Question

What is the probability of obtaining pure homozygous individuals, if a cross is made between AaBbCcDdxaaBBCCdd individuals ?
(1) 1/16
(2) 2/16
(3) 16/248
(4) 1/64

Answer 1

(1) 1/16

Okay explanation would be tricky! Lemme try! AaBbCcDd have 2^4 i.e 16 types of gametes and aaBBCCdd have only one type of gamete.
It is a tetrahybrid cross.
In this all types of plants would be 16(only in this cross).

So 16/256=1/16

Hope it helps.

Answer 2

Number of gametes produced depends on number of Heterozygous pairs of genes:-

2^n where n is numbers of Heterozygous Gene pairs

In Genotype AaBbCcDd there are 4 numbers of Heterozygous Gene pairs
So the number of gametes are 4^4=16

The Genotype aaBBCCdd is Homozygous for all the Gene pairs so the gamete produced by it will be only 1 aBCd

There will be 16 male gametes and 1 female gamete So 16 offsprings
Will be produced

Out of 16 there will be only one genotype AABBCCDD Homozygous for all genes

So the offsprings Homozygous for all gene pairs will be

One out of 16
1/16
Hope it helps.