BISC 307 - Exam 1 (20071)

BISC 307 - Exam 1 (20071) - First Exam - ANSWERS BISC 307L...

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First Exam - ANSWERS BISC 307L - General Physiology February 5, 2007 1. Indicate whether each of the following is controlled by negative feedback or positive feedback by writing N (for negative feedback) or P (for positive feedback) in the blanks. Write only one answer in each blank. a-P, b-N, c-P, d-N ______ a. Influx of Na+ ions during the rising phase of the action potential in a squid axon. ______ b. A decrease in urine pH that occurs after ingestion of acidic food. ______ c. Contraction of uterine smooth muscle in response to the babyAEs head descending through the birth canal. ______ d. An increase in secretion from sweat glands in the skin immediately following a rise in body temperature. 2. While preparing a turkey dinner for the celebration of Walter CannonAEs birthday, a physiology student conceived of the following experiment. She cut 3 pieces of turkey liver, and then measured the volume of each piece. Next, she soaked the liver pieces in aqueous solutions of various salinities for 30 minutes. After 30 minutes, she re- measured the volume of the slices. Here are her results: Solution Change in liver volume Tap water + 10.1 % 1% NaCl - 0.1 % 9% NaCl
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- 9.3 % Explain these results by answering the following 3 questions: a) why did the liver piece swell in the 1st case, b) not change significantly in the 2nd case, and c) shrink in the 3rd case? ANS: a) In the 1st case, the solution was hypotonic so water entered the liver cells by osmosis and cell volume increased. b) In the 2nd case, the solution was approximately isotonic, so there was no net movement of water to swell or shrink the cells. c) In the 3rd case, the solution was hypertonic, so water left the liver cells by osmosis and cell volume decreased. 3. Write a number in each blank to match each term on the left with its most appropriate definition on the right. A given definition should only be used only once or not at all. ________ a. Na+/K+ ATPase 1. passive transport across cell membranes ________ b. Ca2+ ion 2. movement of water toward higher solute concentration ________ c. facilitated diffusion 3. secondary active transporter ________ d. Na+/glucose symporter 4. primary active transporter ________ e. unsaturated fatty acids 5. a peripheral membrane protein ________ f. Cl- ion 6. trigger for exocytosis in many cells 7. causes cells to be positive inside compared to outside 8. permeates through the CFTR channel 9. decrease fluidity of cell membranes 4 pts.
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ANS: a-4, b-6, c-1, d-3, e-10, f-8 10. increase fluidity of cell membranes 4. Indicate whether each of the following statements is true or false by writing the word ôTrueö or ôFalseö in the blank (do not mark with T or F). ANS: a-T, b-F, c-T, d-T ________ a. Receptors for inositol trisphosphate (IP3) are located on endoplasmic reticulum membranes. ________ b. Nitric oxide (NO) is released from NO-secreting cells by exocytosis.
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This note was uploaded on 05/03/2010 for the course BISC 307L taught by Professor Herrera during the Spring '08 term at USC.

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BISC 307 - Exam 1 (20071) - First Exam - ANSWERS BISC 307L...

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