O-Level Combined Science — Biology

Question 1

What is the basic unit of life?

Accepted Answer

Cell

Answer

The cell is the basic structural and functional unit of all living organisms. All life is made up of cells.

Question 2

Which organelle is responsible for producing energy (ATP) in the cell?

Accepted Answer

Mitochondria

Answer

Mitochondria are the sites of cellular respiration, producing ATP (adenosine triphosphate), the cell's energy currency.

Question 3

What is the process by which plants make their own food?

Accepted Answer

Photosynthesis

Answer

Photosynthesis is the process by which plants use light energy, carbon dioxide, and water to produce glucose and oxygen.

Question 4

Which blood cells are responsible for fighting infection?

Accepted Answer

White blood cells

Answer

White blood cells (leukocytes) are part of the immune system, fighting infections by engulfing pathogens or producing antibodies.

Question 5

What is the word equation for aerobic respiration?

Accepted Answer

Glucose + oxygen → carbon dioxide + water + energy

Answer

Aerobic respiration: Glucose + Oxygen → Carbon dioxide + Water + Energy (ATP). This occurs in the mitochondria.

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