N-Level Combined Science 4 — Questions and Answers
Question 1: What is meant by 'adaptation' in biology?
- The change in an organism's behaviour only
- A feature of an organism that helps it survive and reproduce in its environment (Correct answer)
- The movement of organisms to new areas
- The extinction of a species
Correct answer: A feature of an organism that helps it survive and reproduce in its environment
An adaptation is a feature (structural, behavioural, or physiological) that improves an organism's chances of survival and reproduction in its particular environment.
Question 2: What type of reaction produces a precipitate?
- Combustion
- Neutralisation only
- A reaction where an insoluble solid forms from mixing two solutions (Correct answer)
- Electrolysis
Correct answer: A reaction where an insoluble solid forms from mixing two solutions
A precipitate is an insoluble solid formed when two solutions are mixed. For example, mixing lead nitrate and sodium iodide solutions produces a yellow precipitate of lead iodide.
Question 3: What is the speed of light in a vacuum?
- 3 × 10⁶ m/s
- 3 × 10⁸ m/s (Correct answer)
- 3 × 10¹⁰ m/s
- 3 × 10⁴ m/s
Correct answer: 3 × 10⁸ m/s
The speed of light in a vacuum is approximately 3 × 10⁸ m/s (300,000,000 m/s or 300,000 km/s).
Question 4: In photosynthesis, what does the plant produce?
- Carbon dioxide and water
- Oxygen and glucose (Correct answer)
- Nitrogen and protein
- Water and carbon
Correct answer: Oxygen and glucose
Photosynthesis: CO₂ + H₂O + light energy → glucose + O₂. Plants produce glucose (food) and oxygen as a by-product.
Question 5: What is the difference between mass and weight?
- They are the same thing
- Mass is the amount of matter in an object (kg); weight is the gravitational force on an object (N) (Correct answer)
- Weight is measured in kg; mass in N
- Mass changes with location; weight does not
Correct answer: Mass is the amount of matter in an object (kg); weight is the gravitational force on an object (N)
Mass is the amount of matter in an object, measured in kg — it stays constant anywhere. Weight is the gravitational force on an object (W = mg), measured in Newtons, and varies with gravity.
Question 6: What is a food web?
- A spider's web made of food
- A single food chain
- A network of interconnected food chains showing feeding relationships in an ecosystem (Correct answer)
- A diagram of plant growth
Correct answer: A network of interconnected food chains showing feeding relationships in an ecosystem
A food web shows the complex feeding relationships in an ecosystem, with multiple interconnected food chains. It is more realistic than a single food chain.
N-Level Combined Science 4
What is meant by 'adaptation' in biology?