Cell Division

Meiosis

Meiosis is the cell division which leads to the production of sex cells or gametes. It takes place in the reproductive organs (testis and ovary in animals; anthers and ovary in plants).

The number of chromosomes in each daughter cell is half of that in the parent cell. Hence, this division is also called the reductional division.

In contrast to Mitosis where two daughter cells are formed, Meiosis leads to the generation of four daughter cells.

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Cell Division

Mitosis

Mitosis is a cell division in which two identical daughter cells are produced by the division of one parent cell.

In this type of division, same chromosome number is maintained in all cells. Mitosis is the cell division which leads to growth and development.

As the number of chromosomes in the daughter cell remain equal to the parent cell this type of cell division is also known as equational division.

mitosis

Class 8, Reproduction

Reproduction- Introduction

Reproduction: It is a biological process by which a new individual (offspring) is produced from pre-existing individuals (parents).

  • Reproduction is one the key life processes crucial to all living beings. It is of two types: Asexual and Sexual

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Asexual Reproduction:

  • Only a single individual is involved
  • Offsprings are formed by splitting of one parent (Uniparental)
  • Offsprings look very similar to their parents

Types of Asexual Reproduction:

  1. Fragmentation: Organism breaks into several pieces, each piece regenerates into a new organism. Example: Hydra and Flatworms
  2. Binary Fission: Organism splits into two equal halves. Nucleus divides first, followed by cytoplasm. Example: Amoeba, paramecium
  3. Multiple Fission: Organism develops a cyst around itself under unfavourable Nucleus divides several times mitotically. Nuclear division is followed by separation of cytoplasm, each nucleus give rise to a new individual. Example: Amoeba
  4. Budding: A small outgrowth develops from parent body, grows in size and eventually separates from parent into an independent organism. Example: Hydra
  5. Regeneration: Organism forms many of its own kind from cut pieces of the body. Example: Flatworms, Sponges and Hydra.