GRADES: Grade based on total 400 pts (3x 100 pts midterms + 100 pts final).

NO MAKE-UP EXAMS

MCB 32: Human Physiology Fall, 2002
1st Midterm Exam: September 26

Choose the best answer for each question and mark the corresponding box on the scantron form. All 49 questions have equal value, and will be pro-rated so that the total value of the exam is 100 points.

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

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


1. Chiral molecules a) cannot be superimposed on their mirror images

2. The section of a transmembrane protein that is in the lipid bilayer is a)
hydrophobic

3. A section of DNA template with bases in the sequence TTCAG is transcribed into the following mRNA sequence: d)AAGUC

4. Put the following steps of cell division in order

1-Prophase
2-Cytokinesis
3-Metaphase
4-Telophase
5-Anaphase

d) 1, 3, 5, 4, 2

5. During oxidative phosphorylation a) protons are pumped into the
intermembrane space b)diffusion of protons is coupled to ATP synthesis
c) electrons are transferred from NADH, ultimately to oxygen d) all of the above

6. Metabotropic receptors c)activate signaling molecules inside cells

7. Hydrogen bonds are least important in (b) the parallel association of fatty acid side chains in a phospholipid bilayer
Homeostasis is often achieved by the balancing effects of antagonistic processes. In questions 8-10, identify the antagonistic processes at work:

8. As NADH is produced during anaerobic metabolism, physiological levels of NAD are maintained by (d) reducing pyruvate to lactate.

9. After Na+ influx depolarizes the membrane during the action potential, the main process for restoring the resting potential is (a) K+ efflux through the channels, because now the concentration gradient driving K+ out is greater than the electrical forces pulling K+ into the cell;

10. As cytoplasmic Na+ increases and K+ decreases from sustained neural activity, the concentration gradients of these ions are restored by (b) pumping Na+ out and K+ in by the Na/K ATPase (ion pump);

11. Enzymes catalyze biochemical reactions by ; (b) reducing the activation barrier for the reaction;

12. Enzymes can drive energetically unfavorable reactions by (a) coupling them to the hydrolysis of ATP;

13. A major difference between voltage sensitive channels distributed along the axons versus those at nerve terminals is that the channels at nerve terminals (c) are selective for Ca+2 instead of Na+;

• 
  14. Inhibitory chemical synapses work through by selectively allowing (d) Cl- ions to enter the cell.
  
  15. Which of the following features does not contribute to synaptic integration? (a) the incorporation of voltage-sensitive Na+ channels near the receptors;
  
  16. The Krebs cycle operates (a) in mitochondria; (b) only when oxygen is present in cells; (c) both;
  
  17. Fatty acids are metabolized to generate ATP by (d) the Krebs cycle after being converted to 2 carbon fragments (acetyl CoA).
  
  18. 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;
  
  19. Proteins do NOT serve as (a) storage of genetic information during cell division;
  
  TRUE/FALSE For items 20-26, mark (a) if the statement is true (b) if it is false.
  
  20-T. Learning and memory must represent long lasting changes in the connections between neurons.
  21-F. Oxidative phosphorylation cannot proceed under anaerobic conditions, but the Krebs cycle can.
  22-F. The Krebs cycle generates roughly 1000 times more ATP than glycolysis
  23-F. Muscle cells differ from connective tissue cells because they contain different genes in their nuclei.
  24-F. The rate at which a chemical reaction proceeds is determined solely by the difference in energy between the starting materials and the products.
  25-T. Most neurons in the body are sensitive to more than one kind of neurotransmitter.
  26-F. The analysis of accidentally occurring and surgically induced lesions in the human nervous system demonstrates that specific neural functions are distributed throughout the brain and cannot be localized to any particular structures.
  
  27. 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 [hint: what will this mean in terms of Ca++ entry into the presynaptic cell?] (b) increase in the size of the postsynaptic potential.
  
  28. Fusion of a primary lysosomes with another membranous organelle is followed by (c) digestion of the other organelle by the lysosome
  
  Matching. For questions 29-35, mark (a) if the feature pertains only to microtubules, (b) if it pertains only to microfilaments; (c) both; (d) neither.
  
  29-A. main structural elements of flagella and cilia
  30-B. main structural element in filopodia
  31-D. secreted from cell to form basement membrane
  32-A. main structural component of mitotic spindle
  33-C. important in determining cell shapes
  
  34. important in transporting cellular components from nerve cell bodies along the axon CORRECT ANSWER IS "C", BUT WE FELT THERE WAS SOME CONFUSION ON THIS AND SO THIS QUESTION WAS NOT COUNTED.
  
  35-D. required for proper alignment of tRNA with the mRNA during protein synthesis
  
  36. What determines the pattern of protein folding? b) the primary structure, i.e., the sequence of amino acids with their different side chains
  
  37. "beta-pleated sheets" are associated with c) secondary protein structure
  
  38. What types of protein are translated by ribosomes on the rough endoplasmic reticulum? b) proteins destined to be secreted from the cell c) proteins destined to be embedded in the cell membrane d) b and c
  
  39. The main advantage of electrical synapses compared to chemical synapses is (c) they are faster; .
  
  40. Which of the following is NOT an advantage of chemical synapses compared with electrical synapses? (c) they are more certain to pass an action potential from one neuron to the next than with electrical synapses;
  
  41. Glia do NOT have a role in: c) maintaining the proper temperature of the brain
  
  Many important biological molecules are polymers, i.e., long chains made up of covalently linked subunits (monomers). Answer questions 42-46 using the following a) glycogen b) protein c) RNA d) DNA [Each answer may be used more than once or not at all.]
  
  42-C. composed of A, G, U and C subunits,
  43-B. composed of amino acids linked by peptide bonds
  44-D. occurs in a double helical structure held together by hydrogen bonds
  45-A. a polymer of glucose
  46-A. occurs as a highly branched polymer
  
  47. Mass activation of the sympathetic nervous system reflects a) the patterns by which preganglionic neurons connect to ganglionic neurons
  
  48. From our discussion of energy metabolism, one substance that should be able to cross the blood-brain barrier is b) glucose
  
  49. Compared with lower vertebrates, the most dramatically enlarged part of the human brain is the a) left ventricle b) pons c) medulla oblongata d) none of the above
  
  
• Histogram: grade distribution for midterm #1
• Histogram: grade distribution for midterm #2