Any answers/explanations for the following cell biology questions would be very

Question

Any answers/explanations for the following cell biology questions would be very helpful. Thank you.

1. The resting potential of a particular nerve cell is -66 mV. Depolarization of the membrane will shift the membrane potential toward

A) -90 mV.

B) -66 mV.

C) 40 mV.

D) There will be no change.

E) There is not enough information to tell.

2. Exposure to sarin, a potent nerve gas, causes muscles to be continuously contracted. Therefore, sarin must interfere with which the action of which neurotransmitter?

A) acetycholine

B) GABA  

C) dopamine

D) enkephalins

E) glutamate

3. Multiple sclerosis is a result of:

A) loss of some myelin on nerve cells

B) excess amounts of myelin on nerve cells

C) an immune system attack on nerve fibers

D) blocking the nodes on Ranvier

E) both A and C

Explanation / Answer

1. During depolarization, the membrane potential becomes more positive or in other words the membrane potential increases more than the resting membrane potential.

A) -90 mV < -66 mV. So this is incorrect.

B) -66 mV = -66 mV. Membrane potential should increase. So this is also incorrect.

C) 40 mV > -66 mV. So this is correct.

D) No change indicates that the membrane potential is -66 mV. This is same as optiopn B), which is incorrect. So this is also incorrect.

E) We need only the resting membrane potential. So we have the informatiob we need. So this is also incorrect.

ANSWER: Option C) 40 mV

2. Sarin acts on the contraction of muscles. So the neurotransmittor it affects, must be involved in muscle contration.

A) Acetylcholine: Neurotransmittor released by nervous system for the activation of muscle. So this can be a correct answer.

B) GABA : Decreases neuronal excitability in the nervous system. So this is incorrect.

C) Dopamine : Effects in pleasure and reward, addiction, attention, movement regulation, memory. If sarin interferes with dopamine, the all the above mentioned functions will be affected. Since, only muscle contration occurs, this is also incorrect.

D) Enkephalins: Enodogenous opioids. So this is also incorrect.

E) Glutamate: Role in excitation of neuron. So this is also incorrect.

ANSWER: Option A) Acetylcholine

3. Multiple sclerosis is autoimmune disorder in which the body's immune cells attacks the myelin sheath that protects the nerve cells of brain and spinal cord.

A) In MS, Loss of myelin occurs as a result of immune attack. So this is correct.

B) Myelin sheath is damaged in MS. So this is also incorrect.

C) Nerve fibers are attacked by immune cells in MS. This is correct.

D) There are no myelin in nodes of Ranvier. So there is no immune attack on nodes of Ranvier in case of MS. So this is also incorrect.

E) Option C and A are correct.

ANSWER: Option E) Both A and C

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