Ch 2Human Reproduction — Class 12 Biology, concept-first.

Human reproduction is sexual, involving the fusion of a male gamete (sperm) and a female gamete (ovum) to form a diploid zygote that develops into a new individual over an internal gestation period of…

The male reproductive system consists of a pair of primary sex organs, the testes, together with a system of accessory ducts and accessory glands, and the external genitalia.

A single seminiferous tubule, seen in transverse section under the microscope, has a wall composed of a specialised, thick, multi-layered lining called the germinal (or spermatogenic) epithelium, surr…

The female reproductive system consists of a pair of primary sex organs, the ovaries, together with the fallopian tubes, uterus, cervix and vagina, and the external genitalia (vulva).

The cortex of the ovary contains, at any given time, ovarian follicles at every stage of development, from the many thousands of immature follicles already present at birth to, in a given cycle, a sin…

Spermatogenesis is the process by which diploid spermatogonia, present in the wall of the seminiferous tubule from before puberty, are transformed into haploid, motile spermatozoa; it begins at pubert…

Oogenesis is the process by which the female germ cells develop into a mature ovum, and it differs from spermatogenesis in several fundamental ways: it begins and largely completes its early stages be…

The menstrual cycle is the roughly 28-day cyclical sequence of hormonal, ovarian and uterine changes that recurs from puberty (the first cycle is called menarche) until menopause (when cycles permanen…

Fertilisation is the fusion of a haploid sperm with a haploid secondary oocyte to form a diploid zygote, and in humans it normally takes place in the ampullary-isthmic junction of the fallopian tube,…

Immediately after fertilisation, the zygote begins a rapid series of mitotic cell divisions called cleavage as it is moved along the fallopian tube toward the uterus, a journey that takes roughly thre…

Once the blastocyst has implanted, the trophoblast layer proliferates and develops numerous finger-like projections called chorionic villi, which grow outward into the surrounding endometrial tissue.

Parturition, or childbirth, is the process by which the fully developed foetus, together with the placenta, is expelled from the mother's body, normally occurring at the end of a gestation period of a…

Lactation is the production and release of milk by the mammary glands, and it is the process by which the mother nourishes the newborn after birth.

Human reproduction begins at puberty, when the hypothalamus-pituitary-gonad axis activates the testes and ovaries and the sex hormones bring about the secondary sexual characters.

Sample papers and previous-year board questions for this subject.