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CIE iGCSE Co-Ordinated Science B3.1 Diffusion Exam Style Questions Paper 1

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Question

By which process does oxygen pass from the alveoli to the blood capillaries in the lungs?

A. diffusion
B. active transport
C. osmosis
D. filtration

▶️ Answer/Explanation
Oxygen concentration is higher in the alveolar air than in the blood capillaries.
Molecules move down their concentration gradient without using energy.
This passive movement of oxygen into the blood is diffusion.
✅ Answer: (A)

Question

What is the net movement of molecules during diffusion?

A. from a higher concentration to a lower concentration down a concentration gradient
B. from a higher concentration to a lower concentration up a concentration gradient
C. from a lower concentration to a higher concentration down a concentration gradient
D. from a lower concentration to a higher concentration up a concentration gradient

▶️ Answer/Explanation
Diffusion is the net movement of molecules from a region of higher concentration to a region of lower concentration.
This movement is described as moving down the concentration gradient — no energy (ATP) is required for this process.
✅ Answer: (A)

Question

Which statements about osmosis are correct?

        1 Osmosis requires a membrane.
        2 Water can move out of cells by osmosis.
        3 Water can move into cells by osmosis.

A     1 and 2 only         B 1 and 3 only          C 1, 2 and 3           D 2 and 3 only

▶️Answer/Explanation

Ans :C

Question

By which process does oxygen pass from the alveoli to the blood capillaries in the lungs?

(A) growth and nutrition
(B) growth and sensitivity
(C) respiration and nutrition
(D) respiration and sensitivity

▶️Answer/Explanation

Ans:  A

Question

What is an example of diffusion?

A. movement of blood through the capillaries

B. movement of food from the mouth to the stomach

C. movement of oxygen from alveoli to the blood

D. movement of urine along the urethra

▶️Answer/Explanation

Answer: C. movement of oxygen from alveoli to the blood

Explanation: Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration. The movement of oxygen from the alveoli (high concentration) to the blood (low concentration) is an example of diffusion.

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