Reproduction

The corpus luteum is a temporary endocrine structure formed in the ovary after ovulation. It secretes progesterone to maintain the endometrium for implantation in case of fertilization. If fertilization does not occur, it degenerates.

Amphimixis refers to the fusion of male and female pronuclei during fertilization, leading to the formation of a synkaryon—a zygotic nucleus containing chromosomes from both parents.

The correct path for sperm transport is: seminiferous tubules → rete testis → vasa efferentia → epididymis → vas deferens → ejaculatory duct → urethra.

The chromosomal theory of inheritance was experimentally verified by Thomas Hunt Morgan through his work with fruit flies (Drosophila),
where he demonstrated how traits are inherited through the chromosomes.

In hymenopteran insects like bees, unfertilized eggs develop into male drones. Fertilized eggs develop into female bees, which can either become queen bees or worker bees depending on their environment and diet.

Sperm production starts at puberty in males, typically around 13–14 years of age. This is when hormonal changes trigger spermatogenesis in the testes.

Grafting joins parts from two plants (scion and rootstock) to grow as one. It is common in horticulture to combine traits. Layering and cutting are vegetative propagation methods; conjugation is microbial gene transfer.

Matching the correct years with the respective laws and developments:
- Family planning programme was introduced in 1951 (A - iii),
- The Pre-natal Diagnostic Techniques act came into effect in 1971 (B - ii),
- The Legalisation of Medical Termination of Pregnancy occurred in 1994 (C - iv),
- Advant of amniocentesis was introduced in 1970 (D - i).

- Heart forms by the 4th week
- Limb development occurs by the 8th week
- External genitalia differentiate by the 12th week
- Hair and eyelid separation occur around the 24th week

Cryptorchidism is the condition in which one or both of the testes fail to descend into the scrotum, which is a common issue in infants and requires medical intervention. Other options such as Involution, Delamination, and Capacitation refer to different biological processes.

Both the assertion and the reason are true. The assertion correctly states that the placenta connects to the embryo via the umbilical cord.
The reason is also accurate, as somatomammotropin released from the placenta affects the mother's insulin production, which is part of the biological process during pregnancy.

In perkinetal fission of {Paramecium}, the axis of fission is transverse, hence both A and R are correct but not directly related causally.