How do Organisms Reproduce? Cheat Sheet

Definitions

Reproduction

The biological process by which an organism produces new individuals of its own kind.

Asexual reproduction

Reproduction in which a single parent produces offspring without the fusion of gametes.

Sexual reproduction

Reproduction in which male and female gametes fuse to form a new individual.

Binary fission

Asexual reproduction in which a parent cell divides into two daughter cells; e.g. Amoeba.

Multiple fission

Asexual reproduction in which the parent cell divides into many daughter cells at once; e.g. Plasmodium.

Budding

Asexual reproduction in which a new individual grows out as a bud from the parent; e.g. yeast, Hydra.

Fragmentation

Asexual reproduction in which a multicellular organism breaks into pieces, each growing into a new individual; e.g. Spirogyra.

Regeneration

The ability of an organism to grow a complete new individual from a cut body part; e.g. Planaria.

Spore formation

Asexual reproduction in which spores are formed inside a sporangium and grow into new individuals; e.g. Rhizopus.

Vegetative propagation

Asexual reproduction in plants from vegetative parts such as roots, stems or leaves; e.g. potato, sugarcane.

Gamete

A reproductive cell; the male gamete is the sperm and the female gamete is the egg.

Pollination

The transfer of pollen grains from the anther to the stigma of a flower.

Fertilisation

The fusion of a male and a female gamete to form a zygote.

Zygote

The cell formed by the fusion of gametes, which develops into an embryo.

Placenta

A disc-like tissue in the uterus that provides nutrition and oxygen to the embryo from the mother’s blood.

Menstruation

The monthly shedding of the uterine lining that occurs in females if fertilisation does not take place.

Puberty

The stage of life at which the body becomes capable of sexual reproduction.

Contraceptive

A method or device used to prevent pregnancy.

Key Points

• DNA copying during reproduction produces variations, which help a species survive changes in the environment.
• Asexual modes: fission (Amoeba, Plasmodium), budding (yeast, Hydra), fragmentation (Spirogyra), regeneration (Planaria), spore formation (Rhizopus) and vegetative propagation.
• Vegetative propagation is used to grow plants such as potato (eyes), sugarcane, rose and Bryophyllum (leaf buds).
• In flowering plants the stamen is the male part and the carpel is the female part; pollen from the anther reaches the stigma during pollination.
• After fertilisation the zygote develops into an embryo; the ovary becomes the fruit and the ovule becomes the seed.
• Male reproductive system: testes (sperm and testosterone), vas deferens, seminal vesicles and prostate gland (together form semen) and penis.
• Female reproductive system: ovaries (eggs), fallopian tubes, uterus and vagina; fertilisation usually occurs in the fallopian tube.
• Puberty brings about changes such as growth of body hair, and in boys deepening of voice and in girls development of breasts.
• Menstruation occurs about once every 28 days and stops during pregnancy and at menopause.
• Contraceptive methods: barrier (condoms), hormonal (oral pills), intrauterine devices (copper-T) and surgical methods (vasectomy in males, tubectomy in females).