Why Plant Cells Don’t Lysing The Role of the Cell Wall

Subject : Biology

Question:

What do plant cells have that protect them from lysing, which is missing in animal cells?

A. Chloroplasts

B. A nucleus

C. A cell membrane

D. A cell wall

Expert Verified Solution:

The correct answer is D. A cell wall.

Explanation:

1. The Role of the Cell Wall: The cell wall is a rigid, protective outer layer found in plant cells. It is primarily composed of cellulose, a carbohydrate that provides structural support and rigidity. The cell wall plays several critical roles:

Protection: It acts as a barrier that protects the cell from physical damage and pathogens.
Support: It maintains the shape and structure of the plant cell, preventing it from collapsing under its own weight or external pressure.

Prevention of Lysing: During osmosis, water moves into the plant cell, increasing internal pressure. The cell wall resists this pressure, preventing the cell from lysing, or bursting, due to excess water intake.

2. Comparison with Animal Cells: Animal cells lack a cell wall and are surrounded only by a flexible cell membrane (or plasma membrane). This membrane is composed of a lipid bilayer with embedded proteins, which provides some protection and regulation of substances entering and exiting the cell. However, the absence of a rigid cell wall means that animal cells are more vulnerable to lysing under high osmotic pressure.

3. Cell Wall Composition and Function: The cell wall is made up of:

Cellulose: A polysaccharide that forms strong, fibrous structures.

Hemicellulose and Pectin: These substances help bind cellulose fibers together and provide additional structural support and flexibility.

4. Other Structures:

Chloroplasts (A): These are organelles responsible for photosynthesis and are present in plant cells but do not play a role in preventing lysing.

A Nucleus (B): The nucleus contains genetic material and is present in both plant and animal cells but is not involved in protecting against lysing.

A Cell Membrane (C): Present in both plant and animal cells, it regulates the movement of substances in and out of the cell but does not prevent lysing in the absence of a cell wall.

The cell wall is the key structural feature that distinguishes plant cells from animal cells in terms of protection against lysing.