Chapter 7: How do Organisms Reproduce?

Comprehensive vocabulary flashcards covering the biological concepts, reproductive modes, anatomy, and physiological processes from Chapter 7: How do Organisms Reproduce?

DNA (Deoxyribo Nucleic Acid)

Molecules found in the chromosomes of the cell nucleus that contain information for inheriting features from parents to offspring and serve as the source of information for making proteins.

Variation

Differences in body design and genetic makeup resulting from inaccuracies in biochemical DNA copying reactions during reproduction, serving as the raw material for evolution and species adaptation.

Niche

A well-defined position or functional role that a population of organisms occupies within an ecosystem based on its reproductive capability and body design.

Fission

An asexual reproduction method in unicellular organisms where a single parent cell divides to form two or more independent daughter cells.

Binary Fission

A form of asexual division where an organism divides into two equal halves; can occur in any plane in Amoeba or in a definite orientation relative to whip-like structures in Leishmania.

Multiple Fission

The asexual reproductive process where a single-celled organism divides simultaneously into numerous daughter cells, as observed in the malarial parasite Plasmodium.

Fragmentation

An asexual reproductive mode in simple multi-cellular organisms, such as Spirogyra, where the mature organism breaks into smaller pieces that subsequently grow into complete new individuals.

Regeneration

The ability of fully differentiated organisms (such as Hydra and Planaria) to develop complete new individuals from cut or broken body parts using specialised proliferating cells.

Budding

An asexual reproductive process where repeated cell divisions at a specific site produce an outgrowth (bud) that develops into a miniature individual and detaches upon maturity (e.g., in Hydra and yeast).

Vegetative Propagation

An asexual reproductive method in plants where vegetative structures such as roots, stems, or leaves give rise to new plants under suitable environmental conditions.

Callus

An unorganised, rapidly dividing group of cells formed when plant tissues or cells from the growing tip are placed in an artificial nutrient medium during tissue culture.

Tissue Culture

A laboratory technique in which isolated plant cells or tissues from growing tips are cultivated in synthetic nutrient and hormone media under sterile conditions to produce disease-free plantlets.

Sporangia

Blob-like structures located at the ends of upright hyphae in Rhizopus (bread mould) that enclose reproductive cells called spores protected by thick walls.

Asexual Reproduction

The generation of offspring from a single parent individual without the involvement or fusion of gametes.

Sexual Reproduction

A mode of reproduction requiring the participation of two individuals of opposite sexes, combining their DNA through the fusion of specialised germ-cells.

Meiosis

A specialised type of cell division occurring in reproductive organs that reduces chromosome number and DNA content by half, producing haploid germ-cells.

Male Gamete

A small, typically motile germ-cell (such as a sperm or pollen tube cell) specialised for travelling to and fertilising a female germ-cell.

Female Gamete

A non-motile, comparatively large reproductive cell (such as an ovum or egg cell) containing stored nourishment to support the developing zygote.

Stamen

The male reproductive organ of an angiosperm flower, composed of a pollen-producing anther supported by a slender filament.

Pistil

The female reproductive structure positioned in the center of a flower, consisting of a basal ovary, an elongated style, and a receptive terminal stigma.

Unisexual Flower

A flower possessing either male reproductive parts (stamens) or female reproductive parts (pistil), but not both, exemplified by papaya and watermelon.

Bisexual Flower

A flower that contains both male (stamens) and female (pistil) reproductive organs, such as Hibiscus and mustard.

Pollination

The transfer of pollen grains from the anther to the stigma of a flower, categorised as self-pollination within the same flower or cross-pollination between separate flowers.

Fertilisation

The biological fusion of a male germ-cell with a female germ-cell to form a diploid zygote capable of developing into a new organism.

Germination

The developmental process wherein a plant embryo housed within a seed resumes metabolic growth to produce a seedling under favourable moisture and temperature conditions.

Plumule

The portion of a plant embryo within a seed that elongates and differentiates to form the future aerial shoot system.

Radicle

The embryonic root structure of a plant seed that emerges during germination to establish the future root system.

Cotyledon

An embryonic leaf present within a seed that stores food reserves used to nourish the germinating embryo.

Puberty

The transitional developmental period during adolescence when general body growth decelerates and the reproductive system and secondary sexual characteristics mature.

Testes

The paired primary male reproductive organs situated in the scrotum that produce sperms and synthesize the hormone testosterone.

Scrotum

An external sac of skin holding the testes outside the abdominal cavity to maintain a temperature lower than normal body temperature, necessary for spermatogenesis.

Testosterone

A male steroid hormone secreted by the testes that regulates sperm production and stimulates the emergence of secondary sexual traits during puberty.

Vas Deferens

A muscular duct that transports mature sperms from the testes to merge with the duct from the urinary bladder, leading into the urethra.

Prostate Gland and Seminal Vesicles

Male accessory glands whose alkaline secretions provide nutrients and a fluid medium to ease the mobility and transport of sperms.

Urethra (Male)

A common shared tubular pathway extending through the penis that conducts both urine from the bladder and semen from the reproductive tract.

Ovaries

The primary female reproductive organs responsible for releasing mature ova (eggs) and secreting female sex hormones.

Oviduct (Fallopian Tube)

A paired conduit that conveys released eggs from an ovary to the uterus and serves as the physiological site of fertilisation.

Uterus

An elastic, pear-shaped muscular organ in females where an embryo implants, develops, and is nourished throughout pregnancy until birth.

Placenta

A vascular disc embedded in the uterine wall composed of fetal villi and maternal blood spaces that facilitates gas, nutrient, and metabolic waste exchange between mother and embryo.

Menstruation

The cyclical monthly shedding of the thickened, vascularised uterine lining through the vagina as blood and mucus when ovulated egg fertilisation does not occur.

Contraception

Intentional practices or devices—such as barrier methods, hormonal pills, intrauterine devices (copper-T), and surgical sterilisation—utilised to prevent pregnancy.

Sexually Transmitted Infections (STIs)

Infectious illnesses passed between individuals via intimate sexual contact, comprising bacterial diseases (gonorrhoea, syphilis) and viral infections (warts, HIV-AIDS).