Class 12 Biology Human Reproduction Notes

Class 12 Biology Human Reproduction Notes

Human Reproduction – Short Notes

1. Male Reproductive System

  • Testes – produce sperm and testosterone.
  • Accessory ducts: Epididymis, Vas deferens, Ejaculatory duct, Urethra.
  • Accessory glands: Seminal vesicle, Prostate, Bulbourethral glands – secrete seminal fluid.
  • Sperm structure: Head (nucleus + acrosome), midpiece (mitochondria), tail (flagellum).

2. Female Reproductive System

  • Ovaries: Produce eggs (ova) and hormones (estrogen, progesterone).
  • Fallopian tubes / Oviducts: Site of fertilization.
  • Uterus: Site of implantation and fetal development.
  • Cervix and Vagina: Birth canal and copulatory organ.

3. Gametogenesis

  • Spermatogenesis: Formation of sperm in testes.
    • Spermatogonia → primary spermatocyte → meiosis → 4 sperms.
  • Oogenesis: Formation of ova in ovaries.
    • Oogonia → primary oocyte → meiosis → 1 ovum + polar bodies.

4. Menstrual Cycle

  • Duration: ~28 days, controlled by hormones.
  • Phases:
    1. Menstrual phase: Shedding of endometrium (days 1–5)
    2. Follicular phase: Follicle development, estrogen rise (days 6–13)
    3. Ovulation: Release of ovum (day 14)
    4. Luteal phase: Corpus luteum secretes progesterone (days 15–28)

5. Fertilization and Pregnancy

  • Fertilization: Occurs in fallopian tube.
  • Zygote → cleavage → morula → blastocyst → implantation in uterus.
  • Placenta: Exchange of nutrients, gases, and waste; secretes hormones.
  • Pregnancy: ~9 months; stages: First, second, third trimester.
  • Parturition: Process of childbirth, triggered by hormonal changes.

6. Reproductive Health

  • Contraception:
    • Natural: Abstinence, rhythm method
    • Barrier: Condoms, diaphragm
    • Hormonal: Pills, injectables
    • IUDs: Copper-T, hormonal
  • Assisted Reproductive Technologies (ART): IVF, IUI, ICSI.
  • Sexually Transmitted Diseases (STDs): HIV, syphilis, gonorrhea.

MCQs

1. Male Reproductive System

  1. Which of the following produces sperm and testosterone?
    a) Epididymis
    b) Seminal vesicle
    c) Testes
    d) Prostate
    Answer: c) Testes
  2. The long coiled tube where sperm mature and are stored is:
    a) Vas deferens
    b) Epididymis
    c) Urethra
    d) Ejaculatory duct
    Answer: b) Epididymis
  3. The male accessory gland that contributes fructose-rich fluid to semen is:
    a) Prostate
    b) Seminal vesicle
    c) Bulbourethral gland
    d) Testes
    Answer: b) Seminal vesicle
  4. The acrosome of sperm contains:
    a) Mitochondria
    b) Digestive enzymes
    c) DNA
    d) Ribosomes
    Answer: b) Digestive enzymes

2. Female Reproductive System

  1. Fertilization in humans occurs in the:
    a) Ovary
    b) Uterus
    c) Fallopian tube
    d) Vagina
    Answer: c) Fallopian tube
  2. Which hormone is primarily responsible for maintaining pregnancy?
    a) Estrogen
    b) Progesterone
    c) FSH
    d) LH
    Answer: b) Progesterone
  3. Ovary produces:
    a) Only ova
    b) Only hormones
    c) Ova and hormones
    d) Sperm and hormones
    Answer: c) Ova and hormones
  4. The site of implantation of the blastocyst is:
    a) Ovary
    b) Fallopian tube
    c) Uterus
    d) Vagina
    Answer: c) Uterus

3. Gametogenesis

  1. The diploid cell that undergoes meiosis in males is called:
    a) Spermatogonia
    b) Primary spermatocyte
    c) Secondary spermatocyte
    d) Spermatid
    Answer: b) Primary spermatocyte
  2. Oogenesis results in:
    a) Four ova
    b) One ovum + three polar bodies
    c) Two ova + two polar bodies
    d) Four polar bodies
    Answer: b) One ovum + three polar bodies
  3. Spermatogenesis occurs in:
    a) Seminiferous tubules
    b) Epididymis
    c) Vas deferens
    d) Prostate
    Answer: a) Seminiferous tubules
  4. Primary oocytes are arrested in:
    a) Prophase of meiosis I
    b) Metaphase of meiosis I
    c) Prophase of meiosis II
    d) Telophase of meiosis II
    Answer: a) Prophase of meiosis I

4. Menstrual Cycle

  1. The follicular phase is associated with:
    a) Shedding of endometrium
    b) Ovulation
    c) Follicle development and estrogen secretion
    d) Progesterone secretion
    Answer: c) Follicle development and estrogen secretion
  2. Ovulation occurs approximately on:
    a) Day 7
    b) Day 14
    c) Day 21
    d) Day 28
    Answer: b) Day 14
  3. Corpus luteum secretes:
    a) FSH
    b) LH
    c) Progesterone
    d) Estrogen only
    Answer: c) Progesterone
  4. Menstruation occurs due to:
    a) Rise in estrogen
    b) Fall in progesterone and estrogen
    c) Fertilization
    d) Ovulation
    Answer: b) Fall in progesterone and estrogen

5. Fertilization and Pregnancy

  1. Fertilization is:
    a) Union of two polar nuclei
    b) Fusion of sperm and egg
    c) Formation of embryo sac
    d) Implantation in uterus
    Answer: b) Fusion of sperm and egg
  2. Placenta is formed from:
    a) Endometrium and chorion
    b) Ovary and uterus
    c) Fallopian tube
    d) Cervix
    Answer: a) Endometrium and chorion
  3. Which hormone triggers parturition (childbirth)?
    a) Estrogen
    b) Progesterone
    c) Oxytocin
    d) Prolactin
    Answer: c) Oxytocin
  4. During pregnancy, the hormone hCG is secreted by:
    a) Corpus luteum
    b) Placenta
    c) Embryo
    d) Ovary
    Answer: c) Embryo

6. Reproductive Health

  1. Copper-T is an example of:
    a) Barrier method
    b) Hormonal contraceptive
    c) Intrauterine device (IUD)
    d) Natural method
    Answer: c) Intrauterine device (IUD)
  2. IVF stands for:
    a) In vivo fertilization
    b) In vitro fertilization
    c) In vivo fusion
    d) In vitro fusion
    Answer: b) In vitro fertilization
  3. Which STD is caused by a virus?
    a) Syphilis
    b) Gonorrhea
    c) HIV/AIDS
    d) Bacterial vaginosis
    Answer: c) HIV/AIDS
  4. Condom is an example of:
    a) Hormonal method
    b) Barrier method
    c) Natural method
    d) IUD
    Answer: b) Barrier method