**Contents**show

## What is the genotype of Trihybrid cross?

For a trihybrid cross, the F2 phenotypic ratio is 27:9:9:9:3:3:3:1. There are **27 different genotypes** possible in trihybrid cross, hence, its genotypic ratio is not mentioned.

## What would be the sum of phenotype and genotype obtained from a Trihybrid test cross?

The sum of phenotypes and genotypes obtained from a trihybrid test cross: As a “dihybrid cross”, the phenotypic ratio is 9:3:3:1. … Therefore, the total number of phenotypes and genotypes produced in a “dihybrid cross” are **4 + 9 = 13**. The phenotype ratio concluded for dihybrid cross is “9:3:3:1”.

## How do you find the phenotypic ratio of a Trihybrid cross?

For a trihybrid cross, the F_{2} phenotypic ratio is **27:9:9:9:3:3:3:1**. The forked-line method can be used to analyze a trihybrid cross. Here, the probability for color in the F_{2} generation occupies the top row (3 yellow:1 green).

## Which genotype ratio will appear by the Trihybrid test cross in a completely linked plant?

**1 : 1 : 1 : 1**.

## How do you determine the number of genotypes?

The number of different genotypes is **3 ^{n} where n = number of genes**. For simple dominant–recessive relations, the number of different phenotypes is 2

^{n}, where n = number of genes.

## How many different types of gametes would be produced by an organism of genotype AaBbCcDdEe if all of the genes assort independently?

The number of different possible gametes produced by the diploid genotype (AaBbCcDdEe) is 2 x 2 x 2 x 2 x 2 = **32** (2 for each pair of heterozygous genes).

## How many different gametes can be produced from the genotype AaBbCc?

Hints For Biology 101 Exam #4

No. of homologous chromosome pairs (heterozygous genes) | No. of different gametes from each parent |
---|---|

1 (Aa X Aa) | 2 (2^{1}) |

2 (AaBb X AaBb) | 4 (2^{2}) |

3 (AaBbCc X AaBbCc) | 8 (2^{3}) |

4 (AaBbCcDd X AaBbCcDd) | 16 (2^{4}) |