O-Level Combined Science — Biology 1 — Questions and Answers
Question 1: What is the basic unit of life?
- Organ
- Tissue
- Cell (Correct answer)
- Organism
Correct answer: Cell
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?
- Nucleus
- Ribosome
- Vacuole
- Mitochondria (Correct answer)
Correct answer: Mitochondria
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?
- Respiration
- Digestion
- Photosynthesis (Correct answer)
- Fermentation
Correct answer: Photosynthesis
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?
- Red blood cells
- Platelets
- White blood cells (Correct answer)
- Plasma cells
Correct answer: White blood cells
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?
- Glucose + oxygen → carbon dioxide + water + energy (Correct answer)
- Glucose → carbon dioxide + water
- Glucose + water → oxygen + energy
- Carbon dioxide + water → glucose + oxygen
Correct answer: Glucose + oxygen → carbon dioxide + water + energy
Aerobic respiration: Glucose + Oxygen → Carbon dioxide + Water + Energy (ATP). This occurs in the mitochondria.
Question 6: What is the function of chlorophyll?
- To store water in the leaf
- To absorb sunlight for photosynthesis (Correct answer)
- To transport minerals from the roots
- To control gas exchange
Correct answer: To absorb sunlight for photosynthesis
Chlorophyll is the green pigment in chloroplasts that absorbs light energy (mainly red and blue wavelengths) for use in photosynthesis.
O-Level Combined Science — Biology 1
What is the basic unit of life?