We will talk about this more in class, but pigeons have a gene, EphB2, that controls head crest feather development. A recessive allele at this locus reverses the feathers on their head crests and basically makes them look like they have a huge cowlick. There are 100,000 pigeons in the population; 1,000 pigeons are heterozygous for the recessive trait; and 1,674 pigeons have reversed head-crest feathers. If we call the dominant allele A1 and the recessive allele A2, which of the following is closest to the frequency of the A2 allele?

Select one:
a. 0.973
b. 0.978
c. 0.017
d. 0.022

the answer is C

Explanation:

The total number of pigeons with the recessive allele A2 can be represents as q, thus the frequency of q in the population will be

The number of pigeons with the q allen / the total number of pigeons in the population

1674/ 100000

= 0.01674 ~ 0.017

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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since there are no options posted i'll give you a few examples.

a dolphin's flipper, bird's wing, cat's leg.