Question:
Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Atavism refers to the reappearance of a trait after it remains hidden for several generations.
Reason R: The chance combination of genes allows long-suppressed hidden traits to reappear and express.
In light of the above statements, choose the correct answer from the options given below:
Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Atavism refers to the reappearance of a trait after it remains hidden for several generations.
Reason R: The chance combination of genes allows long-suppressed hidden traits to reappear and express.
In light of the above statements, choose the correct answer from the options given below:
Assertion A: Atavism refers to the reappearance of a trait after it remains hidden for several generations.
Reason R: The chance combination of genes allows long-suppressed hidden traits to reappear and express.
In light of the above statements, choose the correct answer from the options given below:
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Atavism is a "genetic throwback" where dormant genes are reactivated. Since the activation occurs due to chance gene combinations or mutations breaking the suppression, R is the direct cause of A.
Updated On: Aug 13, 2026
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is NOT the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
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The Correct Option is A
Solution and Explanation
Step 1: Understanding the Concept:
Atavism (or genetic throwback) is an evolutionary phenomenon where a phenotypic trait belonging to an ancestral species suddenly reappears in an organism after being absent for several generations.
Step 2: Detailed Explanation:
Let us analyze the biological and genetic basis of both statements:
Assertion A: Atavism is defined as the sudden re-emergence of an ancestral character that had been lost during the recent evolutionary history of the lineage.
This character remains hidden/silenced for multiple generations before expressing again.
Thus, Assertion A is true.
Reason R: The genetic basis of atavism lies in the preservation of ancestral genes in the DNA.
These genes are not lost but are simply silenced or suppressed by regulatory pathways or modifier genes during evolution.
Through a chance genetic recombination, mutation, or hybridization, the suppressive mechanism can be bypassed, or a complete set of complementary recessive alleles can come together.
This chance combination of genes allows these long-suppressed, hidden traits to be expressed once again.
Thus, Reason R is true and represents the exact genetic explanation for the phenomenon described in Assertion A.
Step 3: Final Answer:
Both Assertion A and Reason R are true, and R is the correct explanation of A.
Therefore, the correct option is (A).
Atavism (or genetic throwback) is an evolutionary phenomenon where a phenotypic trait belonging to an ancestral species suddenly reappears in an organism after being absent for several generations.
Step 2: Detailed Explanation:
Let us analyze the biological and genetic basis of both statements:
Assertion A: Atavism is defined as the sudden re-emergence of an ancestral character that had been lost during the recent evolutionary history of the lineage.
This character remains hidden/silenced for multiple generations before expressing again.
Thus, Assertion A is true.
Reason R: The genetic basis of atavism lies in the preservation of ancestral genes in the DNA.
These genes are not lost but are simply silenced or suppressed by regulatory pathways or modifier genes during evolution.
Through a chance genetic recombination, mutation, or hybridization, the suppressive mechanism can be bypassed, or a complete set of complementary recessive alleles can come together.
This chance combination of genes allows these long-suppressed, hidden traits to be expressed once again.
Thus, Reason R is true and represents the exact genetic explanation for the phenomenon described in Assertion A.
Step 3: Final Answer:
Both Assertion A and Reason R are true, and R is the correct explanation of A.
Therefore, the correct option is (A).
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