Question 21N.2.SL.TZ0.5c
| Date | November 2021 | Marks available | [Maximum mark: 7] | Reference code | 21N.2.SL.TZ0.5c |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Explain | Question number | c | Adapted from | N/A |
Substances can move into and out of cells through the cell membrane.
Explain the adaptations of the small intestine to its function.
[7]
a. small intestine is where nutrients are absorbed into the bloodstream;
b. very long to maximize absorption;
c. (the small intestine) is lined with (smooth) muscle to allow for the mixing/ and moving of digested food;
d. muscles are circular and longitudinal;
e. that perform peristalsis;
f. the pancreas (and gall bladder) secretes substances into the small intestine to aid digestion;
g. contain villi, to increase surface area;
h. villi have microvilli to increase surface area even more;
i. villi absorb products of digestion/mineral ions/vitamins/glucose;
j. dense capillary network rapidly transports absorbed products;
k. lacteal absorbs lipids from the intestine (into the lymphatic system);
l. (most of the) chemical digestion (into monomers) occurs in small intestine/description of specific enzyme action;
Accept annotated diagrams as part of the explanation.
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The structure and function of the small intestine was quite well known. Many missed a mark for omitting to say that the products of digestion are absorbed into the blood. Some of the descriptions of microvilli were not clear, not making it evident that they were on the epithelial cells of the villi. The presence and functions of the muscle layers were well known.
