Chapter 11: Reproduction: How Life Continues

Comprehensive vocabulary flashcards covering asexual and sexual reproduction in plants, animals, and humans, based on NCERT Class 9 Science Chapter 11.

Reproduction

The biological process by which living organisms produce new individuals of their own kind, ensuring the continuity of life across generations.

Asexual Reproduction

A mode of reproduction involving only a single parent that produces offspring genetically identical to the parent (clones) via mitosis.

Vegetative Propagation

A form of asexual reproduction in plants where new plants develop directly from vegetative or growing structures such as underground stems, runners, stem cuttings, or leaves.

Cutting

An artificial method of vegetative propagation in which a shoot cutting with nodes is planted in compost-mixed soil at an angle of $45^\text{o}\text{–}60^\text{o}$ to develop roots and shoots.

Grafting

A vegetative propagation technique where a stem piece from one variety (Plant B) is inserted and secured into a slit made in a rooted host plant (Plant A) so they grow together.

Layering

A propagation method where a flexible, thin twig of a plant is bent and buried in the soil until adventitious roots develop (typically after $10\text{–}15\text{ days}$), after which it is severed to grow independently.

Tissue Culture

A laboratory method of plant propagation where cells or tissues from shoot tips (apical meristems) are cultured on artificial nutrient media to mass-produce virus-free plantlets.

Budding

A type of asexual reproduction where repeated mitotic cell division at a specific site produces a small outgrowth (bud) that matures and eventually detaches to live independently, as seen in yeast and hydra.

Spore Formation

An asexual reproductive method in fungi (such as Rhizopus and Aspergillus) where numerous lightweight, single-celled spores develop inside sacs or swollen vesicles atop fungal hyphae and disperse through the air.

Mitosis

A type of cell division central to asexual reproduction that yields two daughter cells having the exact same chromosome number and genetic constitution as the parent cell.

Sexual Reproduction

A mode of reproduction involving two parents that each contribute genetic material through specialized gametes, resulting in genetic variation in offspring.

Meiosis

A specialized cell division that reduces the chromosome number of a diploid parent cell by half, producing haploid gametes and creating new genetic combinations through chromosome segregation.

Gametes

Haploid reproductive sex cells produced by meiosis (sperm in males, eggs in females) containing half the species' standard chromosome count ($23\text{ chromosomes}$ in humans).

Sepal

The outermost green leaf-like whorl of a flower that encloses and protects the floral organs during the bud stage.

Petal

The bright, pigmented floral structure located inside the sepals that serves primarily to attract animal and insect pollinators.

Stamen

The male reproductive organ of a flower consisting of a slender stalk (filament) and an anther, which produces pollen grains containing male gametes.

Pistil

The female reproductive organ of a flower consisting of three subparts: a terminal receptive surface (stigma), an elongated neck (style), and an expanded base (ovary) housing ovules.

Pollination

The transfer of pollen grains from the anther to the stigma of a flower by agents such as wind, water, insects, or birds.

Self-Pollination

The transfer of pollen grains from an anther to the stigma of the same flower or another flower on the same individual plant.

Cross-Pollination

The transfer of pollen grains from the anther of one plant's flower to the receptive stigma of a flower on a different plant of the same species.

Fertilisation (in Plants)

The fusion of a male gamete (carried through a pollen tube growing down the style) with an egg cell inside an ovule to form a diploid zygote.

Zygote

The diploid cell resulting from the union of male and female gametes, which subsequently undergoes mitotic divisions to develop into an embryo.

P. Maheshwari

An Indian botanist known as the 'Father of Indian Embryology' who developed in-vitro fertilisation in flowering plants and authored 'An Introduction to the Embryology of Angiosperms' ($1950$).

External Fertilisation

A reproductive strategy common in aquatic organisms (such as frogs and many fish) where females release eggs and males release sperm directly into water, where fusion takes place outside the body.

Internal Fertilisation

A reproductive strategy occurring in reptiles, birds, and mammals where sperm is deposited inside the female body, providing higher protection to gametes and developing embryos.

Testes

A pair of oval-shaped male primary reproductive organs housed in the scrotum that produce sperm and secrete male hormones controlling sperm production and puberty changes.

Scrotum

An external sac of skin holding the testes outside the abdominal cavity to maintain them at a slightly lower temperature than normal body temperature, which is essential for sperm formation.

Vas Deferens

A long duct in the male reproductive system that transports mature sperm from the testes toward the urethra.

Ovaries

A pair of female reproductive organs that produce mature eggs (ova) and release hormones responsible for secondary sexual characteristics and reproductive cycles.

Fallopian Tube (Oviduct)

A ciliated duct that conveys the released egg from an ovary toward the uterus and serves as the usual site of fertilisation by a sperm.

Uterus

A hollow, muscular organ in the female pelvis where a fertilised egg implants, receives maternal nourishment, and develops throughout pregnancy.

Gametogenesis

The biological process of forming mature haploid gametes through meiosis within the testes (producing sperm) and ovaries (producing eggs).

Ovulation

The periodic biological event, occurring roughly around day $14$ of a standard $28\text{-day}$ menstrual cycle, during which a mature egg is released from an ovary into the oviduct.

Implantation

The process wherein a developing ball of cells (derived from a fertilised zygote) embeds itself into the thickened, vascular inner lining of the uterus, marking the onset of pregnancy.

In-vitro Fertilisation (IVF)

An assisted reproductive procedure where an egg and sperm are fused outside the female body in a laboratory culture dish, after which the resulting embryo is transferred to the uterus.

Subhash Mukhopadhyay

A physician-scientist from Kolkata who created India's first IVF test tube baby, Kanupriya Agarwal (nicknamed Durga), in $1978$.

Menstruation

The cyclic breakdown and discharge of the unfertilised egg and thickened uterine lining accompanied by blood through the vagina, typically lasting $3\text{ to }7\text{ days}$.

Foetus

The developing human unborn offspring from roughly the ninth week of pregnancy until childbirth, characterized by ongoing growth and the maturation of organs.

Sexually Transmitted Infections (STIs)

Infections transmitted through intimate sexual contact, including bacterial and viral conditions such as gonorrhoea, syphilis, genital warts, herpes, and HIV.

Intra-Uterine Device (IUD)

A medical birth-control implement, such as a Copper-T, inserted into the cavity of the uterus by a healthcare professional to prevent pregnancy.

ASHA (Accredited Social Health Activist)

Trained community health workers operating under India's National Health Mission who promote hygiene, immunisation, maternal care, and family planning.

Post-partum Depression

A treatable medical condition characterized by anxiety, extreme fatigue, and prolonged low mood experienced by some mothers following childbirth.