Risk factors for cardiovascular diseaseEdexcel International A Level Biology: Subtopic test

1. 1
   A hospital clinic measures the concentrations of lipoproteins in patients' blood to assess their risk of cardiovascular disease (CVD).

   (a)

   Which lipoprotein transports cholesterol from the body tissues to the liver?

   [1 mark]

   • AHigh-density lipoprotein (HDL)
   • BLow-density lipoprotein (LDL)
   • CFibrinogen
   • DHaemoglobin

   (b)

   Which combination of lipoprotein concentrations is associated with the highest risk of CVD?

   [1 mark]

   • AHigh HDL and low LDL
   • BHigh HDL and high LDL
   • CLow HDL and high LDL
   • DLow HDL and low LDL

   (c)

   Explain why a high concentration of HDL in the blood reduces the risk of CVD.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   Researchers are investigating whether dietary antioxidants such as vitamin C reduce the risk of CVD. In a laboratory practical, students compare the vitamin C content of fruit juices by seeing how much of each juice is needed to decolourise a fixed volume of DCPIP solution.

   (a)

   How might antioxidants such as vitamin C reduce the risk of CVD?

   [1 mark]

   • ABy increasing the concentration of LDL in the blood
   • BBy removing free radicals that damage the endothelium and oxidise LDL
   • CBy increasing the blood pressure
   • DBy converting LDL into HDL

   (b)

   Why is DCPIP suitable for comparing the vitamin C content of juices?

   [1 mark]

   • AIt reacts with vitamin C to form a blue precipitate
   • BIt is an acid that neutralises vitamin C
   • CIt is oxidised by vitamin C and becomes darker
   • DIt is decolourised when it is reduced by vitamin C

   (c)

   A student finds that 2.5 cm³ of orange juice decolourises 1.0 cm³ of DCPIP solution, whereas 4.0 cm³ of apple juice is needed. Deduce which juice contains the higher concentration of vitamin C and explain your answer.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A study followed 4,000 men for ten years. Men with a total blood cholesterol concentration below 5 mmol dm⁻³ had 15 cases of coronary heart disease (CHD) per 1,000 men per year. Men with a concentration between 5 and 6.5 mmol dm⁻³ had 25 cases per 1,000 per year, and men above 6.5 mmol dm⁻³ had 45 cases per 1,000 per year. The men in the highest cholesterol group were on average three years older and more of them smoked.

   (a)

   Describe the relationship between blood cholesterol concentration and CHD shown by the data, and calculate how many times greater the rate of CHD is in the highest cholesterol group than in the lowest group.

   [3 marks]

   (b)

   Evaluate whether the data show that a high blood cholesterol concentration causes CHD.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A public health team is reviewing the risk factors for CVD in a town where a quarter of adults smoke, many do little exercise and many have high blood pressure. Cases of CVD also seem to run in some families.

   (a)

   Explain how smoking, high blood pressure and physical inactivity each increase the risk of CVD.

   [6 marks]

   (b)

   Explain how genetics, age, gender and diet affect the risk of CVD, and justify why public health campaigns concentrate on diet and exercise.

   [6 marks]

   Total for question 4: 12 marks

End of questions