Cell physiology: osmosis — KCSE Biology

KCSE Biology · 157 practice questions · 4 syllabus objectives

52 easy53 medium52 hard

What You'll Learn

Key learning outcomes for this topic, aligned to the KNEC KCSE syllabus.

Define osmosis and distinguish it from diffusion

Explain plasmolysis and turgidity in plant cells

Describe experiments to demonstrate osmosis

Cell physiology: osmosis

Try 3 questions free. Sign up to access all 157 questions with full marking schemes.

easySHORT ANSWER4 marks

Identify the process that occurs when a plant cell loses water and explain its effect on the cell. (4 marks)

View Marking Scheme

Part (a) — 4 marks

The process is plasmolysis (1 mk)

During plasmolysis, the cell membrane pulls away from the cell wall as water exits the cell (1 mk)

This leads to wilting and loss of turgor pressure in the cell (1 mk)

If severe, plasmolysis can lead to cell death (1 mk)

easySHORT ANSWER3 marks

Explain how turgidity in plant cells is achieved and its significance. (3 marks)

View Marking Scheme

Part (a) — 3 marks

Turgidity is achieved when water enters the cell by osmosis, causing the vacuole to swell (1 mk)

The swelling of the vacuole pushes the cytoplasm against the cell wall, creating turgor pressure (1 mk)

Turgidity is significant as it provides support and maintains the structural integrity of the plant (1 mk)

easySHORT ANSWER2 marks

Name two factors that affect the rate of osmosis in plant cells. (2 marks)

View Marking Scheme

Part (a) — 2 marks

Concentration gradient — the difference in solute concentration inside and outside the cell (1 mk)

Temperature — higher temperatures increase kinetic energy and speed up the process (1 mk)

Define osmosis and explain how it differs from diffusion. (4 marks)

Sign up free to access all 157 questions with marking schemes, track your progress, and get personalised recommendations.