2013年05月IB生物SL真题下载-Paper3

2013年05月IB生物SL真题下载-Paper3

A1. Elderly people lose bone mineral density (BMD) with age, and this is the source of many health issues, including higher risk of bone fractures. Researchers measured the change in BMD amongst elderly men considering many factors, over a period of four years. The results presented below show the difference between bone density change due solely to vitamin C intake and bone density loss considering a combination of the other factors represented by the baseline (zero). BMD was measured in the spine and at two femur (thigh bone) locations (femoral neck and trochanter) using scanner images. Daily intake of total vitamin C was categorized as high, medium or low.

(a) Outline the effect of vitamin C intake on changes in bone density in the spine. 

(b) Compare the changes in bone density of the femoral neck with those of the spine. 

(c) Evaluate the evidence provided by the data that the intake of vitamin C supplements may reduce bone density loss in elderly people.

 

A2. (a) (i) Define the term nutrient. 

(ii) Define the term non-essential amino acid. 

(b) The following are from the labels of a bag of all purpose white flour (wheat) and a bag of parboil long grain rice. Amounts shown are per serving.

(i) Using your knowledge of the energy content of nutrients, calculate the protein energy value of a serving of rice, showing the units.

(ii) Compare wheat flour and rice as main dietary sources of energy for humans.

(c) Evaluate the benefits of reducing dietary cholesterol in lowering the risk of coronary heart disease.

 

A3. (a) Outline the control mechanism for appetite in humans.

(b) Explain the possible health consequences of a diet rich in protein.

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