Biology IGCSE Combined SCIENCE

Which statements about enzymes are correct?
1 Enzymes are proteins.
2 Some enzymes carry out chemical digestion.
3 Enzymes speed up the rate of chemical reactions.
4 All enzymes work fastest at pH7.

• 1, 2 and 3
• 1 and 2 only
• 1 and 3 only
• 2, 3 and 4

Which substance in leaves traps light energy for use in photosynthesis?

• carbohydrate
• carbon
• carbon dioxide
• chlorophyll

The statements show how a person’s diet can be unbalanced.
1 eating too much fibre
2 eating too much saturated fat
3 eating too much salt
Which of these increase the risk of coronary heart disease?

• 1, 2 and 3
• 1 and 2 only
• 1 and 3 only
• 2 and 3 only

Which molecule contains the energy that is released in aerobic respiration?

• C₆H₁₂O₆
• CO₂
• H₂O
• O₂

A shoot is illuminated from one side only. What collects on the dark side of the shoot?

• auxin
• chlorophyll
• glucose
• starch

What is an undesirable effect of overuse of fertilisers in agriculture?

• acid rain
• deforestation
• eutrophication
• global warming

Process Q happens in cells.
carbohydrates → process Q → energy released
What is process Q?

• growth
• nutrition
• respiration
• sensitivity

Which component of tobacco smoke increases the risk of lung cancer?

• carbon dioxide
• carbon monoxide
• nicotine
• tar

What effect does HIV have on the components of blood?

• Blood does not clot as quickly.
• Plasma can no longer carry hormones.
• Red blood cells carry less oxygen.
• White blood cells make fewer antibodies.

Which statement about decomposers is not correct?

• They are the final stage of food chains.
• They break down dead organic matter.
• They produce oxygen.
• They release heat energy into the environment.