Question

If 25% of the individuals in a population have the recessive trait, does that mean that 25% of the alleles in the population are recessive alleles? Explain. (2 marks)

Answer 1

This is not correct.

I explain it you with an simple example :

A cross between pure homozygous tall pea plants and pure homozygous dwarf pea plants.

Alleles for tall homozygous =TT

Alleles for dwarf homozygous = tt

Parents ( population ) TT * tt  

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Gametes = T , T and t, t

PF1 progeny TT ,Tt, Tt and tt

TT , Tt, Tt = tall pea plants as T is dominant over t

tt = dwarf ( 25% of whole phenotypically )

But the allele responsible for dwarfness is 50% in the population

Tt, Tt, Tt, tt

50% are T and 50% are t