Given below are two statements:
Statement (I): Heterosis refers to the phenomenon where the hybrid offspring exhibit superior trait performance compared to their parents.
Statement (II): Heterosis is primarily attributed to the combination of favorable alleles from each parent, resulting in enhanced trait performance of the hybrid offspring.
In light of the above statements, choose the most appropriate answer from the options given below.
Statement (I): Heterosis refers to the phenomenon where the hybrid offspring exhibit superior trait performance compared to their parents.
Statement (II): Heterosis is primarily attributed to the combination of favorable alleles from each parent, resulting in enhanced trait performance of the hybrid offspring.
In light of the above statements, choose the most appropriate answer from the options given below.
Show Hint
Bringing divergent parents together combines favorable alleles, masking deleterious recessive mutations.
- Both Statement (I) and Statement (II) are true.
- Both Statement (I) and Statement (II) are false.
- Statement (I) is true but Statement (II) is false.
- Statement (I) is false but Statement (II) is true.
The Correct Option is A
Solution and Explanation
Heterosis, or hybrid vigor, refers to the increased performance, yield, growth rate, or fertility of a hybrid offspring over those of either parent.
It is widely utilized in crop breeding to increase agricultural productivity.
Step 2: Detailed Explanation:
Let us analyze each statement:
- Statement (I): Heterosis is defined as the superiority of an \(F_1\) hybrid over its parents.
This superiority can be measured relative to the average of both parents (mid-parent heterosis) or the better parent (heterobeltiosis).
This confirms that Statement (I) is true.
- Statement (II): The genetic basis of heterosis is explained by two primary classical hypotheses:
1. Dominance Hypothesis: Suggests that dominant alleles from each parent suppress deleterious recessive alleles from the other parent, resulting in a hybrid with a highly favorable combination of dominant alleles.
2. Overdominance Hypothesis: Suggests that the heterozygous condition (Aa) at specific loci is physiologically superior to either homozygous condition (AA or aa).
In both hypotheses, heterosis is driven by combining favorable, complementary alleles from each parent.
This confirms that Statement (II) is true.
Since both statements are true, Option (A) is correct.
Step 3: Final Answer:
Both Statement (I) and Statement (II) are true.
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Choose the correct answer from the options given below:
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