Q38
1 markMCQSection B

The following figures illustrate binary fission in Amoeba in an incorrect sequence. The correct sequence is

How do Organisms Reproduce?
Fission

Options

(A)III, II, IV, I
(B)III, IV, II, I
(C)II, III, IV, I
(D)IV, III, II, I
Official Answer

The correct sequence of binary fission in Amoeba is III, IV, II, I (Option B).

Parent cellNuclear elongationConstrictionDaughter cellsBinary fission

Marking Scheme

  • 10.25 marks
  • 20.25 marks
  • 30.25 marks
  • 40.25 marks

Hint

Identify the parent cell first, followed by the elongation of the nucleus, then the constriction of the cell body, and finally the separation into two daughter cells.

Quick Oral Answer

In Amoeba, binary fission begins with the replication of DNA and elongation of the nucleus, followed by the constriction of the cytoplasm, which eventually splits the cell into two equal daughter cells.

Analysis & Explanation

Binary fission in Amoeba is an asexual mode of reproduction that occurs in a systematic sequence:

  1. Stage III (Parent Cell): Represents the unicellular parent Amoeba with a normal, spherical nucleus before division begins.
  2. Stage IV (Nuclear Elongation): The nucleus begins to elongate as the genetic material (DNA) prepares to divide (karyokinesis).
  3. Stage II (Cytoplasmic Constriction): A constriction appears in the cell membrane and cytoplasm, and the elongated nucleus divides into two daughter nuclei.
  4. Stage I (Daughter Cells): The constriction deepens and completely divides the cytoplasm (cytokinesis), resulting in two independent, identical daughter cells.

Distractor Analysis:

  • Option A (III, II, IV, I): Incorrect because it places cytoplasmic constriction (II) before nuclear elongation (IV).
  • Option C (II, III, IV, I): Incorrect because it starts with cytoplasmic constriction (II) instead of the parent cell (III).
  • Option D (IV, III, II, I): Incorrect because it starts with nuclear elongation (IV) before the parent cell (III) is established.

Common Mistakes

  1. 1Confusing the sequence of nuclear division (karyokinesis) and cytoplasmic division (cytokinesis) by placing constriction before nuclear elongation.

Interesting Facts

Unlike many other organisms, binary fission in Amoeba can occur along any plane of division because of its highly irregular and dynamic body shape.

Spotted a mistake or something unclear?

Tell us — we fix reported answers fast.

Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2012?

This question carries 1 mark in the CBSE Class 10 Science 2012 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" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2012 paper?

This is a MCQ question from Section B in the CBSE Class 10 Science 2012 paper.