6.1 Digestion and absorption

1.Cladograms can be created by comparing DNA or protein sequences. The cladogram on the left is based on DNA sequences and the cladogram on the right is based on comparing protein sequences.   What is the reason that cladograms based on DNA sequences are more reliable predictors of the phylogenetic relationship of species than cladograms based on protein sequences?

2. Which is a process occurring in the small intestine?

3. The bacterium Neisseria gonorrhoeae causes infections related to the human reproductive system. The graph shows the percentage of samples in which this bacterium showed resistance to six antibiotics over a period of ten years. What is a possible explanation for the total percentage resistance being larger than 100% in 2010?

4. Glucose is absorbed through protein channels in the plasma membrane of epithelium cells in the small intestine. Which characteristics of glucose prevent its diffusion through the phospholipid bilayer?  

5. Which organ in the human body secretes lipase, amylase and protease?

6. Where does the digestion of polypeptides start in humans?  

7. Where is absorption of digested food carried out? I.  Villi II. Pancreas III. Small intestine

8. What is the main method of transport of monosaccharides such as fructose across the intestinal epithelium?  

9. The diagram shows the layers of the tissues in a transverse section of the human small intestine.   Which is the layer labelled with the letter X?

10. What happens to starch in the small intestine?

11. In which process is “surface area” of key importance for humans?

12. What structures in the small intestine transport most fats?

13. What structures in the small intestine transport most fats?

14. What are functions of the stomach, small intestine and large intestine?

15. The graph shows a correlation between the number of new cases of stomach cancer and vegetable consumption for women in Poland. What can be stated from the graph?

16. Some egg white protein was heated until it turned solid. It was then cooled and cut into four cubes of equal size. Each cube was placed in a test tube containing water and a peptidase which was extracted from the stomach of a mammal. Hydrochloric acid was added to two of the tubes. The tubes were kept at constant temperature for 30 minutes. In which tube was the cube of egg white smallest after 30 minutes?

17. What are functions of the stomach, small intestine and large intestine?

18. The graph shows a correlation between the number of new cases of stomach cancer and vegetable consumption for women in Poland. What can be stated from the graph?

19. Colonic irrigation involves regularly flushing the large intestine with water. Why should this practice be avoided?  

20. Which vessel carries deoxygenated blood from the heart to the lungs?

21. What role does the medulla of the brain have in controlling heart rate?

22. Which is a long-term effect of the human immunodeficiency virus (HIV) on the immune system?

23. During expiration, how does air pressure in the lungs compare with atmospheric pressure?

24. Where do motor neurons conduct impulses from and to?

25. What are increasing levels of progesterone responsible for during the female menstrual cycle?  

26. What are features of the enzyme amylase?

27. What are features of the enzyme amylase?

28. Which label represents the lacteal?

29. Which enzyme is amylase?  

30. Enzymes produced by the pancreas could pass out of the body via the anus. Which route would these enzymes take to do this?

31. Why do nutrient molecules enter the blood?

32. Where are structures I, II and III found in the human body?

33. A structure has a thin epithelium of one cell layer and contains a lacteal and blood capillaries. It has protein channels and mitochondria to aid absorption. What is this structure?  

34. The diagram below shows the human digestive system. In which parts of the digestive system are most water and glucose absorbed?

35. What is an important function of the lacteal in the villus?  

36. What is an important function of the lacteal in the villus?

37. Where does most assimilation take place?  

38. Celiac disease causes the destruction of the villi cells. Which of the following is most likely to happen to people with celiac disease?

39. Questions 9 and 10 refer to the following diagram of the human digestive system.     Which structure produces lipase?

40. Which organs are associated with the transformation of glucose into glycogen? (Consider the above picture)  

41. Celiac disease causes the destruction of the villi cells. Which of the following is most likely to happen to people with celiac disease?

42. Which of the following is correct for lipase?

43. What processes occur during assimilation and absorption of lipids?

44. Which feature increases the absorption of glucose in the small intestine?  

45. The diagram below shows water in the human body. Where in the digestive system is the largest volume of water absorbed from?

46. The diagram below shows parts of the human digestive system.   Which points are linked by the small intestine?

47. Which of the following parts of the digestive system secrete proteases?

48. What is the main function of the large intestine?