Cytokinesis in Mitosis: Complete NEET Guide with Examples
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| Comparison of cytokinesis in animal and plant cells showing cleavage furrow, cell plate formation, and daughter cell development. |
Cytokinesis (NEET Level)
What is Cytokinesis?
- Cytokinesis is the division of the cytoplasm of a cell.
- It occurs after karyokinesis (nuclear division).
- It is the last step of mitosis.
- After cytokinesis, one parent cell forms two separate daughter cells.
- Cell division is completed only after cytokinesis.
Easy Definition (NEET)
Cytokinesis = Division of cytoplasm resulting in the formation of two daughter cells.
Line-by-Line Explanation
**1. "Mitosis accomplishes not only the segregation of duplicated chromosomes into daughter nuclei (karyokinesis)..."
Easy Meaning
- During mitosis, the duplicated chromosomes separate equally.
- Each new nucleus receives the same number of chromosomes.
- This process is called karyokinesis.
Remember
Karyo = Nucleus ➡️ Karyokinesis = Division of nucleus
**2. "...but the cell itself is divided into two daughter cells by the separation of cytoplasm called cytokinesis."
Easy Meaning
- After the nucleus divides,
- The cytoplasm also divides.
- This division is called cytokinesis.
- As a result, two daughter cells are formed.
Remember
Cyto = Cytoplasm ➡️ Cytokinesis = Division of cytoplasm
3. "At the end of cytokinesis, cell division gets completed."
Easy Meaning
- Cytokinesis is the final stage of mitosis.
- After it finishes,
- Cell division is completely over.
NEET Point
Cell division is completed only after cytokinesis.
Cytokinesis in Animal Cells
4. "In an animal cell, this is achieved by the appearance of a furrow in the plasma membrane."
Easy Meaning
- Animal cells do not have a cell wall.
- A cleavage furrow appears in the plasma membrane.
- The furrow looks like a small inward groove.
Keyword
Cleavage Furrow
5. "The furrow gradually deepens and ultimately joins in the centre dividing the cell cytoplasm into two."
Easy Meaning
- The cleavage furrow becomes deeper.
- It moves inward from all sides.
- Finally, both sides meet in the centre.
- The cytoplasm is divided into two equal parts.
- Two daughter cells are formed.
Flow
Cleavage furrow appears ⬇ Deepens ⬇ Meets at centre ⬇ Two daughter cells formed
Cytokinesis in Plant Cells
6. "Plant cells however, are enclosed by a relatively inextensible cell wall."
Easy Meaning
- Plant cells have a rigid cell wall.
- The wall cannot bend inward.
- Therefore, cleavage furrow cannot be formed.
Remember
Animal cell → Cleavage furrow Plant cell → Cell plate
7. "Therefore they undergo cytokinesis by a different mechanism."
Easy Meaning
- Since plant cells have a hard cell wall,
- They use another method for cytokinesis.
8. "In plant cells, wall formation starts in the centre of the cell and grows outward to meet the existing lateral walls."
Easy Meaning
- A new wall starts forming at the centre.
- It grows toward both sides.
- Finally, it joins the old cell wall.
Remember
Plant cytokinesis: Centre → Outward
9. "The formation of the new cell wall begins with the formation of a simple precursor, called the cell plate."
Easy Meaning
- First, a cell plate is formed.
- The cell plate is the starting material for the new cell wall.
Important NEET Fact
Cell plate = Precursor of new cell wall
10. "The cell plate represents the middle lamella between the walls of two adjacent cells."
Easy Meaning
- The cell plate later becomes the middle lamella.
- It joins the walls of the two daughter cells.
Remember
Cell Plate ⬇ Middle Lamella ⬇ New Cell Wall
Distribution of Cell Organelles
11. "At the time of cytoplasmic division, organelles like mitochondria and plastids get distributed between the two daughter cells."
Easy Meaning
- During cytokinesis,
- Cell organelles are divided equally.
- Each daughter cell receives:
- Mitochondria
- Plastids (in plants)
- Cytoplasm
- Other organelles
NEET Point
Each daughter cell gets necessary organelles for survival.
Exception (No Cytokinesis)
12. "In some organisms karyokinesis is not followed by cytokinesis."
Easy Meaning
- Sometimes only the nucleus divides.
- The cytoplasm does not divide.
Result
One cell contains many nuclei.
13. "As a result multinucleate condition arises leading to the formation of syncytium."
Easy Meaning
- One cell has many nuclei.
- Such a multinucleate cell is called a syncytium.
Definition
Syncytium = Multinucleate cell formed due to repeated nuclear divisions without cytokinesis.
14. "Example: Liquid endosperm in coconut."
Easy Meaning
- The liquid coconut water is an example of a syncytium.
- It contains many free nuclei in the cytoplasm.
NEET Example
Liquid endosperm of coconut → Syncytium
Animal vs Plant Cytokinesis (NEET Table)
| Feature | Animal Cell | Plant Cell |
|---|---|---|
| Method | Cleavage furrow | Cell plate formation |
| Direction | Outside → Centre | Centre → Outside |
| Cell wall present | No | Yes |
| New wall formed | No | Yes |
| Final result | Two daughter cells | Two daughter cells |
Important Definitions
Karyokinesis
Division of the nucleus.
Cytokinesis
Division of the cytoplasm.
Cleavage Furrow
An inward groove in the plasma membrane that divides an animal cell.
Cell Plate
A precursor structure that develops into the new cell wall during plant cytokinesis.
Middle Lamella
The layer formed from the cell plate that joins the walls of adjacent plant cells.
Syncytium
A multinucleate cell formed when karyokinesis occurs without cytokinesis.
NCERT Keywords
- Cytokinesis
- Karyokinesis
- Cleavage furrow
- Cell plate
- Middle lamella
- Daughter cells
- Cytoplasm
- Mitochondria
- Plastids
- Syncytium
- Liquid endosperm of coconut
One-Minute Revision
- Cytokinesis = Division of cytoplasm.
- Occurs after karyokinesis.
- Animal cells: Cleavage furrow forms and deepens inward.
- Plant cells: Cell plate forms at the centre and grows outward.
- Cell plate becomes the middle lamella.
- Organelles are distributed equally to daughter cells.
- If cytokinesis does not occur after karyokinesis, a multinucleate syncytium forms.
- Example of syncytium: Liquid endosperm of coconut.
CBSE Class 11 Biology – Cytokinesis Question Bank
A. Multiple Choice Questions (MCQs)
1. Cytokinesis is the division of: a) Nucleus b) Chromosomes c) Cytoplasm d) DNA
Answer: c) Cytoplasm
2. Cytokinesis occurs: a) Before karyokinesis b) During prophase c) After karyokinesis d) During metaphase
Answer: c) After karyokinesis
3. Cell division is completed after: a) DNA replication b) Karyokinesis c) Cytokinesis d) Interphase
Answer: c) Cytokinesis
4. Cytokinesis in animal cells occurs by: a) Cell plate formation b) Cleavage furrow formation c) Chromosome duplication d) Cell wall formation
Answer: b) Cleavage furrow formation
5. Plant cells undergo cytokinesis by: a) Cleavage furrow b) Cell plate formation c) Binary fission d) Budding
Answer: b) Cell plate formation
6. Cell plate develops into: a) Plasma membrane b) Cell wall c) Middle lamella d) Nucleus
Answer: c) Middle lamella
7. Cleavage furrow is formed in: a) Plant cells b) Animal cells c) Fungal cells d) Bacterial cells
Answer: b) Animal cells
8. A multinucleate cell formed due to absence of cytokinesis is called: a) Coenocyte b) Syncytium c) Endospore d) Gamete
Answer: b) Syncytium
9. Which organelles are distributed during cytokinesis? a) Mitochondria b) Plastids c) Both (a) and (b) d) Ribosomes only
Answer: c) Both (a) and (b)
10. Liquid endosperm of coconut is an example of: a) Cleavage furrow b) Cell plate c) Syncytium d) Middle lamella
Answer: c) Syncytium
B. Very Short Answer Questions (1 Mark)
1. Define cytokinesis. Answer: Cytokinesis is the division of cytoplasm resulting in the formation of two daughter cells.
2. What is karyokinesis? Answer: Division of the nucleus.
3. What is a cleavage furrow? Answer: An inward groove in the plasma membrane of an animal cell during cytokinesis.
4. What is a cell plate? Answer: A precursor structure that develops into the new cell wall in plant cells.
5. Give one example of a syncytium. Answer: Liquid endosperm of coconut.
C. Short Answer Questions (2–3 Marks)
1. Why is cleavage furrow absent in plant cells?
Answer:
- Plant cells have a rigid cell wall.
- The wall cannot bend inward.
- Therefore, cytokinesis occurs by cell plate formation.
2. Explain cytokinesis in animal cells.
Answer:
- A cleavage furrow appears in the plasma membrane.
- It deepens gradually.
- Opposite sides meet at the centre.
- The cytoplasm divides into two daughter cells.
3. Explain cytokinesis in plant cells.
Answer:
- A cell plate forms at the centre.
- It grows outward.
- It fuses with the existing cell wall.
- It develops into the middle lamella and new cell wall.
4. What happens to organelles during cytokinesis?
Answer: Cell organelles such as mitochondria, plastids and other cytoplasmic components are distributed between the two daughter cells.
D. Long Answer Questions (5 Marks)
1. Compare cytokinesis in plant and animal cells.
| Feature | Animal Cell | Plant Cell |
|---|---|---|
| Method | Cleavage furrow | Cell plate |
| Direction | Outside → Centre | Centre → Outside |
| Cell wall | Absent | Present |
| New cell wall | Not formed | Formed |
| Result | Two daughter cells | Two daughter cells |
2. Explain cytokinesis and describe what happens if it does not occur.
Answer:
- Cytokinesis is the division of cytoplasm after karyokinesis.
- It completes cell division.
- In animal cells it occurs through cleavage furrow.
- In plant cells it occurs through cell plate formation.
- If cytokinesis fails after nuclear division, multinucleate cells called syncytia are formed.
- Example: Liquid endosperm of coconut.
E. Assertion and Reason Questions
1. Assertion (A): Cytokinesis occurs after karyokinesis. Reason (R): Cytokinesis is the division of cytoplasm.
Answer: Both A and R are true, and R is the correct explanation.
2. Assertion (A): Plant cells divide by cleavage furrow. Reason (R): Plant cells possess a rigid cell wall.
Answer: Assertion is false, Reason is true.
3. Assertion (A): Cell plate develops into middle lamella. Reason (R): Cell plate is the precursor of the new cell wall.
Answer: Both A and R are true, and R is the correct explanation.
4. Assertion (A): Cytokinesis distributes organelles into daughter cells. Reason (R): Mitochondria and plastids are equally distributed.
Answer: Both A and R are true, and R is the correct explanation.
F. Fill in the Blanks
- Cytokinesis is the division of cytoplasm.
- Cytokinesis occurs after karyokinesis.
- Animal cells divide by cleavage furrow.
- Plant cells divide by cell plate formation.
- Cell plate later becomes the middle lamella.
- A multinucleate cell is called a syncytium.
- Cell division is completed after cytokinesis.
- Liquid endosperm of coconut is a syncytium.
- Plant cells have a rigid cell wall.
- Mitochondria and plastids are distributed during cytokinesis.
G. Case Study Questions
Case Study 1
A student observed cell division under a microscope. In one cell, an inward groove gradually deepened until the cell separated into two daughter cells.
Questions
-
Which process is occurring? Answer: Cytokinesis.
-
Which type of cell is observed? Answer: Animal cell.
-
Name the groove formed. Answer: Cleavage furrow.
-
What stage occurs before this process? Answer: Karyokinesis.
Case Study 2
Another student observed a plate-like structure developing at the centre of a dividing cell, which gradually extended toward the cell walls.
Questions
-
Which structure is observed? Answer: Cell plate.
-
Which type of cell is dividing? Answer: Plant cell.
-
What does the cell plate become? Answer: Middle lamella.
-
Why is cleavage furrow absent? Answer: Due to the rigid cell wall.
H. Statement-Based Questions
State whether True or False.
- Cytokinesis divides the nucleus. — False
- Karyokinesis precedes cytokinesis. — True
- Animal cells form a cleavage furrow. — True
- Plant cells form a cell plate. — True
- Cell plate becomes middle lamella. — True
- Cytokinesis distributes cell organelles. — True
- Plant cells lack a cell wall. — False
- Liquid endosperm of coconut is syncytium. — True
- Cleavage furrow forms in plant cells. — False
- Cell division completes after cytokinesis. — True
I. Match the Columns
| Column A | Column B |
|---|---|
| 1. Cytokinesis | A. Division of nucleus |
| 2. Karyokinesis | B. Cleavage furrow |
| 3. Animal cell | C. Cell plate |
| 4. Plant cell | D. Division of cytoplasm |
| 5. Cell plate | E. Middle lamella |
| 6. Syncytium | F. Multinucleate cell |
Answers
1 – D
2 – A
3 – B
4 – C
5 – E
6 – F
J. Important Exam Questions
- Define cytokinesis.
- Differentiate between cytokinesis in plant and animal cells.
- Explain cleavage furrow formation.
- Explain cell plate formation.
- What is syncytium? Give one example.
- Why is cytokinesis absent in some cells?
- Explain the distribution of organelles during cytokinesis.
- Why is cell division incomplete without cytokinesis?
- What is the significance of the middle lamella?
- Draw and label cytokinesis in plant and animal cells.
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