Pupil sheet · Absorption
Absorption — final check
Name ______________________ Date ____________
Work alone, with the lesson closed. Answer every question; there are no hints.
1. identify / explain
In one disease the lining of the small intestine is damaged, but the stomach and colon are healthy. (a) Identify the process that is most affected. (b) Explain why the person may be short of glucose in the blood even though they eat plenty of starchy food.
(a) The process most affected
(b) Why glucose is short
2. identify
The table shows the water entering three parts of a person's gut in one day, and the water passing on from each part. Water entering a part includes the digestive juices added to it. Use the data to identify where most of the water is absorbed, and where some of it is absorbed.
| Part of the gut | Water entering / L | Water passing on / L |
|---|---|---|
| stomach | 4.0 | 3.9 |
| small intestine | 8.6 | 1.8 |
| colon | 1.8 | 0.2 |
Circle one answer.
- most from the colon, some from the small intestine
- most from the small intestine, some from the stomach
- most from the small intestine, some from the colon
- most from the stomach, some from the colon
3. explain
Supplement. In one disease the microvilli become short and sparse, while the villi look normal with a light microscope. (a) Explain why a light microscope does not show the damage. (b) Explain why the person absorbs less food.
(a) Why the light microscope misses it
(b) Why less food is absorbed
4. calculate
Supplement. On a 1.0 mm² patch of the lining of the small intestine, the villi give a surface of 7.0 mm². The microvilli on the epithelial cells multiply the surface of the villi by 20. (a) Calculate the total internal surface of the patch. (b) After a course of a medicine, the villi become shorter and give only 5.0 mm²; the microvilli do not change. Calculate the new total surface of the patch. (c) Absorption is proportional to surface area. Calculate how many times faster the patch absorbed glucose before the medicine than after it.
(a) Total surface before: ______________ unit ________
(b) Total surface after: ______________ unit ________
(c) Times faster before: ______________ unit ________
5. identify
Supplement. Five pupils each drew a villus. Each statement below describes one feature of one drawing. Identify each feature as correct or wrong.
Write the number of the matching option.
- wrong
- correct
- The cells covering the villus are drawn side by side, each with its own nucleus, with no cell lying on top of another.: ______
- The lacteal is drawn just under the covering cells, and the capillary network runs up the middle of the villus.: ______
- The lymph vessel is drawn with a sealed end near the tip of the villus.: ______
- The villus is drawn as one large cell with a nucleus in the middle.: ______
- The lacteal is drawn joined to the venule, with red blood cells inside it.: ______
6. identify
Supplement. A meal of pasta in a cream sauce is eaten with a glass of mineral water. Which row shows the vessel in a villus that each substance passes into?
| Row | glucose from the pasta | fatty acids and glycerol from the cream | water and mineral ions |
|---|---|---|---|
| A | capillaries | lacteal | capillaries |
| B | capillaries | lacteal | lacteal |
| C | lacteal | capillaries | capillaries |
| D | capillaries | capillaries | capillaries |
Circle one answer.
- A
- B
- C
- D