How Do Organisms Reproduce?

Introduction to Reproduction

Reproduction is the biological process by which organisms give birth or give rise to a new organism. This process is seen in all living organisms- both plants and animals.

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Reproduction in Animals
Asexual Reproduction
Asexual Reproduction in Plants H
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Types of Reproduction

Reproduction can be of two types:

  • Asexual- Involves  a single parent which gives rise to a new organism
  • Sexual- Involves two parents of the opposite sex that give rise to a new organism.

Sexual Reproduction

This type of reproduction is seen in both plants and most animals. This involves two individuals of opposite sex having specialized sex organs that produce gametes. These gametes fuse in a favourable environment to give rise to a new organism or offspring.

In Plants

Sexual reproduction in plants happens in flowering plants who have both male and female in the same flower or in separate flowers. Flowers that contain either male or female parts are called unisexual plants whereas those with both male and female parts are called as bisexual or hermaphrodite plants.

The female reproductive organs are called the gynoecium consisting of stigma style and ovaries. The ovaries contain ovules which contain the female gametes.The male reproductive organs are collectively known as the androecium which consists of filament anther and stamens. The pollen grains on the stamens contain the male gamete.

Reproduction

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Through different modes of pollination, pollen grains are carried to the stigma of the same or a different flower. Once the pollen lands on the stigma, it is passed through the style to reach the ovaries where fertilization occurs and the ovary becomes the fruit and the ovules become the seeds. These seeds, on finding a favourable environment, give rise to a new plant.

In Animals

  • In animals, in most cases, there are separate sexes of the species that carry either the male or the female reproductive organs. Some organisms like the earthworm are hermaphrodite as they contain both sexes in the same organism.
  • In humans, the reproductive systems in males and females are very different. The male reproductive system is made up of the testes, scrotum, urethra and the penis. The male gamete is known as the sperm. The female reproductive system is made up of ovaries, fallopian tubes, and the vagina. The female gamete is known as the egg. When the sperm fuses with the egg inside the female uterus, a zygote is formed. This zygote undergoes further development to give rise to a fetus and a baby is born.
  • In mammals, who are not egg-laying animals, fertilization generally occurs inside the female and this type of fertilization is known as internal fertilization. In lower species such as birds, reptiles etc, the female lays the eggs from which a new organism arises. It is also the same in case of fishes and amphibians.
Reproduction

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Animals that lay eggs are known as oviparous while those who give rise to an embryo are called as viviparous.

Asexual Reproduction

As mentioned earlier, this type of reproduction needs only one parent. The process of fertilization does not occur as there is no fusion of gametes. Unlike sexual reproduction, there is no mixing of genetic material as the offsprings have the same genetic material as the parent.

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There are many forms of asexual reproduction:

  • Budding- Ex: Yeast
  • Binary fission: Ex: Bacteria, amoeba
  • Fragmentation: Ex: Flatworms, sponges, hydra
  • Vegetative propagation: Ex: Runner and stolons in plants

This type of reproduction is seen in both plants and animals but is more common in plants than in animals. Apart from these two types of reproduction methods, there are artificial modes of reproduction that have evolved due to advances in medicine.

Solved Example for You

Question: What is the female reproductive organ in a flowering plant known as?

  1. Ovaries      
  2. Testes
  3. Androecium        
  4. Gynoecium

Solution: Option D Gynoecium. The female reproductive organ in a flowering plant is collectively known as the gynoecium. It is composed of the stigma, style, ovary, and ovules.

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