10 questions. Work each one out before revealing the answer.
Which gas is released as a product of photosynthesis?
Answer: Oxygen
Photosynthesis uses carbon dioxide and water to make glucose and oxygen.
Common misconception: Mixing up the inputs and outputs of photosynthesis and respiration.
A resultant force of 18 N acts on a 6 kg object. What is its acceleration?
Answer: 3 m/s²
Use F = ma, so a = F ÷ m = 18 ÷ 6 = 3 m/s².
Common misconception: Multiplying force by mass instead of dividing.
A runner covers 150 m in 30 s. What is the average speed?
Answer: 5 m/s
Speed = distance ÷ time = 150 ÷ 30 = 5 m/s.
Common misconception: Dividing time by distance.
Which is the correctly balanced equation for magnesium burning in oxygen?
Answer: 2Mg + O2 → 2MgO
Each side has 2 Mg and 2 O in 2Mg + O2 → 2MgO. The formula MgO must not be changed to balance.
Common misconception: Changing the formula (MgO2) rather than the coefficient.
How many times greater is the hydrogen ion concentration in a solution of pH 2 than in a solution of pH 4?
Answer: 100
Each pH unit is a factor of 10. Two units gives 10 × 10 = 100.
Common misconception: Treating the pH scale as linear.
Which organelle is the main site of aerobic respiration?
Answer: Mitochondrion
Mitochondria release energy from glucose using oxygen.
Common misconception: Saying the nucleus provides energy.
An experiment investigates how temperature affects the rate of an enzyme reaction. What is the independent variable?
Answer: Temperature
The independent variable is the factor deliberately changed. The rate of reaction is the dependent variable.
Common misconception: Confusing independent and dependent variables.
A car increases its speed from 0 to 20 m/s in 5 s. What is its acceleration?
Answer: 4 m/s²
a = (v − u) ÷ t = (20 − 0) ÷ 5 = 4 m/s².
Common misconception: Forgetting to subtract the initial velocity.
Using g = 10 N/kg, what is the weight of a 5 kg object?
Answer: 50 N
W = m × g = 5 × 10 = 50 N.
Common misconception: Confusing weight with mass.
Which type of cell has a cell wall made of cellulose?
Answer: Plant cell
Plant cell walls are made of cellulose. Bacterial cell walls have a different composition.
Common misconception: Saying bacteria have cellulose walls.