Question:
Assertion (A): The loss or gain of a segment of DNA results in alteration of chromosomes.
Reason (R): Genes are known to be located on chromosomes alteration leads to aberrations.
Assertion (A): The loss or gain of a segment of DNA results in alteration of chromosomes.
Reason (R): Genes are known to be located on chromosomes alteration leads to aberrations.
Reason (R): Genes are known to be located on chromosomes alteration leads to aberrations.
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Chromosomal aberrations include deletions, duplications, inversions, and translocations.
They alter gene order or dosage, often resulting in severe genetic disorders or malignancies.
They alter gene order or dosage, often resulting in severe genetic disorders or malignancies.
Updated On: Jul 22, 2026
- Both (A) and (R) are correct and (R) is the correct explanation to (A)
- Both (A) and (R) are correct but (R) is not correct explanation for (A)
- (A) is correct (R) is wrong
- (A) is wrong (R) is correct
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The Correct Option is A
Solution and Explanation
Step 1: Understanding the Question:
The question presents an Assertion regarding how changes in DNA segments alter chromosomes, and a Reason linking gene location on chromosomes to chromosomal aberrations.
Step 2: Key Concepts and Approach:
We analyze the physical relationship between DNA, genes, and chromosomes.
Chromosomes are made of DNA and proteins.
Genes are linear segments of DNA arranged along the chromosome.
Step 3: Detailed Explanation:
• Assertion (A): Chromosomes are the structural carriers of genetic material.
Any deletion (loss) or duplication (gain) of a DNA segment changes the physical structure and genetic content of the chromosome. This structural change alters the chromosome, making Assertion (A) correct.
• Reason (R): Genes are located at specific positions (loci) along chromosomes.
Because of this close structural relationship, any gain or loss of chromosomal DNA segments alters the genes, leading to abnormalities known as chromosomal aberrations.
These structural changes are commonly observed in cancer cells. Thus, Reason (R) is correct.
• Connecting A and R: The fact that genes are physically located on chromosomes explains why altering a DNA segment (which contains these genes) directly changes the chromosome's structure and function.
Therefore, Reason (R) is the correct explanation for Assertion (A).
Step 4: Final Answer:
Both (A) and (R) are correct, and (R) is the correct explanation of (A).
The question presents an Assertion regarding how changes in DNA segments alter chromosomes, and a Reason linking gene location on chromosomes to chromosomal aberrations.
Step 2: Key Concepts and Approach:
We analyze the physical relationship between DNA, genes, and chromosomes.
Chromosomes are made of DNA and proteins.
Genes are linear segments of DNA arranged along the chromosome.
Step 3: Detailed Explanation:
• Assertion (A): Chromosomes are the structural carriers of genetic material.
Any deletion (loss) or duplication (gain) of a DNA segment changes the physical structure and genetic content of the chromosome. This structural change alters the chromosome, making Assertion (A) correct.
• Reason (R): Genes are located at specific positions (loci) along chromosomes.
Because of this close structural relationship, any gain or loss of chromosomal DNA segments alters the genes, leading to abnormalities known as chromosomal aberrations.
These structural changes are commonly observed in cancer cells. Thus, Reason (R) is correct.
• Connecting A and R: The fact that genes are physically located on chromosomes explains why altering a DNA segment (which contains these genes) directly changes the chromosome's structure and function.
Therefore, Reason (R) is the correct explanation for Assertion (A).
Step 4: Final Answer:
Both (A) and (R) are correct, and (R) is the correct explanation of (A).
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