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Biology · 2026 · 2 marks
CBSE 2026 · Region 2 · Set 1 · Q21
(a) (i) Name the organ that forms a connection between foetus and the uterus of a pregnant human female. (ii) How does it support both nutrition and…
(a)(i)
Name the organ that forms a connection between foetus and the uterus of a pregnant human female.
(ii)
How does it support both nutrition and hormonal regulation?
OR
(b)
Give reasons for :
(i)
All copulations do not lead to pregnancy.
(ii)
Meiosis I in spermatogenesis and oogenesis are markedly different.
Marking-scheme solution
(i)
Placenta
(ii)
Nutrition: It facilitates the supply of nutrients to embryo.
Hormonal regulation: Acts as an endocrine gland and produces hCG /Human Chorionic Gonadotropin, hPL / Human Placental Lactogen, estrogen, progestogens.
(i)
Fertilisation can only occur if the ovum and sperms are transported simultaneously to the ampullary region / use of contraceptive devices / low sperm count or poor sperm quality / absence of ovulation / lactational amenorrhea / coitus interruptus / periodic abstinence
(Any Other Correct Reason)
(ii)
| Meiosis I in Spermatogenesis | Meiosis I in Oogenesis |
| Starts at puberty | Starts during embryonic stage |
| Results in production of two equal haploid secondary spermatocyte | Results in production of unequal haploid secondary oocyte and first polar body |
(Any One Correct Difference)
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CBSE Class 12 Biology past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.