Cholesterol, diet and energy budgetsEdexcel A-Level Biology A: Subtopic test

1. 1
   A 52-year-old man has a routine health check. His total blood cholesterol is 6.4 mmol dm⁻³, his LDL cholesterol is 4.6 mmol dm⁻³ and his HDL cholesterol is 0.8 mmol dm⁻³. His doctor tells him that his lipoprotein profile puts him at increased risk of cardiovascular disease (CVD).

   (a)

   Which lipoprotein carries cholesterol from the liver to the body tissues, including the artery walls?

   [1 mark]

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

   (b)

   Which change to the man's blood profile would most reduce his risk of CVD?

   [1 mark]

   • AA rise in LDL cholesterol and a fall in HDL cholesterol
   • BA rise in both LDL cholesterol and HDL cholesterol
   • CA fall in LDL cholesterol and a rise in HDL cholesterol
   • DA fall in both LDL cholesterol and HDL cholesterol

   (c)

   Explain why a high ratio of HDL to LDL in the blood is associated with a lower risk of CVD.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A 45-year-old woman is 1.64 m tall and has a body mass of 82 kg. Her waist measures 98 cm and her hips measure 102 cm. A health adviser uses her measurements to assess her risk of coronary heart disease (CHD). For women, a waist-to-hip ratio above 0.85 is regarded as indicating raised risk.

   (a)

   Calculate her body mass index (BMI) in kg m⁻².

   [1 mark]

   • A30.5
   • B50.0
   • C220.5
   • D0.033

   (b)

   Which statement about her waist-to-hip ratio (WHR) is correct?

   [1 mark]

   • AHer WHR is 1.04, which is above 0.85, so her risk of CHD is raised
   • BHer WHR is 0.96, which is above 0.85, so her risk of CHD is lowered
   • CHer WHR is 0.85, which is on the threshold, so her risk cannot be assessed
   • DHer WHR is 0.96, which is above 0.85, so her risk of CHD is raised

   (c)

   Suggest why waist-to-hip ratio can give more useful information about the risk of CHD than BMI alone.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A man's energy intake from food averages 11 500 kJ per day. His total daily energy expenditure (basal metabolism plus activity) averages 9 800 kJ per day. Assume that any surplus energy is stored as body fat and that 1.0 kg of body fat stores 37 000 kJ.

   (a)

   Calculate the mass of body fat the man would gain in 30 days. Show your working.

   [3 marks]

   (b)

   The man's energy intake and expenditure stay the same for several years. Describe the likely consequences for his health and suggest how he could restore energy balance.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A student carries out a core practical to compare the vitamin C (ascorbic acid) content of foods using the blue dye DCPIP, which is decolourised by vitamin C. She first adds ascorbic acid solution of concentration 1.00 mg cm⁻³ from a burette to 1.0 cm³ of DCPIP solution until the blue colour just disappears, and finds that 0.40 cm³ is needed. She then repeats the titration using fresh orange juice in the burette and finds that a mean of 0.80 cm³ of juice is needed to decolourise 1.0 cm³ of the same DCPIP solution.

   (a)

   Describe how the student could use this method to find the vitamin C concentration of the orange juice and make her results reliable.

   [6 marks]

   (b)

   Calculate the concentration of vitamin C in the juice in mg cm⁻³ and the mass of vitamin C in a 250 cm³ glass. Evaluate how far the student can rely on her result, and suggest one improvement.

   [6 marks]

   Total for question 4: 12 marks

End of questions