Biology Homework Help

Sorry, I just give out 1.5 hours because its due at 5. Hope you can help me out with the correct answer within this limited time. I can raise up the price. Thanks again.

1) Which of the following is true in a negative feedback system, regulating plasma glucose concentration?a. The sensor would act to raise blood glucose levels after a meal.b. Rising glucose concentrations would feedback to increase insulin secretion.c. Falling glucose concentrations would feedback to decrease glucagon secretion.

d. The role of the integrating center is to directly measure the plasma glucose concentration.

e. None of the choices is true.

2) Myasthenia gravis is an autoimmune disease – that is, a disease in which one’s immune system gradually attacks a part of one’s own body, in this case the receptors for acetylcholine at the neuromuscular junction. Which of the following drugs might be useful in treating this disease?a. A drug that stimulates acetylcholinesterase.b. A drug that stimulates release of acetylcholine.c. Curared. Prozace. None of the choices would be useful.

3) When undergoing physical exercise, healthy adult skeletal muscle will likely respond with an increase in all of the following EXCEPTa. glycolysisb. the citric acid cyclec. hyperplasiad. protein productione. All of the choices will be increased

4) Which of the following statements regarding the action potential of a skeletal-muscle fiber is true?a. Muscarinic receptors in the end plate are activated by binding to acetylcholine.b. Temporal summation of end plate potentials is required in order to trigger an action potential in the muscle-fiber membrane.c. Calcium ions are involved in its depolarization.

d. Sympathetic nerve fibers innervate skeletal muscle.e. All of the above choices are false.

5) All of the following are true concerning smooth muscles EXCEPTa. Smooth muscle contractions are longer and slower than skeletal muscle contractions.b. A chemical change in the environment around smooth muscle may create a contraction.

c. They may be connected to each other by gap junctions.d. Extracellular calcium is required for contraction.

e. All of the statements are true.

6) ATP is necessary for each of the following mechanisms or functions in skeletal muscle EXCEPT

a. Sequestration of Ca2+ into the sarcoplasmic reticulumb. Dissociation of actin from myosinc. Release of Ca2+ from the sarcoplasmic reticulumd. Movement of myosin headse. Maintenance of the polarized state of the skeletal-muscle membrane

7) Summation of action potentials in skeletal muscle cells to give tetanus contraction:

                I. is an example of spatial summation

                II. is an example of temporal summation

                III. results in saturating myoplasmic Ca2+ concentration

a. Only II and III are true

b. Only I is true

c. Only II is true

d. Only I and III are true

e. I, II and III are true

8) Which of the following statements about electrical synapses is false?

a. They are less abundant than chemical synapses.b. They are faster than chemical synapses.

c. They allow impulse transmission in one direction only.d. They don’t allow for much integration of information in the post-synaptic cell.

e. All the statements are true.