By which time, during the pregnancy, most of the major organ systems of the foetus are formed?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → By the end of 12 weeks
A human pregnancy lasts 9 months, and the foetus develops stage by stage. The first trimester is the first 12 weeks.
(1) By the end of 6 months — Incorrect. The organ systems are already formed by then. At the end of about 24 weeks (the second trimester) the body is covered with fine hair, the eyelids separate and eyelashes form.
(2) By the end of 4 months — Incorrect. The major organ systems have been formed well before this. The first movements of the foetus and hair on the head appear in the fifth month.
(3) By the end of 12 weeks — Correct. By the end of 12 weeks (the first trimester) most of the major organ systems are formed. For example, the limbs and external genital organs are well developed.
(4) By the end of 4 weeks — Incorrect. After one month only the heart has formed. Limbs and digits appear by the end of the second month.
NCERT Extract:
Pregnancy and Embryonic Development – …
