Fig. 1 shows a simplified food label for an emergency ration bar used by mountain walkers. A walker eats one bar after several hours of exercise. RATION BAR...
Question 1 Report
Fig. 1 shows a simplified food label for an emergency ration bar used by mountain walkers. A walker eats one bar after several hours of exercise.
| Nutrient | Energy released per g / kJ |
|---|---|
| Carbohydrate | 17 |
| Protein | 17 |
| Fat | 37 |
(a) Use the label to calculate the energy available from carbohydrate in one bar. [1]
(b) Which nutrient provides the greatest energy per gram? [1]
(c) Suggest why carbohydrate is useful to the walker after exercise. [1]
(d) Describe the route of digested glucose from the small intestine to body cells. [2]
Fig. 1 shows part of the wall of the small intestine from a human patient. The folds are villi. A doctor compared this tissue with healthy tissue because the patient had lost body mass.
| Tissue sample | Mean villus height / mm | Glucose in blood 1 h after meal / mmol dm-3 |
|---|---|---|
| Healthy person | 1.1 | 7.2 |
| Patient | 0.4 | 5.1 |
(a) Describe the difference in villus height shown in Table 1. [1]
(b) Use Fig. 1 to suggest how villi help absorption. [2]
(c) Which transport system carries absorbed glucose away from the intestine? [1]
(d) Suggest why the patient may lose mass. [1]
Answer Details
Ration bar
(a)
\[48\text{ g}\times17\text{ kJ g}^{-1}=816\text{ kJ}\]
Energy from carbohydrate is 816 kJ [1].
(b) Fat provides the greatest energy per gram [1].
(c) Carbohydrate is useful because glucose can be used in respiration to release energy [1].
(d) Glucose is absorbed through the intestinal wall into the blood [1]. The blood carries it to body cells [1].
Villi
(a) The patient's villi are \(1.1-0.4=0.7\) mm shorter, or less than half the healthy height [1].
(b) Villi provide a large surface area for absorption [1]. Blood capillaries carry absorbed molecules away, maintaining a concentration gradient [1].
(c) The blood circulatory system carries absorbed glucose away [1].
(d) The patient may lose mass because less digested food, including glucose, is absorbed for respiration or growth [1].
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