Question

Grain colour in wheat is determined by three pairs of polygenes. Following the cross AABBCC (dark colour) x aabbcc (light colour), how many plants will be produced with the genotype AABBCC?

• A. None
• B. Five
• C. One
• D. Ten

Answer 1

Answer: (C)

One

The above cross is a trihybrid cross as it involves three pairs of genes showing grain colour in a Wheat plant. By self crossing the given F${}_1$ generation that is AABBCC (dark colour) X aabbcc (light colour), we will get F${}_2$ generation, using punnett square. The results obtained will be :-

female male gamets	ABC	ABc	AbC	Abc	aBC	aBc	abC	abc
ABC	AABBCC	AABBcc	AABbCc	AABbCC	AaBBCC	AaBBCc	AaBbCC	AaBbCc
ABc	AABBCc	AABBcc	AABbCc	AABbcc	AaBBCc	AaBBcc	AaBbCc	AaBbcc
AbC	AABbCC	AABbCc	AAbbCC	AAbbCc	AaBbCC	AaBbCc	aAbbCC	AabbCc
Abc	AABbCc	AABbcc	AAbbCc	AAbbcc	AaBbCc	AaBbcc	AabbCc	Aabbcc
aBC	AaBBCC	AaBBCc	AaBbCC	AaBbCc	aaBBCC	aaBBCc	aaBbCC	aaBbCc
aBc	AaBBCc	AaBBcc	AaBbCc	AaBbcc	aaBBCc	aaBBcc	aaBbCc	aaBbcc
abC	AaBbCC	AaBbCc	AabbCC	AabbCc	aaBbCc	aabbCC	aabbCC	aabbCc
abc	AaBbCc	AaBbcc	AabbCc	Aabbcc	aaBbcc	aaBbCc	aabbCc	aabbcc

Here in the punnett square table it is seen that only one plant with the genotype AABBCC is produced.

The Phenotypic ratio obtained is - 27 : 9 : 9 : 9 : 3 : 3 : 1.