Reproduction: How Life Continues — Class 9 MCQs with Answers

Key concepts: Reproduction: How Life Continues (Class 9 Science)

Reproduction is the process by which living organisms produce new individuals of their own kind, and it is essential for the continuity of a species rather than the survival of an individual. This chapter contrasts asexual and sexual reproduction, then works through reproduction in flowering plants and in humans.

Reproduction

The production of new individuals of the same species. Unlike nutrition or respiration it is not needed to keep an individual alive, but without it a species dies out.

Asexual reproduction

Reproduction involving a single parent and no gametes. The offspring are genetically identical to the parent, so they are clones.

Binary fission

A single-celled organism such as Amoeba divides into two roughly equal daughter cells, each receiving a copy of the genetic material.

Budding

A small outgrowth on the parent grows, develops the parent's features and detaches, as in Hydra and yeast.

Fragmentation and regeneration

The body breaks into pieces and each piece grows into a complete organism, as in Spirogyra; regeneration is the related ability to rebuild lost body parts, as in Planaria.

Vegetative propagation

New plants arise from a vegetative part — root, stem or leaf — rather than from seed. It preserves the parent's characters exactly and is widely used in horticulture.

Sexual reproduction

Reproduction involving two parents and the fusion of male and female gametes, producing offspring with a new combination of characters.

Gamete and fertilisation

A gamete is a reproductive cell carrying half the genetic material; fertilisation is the fusion of a male and a female gamete to form a zygote.

Zygote

The single cell formed at fertilisation. It divides repeatedly to form the embryo and eventually the new individual.

Structure of a flower

The four whorls are sepals, petals, stamens and carpel. Stamens and carpel are the essential (reproductive) whorls; sepals and petals are accessory.

Stamen and carpel

The stamen is the male part, made of anther and filament, producing pollen. The carpel is the female part, made of stigma, style and ovary, containing ovules.

Pollination

The transfer of pollen from anther to stigma. Self-pollination occurs within the same flower, cross-pollination between different flowers of the same species.

Agents of pollination

Pollen is carried by wind, water or animals such as insects and birds. Flower features like bright petals, scent and nectar are adaptations to attract animal pollinators.

Fertilisation in plants

The pollen grain grows a tube down the style to the ovule, where the male gamete fuses with the egg. The ovule then becomes the seed and the ovary becomes the fruit.

Human male reproductive system

Testes produce sperm and the hormone testosterone; the sperm travel through the vas deferens and are released with secretions from associated glands.

Human female reproductive system

Ovaries produce eggs and female hormones; the egg travels along the oviduct, where fertilisation occurs, to the uterus in which the embryo develops.

Placenta

The tissue connecting the embryo to the mother's uterine wall, through which the embryo receives nutrients and oxygen and passes out waste.

Reproductive health

Complete physical and mental well-being in reproductive matters, including awareness of contraception and of sexually transmitted infections.