Biology — Reproduction: Asexual, Sexual, Human Reproductive System

Reproduction is a fundamental biological process tested in Kerala PSC science sections. Questions cover types of reproduction, human reproductive system, and population control measures. Expect 1-3 questions.

Types of Reproduction

Type	Description	Organisms
Asexual	Single parent; no gamete fusion; offspring genetically identical (clones)	Bacteria, Amoeba, Hydra, yeast, many plants
Sexual	Two parents (usually); gamete fusion; offspring genetically varied	Most animals, flowering plants, humans

Asexual Reproduction — Methods

Method	Description	Example
Binary fission	Parent splits into two equal halves	Amoeba, bacteria, Paramecium
Multiple fission	Parent divides into many daughter cells simultaneously	Plasmodium (malaria parasite)
Budding	Outgrowth (bud) develops on parent body, detaches as new organism	Hydra, yeast
Fragmentation	Body breaks into fragments, each grows into new organism	Spirogyra, sea stars
Regeneration	Regrowth of lost body parts or whole organism from a part	Planaria, Hydra, lizard tail
Spore formation	Spores produced in sporangia; germinate in favorable conditions	Rhizopus (bread mould), ferns, mosses
Vegetative propagation	New plant from vegetative parts (root, stem, leaf)	Potato (tuber), Bryophyllum (leaf), Rose (cutting)

Vegetative Propagation in Plants

Plant Part	Method	Example
Stem tuber	Underground stem with buds	Potato
Runner	Horizontal stem along ground	Grass, strawberry
Rhizome	Underground horizontal stem	Ginger, turmeric
Bulb	Short stem with fleshy leaves	Onion, garlic
Leaf buds	Buds on leaf margin	Bryophyllum
Cutting	Stem piece planted	Rose, sugarcane
Grafting	Scion joined to rootstock	Mango, citrus
Layering	Branch bent and buried	Jasmine, bougainvillea
Tissue culture	Cells grown in lab medium	Orchids, banana, disease-free plants

Sexual Reproduction in Flowering Plants

Structure	Function
Stamen (male)	Consists of anther (produces pollen) and filament
Pistil/Carpel (female)	Consists of stigma, style, and ovary (contains ovules)
Pollination	Transfer of pollen from anther to stigma
Self-pollination	Same flower or same plant (autogamy)
Cross-pollination	Different plant of same species (allogamy)
Agents	Wind (anemophily), insects (entomophily), water (hydrophily), birds (ornithophily)
Fertilization	Fusion of male gamete with egg cell inside ovule
Double fertilization	Unique to angiosperms — one sperm fuses with egg (zygote), another with polar nuclei (endosperm)

Human Reproductive System

Male Reproductive System

Organ	Function
Testes (pair)	Produce sperm (spermatogenesis) and testosterone; located in scrotum (2-3 degrees C below body temp)
Epididymis	Stores and matures sperm
Vas deferens	Transports sperm from epididymis to urethra
Seminal vesicles	Secrete fluid (fructose-rich) that nourishes sperm
Prostate gland	Secretes alkaline fluid that forms part of semen
Cowper’s glands	Secrete lubricating fluid
Urethra	Common passage for urine and semen
Penis	Copulatory organ

Key Fact	Details
Sperm production begins	At puberty (about 13-14 years)
Sperm count (normal)	15-200 million per mL of semen
Hormone	Testosterone (male sex hormone; produced by Leydig cells in testes)
FSH and LH	From anterior pituitary; regulate sperm and testosterone production

Female Reproductive System

Organ	Function
Ovaries (pair)	Produce ova (eggs) and hormones (estrogen, progesterone); located in pelvic cavity
Fallopian tubes (Oviducts)	Site of fertilization; transport ovum to uterus; fimbriae collect released ovum
Uterus (Womb)	Pear-shaped muscular organ; site of implantation and fetal development
Endometrium	Inner lining of uterus; thickens each cycle; shed during menstruation
Cervix	Narrow lower end of uterus opening into vagina
Vagina	Birth canal; receives sperm during copulation

Key Fact	Details
Ovulation	Release of mature ovum from ovary; typically day 14 of a 28-day cycle
Hormone	Estrogen (primary female hormone; from ovarian follicles) and Progesterone (from corpus luteum)
Total eggs	A female is born with about 2 million egg cells; only about 400 mature during lifetime
Fertile window	About 24-48 hours around ovulation

Menstrual Cycle

Phase	Days (approx.)	Hormone	Events
Menstrual phase	Days 1-5	Low estrogen and progesterone	Endometrium sheds; bleeding
Follicular phase	Days 1-13	FSH rises; estrogen increases	Follicle develops in ovary; endometrium rebuilds
Ovulation	Day 14	LH surge triggers ovulation	Mature ovum released from ovary
Luteal phase	Days 15-28	Progesterone from corpus luteum	Endometrium maintained for possible implantation
If fertilization occurs	—	hCG maintains corpus luteum	Implantation; pregnancy begins
If no fertilization	Day 28	Corpus luteum degenerates; hormones drop	Cycle restarts with menstruation

Key Fact	Details
Average cycle length	28 days (can vary 21-35 days)
Menarche	First menstruation; typically age 11-14
Menopause	Permanent cessation of menstruation; typically age 45-55
Pregnancy test detects	hCG (human Chorionic Gonadotropin) in urine

Fertilization and Development

Stage	Details
Fertilization	Sperm meets egg in fallopian tube; zygote formed
Zygote	Single cell; begins dividing (cleavage)
Implantation	Blastocyst implants in uterine wall (about 7 days after fertilization)
Placenta	Organ connecting mother and fetus; exchange of nutrients, oxygen, waste
Umbilical cord	Connects fetus to placenta
Gestation period	About 280 days (40 weeks / 9 months)
Parturition	Childbirth; oxytocin triggers uterine contractions

Assisted Reproductive Technologies

Technology	Description
IVF (In Vitro Fertilization)	Egg and sperm fertilized in lab dish; embryo transferred to uterus; “test tube baby”
ICSI	Single sperm injected directly into egg (for severe male infertility)
IUI	Sperm inserted directly into uterus
GIFT	Gametes transferred to fallopian tube
ZIFT	Zygote transferred to fallopian tube
Surrogacy	Another woman carries and delivers baby
First IVF baby	Louise Brown (UK, 1978); in India — Kanupriya Agarwal (also known as Durga, 1978, by Dr. Subhash Mukhopadhyay)

Population Control Methods — Contraception

Category	Method	How It Works
Barrier	Male condom	Physical barrier preventing sperm from reaching egg
Barrier	Female condom (Femidom)	Lines the vagina
Barrier	Diaphragm / Cervical cap	Covers cervix
Chemical	Spermicides	Kill or immobilize sperm
Hormonal	Oral contraceptive pills (OCPs)	Estrogen + progesterone prevent ovulation
Hormonal	Injection (Depo-Provera)	Progesterone injection every 3 months
IUD	Copper-T	Inserted into uterus; copper ions prevent implantation
IUD	Hormonal IUD (Mirena)	Releases progesterone locally
Surgical	Vasectomy (male)	Vas deferens cut and tied; sperm cannot reach semen
Surgical	Tubectomy (female)	Fallopian tubes cut and tied; egg cannot reach uterus
Natural	Rhythm method	Avoiding intercourse during fertile period
Emergency	Morning-after pill	High-dose hormones within 72 hours of unprotected intercourse

India’s Population Policy

Aspect	Details
First country to launch family planning	India (1952)
National Population Policy, 2000	Target: TFR of 2.1 by 2010 (achieved by 2020-21 at national level)
Current TFR (NFHS-5, 2019-21)	2.0 (below replacement level of 2.1)
Kerala’s TFR	1.8 (well below replacement)
Mission Parivar Vikas	Focus on high-fertility districts

PSC Quick Recall

Question	Answer
Binary fission occurs in	Amoeba, bacteria
Budding is seen in	Hydra, yeast
Double fertilization occurs in	Angiosperms (flowering plants)
Site of fertilization in humans	Fallopian tube
Ovulation occurs on which day?	Day 14 of 28-day cycle
Pregnancy hormone detected in test	hCG
First IVF baby	Louise Brown (1978, UK)
Gestation period in humans	280 days (40 weeks)
Vasectomy involves	Cutting vas deferens (male sterilization)
Tubectomy involves	Cutting fallopian tubes (female sterilization)
Copper-T is a type of	IUD (Intrauterine Device)
India launched family planning in	1952 (first country)
Kerala’s TFR (NFHS-5)	1.8
Menopause typical age	45-55 years