Black fur in mice (B) is dominant to brown fur (b) short tails (T) is dominant of long tails (t).What proportion of the progeny of the cross BbTt x Bbtt will have black fur and long tails?
a) 1/16;
b) 3/16;
c) 3/8;
d) 1/2;
e) 9/16.

This is typical dihybrid cross involving two genes B and T coding for fur colour and tail length in mice respectively. The alleles for Black fur (B) and short tail (T) are dominant over alleles for brown fur (b) and long tail (t) respectively.

Hence, in a cross between a BbTt and Bbtt mice. The following possible gamete combinations will be produced by each parent:

BbTt - BT, Bt, bT, bt.

Bbtt - Bt, Bt, bt, bt

According to the dominance pattern of each allele, a black furred and long tailed offspring will have either Bbtt or BBtt genotype. Hence, using a punnet square what a possible 16 offsprings will result, 6 out of 16 have this genotype i.e. 6 offsprings have a Black fur and long tail.

Hence, the probability is 6/16 equivalent to 3/8.

See attached image containing the punnet square.

Black fur in mice (B) is dominant to brown fur (b) short tails (T) is dominant of long tails (t).What proportion of the progeny of the cross BbTt x Bbtt will have black fur and long tails? a) 1/16; b) 3/16; c) 3/8; d) 1/2; e) 9/16.

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Black fur in mice (B) is dominant to brown fur (b) short tails (T) is dominant of long tails (t).What proportion of the progeny of the cross BbTt x Bbtt will have black fur and long tails?
a) 1/16;
b) 3/16;
c) 3/8;
d) 1/2;
e) 9/16.