Question

question 23 of 26

scientists have observed that fruit flies with red eyes usually have tan-colored bodies. which statement most likely explains this observation?

a. the two genes are on different sex chromosomes.
b. eye color and body color are each controlled by multiple genes.
c. each gene has only one allele.
d. the two genes are linked and on the same chromosome.

Explanation:

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<reasoning>

Analyze the genetic observation

The observation states that fruit flies with red eyes usually have tan-colored bodies. This indicates that these two specific phenotypic traits (eye color and body color) are frequently inherited together rather than assorting independently.

Evaluate the genetic mechanisms

When two different genes are consistently inherited together, it is typically because they are located close to each other on the same chromosome. This physical proximity prevents them from assorting independently during meiosis, a phenomenon known as gene linkage.

Assess the given options

• Option A suggests they are on different sex chromosomes, which would lead to independent assortment or sex-specific patterns, not consistent co-inheritance.
• Option B suggests polygenic inheritance, which does not directly explain why these two specific traits consistently co-occur.
• Option C is incorrect because genes for eye and body color in fruit flies have multiple known alleles (e.g., red/white eyes, tan/black bodies).
• Option D correctly identifies that the two genes are linked on the same chromosome, which directly explains why they are usually inherited together.

</reasoning>

<answer>
<mcq-option>A. The two genes are on different sex chromosomes.</mcq-option>
<mcq-option>B. Eye color and body color are each controlled by multiple genes.</mcq-option>
<mcq-option>C. Each gene has only one allele.</mcq-option>
<mcq-correct>D. The two genes are linked and on the same chromosome.</mcq-correct>
</answer>

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Answer:

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<reasoning>

Analyze the genetic observation

The observation states that fruit flies with red eyes usually have tan-colored bodies. This indicates that these two specific phenotypic traits (eye color and body color) are frequently inherited together rather than assorting independently.

Evaluate the genetic mechanisms

When two different genes are consistently inherited together, it is typically because they are located close to each other on the same chromosome. This physical proximity prevents them from assorting independently during meiosis, a phenomenon known as gene linkage.

Assess the given options

• Option A suggests they are on different sex chromosomes, which would lead to independent assortment or sex-specific patterns, not consistent co-inheritance.
• Option B suggests polygenic inheritance, which does not directly explain why these two specific traits consistently co-occur.
• Option C is incorrect because genes for eye and body color in fruit flies have multiple known alleles (e.g., red/white eyes, tan/black bodies).
• Option D correctly identifies that the two genes are linked on the same chromosome, which directly explains why they are usually inherited together.

</reasoning>

<answer>
<mcq-option>A. The two genes are on different sex chromosomes.</mcq-option>
<mcq-option>B. Eye color and body color are each controlled by multiple genes.</mcq-option>
<mcq-option>C. Each gene has only one allele.</mcq-option>
<mcq-correct>D. The two genes are linked and on the same chromosome.</mcq-correct>
</answer>

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