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Assertion (A): The zygote formed after fertilisation immediately attaches to the uterus wall. Reason (R): The uterus wall is always prepared to receive the zygote. (i) Both A and R are true, and R is the correct explanation of A. (ii) Both A and R are true, but R is not the correct explanation of A. (iii) A is true, but R is false. (iv) A is false, but R is true.
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Answer: (iv) A is false, but R is (treated as) true
- A is false: the zygote does not attach immediately — it undergoes mitotic divisions while travelling to the uterus and only then implants.
- The uterine lining is prepared to receive a zygote (though it is prepared cyclically, not literally “always”), so R is taken as the true statement; since A is false, option (iv) fits best.
Option
Verdict & why
(i)
Both A and R are true, and R is the correct explanation of A.
Wrong
— A is false, so this cannot hold.
(ii)
Both A and R are true, but R is not the correct explanation of A.
Wrong
— A is false.
(iii)
A is true, but R is false.
Wrong
— it is the other way round.
(iv)
A is false, but R is true.
Correct answer.
A is false
— the zygote divides by mitosis while travelling down the oviduct, and only then implants.
R is true
— the uterine lining thickens each cycle, ready to receive a zygote.
