PassNova has 13 free KS3 Science practice questions on Biology, each with a clear explanation. Practise them in the browser with instant feedback — 100% free, no sign-up, on any device. Updated for 2026.
Biology: example questions & answers
12 worked examples with answers and explanations below. Practise all 13 Biology questions free in the browser, with instant feedback on every answer.
What is the basic building block of all living things?
- AThe atom
- BThe cell✓
- CThe organ
- DThe molecule
Answer: Cells are the smallest unit of life; all living organisms are made of one or more cells.
Which part of a plant cell carries out photosynthesis?
- ANucleus
- BCell wall
- CChloroplast✓
- DVacuole
Answer: Chloroplasts contain chlorophyll, which traps light energy for photosynthesis.
Which gas do plants take in for photosynthesis?
- AOxygen
- BNitrogen
- CCarbon dioxide✓
- DHydrogen
Answer: Plants absorb carbon dioxide and release oxygen during photosynthesis.
Which organ pumps blood around the body?
- ALungs
- BHeart✓
- CLiver
- DKidney
Answer: The heart is a muscular organ that pumps blood through the circulatory system.
In a food chain, the arrows show:
- AWho eats who, pointing to the eater✓
- BThe direction animals walk
- CWhich animal is biggest
- DThe order of birth
Answer: Food-chain arrows point in the direction energy flows — towards the organism doing the eating.
What do we call animals that eat only plants?
- ACarnivores
- BHerbivores✓
- COmnivores
- DPredators
Answer: Herbivores eat only plants; carnivores eat meat; omnivores eat both.
Which system in the body includes the lungs and is used for breathing?
- ADigestive system
- BRespiratory system✓
- CNervous system
- DSkeletal system
Answer: The respiratory system (lungs, trachea, etc.) takes in oxygen and removes carbon dioxide.
What is the job of the skeleton?
- ATo digest food
- BTo support and protect the body✓
- CTo pump blood
- DTo produce light
Answer: The skeleton supports the body, protects organs, and allows movement with muscles.
Which of these is a healthy way to keep the heart strong?
- ARegular exercise✓
- BSmoking
- CEating only sugar
- DNever moving
Answer: Regular exercise strengthens the heart muscle and improves circulation.
During reproduction in mammals, the male sex cell is the:
- AEgg
- BSperm✓
- CPollen
- DSeed
Answer: In mammals the male gamete (sex cell) is the sperm; the female gamete is the egg.
Bacteria that cause disease are sometimes called:
- ANutrients
- BPathogens✓
- CMinerals
- DCells
Answer: A pathogen is a microorganism (such as some bacteria or viruses) that causes disease.
A balanced diet should include a variety of:
- AOnly carbohydrates
- BFood groups including protein, carbohydrate, fat, vitamins and minerals✓
- COnly fats
- DOnly sugar
Answer: A balanced diet contains the right amounts of all the main food groups.