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## What fraction of offspring would be homozygous dominant for at least one trait?

In any cross involving at least one parent that is homozygous dominant (2 CAPITAL letters), **100% of** the offspring will have the dominant trait in their phenotype.

## What fraction of the offspring is heterozygous?

On average, **half of the children** will be heterozygous (Aa) and, therefore, carriers. The remaining half will inherit 2 recessive alleles (aa) and develop the disease. It is likely that every one of us is a carrier for a large number of recessive alleles.

## What fraction of this cross will be recessive for both traits?

The correct answer is **1/16**. A dihybrid cross results in a phenotypic ratio of 9:3:3:1. The 1 in the ratio is indicative of the double recessive phenotype, with a homozygous recessive genotype for both traits. Thus, only 1/16 of the offspring will display both recessive phenotypes.

## Which parent is homozygous for the dominant trait?

~homozygous dominant parents means **each parent has 2 dominant (rolling tongue) alleles**. Therefore, each parent has no choice but to pass on those dominant alleles to their offspring (RR). All offspring, 4/4 will also be homozygous and able to roll their tongues.

## How do you find the percentage of heterozygous?

The percentage of heterozygous individuals (carriers) in the population. Answer: Since 2pq equals the frequency of heterozygotes or carriers, then the equation will be as follows: 2pq = (2)(.

…

- The frequency of the recessive allele. …
- The frequency of the dominant allele. …
- The frequency of heterozygous individuals.

## What is the probability of a heterozygous offspring?

The possibilities are summarized: There is a 50% x 50% = **25%** probability that both of the offspring’s alleles are dominant. There is a 50% x 50% = 25% probability that both of the offspring’s alleles are recessive. There is a 50% x 50% + 50% x 50% = 25% + 25% = 50% probability that the offspring is heterozygous.

## When you cross 2 heterozygous individuals in a Dihybrid cross what fraction of the offspring will be dominant for both traits?

Explanation: When crossing organisms that are heterozygous for two traits, the result is a dihybrid cross. The phenotypic ratio of a heterozygous dihybrid cross for autosomal (none-sex-linked) traits is always 9:3:3:1. **Nine offspring** will show both dominant traits (AABB, AaBB, AABb, AaBb).