Q23
2 marksShort AnswerSection B

With the help of diagrams show the different stages of binary fission in Amoeba.

How do Organisms Reproduce?
Fission in Amoeba
Official Answer

Binary fission in Amoeba is a method of asexual reproduction where a single-celled organism splits into two equal halves. In Amoeba, this splitting can take place in any plane.


Stages of Binary Fission in Amoeba:

  1. Parent Cell: The cell has a well-defined nucleus and cytoplasm.
  2. Nuclear Division (Karyokinesis): The nucleus of the parent cell begins to elongate and divide into two.
  3. Cytoplasmic Division (Cytokinesis): A constriction appears in the cell membrane and cytoplasm, which deepens gradually.
  4. Daughter Cells: The cytoplasm splits completely, resulting in two independent, identical daughter Amoeba cells.


1. Parent Cell (Distinct Nucleus)2. Nucleus Elongates (Karyokinesis)3. Cytoplasm Constricts (Cytokinesis)4. Two Daughter Cells (Formed in any plane)
Binary fissionAmoebaNucleus elongatesCytoplasm constrictsDaughter cellsAny plane

Marking Scheme

  • 1Correct description or representation of the stages (Parent cell -> Nuclear elongation -> Cytoplasmic division -> Two daughter cells) (1.5 marks)
  • 2Mentioning that the splitting can take place in any plane (0.5 marks)

Hint

Recall that binary fission in Amoeba involves the division of the nucleus followed by the division of the cytoplasm, and it can happen in any plane.

Quick Oral Answer

Binary fission in Amoeba is a type of asexual reproduction where the parent cell divides into two equal daughter cells. The division of the nucleus is followed by the division of the cytoplasm, and it can occur in any plane.

Analysis & Explanation

In unicellular organisms like Amoeba, reproduction occurs via simple cell division or binary fission. Since Amoeba does not have a highly organized body structure (unlike Leishmania which has a whip-like structure at one end), its division can occur along any plane. The process begins with the replication and division of its genetic material (nucleus), followed by the division of the cytoplasm, ensuring both daughter cells receive a copy of the DNA and the necessary cellular apparatus to survive.

Common Mistakes

  1. 1Drawing the division in a fixed orientation (like Leishmania) instead of showing that it can occur in any plane.
  2. 2Forgetting to show the elongation and division of the nucleus before the cytoplasm divides.

Interesting Facts

Unlike Leishmania, which has a whip-like structure at one end and must divide in a definite orientation, Amoeba is completely asymmetrical and can split in any direction.

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2010?

This question carries 2 marks in the CBSE Class 10 Science 2010 examination.

Which chapter does this question come from in Science?

This question is from the chapter "How do Organisms Reproduce?" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Fission in Amoeba" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2010 paper?

This is a Short Answer question from Section B in the CBSE Class 10 Science 2010 paper.