Biology · Human Reproduction · NEET
Gametogenesis is the process by which the body makes gametes (sex cells). In males it makes sperms and in females it makes the ovum (egg). NCERT names two types: spermatogenesis (sperm making) and oogenesis (ovum making). For NEET, remember the word breaks into 'gamete' + 'genesis' = the birth of a gamete.
The primary sex organs produce gametes. In males the testis produces sperms, and in females the ovary produces the ovum. NCERT calls these the primary sex organs (gonads). Ducts, glands and external genitalia do NOT make gametes — they only help transport or nourish them.
Primary sex organs are the gonads — testes and ovaries — that make gametes and also secrete sex hormones. Secondary (accessory) sex organs, like the vas deferens, uterus, accessory glands and external genitalia, help in transport, storage or delivery but do not make gametes. NEET often traps students by listing an accessory organ as a gamete producer.
Gametogenesis uses BOTH. First the germ cells (spermatogonia or oogonia) multiply by mitosis. Then they undergo meiosis (reductive division) to become haploid gametes with 23 chromosomes. So the final gamete is always haploid, but the process starts with mitotic multiplication. This is why NEET calls the meiotic step the 'reductive division'.
Yes. Gametogenesis is the umbrella term. Spermatogenesis is gametogenesis in the male testis (forms sperms), and oogenesis is gametogenesis in the female ovary (forms the ovum). Both begin from diploid germ cells and end in haploid gametes, but the timing differs — oogenesis starts before birth, spermatogenesis starts at puberty.
Consider the following: A. The reductive division for the human female gametogenesis starts earlier than that of the male gametogenesis. B. The gap between the first meiotic division and the second meiotic division is much shorter for males compared to females. C. The first polar body is associated with the formation of the primary oocyte. D. Luteinizing Hormone (LH) surge leads to disintegration of the endometrium and onset of menstrual bleeding. Choose the correct answer.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Gametes are haploid. Each human gamete (sperm or ovum) carries 23 chromosomes. When sperm and ovum fuse at fertilisation, the diploid number of 46 is restored in the zygote.
In males, spermatogenesis begins at puberty. In females, oogenesis begins during the embryonic (foetal) stage itself, but the process pauses and is completed much later, cycle by cycle after puberty.
Yes. Besides producing gametes, the testis and ovary are endocrine glands. Leydig cells of the testis make androgens, and the ovary secretes oestrogen and progesterone. That is why they are called primary sex organs.
It is the foundation of the whole Human Reproduction chapter. Understanding that only the testes and ovaries make gametes, and that gametes are haploid, helps you answer match-the-column and assertion-reason questions that NEET repeats almost every year.
