Question

Genetic testing of giraffes in the wild indicates that shorter animals possess a recessive gene that affects their height. The alleles for height are T for tall and t for short.



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A student was comparing the offspring resulting from two different crosses, a heterozygous male with a heterozygous female versus a heterozygous male with a homozygous recessive female.



What percentage of the offspring will be short from the heterozygous/heterozygous pair as compared to the heterozygous/homozygous pair?



A.
25% of the offspring from the heterozygous/heterozygous pair will be short

100% of the offspring of the heterozygous/homozygous pair being short

B.
25% of the offspring from the heterozygous/heterozygous pair will be short

50% of the offspring from the heterozygous/homozygous pair being short

C.
100% of the offspring from the heterozygous/heterozygous pair will be tall

50% of the offspring from the heterozygous/homozygous pair being short

D.
0% of the offspring from the heterozygous/heterozygous pair will be short

50% of the offspring from the heterozygous/homozygous pair being short

Answer 1

Answer: B.

Explanation: Tt × Tt gives genotypes TT, Tt, Tt, tt → 25% tt (short).
Tt × tt gives genotypes Tt, tt → 50% tt (short).