🧬 Chapter 12 · MDCAT Biology
📅 Updated Jan 2026
⏱️ 30 min read
🎯 High-yield
Reproduction — Complete MDCAT Notes & MCQs
Full MDCAT Biology Chapter 12 on reproduction: male and female reproductive systems, hormones (FSH, LH, testosterone, estrogen, progesterone), menstrual cycle phases, ovulation, fertilization, implantation, and sexually transmitted diseases (AIDS, gonorrhea, syphilis, hepatitis B, chlamydia, HPV, genital herpes, trichomoniasis). Includes 200 solved MCQs with explanations and year-wise past papers.
❓People Also Ask — Reproduction
Questions students most frequently search about this chapter. Answers are direct and exam-focused.
QWhat is the function of the blood-testis barrier?
The blood-testis barrier is formed by tight junctions between Sertoli cells. It protects developing sperm from the immune system and creates a specialized environment for spermatogenesis.
QWhy is the epididymis important?
The epididymis is where sperm undergo maturation, gain motility, and are stored until ejaculation. Spermatogenesis occurs in the testes, but final maturation occurs here.
QWhat is semen composed of?
Semen = sperm (~5%) + seminal vesicle fluid (~60-70%, fructose-rich) + prostatic fluid (~20-30%, alkaline) + bulbourethral gland fluid (~5%, mucus).
QWhat is the significance of fructose in semen?
Fructose from seminal vesicles provides the primary energy source for sperm motility, particularly important during the journey through the female reproductive tract.
QWhat is the difference between spermatogenesis and oogenesis?
Spermatogenesis: continuous from puberty, produces 4 sperm per cell, occurs in testes. Oogenesis: starts before birth, produces 1 ovum per cell (plus polar bodies), occurs in ovaries, arrested in prophase I until puberty.
QWhy does the LH surge trigger ovulation?
Peak estrogen from the mature follicle causes positive feedback on the pituitary, triggering a large LH surge. This causes follicle rupture and release of the oocyte.
QWhat happens to the corpus luteum if fertilization occurs?
The embryo secretes hCG (human chorionic gonadotropin), which maintains the corpus luteum. It continues to secrete progesterone, preventing menstruation and supporting pregnancy.
QWhat causes menstruation?
Menstruation occurs when progesterone drops (due to corpus luteum degeneration with no fertilization), causing the endometrium to shed.
QWhat is the difference between HIV and AIDS?
HIV is the virus that attacks CD4+ T cells. AIDS is the final stage when CD4+ count drops below 200 cells/mm³, leading to opportunistic infections.
QWhich STDs are bacterial and curable?
Gonorrhea, syphilis, chlamydia are bacterial STDs curable with antibiotics. AIDS, hepatitis B, genital herpes, HPV are viral (not fully curable). Trichomoniasis is protozoan (curable with antiprotozoal drugs).
QWhat are the stages of syphilis?
Primary: painless chancre. Secondary: rash, fever, lymphadenopathy. Latent: asymptomatic. Tertiary: cardiovascular damage, neurosyphilis, gummas.
QWhich STD causes cervical cancer?
HPV (Human Papillomavirus), particularly high-risk types (16, 18), causes genital warts and is strongly associated with cervical cancer. Prevented by the HPV vaccine.
QWhat is a threatened abortion?
A threatened abortion is vaginal bleeding during early pregnancy with a viable fetus. It's a warning sign of possible miscarriage but not inevitable.
QWhat is an ectopic pregnancy?
An ectopic pregnancy is implantation outside the uterus, usually in the fallopian tube (due to blockage or damage). It's life-threatening and requires medical intervention.
QWhat is the function of oxytocin?
Oxytocin stimulates uterine contractions during labor and triggers milk ejection (let-down reflex) during breastfeeding.
QWhat is prolactin's role?
Prolactin stimulates mammary glands to produce milk after childbirth. It's inhibited during pregnancy by high estrogen and progesterone.
QWhy is the follicular phase also called proliferative?
During the follicular phase, rising estrogen from the growing follicle causes the endometrium to proliferate (thicken), hence "proliferative phase."
QWhat is the difference between primary and secondary oocyte?
Primary oocyte (diploid, 2n) is present before ovulation. It completes meiosis I just before ovulation, becoming a secondary oocyte (haploid, n) with a polar body. Meiosis II completes only after fertilization.
QHow many days does sperm take to mature in the epididymis?
Sperm maturation in the epididymis takes approximately 10-14 days. They gain motility and fertilizing ability during this transit.
QWhat is the normal sperm count for fertility?
Normal sperm count is ≥15 million/mL with ≥40% motility and ≥4% normal morphology. Below these thresholds, fertility is significantly reduced.
📋Syllabus & Learning Outcomes
According to PMDC/PMC MDCAT syllabus, Reproduction covers:
- 8.1 Describe the functions of various parts of the male & female reproductive systems and the hormones that regulate those functions.
- 8.2 Describe the menstrual cycle (female reproductive cycle) emphasizing the role of hormones.
- 8.3 List the common sexually transmitted diseases along with their causative agents and main symptoms.
📝Full Notes — Reproduction
🧬 Reproduction – Schematic Notes
🧑⚕️ 8.1 Male Reproductive System – Parts & Hormones
- Testes: Seminiferous tubules (spermatogenesis); Leydig cells (testosterone).
- Epididymis: Sperm maturation & storage.
- Vas deferens: Transports sperm to urethra.
- Seminal vesicles, prostate, Cowper's glands: Produce seminal fluid (nourishes & activates sperm).
- Penis: Copulation; urethra carries semen/urine.
Hormones: GnRH (hypothalamus) → FSH (acts on Sertoli cells – spermatogenesis) & LH (acts on Leydig cells – testosterone). Testosterone: secondary sexual characteristics, libido, feedback inhibition.
👩⚕️ 8.1 Female Reproductive System – Parts & Hormones
- Ovaries: Follicles mature → ovulation → corpus luteum. Produce oestrogen & progesterone.
- Oviducts (Fallopian tubes): Site of fertilisation; fimbriae collect ovum.
- Uterus: Endometrium thickens for implantation; myometrium sheds during menstruation.
- Cervix & Vagina: Passage for sperm, menstrual flow, birth canal.
- Mammary glands: Milk production under prolactin & oxytocin.
Hormonal regulation: GnRH → FSH (follicle growth, oestrogen secretion) & LH (surge → ovulation, corpus luteum formation → progesterone). Oestrogen: endometrial repair, secondary sex characteristics. Progesterone: maintain endometrium, inhibit uterine contractions.
🔄 8.2 Menstrual Cycle (28 days) & Hormone Roles
| Phase | Days | Key Events | Dominant Hormones |
| Menstrual | 1–5 | Shedding of endometrium | Low oestrogen, progesterone |
| Proliferative (Follicular) | 6–13 | Follicle growth, endometrial thickening | FSH → oestrogen rises |
| Ovulation | 14 (±1) | Release of secondary oocyte | LH surge (trigger); oestrogen peak |
| Secretory (Luteal) | 15–28 | Corpus luteum → progesterone; endometrial glands secrete; preparation for implantation | Progesterone (+ oestrogen) |
- Negative feedback: Oestrogen/progesterone inhibit FSH/LH; low levels trigger new cycle.
- If no fertilisation: Corpus luteum degenerates → progesterone falls → menstruation.
- If fertilisation: hCG from embryo maintains corpus luteum → continued progesterone.
🦠 8.3 Common STDs – Causative Agents & Symptoms
| Disease | Pathogen | Main Symptoms |
| Gonorrhoea | Neisseria gonorrhoeae (bacterium) | Painful urination, pus‑like discharge; may cause pelvic inflammatory disease (PID) |
| Syphilis | Treponema pallidum (bacterium) | Primary: painless chancre; Secondary: rash, fever; Tertiary: cardiovascular/neurologic damage |
| Chlamydia | Chlamydia trachomatis (bacterium) | Often asymptomatic; discharge, pain; can lead to PID, infertility |
| Genital herpes | Herpes simplex virus (HSV‑2) | Painful blisters/ulcers; recurrent outbreaks; no cure |
| Genital warts | Human papillomavirus (HPV) | Warts on genital area; some strains linked to cervical cancer |
| AIDS | HIV (retrovirus) | Immunosuppression; opportunistic infections; weight loss (see Biodiversity) |
| Trichomoniasis | Trichomonas vaginalis (protozoan) | Frothy, yellow‑green discharge; itching; odour |
🔑 High‑Yield MCQs & Traps
- FSH: spermatogenesis (male) / follicle growth (female).
- LH: testosterone production (male) / ovulation & corpus luteum (female).
- Testosterone from Leydig cells; Sertoli cells support spermatogenesis.
- Ovulation at day 14 (±1) triggered by LH surge.
- Progesterone maintains endometrium; fall leads to menstruation.
- hCG maintains corpus luteum if pregnancy occurs.
- Gonorrhoea – bacterium; genital herpes – virus; trichomoniasis – protozoan.
- Syphilis has three stages: painless chancre (primary), rash (secondary), gummas/neurologic (tertiary).
- Chlamydia most common bacterial STD; often asymptomatic.
- ⚠️ Traps: "FSH triggers ovulation" → False (LH surge). "Progesterone causes ovulation" → False (helps maintain). "Gonorrhoea is viral" → False. "Trichomoniasis is bacterial" → False (protozoan).
💡 MDCAT focus: Hormonal control of testis & ovary, menstrual cycle phases, and STD pathogen types.
❔Frequently Asked Questions
What is reproduction?
Reproduction is the biological process by which organisms produce offspring, ensuring species continuity. In humans, it involves the male and female reproductive systems, hormones (FSH, LH, testosterone, estrogen, progesterone), gamete formation, fertilization, and development of the embryo.
What are the main parts of the male reproductive system?
Testes (sperm + testosterone), epididymis (sperm maturation), vas deferens (transport), seminal vesicles, prostate gland, Cowper's (bulbourethral) glands (seminal fluid), and penis.
What are the main parts of the female reproductive system?
Ovaries (ova + estrogen/progesterone), fallopian tubes (fertilization site), uterus (implantation + development), cervix, vagina, and mammary glands.
What is the function of Leydig cells and Sertoli cells?
Leydig (interstitial) cells secrete testosterone. Sertoli (nurse) cells support and nourish developing sperm and form the blood-testis barrier.
What are the functions of FSH and LH?
FSH: stimulates spermatogenesis (male) and follicle development (female). LH: stimulates testosterone production (male) and triggers ovulation + corpus luteum formation (female).
What are the phases of the menstrual cycle?
Menstrual (days 1-5), Follicular/Proliferative (6-13), Ovulation (day 14), Luteal/Secretory (15-28). Controlled by FSH, LH, estrogen, and progesterone.
When does ovulation occur?
Around day 14 of a 28-day cycle, triggered by the LH surge due to positive feedback from peak estrogen levels.
Where does fertilization occur?
In the fallopian tube (ampulla), where sperm meets the ovum within 12-24 hours of ovulation.
What is the function of the corpus luteum?
Secretes progesterone to maintain the endometrium for implantation. If no fertilization, it degenerates into corpus albicans; if fertilization occurs, hCG from the embryo maintains it.
What is the function of progesterone?
Maintains endometrial lining, prevents uterine contractions, and inhibits FSH/LH release during the luteal phase.
What is the function of estrogen?
Stimulates endometrial proliferation, develops female secondary sexual characteristics, and triggers the LH surge at high levels.
What is the function of testosterone?
Promotes spermatogenesis, develops male secondary sexual characteristics, maintains libido, and provides negative feedback on FSH/LH.
What is AIDS and how is it transmitted?
AIDS (Acquired Immune Deficiency Syndrome) is caused by HIV, a retrovirus that attacks CD4+ helper T cells. Transmission: unprotected sex, blood transfusion, sharing needles, mother-to-child.
What STD is caused by a spirochete?
Syphilis is caused by Treponema pallidum (a spirochete bacterium). It has 3 stages: primary (painless chancre), secondary (rash), tertiary (cardiovascular/neurologic damage).
Which STD is caused by Neisseria gonorrhoeae?
Gonorrhea — a bacterial STD causing painful urination and pus-like discharge. Can lead to pelvic inflammatory disease and infertility if untreated.
Which STD is preventable by vaccine?
Hepatitis B is preventable by vaccine. HPV also has a vaccine (linked to cervical cancer).
What is the difference between HIV and AIDS?
HIV is the virus that attacks CD4+ T cells. AIDS is the final stage of HIV infection when CD4+ count drops below 200 cells/mm³ and opportunistic infections occur.
What causes menstruation?
Menstruation is triggered by the drop in progesterone when the corpus luteum degenerates (no fertilization), causing endometrial shedding.
How many MCQs come from Reproduction in MDCAT?
Reproduction typically contributes 4–6 MCQs out of 81 Biology MCQs in MDCAT.
Which topics from Reproduction are most frequently asked in MDCAT?
Leydig vs Sertoli cells, FSH vs LH functions, ovulation timing and LH surge, menstrual cycle phases, progesterone's role, corpus luteum, STD pathogens (bacterial vs viral), and HIV/AIDS transmission.