Question

Given below are two statements:
Statement I: When one dominant allele of one gene and recessive allele of another gene are present on one chromosome and their opposite alleles are present on the homologous chromosome, the arrangement is called Cis-heterozygote.
Statement II: When the dominant alleles of two genes are present on one chromosome and their corresponding recessive alleles are present on the homologous chromosome, the arrangement is called Cis-heterozygote.
In the light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is correct but Statement II is false
• D. Statement I is incorrect but Statement II is true

Hint:

Linkage phases:
- Cis (coupling): AB ab (dominants together).
- Trans (repulsion): Ab aB (dominants separated).
- Test cross helps identify linkage phase.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
This question tests knowledge of linkage phases (cis and trans).

Step 2: Detailed Explanation:
Statement I:
When one dominant allele of one gene and a recessive allele of another gene are present on one chromosome, and their opposite alleles on the homologous chromosome, the arrangement is called Trans-heterozygote (or repulsion phase).
Example: Ab aB.
Thus, this statement is false.
Statement II:
When dominant alleles of two genes are present on one chromosome, and their corresponding recessive alleles are present on the homologous chromosome, the arrangement is called Cis-heterozygote (or coupling phase).
Example: AB ab.
Thus, this statement is true.

Step 3: Final Answer:
Thus, Statement I is incorrect but Statement II is true, which corresponds to option (D).
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