The Circulatory System in Animals (AQA A Level Biology)

Exam Questions

3 hours15 questions
1a1 mark

Figure 1 below shows the cross section of an artery.

Figure 1

e-q1

Identify the region marked X on Figure 1.

1b2 marks

Explain how the endothelium layer of the artery in part (a) in Figure 1 is adapted for the transport of blood.

1c2 marks

Table 1 below shows the relative thickness of layers in the wall of an artery and a vein.

Table 1

Layer in wall

Thickness / µm
Artery Vein
Endothelium 25 25
Smooth muscle 495 245
Elastic tissue 375 245
Connective tissue 125 125

Explain the function of the elastic tissue in the wall of an artery.

1d2 marks

Use Table 1 to calculate the ratio of the total thickness of an artery wall to the total thickness of a vein wall. Your answer should be expressed as __ : 1.

Did this page help you?

2a4 marks

Figure 1 below shows the blood circulation in a mammal. 

Figure 1

e-q2

Fill in the missing arrows to show the direction of blood flow in blood vessels A-D of Figure 1.

2b3 marks

Why does the heart require its own blood supply?

2c2 marks

Figure 2 shows a section through a human heart. 

Figure 2-1eWuinl_e-q3

Use Figure 2 to give the letter which represents each of the following: 

The right atrium                                     square                                                          

The pulmonary vein                            square

2d3 marks

Babies can sometimes be born with a small hole in the wall that separates the right and left ventricles of their heart. Suggest why this is a dangerous health condition.

Did this page help you?

3a3 marks

Describe what happens to the muscle tension of the different heart chambers during the events of the cardiac cycle.

3b1 mark

Figure 1 below shows changes in pressure in parts of a human heart during 0.8 seconds.

Figure 1

e-q4

Which letter in Figure 1 represents the point at which the semilunar valves open? 

3c2 marks

Describe what happens to the aortic pressure in Figure 1 between 0.22 and 0.32 seconds. Name which part of the heart causes this. 

3d4 marks

List four ways in which the structure of capillaries are adapted to act as exchange surfaces.

Did this page help you?

4a2 marks

Describe the function of the coronary arteries.

4b2 marks

Arteries near the heart have a high proportion of elastic fibres compared to muscle Fibres in their walls, allowing them to absorb the shock waves caused by the pumping of the heart. Arterioles however tend to have a higher proportion of muscle fibres compared to elastic fibres. Suggest why this would be beneficial during exercise. 

4c2 marks

Describe two ways in which the blood pressure in a vein differs to that in an artery.

4d4 marks

Coronary heart disease is a major cause of death in the UK. List four risk factors associated with CHD.

Did this page help you?

5a3 marks

Plasma makes up over half the volume of blood in a mammal. It transports essential dissolved substances around the body such as glucose. List three other dissolved substances which are also present in blood plasma.

5b3 marks

Fill in the blanks below. 

Tissue fluid is the liquid which surrounds cells. At the start of the capillary bed, the hydrostatic pressure in the capillary is __________ than the hydrostatic pressure within the tissue fluid. This difference in pressure forces fluid to _______ the capillaries and  move into the surrounding tissues. ______ molecules such as water, oxygen and nutrients pass through the capillary bed and into the tissue fluid.

5c1 mark

High blood pressure can have serious health implications. Predict its effect on tissue fluid in an individual.

5d1 mark

Why are plasma proteins not present in high concentrations in tissue fluid?

Did this page help you?

1a3 marks

Figure 1 below shows part of the blood circulation in a mammal. 

Figure 1

mq1a

Use Figure 1 to give the letter that represents each of these blood vessels: 

Pulmonary vein

square

Pulmonary artery     

square

Renal artery

square

        

1b3 marks

Describe the function of the coronary arteries and explain why the heart requires its own blood supply. 

1c3 marks

Figure 2

e-q3

Figure 2 above shows a section through a human heart. 

Give the letter which represents each of the following: 

The chamber where deoxygenated blood first enters the heart 

square

The blood vessel carrying blood with the highest percentage of oxygen saturation

square

The chamber of the heart where blood pressure is highest during the cardiac cycle

square

1d2 marks

Babies can sometimes be born with a small hole between the right and left ventricles of their heart. Suggest why these babies often have problems supplying their tissues with enough oxygen.

Did this page help you?

2a1 mark

Figure 1 below shows changes in pressure in parts of a human heart during one second. 

Figure 1

u1rjsI9u_m-q2

At what time do the semilunar valves open? 

2b1 mark

Use Figure 1 to calculate the heart rate in beats per minute (bpm)

2c2 marks

Valves are important for maintaining blood pressure in the heart. Using a specific example, explain how they work.

2d4 marks

Name which part of the heart causes the increase in pressure in the aorta and explain why this increase is important for the organism.

Did this page help you?

3a1 mark

Figure 1 below shows the rate of blood flow in various blood vessels in the body. It also shows the total cross-sectional area of the vessels.

Figure 1mq3a

As shown in Figure 1 the rate of blood flow increases from the venules to the vena  cava. This is despite a large decrease in the total cross-sectional area. 

Suggest why. 

3b3 marks

Table 1 below shows the relative thickness of layers in the wall of an artery and a vein.

Table 1

Layer in wall Thickness / µm
Artery Vein
Endothelium 25 25
 Smooth muscle 495 245
Elastic tissue 375 245
Connective tissue 25 125

Describe and explain the difference in the thickness of elastic tissue for the artery versus the vein.

3c2 marks

The diameter of a vein was 1.5 mm. 

Calculate the diameter of the lumen of the vein. Show your working.

3d6 marks

Deep vein thrombosis (DVT) is a serious medical condition in which blood forms a clot in a vein, typically in the legs.

Sitting for long periods of time, such as on a long flight, can increase the risk of developing a DVT due to the fact that sitting for extended periods decreases blood flow. 

To reduce the risk, people are advised to stretch and move their legs often during long flights.

Using this information and your own knowledge, explain how blood returns to the heart from the legs.

Did this page help you?

4a3 marks

Explain the formation of tissue fluid. 

Include why proteins are not found in it.  

4b3 marks

Explain how high blood pressure may affect tissue fluid.

4c2 marks

Molecules of different substances differ in size. Table 1 below shows the relative molecular mass of molecules and their relative permeability of capillary walls to them. 

Table 1

Named substance

 Relative molecular mass     (RMM)

 Relative permeability of the   capillary wall

Urea 60 0.96
Water 18 1.00
Haemoglobin 68 000 0.01
Glucose 180 0.60
Albumin (plasma protein) 69 000 0
Globulin (plasma protein) 140 000 0

Using the table and your own knowledge, explain why the water potential of the plasma at the arteriole end is more positive than at the venule end. 

4d4 marks

This question should be answered in continuous prose.

Quality of written communication will be assessed in this answer.

Describe and explain four ways in which the structure of capillaries enable them to function efficiently as exchange surfaces.

Did this page help you?

5a2 marks

Read the following passage. 

Plant sterols and plant stanols are found in a range of food, including vegetables, cereals, seeds and nuts.

Plant sterols and stanols have a similar structure to cholesterol and reduce the absorption of cholesterol in the small intestine, so more cholesterol is lost in the faeces. This helps to lower the levels of cholesterol in the blood and in turn, reduce the risk of coronary heart disease (CHD). 

A group of scientists wanted to investigate the effects of eating plant sterols and stanols on the risk of coronary heart disease. The scientists randomly divided healthy volunteers into two groups. Every day, one group was given plant sterols and stanols to eat for eight weeks. The other group acted as a control. 

Each week, the scientists measured the diameter of the lumen of the main artery in the arm of the volunteers. After the trial, the diameter of the lumen of the main artery in the arm of the volunteers who had eaten foods containing plant sterols and stanols had increased. 

Use the passage and your own knowledge to answer the questions.

Describe how the control group should have been treated. 

5b1 mark

The scientists randomly divided the participants into two groups (line 8). Suggest how they may have done this.

5c3 marks

The results of the experiment are shown in Table 1 below: 

Table 1

 

Mean maximum diameter of lumen of main artery in the arm (mm)

 

            Experimental group             (± standard deviation)

                Control group                   (± standard deviation)

Before experiment 0.69 (± 0.02) 0.71 (± 0.02)
After 8 weeks  0.74 (± 0.03) 0.72 (± 0.05)


The scientists concluded that there was sufficient evidence to assume a causal
relationship between plant sterols and stanols and a reduced risk of coronary heart disease. 

Use the standard deviations above and your knowledge of correlation to evaluate whether the scientist's conclusion is correct?

5d2 marks

Table 2 below shows pressure changes during one cardiac cycle in the left side of the heart.

Table 2

 

Blood pressure/ k Pa
Time /s Left atrium  Left ventricle 
0 0.8 0.4
0.1 1.1 2.1
0.2 0.3 12.2
0.3 0.3 16.1
0.4 1.1 4.9
0.5 0.6 1.2
0.6 0.7 0.4
0.7 0.7 0.4
0.8 1 0.4

During which times is the atrioventricular valve between the left atrium and ventricle closed? 
Explain your answer. 

Times __________________s and ____________________s

Explanation: 

Did this page help you?

1a2 marks

Figure 1 below shows changes in pressure in parts of a human heart during one second.   

Figure 1

h-q1

What does curve Y in Figure 1 represent? Explain your answer.

1b2 marks

Between 0.5 and 0.8 seconds in Figure 1 there is a period of low blood pressure in the left ventricle. Use your knowledge of the cardiac cycle and the human heart to suggest a reason for this.

1c3 marks

Describe two functions of valves in the mammalian circulatory system. Include a named example.

1d4 marks

Oedema is a condition characterised by an abdomen and limbs that are swollen with  fluid. It is prevalent in poorly developed areas in the African continent due to the low  protein diet of the people living there. Explain how a low protein diet could result in oedema.

Did this page help you?

2a4 marks

This question should be answered in continuous prose. 

Quality of written communication will be assessed in this answer. 

Describe and explain how the structure of capillaries enables them to function efficiently as exchange surfaces. 

2b3 marks

Figure 1 below shows part of the blood circulation in a mammal. 

Figure 1

h-q3-1

Name the blood vessels represented by letters C, D and G in Figure 1. 

2c3 marks

Figure 2 shows a section through a human heart. 

Figure 2

h-q2-2

Use Figure 2 to name the chamber / blood vessel and state whether it fills with oxygenated or deoxygenated blood.  
 
 

Letter Name of chamber / blood vessel Oxygenated or Deoxygenated blood
 A    
 D    
 E    

2d2 marks

Suggest why it is advantageous that the heart has four chambers, and therefore acts as a ‘double pump’, providing a double circulation system. 

Did this page help you?

3a3 marks

Figure 1 below shows a dissected pig’s heart.

Figure 1

h-q3-2

 Name the chambers and the valve the pencil passes through in Figure 1

3b2 marks

There are many factors that can increase the risk of an individual developing coronary heart disease (CHD). Some factors are out of the individual's control such as their sex, genetics and increasing age while other factors can be influenced by the individual’s lifestyle.

Scientists used a risk factor points system to assess women's risk of developing CHD. They included the following risk factors: age, smoking, systolic blood pressure, blood cholesterol and blood HDL concentration. To calculate the point score of an individual you must add together the scores of all five categories. A higher score indicates a higher risk of developing CHD in the next 10 years. 

The effect of the chosen risk factors on an individual’s point score can be seen in Table 1 below. 

Table 1

Factor

Range

Points for each age group
Age groups / years
40 - 49 50 -59 60 -69 70 - 79

Age

  2 6 9 11
Blood cholesterol / mg 100 cm-3

<160

160 - 199

200 - 239

240 - 279

280+

0

2

4

5

7

0

1

2

3

4

0

0

1

1

2

0

0

0

0

1
Smoking

Smoker / 

Non - smoker

4

0

2

0

1

0

1

0
Systolic blood pressure / kPA

<16

16 - 17.2

17.3 - 18.5

18.7 - 21.2

21.3+

0

0

1

1

3

0

0

1

1

2

0

0

1

1

2

0

0

1

1

2
Blood HDL content / mg 100 cm-3

<40

40 - 49

50 - 59

60+

2

1

0

-1

2

1

0

-1

2

1

0

-1

2

1

0

-1

Describe the effect of blood HDL content on an individual's point score shown in Table 1.

3c2 marks

The point score can be directly related to the probability of developing CHD in the next 10 years, as shown in Table 2.

Table 2

Point Score Percentage increased risk of CHD in next 10 years

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17+

1

1

1

1

1

2

2

3

4

5

7

9

11

14

17

21

26

Using the data in Table 1 and Table 2 work out the 10 year risk for a female smoker, aged 62, blood cholesterol 260 mg 100 cm-3, blood pressure 20.5 kPa, and HDL 57 mg 100 cm-3

3d2 marks

Describe and explain the point scores for high cholesterol (>280 mg 100cm-3) across the age groups.

Did this page help you?

4a2 marks

Read the following passage. 

Plant sterols and plant stanols are found in a range of food, including vegetables, cereals, seeds and nuts. Plant sterols and stanols have a similar structure to cholesterol and reduce the absorption of cholesterol in the small intestine, so more cholesterol is lost in the faeces. This helps to lower the levels of cholesterol in the blood and in turn, reduce the risk of coronary heart disease (CHD). 

A group of scientists wanted to investigate the effects of eating plant sterols and stanols on the risk of coronary heart disease. The scientists randomly divided healthy volunteers into two groups. One group was given plant sterols and stanols to eat every day for eight weeks. The other group acted as a control. 

Each week, the scientists measured the diameter of the lumen of the main artery in the arm of the volunteers. After the trial, the diameter of the lumen of the main artery in the arm of the volunteers who had eaten foods containing plant sterols and stanols had increased. 

Use the passage and your own knowledge to answer the questions.

Describe how the control group should have been selected and treated. 

4b4 marks

The results of the experiment are shown in Table 1 below: 

Table 1

 

Mean maximum diameter of lumen of main artery in the arm (mm)

 

Experimental group
(± standard deviation)

Control group
(± standard deviation)

Before experiment

0.69 (± 0.02)

0.71 (± 0.02)

After 8 weeks 

0.74 (± 0.03)

0.72 (± 0.05)



The scientists concluded from Table 1 that there was sufficient evidence to assume a causal relationship between plant sterols and stanols and a reduced risk of coronary heart disease. 

Evaluate this conclusion. 

4c5 marks

Table 2 below shows pressure changes during one cardiac cycle in the left side of the heart.

Table 2

 

Blood pressure/ kPa
Time /s Left atrium Left ventricle 
0 0.8 0.4
0.1 1.1 2.1
0.2 0.3 12.2
0.3 0.3 16.1
0.4 1.1 4.9
0.5 0.6 1.2
0.6 0.7 0.4
0.7 0.7 0.4
0.8 1 0.4

Sketch a graph of the results shown in Table 2

4d1 mark

Calculate the heart rate in beats per minute from the data in Table 2.

Did this page help you?

5a2 marks

Figure 1 below represents a capillary and the surrounding tissue fluid.

Figure 1h-q5


Use the information in Figure 1 to explain the formation of tissue fluid.

5b3 marks

The blood plasma in Figure 1 has a more negative water potential at the venule end of the capillary compared to the arteriole end of the capillary. Explain why.

5c5 marks

Genetics and nutrition are two factors that influence blood pressure in humans. Explain how very high blood pressure may affect an individual’s circulatory and lymphatic system.

5d2 marks

Molecules of different substances differ in size. Table 1 below shows the relative molecular mass of molecules and the relative permeability of capillary walls to them. 

Table 1

Substance

Relative molecular mass

Relative permeability of capillary wall

 Water 18  1
 Glucose 180  0.6
 Haemoglobin 68 000  0.01

 Albumin (a plasma   protein)

140 000

 0

Haemoglobin is not present in the tissue fluid. Use Table 1 to explain why this could be considered surprising and your own knowledge to explain why it is, in fact, the case.

Did this page help you?