MCB 32: Human Physiology Fall, 2001
1st Midterm Exam

Choose the best answer for each question and mark the corresponding box on the scantron form. All 58 questions have the same value.

Read the questions and possible answers CAREFULLY--some are a bit tricky

Remember to put your name and SID on the scantron form.

In matching questions 1-4, choose among the following (answers may be used more than once or not at all): (a)nervous tissue; (b) connective tissue; (c) muscular tissue; (d) epithelial tissue

1. Blood and adipose cells are examples of
2. The origin of the nervous system in the embryo is from
3. Glands derive from
4. The longest cells in the body are found in

5. Hydrogen bonds are least important in (a) maintaining the alpha-helical structures of proteins; (b) the parallel association of fatty acid side chains in a phospholipid bilayer; (c) the parallel associations of complementary halves of the DNA molecules in the nucleus; (d) maintaining water as a liquid at physiological temperatures.

Homeostasis is often achieved by the balancing effects of antagonistic processes. In questions 6-10, identify the antagonistic processes at work:

6. As NADH is produced during anaerobic metabolism, physiological levels of NAD are maintained by (a) synthesis of new NAD molecules; (b) oxidizing NADH to NAD via the electron transport chain in mitochondria; (c) transferring protons to the bicarbonate buffer in the blood stream; (d) reducing pyruvate to lactate.

7. After Na+ influx depolarizes the membrane during the action potential, the main process for restoring the resting potential is (a) K+ efflux through channels; (b) pumping Na+ out and K+ in by the Na/K ATPase (ion pump); (c) sequestration of Na+ into lysosomes; (d) enzymatic conversion of Na+ to K+

8. As cytoplasmic Na+ increases and K+ decreases from sustained neural activity, the concentration gradients of these ions are restored by (a) K+ efflux through channels; (b) pumping Na+ out and K+ in by the Na/K ATPase (ion pump); (c) sequestration of Na+ into lysosomes; (d) enzymatic conversion of Na+ to K+

9. Mass activation of the sympathetic nervous system causes a rise in extracellular (synaptic) levels of the transmitter acetylcholine (Ach) in sympathetic ganglia. Ach is cleared from the synapses by (a) diffusion; (b) reverse osmosis; (c) the enzyme acetylcholinesterase; (d) phagocytosis.

10. Activation of the sympathetic nervous system activates secretion by sweat glands, which is counteracted by (a) slow acting neuropeptides that are released from the nerve endings along with the regular neurotransmitter; (b) the eventual decline in activity of the sympathetic nervous system; (c) wearing absorbant pads; (d) ) activation of the parasympathetic nervous system, which shuts down the secretion

11. Enzymes catalyze biochemical reactions by (a) coupling them to the hydrolysis of ATP; (b) reducing the activation barrier for the reaction; (c) providing a hydrophobic environment for the reacting molecules; (d) transcribing information present in the DNA.

12. Enzymes can drive energetically unfavorable reactions by (a) coupling them to the hydrolysis of ATP; (b) threats of massive retaliation; (c) providing a hydrophobic environment for the reacting molecules; (d) reducing the activation barrier for the reaction.

13. A major difference between voltage sensitive channels distributed along the axons versus those at nerve terminals is that the channels at nerve terminals (a) are selective for Cd+2 instead of K+ ; (b) open and close much faster; (c) are selective for Ca+2 instead of Na+; (d) are selective for Ca+2 instead of Mg+2

14. The main advantage of electrical synapses compared to chemical synapses is (a) they require less energy; (b) they allow large proteins to pass from one cell to the other; (c) they are faster; (d) all of the above.

15. Which of the following is NOT an advantage of chemical synapses compared with electrical synapses? (a) they allow for both excitatory and inhibitory signaling between neurons; (b) they allow for a variety of presynaptic neurons to have different effects on a given postsynaptic neuron; (c) they are more certain to pass an action potential from one neuron to the next; (d) they allow individual neurons to have multiple postsynaptic effects by releasing more than one transmitter.

16. Inhibitory chemical synapses work through by selectively allowing (a) Na+; (b) K+; (c) OH-; (d) Cl- ions to enter the cell.

17. Which of the following features does not contribute to synaptic integration? (a) the incorporation of voltage-sensitive Na+ channels near the receptors; (b) the absence of voltage-sensitive Na+ channels from the dendrites; (c) the "summation" of excitatory and inhibitory potentials in the postsynaptic membrane; (d) the numbers and positions of presynaptic endings on the cell.

18. The Krebs cycle operates (a) in mitochondria; (b) only when oxygen is present in cells; (c) both; (d) neither.

19. Which of the following is NOT a common feature of receptor proteins, ion channels and peptide neurotransmitters (a) their individual mRNAs encode one or more signal peptides; (b) their mRNAs are translated by ribosomes at the surface of the rough ER; (c) their mature forms invariably include one or more transmembrane domains; (d) none of the above

20. Fatty acids are metabolized to generate ATP by (a) lysosomes; (b) glycolysis, after preliminary conversion to phospholipids or triglycerides; (c) the smooth endoplasmic reticulum; (d) the Krebs cycle after being converted to 2 carbon fragments (acetyl CoA).

21. Most of the energy in our body is stored as (a) ATP; (b) lipids; (c) pyruvate; (d) theta waves.

22. Short term memories are disrupted by (a) electroconvulsive shock treatments (b) long term memories; (c) inhibitors of protein synthesis; (d) peptide neurotransmitters.

23. Order the following events into a coherent sequence through which a patch of plasma membrane might proceed: I. endocytosis ; II. pinching off in a vesicle from rough ER; III. fusion with primary lysosome; IV. fusion with Golgi; V. fusion with external plasma membrane; VI . fusion with mitochondria; VII. pinching off from Golgi.

(a) V-IV-I-III
(b) I-III-VI-IV-V
(c) II-IV-VII-V-I-III
(d) IV-VII-V-VI

24. The critical difference between action potentials conveying information in the visual system as opposed to the olfactory system is (a) the sources of the inputs and outputs (presynaptic and postsynaptic neurons) for the axons conducting the action potential; (b) the duration and amplitude of the action potential; (c) the identify of the ions carrying the current; (d) all of the above

25. Amnesia is to memory as aphasia is to our sense of (a) balance (b) smell (c) taste (d) none of the above.

26. RNA serves a structural role in (a) the nucleus (b) ribosome (c) peroxisome (d) both b and c.

27. Proteins do NOT serve as (a) storage of genetic information during cell division; (b) catalysts (c) cytoskeleton (d) signaling molecules.

28. Which of the following are particularly associated with the limbic system ? I. use of dopamine as a neurotransmitter ; II. regulation of emotional states such as fear and aggression; III. anatomically part of the hindbrain.
(a) all of the above
(b) I and II only
(c) I and III only
(d) II and III only

Comparisons of sympathetic and parasympathetic nervous systems. For questions 29-37, mark (a) if the feature is characteristic of the sympathetic nervous system only; (b) if it is a feature of the parasympathetic nervous system only; (c) if it is a feature of both; (d) if it is not a feature of either.

29. mass activation
30. acetylcholine (Ach) as neurotransmitter in preganglionic neurons
31. Ach as neurotransmitter in postganglionic fibers
32. innervation of heart
33. innervation of smooth muscles in blood vessels of skeletal muscle
34. innervation of cerebral cortex
35. innervation of iris
36. autonomic ganglia near or in target organ
37. projects to periphery mainly via spinal nerves in thoracic and lumbar regions of spinal cord

TRUE/FALSE For items 38-46, mark (a) if the statement is true (b) if it is false.

38. Learning and memory must represent long lasting changes in the connections between neurons.
39. Oxidative phosphorylation cannot proceed under anaerobic conditions, but the Krebs cycle can.
40. The Krebs cycle generates roughly 1000 times more ATP than glycolysis
41. Muscle cells differ from connective tissue cells because they contain different genes in their nuclei.
42. The patterns of ridges and fissures in the surface of the cerebral cortex is well conserved from one individual to another.
43. The area in the cerebral cortex that responds to touching two different parts of the body (e.g. lips and back) is proportional the amount of skin in the two parts.
44. The rate at which a chemical reaction proceeds is determined solely by the difference in energy between the starting materials and the products.
45. The synthesis of urea in the 19th century was important because it contradicted the notion that living matter contains a special "vital force" that is missing from non-living matter.
46. Each neuron in the body is sensitive to just one kind of neurotransmitter.

47. Broca's Aphasia results from (a) defects in generating the motor patterns needed to generate speech; (b) defects in the motor neurons controlling the tongue and lips; (c) difficulties in integrating visual and auditory linguistic cues; (d) inability to conceive of real words.

48. The various neurotoxins discussed in class act by I. blocking electrically excitable channels; II. blocking receptors; III. blocking transmitter release; IV. impeding the breakdown or removal of neurotransmitter from the synapse; V. accelerating the removal of neurotransmitter from the synapse.
(a) all of the above
(b) I, II or III
(c) II, III, IV or V
(d) I, II, III or IV

49. From what you know of the mechanisms of synaptic transmission, what effects would you expect to see in the postsynaptic cell if you selectively increased the duration of the action potential in the presynaptic cell (a) increase the length of the action potential; (b) increase in the size of the postsynaptic potential; (c) increase in the resting potential; (d) no effect.

50. Differences in the electroencephalogram patterns between awake adults and awake infants suggests that (a) adults have more neurons; (b) infants use different neurotransmitters; (c) infants are more relaxed; (d) brain development is incomplete at birth.

51. Fusion of primary lysosomes with other membranous organelles is followed by (a) repair of the other organelle; (b) ATP transfer from one to the other; (c) digestion of the other organelle by the lysosome

52. Differences in protein content and pH of the lysosomes, peroxisomes, secretory storage vesicles, Golgi is evidence of (a) the evolutionary origins of these organelles as symbiotic bacteria; (b) differences in gene expression between the different organelles; (c) protein sorting in the ER and Golgi; (d) all of the above.

Matching. For questions 52-56 , mark (a) if the feature pertains only to microtubules, (b) if it pertains only to microfilaments; (c) both; (d) neither.

52. main structural elements of flagella and cilia
53. dynamic structures that grow and shrink by addition and removal of monomeric protein subunits from polymeric chains
54. main structural element in filopodia and microvilli
56. secreted from cell to form basement membrane

57. The fact that action potentials propagate without degradation throughout the length of the neuron, but die out suddenly when they reach the synapse (without being "reflected" back toward the dendrites) results from (a)the absence of voltage sensitive channels in the synaptic terminals of the cell; (b) the fact that membrane is temporarily inexcitable just after an action potential has passed through; (c) depletion of the transmembrane Na+ and K+ concentration differences by the action potential; (d) all of the above.

58. The primary effect of any disease that degrades the myelin sheath should be (a) decrease in the amount of neurotransmitter released at the endings; (b) decrease in the rate of propagation of action potentials along the nerve; (c) decrease in the amplitude of the action potentials; (d) both a and c.