Question

If individuals of genotype Aa Bb Cc are intercrossed, how many different genotypes can occur in their progeny.
(a) 6
(b) 9
(c) 15
(d) 27

Answer 1

Hint: When two individuals are heterozygous for three different traits, the cross done between them is known as a trihybrid cross.

Complete answer:
For a trihybrid cross, there are 27 unique genotypic combinations.

Additional information:
Mendel’s first set of experiments consisted of crossing pure lines that differed in just one trait. Starting with the simplest possible situation as Mendel did is an important research strategy. Mendel first did his single-trait crosses with plants from round-seed and wrinkled-seed pure lines. The plants in the first cross are known as the parental generations. Their progeny (offspring) are the F1 generation. F1 stands for “first filial”; the Latin roots Filius and filia mean “son” and “daughter,” respectively. Offspring from a mating between two F1 individuals are called the F2 generation; an F2 mating leads to an F3 generation, and so on.
When 3 traits are crossed we do a trihybrid cross.
For the given question we have to perform a trihybrid cross.
The formula used for the different combination of gametes produced is: 2n
Here, n = number of heterozygous traits.
So, the total number of gametes produced are:
 2n where n = 3;
 23 = 8
A total of 8 gametes will form here.
Now when we will perform a trihybrid cross using Punnett square.
Parents: AaBbCc X AaBbCc
Gametes formed: ABC, ABc, AbC, aBC, Abc, aBc, abC, abc

The phenotypic ratio is - 27:9:9:9:3:3:3:1
There are 8 different phenotypes for the given cross.
And there are 27 different genotypes.

So, the correct answer is ‘27’.

Note:
-Mendel is known as the father of genetics.
-Bateson coined the term genetics and is called the father of modern genetics.
-For performing a mendelian cross a Punnett square is used.