Question: Sand Shrews are normally yellow in colour. However there is a
random mutation that can cause the …


Sand Shrews are normally yellow in colour. However there is a
random mutation that can cause the scales to be metallic blue in
colour. Professor Ash investigates this situation and makes the
following observations.

Crosses between Blue Sand Shrews always result in ¼ of the
offspring being yellow and the remaining ¾ of the offspring showing
blue scales.

Crosses between Blue Sand Shrews and regular yellow Sand Shrews
always result with ½ the offspring yellow and the other ½ blue.

Crosses between yellow Sand Shrews always results in yellow
offspring.

a) Is the blue allele dominant or recessive? Explain

b) If 6 of 15000 sand shrews has blue scales what is the
frequency of the blue phenotype in the population?

c) Calculate the frequency of the blue allele in the
population.

d) Calculate the expected frequency of the homozygous dominant
genotype and the frequency of the heterozygote.

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