Key Points

Reproduction fundamentally involves creating copies of the DNA, which serves as the blueprint for an organism's body design. This process ensures the inheritance of features from parents to offspring.

Inaccuracies in DNA copying lead to variations, which are essential for the survival of a species. Variations allow populations to adapt to changing environmental conditions, forming the basis of evolution.

Asexual reproduction is a mode where a new generation is created from a single parent. Offspring are genetically very similar to the parent, and common methods include fission, budding, and vegetative propagation.

Fission is cell division in unicellular organisms. Binary fission produces two daughter cells (e.g., Amoeba), while multiple fission produces many daughter cells simultaneously (e.g., Plasmodium).

In budding, a new individual develops from an outgrowth on the parent (e.g., Hydra, Yeast). In fragmentation, the parent body breaks into pieces, each growing into a new organism (e.g., Spirogyra).

This is a type of asexual reproduction where new plants grow from vegetative parts like roots, stems, or leaves. Examples include potatoes from buds (eyes) and Bryophyllum from leaf notches.

Some organisms, like the bread mould Rhizopus, reproduce using spores. Spores are tiny cells protected by a thick wall that can develop into new individuals under favorable moist conditions.

Sexual reproduction involves two individuals, a male and a female, and the fusion of their specialized reproductive cells called gametes. This process generates greater genetic variation compared to asexual reproduction.

The flower is the reproductive organ. The stamen is the male part producing pollen grains, and the pistil (or carpel) is the female part containing ovules with the egg cell.

Pollination is the transfer of pollen from the anther to the stigma. Fertilization is the fusion of the male gamete from the pollen grain with the female gamete (egg) inside the ovule to form a zygote.

After fertilization, the zygote develops into an embryo. The ovule develops a tough coat and becomes a seed, while the ovary grows and ripens to form a fruit.

Puberty is the period of adolescence when reproductive tissues mature. Changes include breast development in girls and facial hair growth in boys, signaling sexual maturation.

The male reproductive system includes testes, which produce sperm and the hormone testosterone. Sperms are delivered through the vas deferens, and glands like the prostate add fluid to form semen.

The female reproductive system includes ovaries, which produce eggs (ova) and hormones. The egg travels through the fallopian tube to the uterus, which is where a fertilized egg develops.

Fertilization occurs when a sperm fuses with an egg in the fallopian tube, forming a zygote. The resulting embryo travels to the uterus and implants in its lining to continue development.

The placenta is a special tissue that connects the developing embryo to the uterine wall. It facilitates the transfer of nutrients like glucose and oxygen from the mother to the embryo and removes waste products.

If an egg is not fertilized, the thickened lining of the uterus is not needed and breaks down. This lining is discharged through the vagina as blood and mucous, a process known as menstruation.

Contraception refers to methods used to prevent pregnancy. These include mechanical barriers (condoms), hormonal methods (oral pills), intrauterine devices (Copper-T), and surgical methods (vasectomy and tubectomy).

STDs are infections transmitted through sexual contact, including bacterial (gonorrhoea, syphilis) and viral (warts, HIV-AIDS) diseases. Using a condom helps prevent the transmission of many of these infections.