NEET · Biology · STD 12 - 4. principal of inheritance and variation

In a population of a grasshopper species, the chromosome number of some members is 23 and some other members possess 24 chromosomes. The 23 and 24 chromosome-bearing members in this species are :

A females and males, respectively
B all males
C males and females, respectively
D all females

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Answer & Solution

Correct Answer

(C) males and females, respectively

Step-by-step Solution

Detailed explanation

(C) males and females, respectively
Grasshoppers exhibit the XX-XO type of sex determination.
In this system, females have a pair of X chromosomes (XX) along with autosomes, while males have only one X chromosome (XO) along with autosomes.
Thus, females have one more chromosome than males.
Given the chromosome numbers 23 and 24 , the members with 23 chromosomes are males ( 22 autosomes +1 X chromosome) and the members with 24 chromosomes are females ( 22 autosomes \(+2 \times\) chromosomes).
Therefore, the 23 and 24 chromosome-bearing members are males and females, respectively.

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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