Question
Biology Question on Chromosomal Theory of Inheritance
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Mendel’s law of Independent assortment does not hold goods for the genes that are located closely on the same chromosome.
Reason (R): Closely located genes assort independently.
Answer from the options given below:
Both (A) and (R) are correct and (R) is the correct explanation of (A)
Both (A) and (R) are correct but (R) is not the correct explanation of (A)
(A) is correct but (R) is not correct
(A) is not correct but (R) is correct
(A) is correct but (R) is not correct
Solution
The statement "Mendel's law of Independent assortment states that the alleles of two different genes get sorted into gametes independently of one another" can be rephrased as "According to Mendel's law of Independent assortment, the inheritance of one gene does not influence the inheritance of another gene."
However, the statement goes on to say that Morgan's experiment showed that genes on the same chromosome can be tightly or loosely linked, and due to the process of crossover, two genes on the same chromosome can behave either independently or as if they are linked. This linkage can affect the isolation of alleles into gametes, and genes located closely together on the same chromosome tend to be inherited together, which is why the law of Independent assortment does not hold true for these genes.
The revised statement that accurately reflects the information is "Although Mendel's law of Independent assortment asserts that genes are inherited independently, Morgan's experiment revealed that genes located on the same chromosome can be tightly or loosely linked, and their inheritance can be influenced by the process of crossover. Due to linkage, genes located closely together on the same chromosome tend to be inherited together, violating the law of Independent assortment."