question_answer

In pea plants, red flowers (R) are dominant over to white flowers (r) and tall plants (T) are dominant over to dwarf plants (t). The table below shows the gametes and the possible offsprings produced in a dihybrid cross. The numbers 1 to 16 represent the genotypes of each individual cross (e.g. 3 = RrTT) RT Rt rT rt RT 1 2 3 4 Rt 5 6 7 8 rT 9 10 11 12 rt 13 14 15 16 If plant 7 is crossed with plant 12, then what proportion of the offsprings produced will be homozygous for both the recessive characters

A) 50%

B) 37.5%

C) 25%

D) 12.5%

Correct Answer: C

Solution :

  The genotype of plant 7 is RrTt of plant 12 is rrTt, when they are crossed they produce 2 plants out of 8 with the genotype rrtt, rrTT i.e., 25%.

	RT	Rt	rT	rt
rT	RrTT	RrTt	rrTT	rrTt
rt	RrTt	Rrtt	rrTt	rrtt