Question:
Given below are two statements:
Statement (I) : Self pollination leads to a very rapid increase in homozygosity and self pollinated crops do not show inbreeding depression.
Statement (II) : Cross pollination preserves and promotes heterozygosity in a population and shows mild to severe inbreeding depression.
In light of the above statements, choose the most appropriate answer from the options given below.
Given below are two statements:
Statement (I) : Self pollination leads to a very rapid increase in homozygosity and self pollinated crops do not show inbreeding depression.
Statement (II) : Cross pollination preserves and promotes heterozygosity in a population and shows mild to severe inbreeding depression.
In light of the above statements, choose the most appropriate answer from the options given below.
Statement (I) : Self pollination leads to a very rapid increase in homozygosity and self pollinated crops do not show inbreeding depression.
Statement (II) : Cross pollination preserves and promotes heterozygosity in a population and shows mild to severe inbreeding depression.
In light of the above statements, choose the most appropriate answer from the options given below.
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To remember:
- Self-pollinated crops are already inbred, so they have zero to minimal inbreeding depression.
- Cross-pollinated crops are highly outbred, so they exhibit severe inbreeding depression upon forced selfing.
- Self-pollinated crops are already inbred, so they have zero to minimal inbreeding depression.
- Cross-pollinated crops are highly outbred, so they exhibit severe inbreeding depression upon forced selfing.
Updated On: Jul 23, 2026
- Both Statement (I) and Statement (II) are correct.
- Both Statement (I) and Statement (II) are incorrect.
- Statement (I) is correct but Statement (II) is incorrect.
- Statement (I) is incorrect but Statement (II) is correct.
Show Solution
Verified By Collegedunia
The Correct Option is A
Solution and Explanation
Step 1: Understanding the Concept:
This question focuses on the genetic and evolutionary consequences of self-pollination versus cross-pollination.
These mating systems shape the genetic structure, homozygosity levels, and inbreeding tolerance of plant populations.
Step 2: Detailed Explanation:
Let us analyze each statement:
Statement (I):
Self-pollination (selfing) naturally increases homozygosity in a population by $50\%$ each generation.
Because naturally self-pollinated crops (such as tomato or pea) are highly homozygous, harmful recessive alleles have already been exposed and eliminated over generations of natural selection.
Therefore, these crops do not suffer from inbreeding depression when selfed.
Thus, Statement (I) is correct.
Statement (II):
Cross-pollination (outcrossing) maintains and promotes high levels of genetic heterozygosity by mixing genes from different individuals.
However, cross-pollinated crops (such as maize or onion) carry many hidden, harmful recessive alleles in a heterozygous state.
When these outcrossing crops are forced to self-pollinate, these recessive alleles become homozygous, leading to mild to severe inbreeding depression (loss of vigor, reduced yield, and developmental defects).
Thus, Statement (II) is correct.
Step 3: Final Answer:
Both Statement (I) and Statement (II) are correct.
This corresponds to Option (A).
This question focuses on the genetic and evolutionary consequences of self-pollination versus cross-pollination.
These mating systems shape the genetic structure, homozygosity levels, and inbreeding tolerance of plant populations.
Step 2: Detailed Explanation:
Let us analyze each statement:
Statement (I):
Self-pollination (selfing) naturally increases homozygosity in a population by $50\%$ each generation.
Because naturally self-pollinated crops (such as tomato or pea) are highly homozygous, harmful recessive alleles have already been exposed and eliminated over generations of natural selection.
Therefore, these crops do not suffer from inbreeding depression when selfed.
Thus, Statement (I) is correct.
Statement (II):
Cross-pollination (outcrossing) maintains and promotes high levels of genetic heterozygosity by mixing genes from different individuals.
However, cross-pollinated crops (such as maize or onion) carry many hidden, harmful recessive alleles in a heterozygous state.
When these outcrossing crops are forced to self-pollinate, these recessive alleles become homozygous, leading to mild to severe inbreeding depression (loss of vigor, reduced yield, and developmental defects).
Thus, Statement (II) is correct.
Step 3: Final Answer:
Both Statement (I) and Statement (II) are correct.
This corresponds to Option (A).
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