A recessive allele on the x chromosome is responsible for red-green color blindness in humans. Alleles are C = normal and c = co
lor blind. A woman with normal vision whose father is color blind marries a color-blind male. What is the probability that this couple's first son will be color-blind? A) 1/4 B) 1/2 C) 2/3 D) 3/4
1 answer:
Answer:
1/2
Explanation:
The allele for the red-green color blindness is X-linked recessive. The father of the woman was colorblind (X^cY) which means that the woman is a carrier for the allele and has genotype (X^cX). The genotype of the colorblind male would be X^cY. A cross between a carrier woman and a color-blind man would produce progeny in following ratio= 1/2 colorblind daughter: 1/2 normal daughter: 1/2 colorblind son: 1/2 normal son.
Therefore, there is a 50% probability that their first son is colorblind.
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Given question is incomplete. Complete question has been attached.
Answer:
C. Excessive potassium has diffused out causing hyperpolarization.
Explanation:
The nerve action potential can be divided into following stages:
- Stimulus is detected by the cell in resting stage.
- Sodium channels in the membrane open from where influx of sodium ions occur which is called depolarization
- After a while, sodium channels close and potassium channels open from where efflux of potassium ions occur which is called repolarization.
- The membrane potential further lowers due to continous efflux of potassium ions which is called hyperpolarization.
- After a while potassium channels close and membrane returns to its resting stage.
In the given figure, stage 4 depicts hyperpolarization because the membrane potential has dropped to the lowest point below -70mV. Hence, option C is correct.
