EDEXCEL | AS Level

BIOLOGY
1C CARDIOVASCULAR HEALTH AND RISK, 2A MEMBRANES AND TRANSPORT

Marks : 70 Duration : 90 mins

1. a) Several factors increase the risk of cardiovascular disease (CVD).

The diagram shows some factors that increase the risk of CVD.
Complete the diagram with one lifestyle risk factor and one non-lifestyle risk factor. [1 Mark]

b) The graph shows the effect of exercise on the relative risk of death from CVD. [2 Marks]

Describe the conclusions that can be made from the information shown in this graph
 c) Dietary antioxidants may reduce the risk of CVD.
(i) Explain how dietary antioxidants reduce the risk of CVD. [3 Marks]
(ii) Devise a study to confirm that antioxidants reduce the risk of CVD. [3 Marks]

d) The coronary artery may become completely blocked in people with CVD.
The graph shows how the energy released by heart muscle cells changes after the coronary
artery becomes completely blocked. [6 Marks]

The heart muscle cells no longer contract 8 minutes after the coronary artery becomes
completely blocked.

The heart muscle cells begin to die 20 minutes after the coronary artery becomes completely
blocked.

Explain the effects on the heart function after the coronary artery becomes completely blocked.

Use the information shown in the graph and your own knowledge to support your answer.

2. a) Obesity increases the risk of cardiovascular disease (CVD).

Body mass index (BMI), waist-to-hip ratio (WHR) and skinfold thickness are indicators of
obesity.
The table shows some measurements taken from two females, female J and female K.

(i) Calculate the waist size of female K. [1 Marks]

(ii) The formula for calculating BMI is:

Calculate the mass of female K, using the data in the table. [3 Marks]
(iii) Comment on the risk of developing CVD in these two women. [2 Marks]
(iv) The diagram shows how the waist and hip measurements should be taken, using a tape
measure.
 Explain how the way a person takes these measurements could produce an
underestimate of their risk of CVD. [2 Marks]

b) The diagram shows how a skinfold thickness measurement is taken over the triceps
muscle at the back of the arm.

Skinfold thickness measures the thickness of the layer of fat under the skin.
Measurements are taken from several sites on the body.
The table shows the skinfold thickness at four sites on a 42-year-old female.

(i) Suggest two reasons why the skinfold thickness values are different at each site on the
body.
Assume that the skin callipers have been used correctly. [2 Marks]
(ii) The table shows a body fat interpretation chart.
The values in the table are the means of the four skinfold thickness measurements.
 Determine the level of body fat of this female. [1 Mark]

3. a) A number of factors affect the risk of a person developing heart disease.

One factor affecting this risk is the level of high-density lipoprotein (HDL) in the blood.
The graph shows the effects of HDL levels and low-density lipoprotein (LDL) levels in the blood
on the risk of men developing heart disease.

For men, a blood HDL level greater than 40mgdm−3 is thought to be optimal.

Explain why a man with a blood HDL level greater than 40mgdm−3 may still have a high risk of
developing heart disease.

Use the information in the graph and your own knowledge to support your answer. [6 Marks]

b) Very high levels of cholesterol in the blood can alter the structure of HDL.
This altered HDL is less effective in reducing the risk of heart disease.

The diagram shows the structure of HDL in blood with a low level of cholesterol and altered
HDL in blood with a high level of cholesterol.
 (i) Compare and contrast the structure of HDL with altered HDL. [3 Marks]
(ii) The antioxidant properties of altered HDL are reduced.
Explain the effect that this has on reducing the risk of heart disease. [3 Marks]

4. Low‐density lipoproteins (LDLs) transport lipids around the body in the blood.
Low‐density lipoproteins can result in the development of atherosclerosis.
They can be absorbed into the endothelial cells lining arteries and broken down by free
radicals.
The diagram shows a low‐density lipoprotein containing cholesterol.

Compare and contrast the structure of a triglyceride and a phospholipid. [3 Marks]

5. The diagram shows the permeability of cell membranes to some chemicals.

The sodium and chloride ions, glucose and water are polar chemicals.
A steroid is a non-polar chemical.
 (i) Describe the dipolar nature of water. [2 Marks]
(ii) Explain the permeability of cell membranes to each chemical shown in the diagram.
[4 Marks]

6. Osmosis can be defined as the movement of free water molecules through a partially permeable
membrane, down a water potential gradient.
Explain this definition.

7. Explain the terms ‘fluid’ and ‘mosaic’ in the Fluid Mosaic model of membrane structure. Give
one advantage of the structure being fluid. [3 Marks]

8. Give four functions of proteins that occupy the plasma membrane. [4 Marks]

9. Pieces of phospholipid bilayer were analysed from two different mammalian cell surface
membranes. Sample A contained phospholipid molecules at a density of 5.0 x 106 molecules
μm-2, whereas sample B contained phospholipid molecules at a density of 4.1 x 106 molecules
μm-2. One sample was from a hormone-secreting liver cell and the other was from a skin cell.
Identify which cell type corresponds to samples A and B. Give reasons for your choice.[3 Marks]

10. Explain how three different factors can affect the fluidity of membranes [6 Marks]

11. Predict and explain the consequences to digestion if mammalian intestinal epithelial cells were
to stop performing active transport of sodium ions. [4 Marks]

12. Malabsorption of glucose in the small intestine may lead to diarrhoea. Explain why. [3 Marks]

13. Suggest three refinements of the Dutch scientists' claim that have arisen from subsequent
research by other scientists, which have led us towards the currently-accepted model of the
structure of membranes. [3 Marks]