with roundworms called Wuchereria bancrofti.

The roundworms block lymph vessels and prevent proteins in tissue fluid entering the lymph vessels.

This causes a disease called lymphatic filariasis (LF). One symptom of LF is swelling of the legs.

The World Health Organisation (WHO) considers LF to be a global health problem affecting over 120 million people in 73 countries.

Scientists investigated whether drug treatment could protect people from LF.

All the people in one area were given drugs to kill the roundworms that cause LF.

This was done every year for six years.

Each year, a sample of five hundred people was randomly selected and tested for signs of LF.

The graph shows the results of this investigation.

The scientists claimed that LF could be eradicated by using this drug treatment.

Analyse the data to criticise this claim.

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(Total for question = 4 marks) 

Q66. 

(a)  (i)  Describe how tissue fluid is formed.

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(ii)  Which of the following substances are exchanged between the capillaries and tissue fluid?(1)

   A    lymph, glucose and oxygen   B    oxygen, water and haemoglobin   C    glucose, lymph and water   D    water, glucose and oxygen

(b)  Blood samples were taken from a vein of a woman using a needle in order to measure the plasma protein concentration during pregnancy.

(i)  Give a reason why the structure of a vein makes it suitable for obtaining blood samples.(1)

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The graph shows changes in the plasma protein concentration in the blood of a pregnant woman.

(ii)  Analyse the data to explain the effect the changes in plasma protein concentration could have on the blood volume of a pregnant woman.

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(Total for question = 8 marks)

Q67. 

Lymphoedema is a condition that causes severe swelling of body tissues due to the accumulation of tissue fluid.

This occurs when lymphatic ducts are blocked.

The diagram shows how the hydrostatic blood pressure and oncotic plasma pressure vary along the length of a capillary.

(i)   With reference to the diagram, explain how tissue fluid is produced and reabsorbed by the capillaries.

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(ii)  Lymphatic ducts remove proteins that are secreted by cells.

Explain how a blockage of a lymphatic duct could lead to lymphoedema.(2)

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(Total for question = 6 marks) 

Q68. 

A farmer used anticoagulant bait to kill rats on his farm.

The anticoagulant prevents the activity of vitamin K that is needed for the synthesis of prothrombin.

The farmer's dog became ill with excessive bleeding in the gums.

A vet carried out a prothrombin test that measures the clotting time of blood plasma.

The diagram shows the test procedure with blood plasma from a healthy dog.

(a)  (i)  Give the reason why thromboplastin and calcium ions were added to the plasma samples.

(1) .............................................................................................................................................

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(ii)  The clotting time for the plasma from the farmer's dog was 73 seconds. The clotting time for the plasma from the healthy dog was 12 seconds.

Explain the difference in these clotting times.(3)

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(b)  Give one way in which the vet could treat the farmer's dog to reduce the symptom of excessive bleeding in the gums.

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(c)  The vet noticed that blood had collected in the lower part of the lungs of the farmer's dog.

Explain how this would affect the farmer's dog.(2)

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(Total for question = 7 marks) 

Q69. 

The production of tissue fluid is vital for cells in the human body.

(i)  Explain why the production of tissue fluid is vital for cells in the human body.

(2) .............................................................................................................................................

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(ii)  Tissue fluid makes up 16% of the mass of a human body.

Calculate the mass of tissue fluid, in grams, that would be found in a person with a mass of 80 kg.(2)

Answer ........................................................... g

 

(Total for question = 4 marks) 

Q70. 

The insect Dytiscus marginalis is a beetle that can dive underwater to feed.

Before diving underwater, the beetle traps an air bubble underneath its wings.

The air bubble is connected to its spiracles.

The diagram shows a beetle with an air bubble attached to its body.

When the beetle is underwater, gases can enter or leave the air bubble.

These gas movements affect the size of the bubble.

When the beetle first dives, the concentration of oxygen is higher in the bubble than in the water.

Explain why these facts will affect the time the beetle can stay underwater.

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(Total for question = 3 marks)