Skip to content
Know.itKnow.it
Create an animated lesson
On request

Read the answer free. Creating a lesson uses your daily or stored credits; review the language and settings before starting.

What is binary fission?

Class 10 ScienceNCERT chapter: How do Organisms Reproduce?इसे हिंदी में पढ़ें

Exam-ready answer

Binary fission is a mode of asexual reproduction in which a single-celled organism divides into two identical daughter cells. The parent cell's nucleus divides first, followed by the cytoplasm. Examples: Amoeba, Paramecium, and bacteria. It is the simplest and fastest method of reproduction.

Explanation

Binary fission is an asexual mode of reproduction seen in unicellular organisms. The word 'binary' means two and 'fission' means splitting. In this process, the parent organism divides into two equal halves, each growing into a new individual. No gametes or fertilisation are involved.

The steps are simple. First, the nucleus of the parent cell divides into two (karyokinesis). Then the cytoplasm divides (cytokinesis), and the cell membrane pinches inwards. This results in two daughter cells that are genetically identical to the parent. In Amoeba, the process is clearly visible under a microscope.

Binary fission is common in bacteria, Amoeba, Paramecium, and Leishmania (which divides in a specific plane). It allows rapid multiplication under favourable conditions. Since the offspring are identical, there is no variation, which is a limitation of asexual reproduction.

Points to remember

  1. Binary fission = asexual reproduction in unicellular organisms.
  2. Parent cell divides into two identical daughter cells.
  3. Steps: nuclear division (karyokinesis) → cytoplasmic division (cytokinesis).
  4. Examples: Amoeba, Paramecium, bacteria, Leishmania.
  5. No gamete formation or fertilisation; offspring are genetically identical.

Exam tip

Draw a simple labelled diagram showing the four stages of binary fission in Amoeba: parent cell, nuclear division, cytoplasmic division, and two daughter cells. Label the nucleus and cell membrane.

Questions students also ask

How is binary fission different from multiple fission?
In binary fission, the parent cell divides into two daughter cells. In multiple fission, the parent cell divides into many daughter cells simultaneously, as in Plasmodium.
Do offspring formed by binary fission show variation?
No, offspring are genetically identical to the parent because only one parent is involved and no mixing of genetic material occurs. This is why variation is absent in asexual reproduction.
Which organelles are involved in binary fission?
The nucleus divides first, followed by the cytoplasm. In bacteria, which lack a true nucleus, the genetic material (DNA) replicates and the cell splits into two.

Chapter labels help you find the topic in your textbook. Check your own edition: chapter names and order can change. These are Know.it explanations, not official NCERT solutions.