Chapter 20 Objective Questions

1. About what fraction of the students in this class are predicted to die of cancer?
- a. 1/5
- b. 1/4
- c. 1/3
- d. 1/2
- e. 2/3

2. When deaths by cancer are plotted vs. Age on a log-log graphical scale, a straight line is obtained. The fact that the line is straight suggests that:
- a. the occurrence of cancer is independent of age
- b. several events are required to get cancer
- c. a single key event is required to get cancer
- d. the older you are, the more likely you are to avoid getting cancer
- e. two of the above

3. In Japan, the incidence of cancer of the large intestine is far lower than in the United States. Japanese living in this country for several generations, however, exhibit rates of this cancer as high as those of other Americans. This is presumably because:
- a. there is a gene in Japanese that protects them from this cancer, which is diluted by American genes
- b. people smoke a lot more in the United States than Japan
- c. there is more industrial pollution in the United States than in Japan
- d. the cancer is caused by an infectious virus
- e. people eat a lot more meat in the United States than Japan

4. Which of the following does NOT cause cancer?
- a. sunshine
- b. diet low in fiber/high in animal protein
- c. high fat diets
- d. secondary smoke from other people's cigarettes
- e. all of these cause cancer

5. In human cancer studies, "transfection" refers to:
- a. infecting a tissue culture with fragments of DNA from a cancer cell
- b. allowing two cell lines to fuse to form a hybridoma
- c. inadvertent contamination of cell line with a virus
- d. inadvertent contamination of one cell line with another
- e. infecting a tissue culture with two different viruses simultaneously

6. The first evidence that cancer can be caused by a virus was obtained by Rous, and he obtained the Nobel Prize for his pioneering studies. From what organism did he isolate a cancer-causing virus?
- a. humans
- b. mice
- c. bacteria
- d. chickens
- e. monkeys

7. How can a virus and a chemical both cause the same cancer?
- a. they can't
- b. a chemical may inactivate a gene preventing neighboring growth genes from functioning, while a virus may move the growth genes away from its control
- c. viruses physically damage the DNA in the same way that chemicals do
- d. viruses cause the production of mutagenic chemicals within the cell that act the same as cancer-causing chemicals from the environment
- e. when viruses multiply in cells, the signals they use to promote their growth also cause the cell to begin to grow

8. What does a src gene do?
- a. promotes growth
- b. phosphorylates tyrosine amino acids in proteins
- c. activates epidermal growth factor
- d. three of the above
- e. two of the above

9. The chemical industry argues that very low levels of chemicals in food or the environment are not dangerous, even if the chemicals cause cancer at high levels, because:
- a. there is no evidence that the chemicals interact with DNA at low doses
- b. the human body repairs low levels of chemical damage to DNA
- effectively
- c. they cannot be detected at very low levels
- d. mice are smaller than humans and so are more sensitive to chemical mutagens
- e. none of the above

10. In a closed circulation system, how does the heart manage to push blood through the great resistance offered by the tiny capillaries of the body?
- a. the arteries have a larger diameter than the capillaries, and so offer less resistance to flow
- b. the capillaries do not offer resistance to flow, because they are open at veinous ends
- c. the walls of the arteries are elastic, allowing arterial diameter to increase to accommodate the blood pushed out by the heart
- d. capillaries have tiny one-way valves that prevent backflow and so facilitate blood movement
- e. two of the above

11. Your heart evolved from the long more-or-less tubular heart of fishes. How many of chambers of the fish heart have been retained as chambers of the human heart?
- a. one
- b. two
- c. three
- d. four
- e. none

12. Which chamber of the human heart pumps first?
- a. ventricle
- b. aorta
- c. atrium
- d. bundle of His
- e. AV node

13. The decrease in arterial diameter caused by cholesterol-induced plaque buildup on the interior walls is called:
- a. arteriosclerosis
- b. atherosclerosis
- c. hypertension
- d. angina
- e. coronary thrombosis

14. The leading cause of death in the USA today is heart disease. The surgeon general attributes a third of heart disease deaths to smoking. Why does the smoking lead to heart disease?
- a. smoking elevates cholesterol levels
- b. nicotine elevates blood pressure
- c. nicotine loosens arterial plaques, leading to embolisms
- d. smoking leads to cancer of the heart
- e. smoking causes constriction of blood vessels in the lungs, causing the heart to work harder

15. Your body contains about 5.6 liters of blood. However, blood pressure forces some of this fluid out across the walls of the capillaries. In your body, how much fluid is lost from the cardiovascular system each day in this way?
- a. none - it is a closed circulatory system
- b. about a liter
- c. two liters
- d. three liters
- e. about a pint

16. Human blood contains 46 grams of serum albumin per liter. What is its function?
- a. no one knows
- b. it is a waste product of protein metabolism
- c. to maintain osmotic balance with the tissues
- d. a food source for protein-metabolizing blood cells
- e. albumin plays a critical role in renal function

17. Which of the following would NOT be expected to cause cancer?
- a. smoking
- b. agricultural chemicals
- c. high-fiber diet
- d. ionizing radiation
- e. Chernobyl

18. Why do most cancers occur in people over 40 years old?
- a. there are a lot more people over 40 than younger
- b. the induction of cancer involves the mutation of two or more genes, which takes time
- c. the habits which lead to cancer (smoking, a high-meat diet) are now more common among older adults
- d. young people's immune systems are more efficient at detecting and eliminating cancer cells when they arise
- e. none of these

19. Your blood is about 90% water, which can easily pass into the cells of your body. How, then are you able to maintain a normal amount of water in the blood?
- a. by the presence of the protein albumin in blood
- b. by the presence of salts in the blood
- c. by the contribution of the lymphatic system
- d. you produce water metabolically
- e. by drinking more water

20. The "pacemaker" of the human heart is found:
- a. in the atrium
- b. in the ventricle
- c. in the aorta
- d. between the atrium and ventricle

21. Starting with the blood flowing out of the human heart, order the following structures as to where the blood flows sequentially on its journey through the body:
1. venules 2. Veins 3. Arterioles 4. Arteries 5. Capillaries
- a. 1,2,3,4,5
- b. 2,1,5,3,4
- c. 4,3,5,2,1
- d. 4,2,5,3,1
- e. 4,3,5,1,2

22. In general, veins are larger in diameter than arteries. Why?
- a. to reduce resistance to flow
- b. to increase resistance to flow
- c. because cholesterol does not build up in veins
- d. because arteries are more elastic than veins
- e. none of the above

23. In what segment of a fish circulatory system would the blood pressure be expected to be highest?
- a. between gill and tail
- b. between gill and head
- c. between gill and heart
- d. between heart and head

24. Atherosclerosis produces heart attacks because:
- a. the heart has to pump too hard to force the blood through the narrowed blood vessels
- b. the heart suffocates because the coronary arteries become blocked
- c. the arteries, hardened by plaque, have lost their ability to expand as the heart pumps

25. If you blocked the blood flow through your capillaries, which vessels would empty of blood?
- a. your veins
- b. your arteries

26. You've just found out that your pet llama has cancer that has spread throughout its body. You tell your parents that these kinds of cancer cells are called _____________________.

27. You are a sun worshipper. But, now the doctor says you have skin cancer and must no longer tan. How did this happen?
- a. some suntan oils have been shown to be carcinogenic
- b. UV radiation from the sun causes the formation of free radicals in your cells
- c. UV radiation from the sun causes the formation of pyrimidine dimmers in your cells
- d. X-rays from the sun cause the formation of pyrimidine dimmers

28. Which of the following is associated with the greatest risk of developing cancer?
- a. living in New York City
- b. smoking
- c. eating 100 grams of meat per day
- d. drinking coffee
- e. premarital sex

29. You have two friends who smoke cigarettes. One has smoked for 30 years and does not have lung cancer, and the other who has only smoked for 5 years but does have lung cancer. This can be explained by the fact that:
- a. the friend with cancer genetically must have inherited that tendency from his father, who also had lung cancer
- b. cigarette smoke does not really cause cancer
- c. mutations hit random targets, and so in some people may not occur in cancer-causing genes
- d. the unaffected friend must be immune to cancer
- e. none of the above provide a reasonable explanation

30. Serum albumin functions in the blood:
- a. as a component of the blood clotting reaction
- b. to transport salts and other ions
- c. as a component of the immune response system
- d. to prevent the loss of H2O (water) from the blood to cells
- e. to facilitate oxygen transport

31. Interstitial fluid, lost from capillaries by osmosis, returns to the heart through:
- a. veins
- b. lymph vessels
- c. arteries
- d. a and b
- e. none of the above

32. Lymph fluid flows back into the circulatory system due to pressure formed by:
- a. the heart's pumping
- b. muscle movement squeezing lymph vessels
- c. the pumping of chambers scattered along the vessels
- d. breathing gravity

33. The following show good correlation with increased incidence of cancer, EXCEPT:
- a. diet high in meat consumption
- b. incidence of venereal disease
- c. (cigarette) smoking
- d. sun bathing
- e. age

34. The elasticity of your arteries is important because:
- a. your circulation is a closed system
- b. it aids transfer of oxygen from blood to cells
- c. it helps hold the water in your blood
- d. plasma cells get very large
- e. arteries are bigger than veins

35. You have eaten an abundance of cholesterol all your life, and now your doctor says you have atherosclerosis. Does this imply that your arteries are hardening? __________________

36. You are a molecular biologist studying a strange new human cancer that affects only the left big toe of afflicted adults. Although you have no idea what actually triggered the formation of this cancer type, you do know that most, and maybe all, human cancers are the result of _________________.

37. The American Cancer Society has estimated that one quarter of the male children and one third of the female children born in 1987 will someday die of cancer. Their prediction implies that boys are only 75% as likely as girls to die of cancer. Can you think of any reason(s) why so many more females than males are expected to die of cancer?

38. Blood contains the protein serum albumin, which acts to:
- a. combat invading micro-organisms
- b. digest excess sugars in the blood
- c. maintain osmotic equilibrium with tissue fluids
- d. remove any over abundance of wastes
- e. stimulates valves in veins to close

39. Veins of the systemic circulation differ from arteries in that they:
- a. carry highly oxygenated blood
- b. deliver blood to capillaries
- c. have thinner walls
- d. take blood away from the heart
- e. store lymph

40. Select the incorrect direction of blood flow:
- b. pulmonary veins - left atrium
- c. right atrium - right ventricle
- d. right ventricle - aorta
- e. superior vena cava - right atrium

41. In a closed circulation system, how does the heart manage to push blood through the great resistance offered by the tiny capillaries of the body?
- a. the arteries have a larger diameter than the capillaries, and so offer less resistance to flow
- b. the capillaries do not offer resistance to flow, because they are open at the veinous ends
- c. the walls of the arteries are elastic, allowing arterial diameter to increase to accommodate the blood pushed out by the heart
- d. capillaries have tiny one way valves that prevent backflow and so facilitate blood movement
- e. two of the above

42. Human blood contains 46 grams of serum albumin per liter. What is its function?
- a. no one knows
- b. it is a waste product of protein metabolism
- c. to maintain osmotic balance with the tissues
- d. a food source for protein-metabolizing blood cells
- e. albumin plays a critical role in renal function