451,129 views
32 votes
32 votes
If an offspring has a recessive trait show up, such as blue eyes, what combination of alleles must be present?

Group of answer choices

1 dominant and 1 recessive gene

2 dominant genes

2 recessive genes

If an offspring has a recessive trait show up, such as blue eyes, what combination-example-1
User Patrick Balada
by
2.7k points

1 Answer

15 votes
15 votes

Answer:

2 recessive genes

Step-by-step explanation:

A recessive trait can only be present in the absence of the dominant gene.

For example the gene for brown eyes are dominant and the gene for blue eyes are recessive.

**the dominant gene is usually represented with a capital letter and vice versa for the recessive*

Denoting:

B for brown eyes

b for blue eyes

We know that gametes (sex cells) have half the number of chromosomes (haploid number) than all the other cells in the body, the reason for this is because during fertilization, both male and female gametes combine and then in total they have the diploid number of chromosomes.

so for each trait, you have an allele from each the mother and father. Heterozygous means that there are two different alleles for the gene and homozygous means that both alleles for a specific gene are the same.

In the case of eye colour, any combination that has the dominant Brown allele in it results in the offspring having brown eyes no matter if there is also a recessive blue allele.

the combinations BB, Br all result in brown eyes and the only possibility of blues eyes are bb

User FLOZz
by
2.9k points