100 POINTSI Would Like to Dedicate This Exam To

BIOLOGY 131NAME: ______

FALL 2015

EXAM #1

100 POINTSI would like to dedicate this exam to:

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** TURN OFF ALL CELL PHONES AND PAGERS (vibration mode not ok)

INSTRUCTIONS:

1. Use Scan-Tron Form 882 for all multiple choice and true-false questions.

* A #2 pencil MUST be used.* Erasures MUST be complete.

* Choose the BEST answer to each question.

2. You may write on the exam itself, but please do not make any extraneous marks on the answer sheet (Scan-Tron form).

3. Answers to short answer questions should be written directly on the exam in the space provided CLEARLY AND LEGIBLY.

4. If you include a diagram, graph, or figure in your explanation, it must be clearly labeled.

5. Make sure you carefully answer ALL portions of the question.

6. Multiple choice and true-false questions are worth 2 points each; short answer questions are labeled with appropriate points.

7.In the event you think a question is “ambiguous”, you may explain your reasoning below. Make certain you include your Scan-Tron answer in your explanation. Limit yourself to 3 questions. Your explanation will not be considered in your grade unless you are a borderline case at the end of the course.

QUESTION # ______

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QUESTION # ______

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QUESTION # ______

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Nernst Equation: Ex =RT/zF log [X]o/[X]I; in a normal, resting cell RMP should be -70mV

MULTIPLE CHOICE QUESTIONS:

1. Which of these is a true statement?

A. In a resting cell, opening a channel for sodium will depolarize the cell.

B. In a resting cell, opening a channel for potassium will depolarize the cell.

C. At a membrane potential of 0 mV, opening a channel for sodium will cause it to enter the cell.

D. Two of these are correct. (A and C)

E. All of these are correct.

2. Opening a leak channel for potassium in a cell at rest would move it out of the cell.

A. TrueB. False

3. In a normal, resting cell, opening a non-specific cation channel (through which all positively charged ions could move) would most likely cause….

A. depolarizationB. hyperpolarizationC. no change in membrane potential

4. Someone who has a higher-than-normal level of K+ in the extracellular fluid would…

A. have a cell that is depolarized

B. have a cell that is hyperpolarized

C. have a cell with a normal RMP

5. If normal cells (300 mOsm) are placed in a 0.9% solution of NaCl, their shape is unchanged. Which of the following would you expect to be true?

A. Placing the cells in a 1.0% NaCl solution would cause lysis.

B. Placing the cells in a 0.5% MgSO4 solution would cause crenation.

C. Placing the cells in a 0.9% solution of glucose would cause lysis.

D. Placing the cells in a 0.9% solution of glucose would cause crenation.

6. During the Membrane Transport lab, you added red blood cells to various solutions and watched the resultant effects on the cells. The cells in test tube #1 (distilled water) appeared to have lysed. Why?

1. The particles were able to cross the cell membrane into the solution, dragging water with them.
2. The cell membranes were hypertonic, and drew water out of the cell.
3. The solution caused the membrane proteins to transport excess NaCl into the cell, therefore driving excess water inside.
4. Water molecules entered the cell through aquaporin channels.
5. The water molecules dissolved the phospholipid bilayer

7. In a resting cell, a chemical binds a receptor causing sodium leak channels to open; this results in

A. a graded potentialB. the automatic opening of voltage-gated sodium channels

C. a reduction in the size of the membrane potentialD. Both A and C are correct.

E. Both B and C are correct.

8. The resulting situation above (#7) is similar to what happens when Ach binds to….

A. receptors on blood vessels in the stomachC. the post-ganglionic neuron

B. receptors on pacemaker cells in the heartD. receptors on pupillary muscles (eye)

9. In the smooth muscle surrounding the lung airways, you would expect receptors for Ach to

A. open sodium channelsB. open chloride channelsC. open potassium channels

D. Both B and C are correct.

10. In order to create temporal summation, the presynaptic neuron would have to:

A. send action potentials with a higher voltage (higher amplitude)

B. send action potentials with longer durations

C. send action potentials with higher frequency

D. do nothing; no change is possible since the all-or-none law is in effect

11. If changing carbon dioxide levels can change the pH of your blood (and blood pH is a regulated variable), which of these is/are true?

1. Breathing too quickly could activate a negative feedback loop
2. the lungs could act as an effector of this feedback loop
3. pH will likely change throughout the day
4. Both A and B are correct.
5. All of these are correct.

12. Compared to the hand, the back of the neck has….

A. a greater density of receptors per square inchB. larger receptive fields

C. more cortical space allotted for sensory reception from the region

D. Both A and C are correct. E. A, B and C are correct.

13. Information coming into the central nervous system is transmitted along ______neurons.

A. afferentB. sensoryC. efferent D. A and BE. B and C

For the next three questions (listed side-to-side), indicate the type of receptor responsible for sensing the stimulus described. Choose one of the following answers and mark its letter on your scantron:

A. mechanoreceptorB. chemoreceptorC. thermoreceptorD. nociceptor

14. smell of vanilla B15. Neurotransmitter bindingB16. Touch A

17. Which of the following systems have neurons with nicotinic receptors?

A. somaticB. sympatheticC. parasympathetic

D. Two of these are correct.E. All of these are correct.

18. Negative feedback…

A. stabilizes the variable being regulatedB. reinforces the stimulus

C. can prevent disturbances to homeostasisD. None of these is correct.

19. Just before the membrane reaches the peak of the action potential (within 5 mV of peak),

A. the electrical gradient for Na+ tends to move this ion outward.

B. the concentration gradient for Na+ tends to move this ion inward

C. Na+ is at equilibrium

D. Two of the above are correct (A and B)

E. A, B, and C are all correct.

20. If receptors for insulin are down-regulated, which of the following would most likely happen?

A. glucose would have more difficulty entering body cells

B. glucose would move more easily from blood into body cells

C. glucose transport in the brain would be increased

D. the individual affected would experience hypoglycemia

21. During the absolute refractory period that follows the peak of the action potential….

A. sodium inactivation (h) gates are closed

B. sodium activation (m) gates are closed

C. potassium gates are open

D. B and C are correct

E. A and C are correct

For the following questions, choose the option (A or B) that is GREATER and mark it on your scantron. Then, in the space below, explain the reasoning behind your choice (explanations worth 3 points each)

22. A. the excitability of a cell when K+ leak channels are opened

B. the excitability of a cell when K+ leak channels are closed

This would cause less K+ to leave the cell, making it more positive, or closer to threshold

23. A. rate of diffusion for ureaB. rate of diffusion for sucrose

As demonstrated in lab, urea is very small and is able to diffuse quickly; sucrose is much larger and diffuses much more slowly

24. A. ease of transport of peptide hormone (insulin) from gland to target cell

B. ease of transport of steroid hormone (cortisol) from gland to target cell

Given that the transport mechanism is blood, having a molecule that is water-soluble will ease the transport process.

25. A. glycogenolysis while you’re watching a cooking show on TV

B. glycogenolysis while you’re waiting to give a speech

Glycogenolysis (glycogen break down) will occur during times that fuel is needed (fight or flight, rather than rest/digest)

SHORT ANSWER QUESTIONS:

1. (8 pts) A cell with all of the normal membrane proteins of human cellshas ions distributed as follows: ICF: 25 K+ ions, 25 protein anions ECF: 25 Cl-, 25 Na+

A) Describe the movement you would expect to see through leak channels

There will be leak channels for Na+ (will move in) and K+ (will move out)

B) Will this cell develop a membrane potential over time? Explain.

Yes, if the Na/K pump is present, its actions will separate charge so that a membrane potential, negative on the inside, develops.

NOTE: This is exactly what you completed in the “bean lab”

2. (9 pts) Identify and explain three symptoms you might expect to see in someone who is injected with a drug that will inhibit acetylcholinesterase in synapses around the body.

Inhibiting Acetylcholinesterase will allow Ach to remain active longer. Thus, any synapse where Ach is the neurotransmitter would be more active – lots of choices, including more bronchoconstriction, more digestive enzymes, more intestinal movement…etc…

3. (5 pts) In the space below, graph the relationship between the size of the receptive field in the skin and the surface area of the brain homunculus. In words, also briefly explain why you chose to graph it the way that you did.

Size of receptive field on the x-axis and surface area of the homunculus on the y-axis with a negative correlation (as the size of the receptive field increases, there is less SA on the brain).

4. (15 pts) Draw the neuron-target cellsynapse causing each of the following. Include the neurotransmitter, receptor type (e.g. muscarinic, β1,, etc.), and which ion channel(s) you’d expect to open as a result of neurotransmitter binding (Na+, K+, and/or Cl-)

(1) peristalsis (muscular contractions of the intestines) after eating

Ps situation: Ach, muscarinic, excitatory action, so Na+ channels open

(2) bronchodilation during a long bike ride

S situation: NE/E, β2, inhibitory (muscles around airways relax), so K+/Cl- channels

(3) Vasoconstriction to the skin as you nervously wait to get married

S situation: NE/E, α1, excitatory (muscles around vessels constrict) so Na+ channels open

(4) blood vessels in the liver dilate to access stored fuel as you take this exam

S situation: NE/E, β2, inhibitory (muscles around vessels relax), so K+/Cl- channels

(5) Heart rate increases while watching a scary movie

S situation: NE/E, β1, excitatory action so Na+ channels open