If an individual who is homorygous for a gene mates with an individual who is heterorygous for the same gene predict what percentage of the offspring with be heterorygous. ◻ 50% None of the offspring will be heterorygous. 25% 75% 100%
The correct answer and explanation is:
Correct Answer: ◻ 50%
Explanation:
To solve this problem, we must understand basic Mendelian genetics, specifically how alleles (forms of a gene) are inherited. Let’s denote:
- A = dominant allele
- a = recessive allele
Step 1: Identify the genotypes
- A homozygous individual has two identical alleles. There are two types: AA (homozygous dominant) or aa (homozygous recessive).
- A heterozygous individual has two different alleles: Aa.
We will consider both cases where the homozygous individual could be AA or aa, since the question does not specify.
Case 1: Homozygous Dominant (AA) × Heterozygous (Aa)
| Parent 1 (AA) | Parent 2 (Aa) |
|---|---|
| A | A or a |
Possible offspring:
- A from AA parent + A from Aa = AA
- A from AA parent + a from Aa = Aa
So, offspring genotypes:
- 50% AA (homozygous dominant)
- 50% Aa (heterozygous)
→ 50% are heterozygous
Case 2: Homozygous Recessive (aa) × Heterozygous (Aa)
| Parent 1 (aa) | Parent 2 (Aa) |
|---|---|
| a | A or a |
Possible offspring:
- a from aa parent + A from Aa = Aa
- a from aa parent + a from Aa = aa
So, offspring genotypes:
- 50% Aa (heterozygous)
- 50% aa (homozygous recessive)
→ 50% are heterozygous
Conclusion:
In either case (AA or aa crossed with Aa), 50% of the offspring will be heterozygous.
This result is consistent with Mendel’s law of segregation, which states that offspring receive one allele from each parent randomly.
✅ Therefore, the correct answer is 50%.