Question

Multiple Choice

1. The mechanisms of nerve impulse transmission include:

a. Decrease in Na⁺ permeability → Repolarization → Na⁺ influx stops → Depolarization

b.  Resting potential → Depolarization → Repolarization → Resting potential

c. Resting potential → Repolarization → Depolarization → Resting potential

d. Myelinization of fibers → decrease action potential → resting potential

2. An animal has a genetic mutation in the gene coding for rhodopsin and phtopsin. What would be the phenotypic outcome of this particular animal?

a. the animal will have normal vision

b. The animal will have normal vision during the day but lack of adaptation in dark conditions

c. The animal will have normal vision during the night but lack of vision in light conditions

d. The animal will have vision problems regardless of the light or dark conditions

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Answer 1

Ans 1.

b.  Resting potential → Depolarization → Repolarization → Resting potential

STEP 1: RESTING STATE

-A neuron is not conducting an impulse.

-The potassium concentration is higher inside the cell than it is outside the cell.

-The sodium concentration is higher outside the cell than inside.

STEP 2: DEPOLARIZATION

- A nerve cell is stimulated

- At stimulation, the membrane becomes preamble to sodium and it quickly moves into the cell.

- The inner surface of the cell membrane is now more positivity charged than the outside

STEP 3: Re- Polarization

- When the cell membrane becomes depolarized, Potassium automatically leaves the cell until the cell is back into complete resting stage.

The quick movements of ions causes a similar change or wave all across the cell and down the axon .

STEP 4 : AGAIN RESTING POTENTIAL

Ans 2.

D. The animal will have vision problems regardless of the light or dark conditions

Rhodopsin

Rhodopsin is a protein that is essential for vision, especially in dim light.Mutations to rhodopsin can lead to stationary night blindness or retinitis pigmentosa.

Photospsin

Photopsin pigments operate in brighter light than scotopsins and occur in the vertebrate cone cells andresponsible for color vision as well as eye color sensitivity; they function best in relatively bright light,so necessary to see during day.

Hence,

The animal will have vision problems regardless of the light or dark conditions