Q1. [1] § 8.2 HEREDITY § 8.2.4 Sex Determination
Consider the following statements :
(i) The sex of a child is determined by what it inherits from the mother.
(ii) The sex of a child is determined by what it inherits from the father.
(iii) The probability of having a male child is more than that of a female child.
(iv) The sex of a child is determined at the time of fertilisation when male and female gametes fuse to form a zygote.
The correct statements are :
- (a) (i) and (iii)
- (b) (ii) and (iv)
- (c) (iii) and (iv)
- (d) (i), (iii) and (iv)
Previously asked in CBSE board exam
2024 31/1/1 Q8
Generated by claude-sonnet-4-6 · 2026-06-15 06:53 · grounding rag
Model Answer
(b) (ii) and (iv)
Statement (ii) is correct — sex depends on what the child inherits from the father (X or Y chromosome). Statement (iv) is correct — sex is determined at fertilisation when gametes fuse.
Source: Chapter 8, Section 8.2.4 Sex Determination
---
Explanation
- Statement (i) is wrong: all children inherit X from the mother, so the mother does not determine sex.
- Statement (iii) is wrong: the passage clearly states half the children will be boys and half will be girls — equal probability.
- Statements (ii) and (iv) are directly supported by the text: the father's gamete (X or Y) decides sex, and this is fixed at fertilisation.
If a question refers to an image, map, graph or diagram that is not shown here, find the actual CBSE question paper on the CBSE website:
cbse.gov.in.