Mini practice paper: 8 questions
Mixed-difficulty questions from across the Biology syllabus. Tap "Show answer" after each to check yourself.
Q1 · Difficulty 1/3
Which part of a plant cell is fully permeable and does not control what enters the cell?
- Cell wall
- Cell membrane
- Nucleus
- Vacuole
Show answer & explanation
✓ Answer: A — Cell wall
The cellulose cell wall is fully permeable and provides support only. The cell membrane inside it is the partially permeable barrier that controls entry and exit.
Q2 · Difficulty 1/3
Which gas released by vehicle exhausts is poisonous because it binds to haemoglobin?
- Oxygen
- Nitrogen
- Carbon monoxide
- Water vapour
Show answer & explanation
✓ Answer: C — Carbon monoxide
Carbon monoxide binds to haemoglobin more strongly than oxygen does, reducing the blood's ability to carry oxygen.
Q3 · Difficulty 1/3
Particles in a liquid are able to spread out because they possess:
- Kinetic energy
- Mass but no energy
- An electrical charge only
- No energy at all
Show answer & explanation
✓ Answer: A — Kinetic energy
Particles in liquids and gases move constantly because they have kinetic energy. This random movement is what produces diffusion.
Q4 · Difficulty 1/3
In a forest ecosystem in Guyana, all the plants, animals, fungi and microorganisms living together in a defined area represent the:
- Population
- Community
- Habitat
- Ecosystem
Show answer & explanation
✓ Answer: B — Community
Award 1 mark for B. A community consists of all the populations of different species living together in the same area. A is incorrect — a population is all individuals of one species only. C is incorrect — habitat is the place where an organism lives. D is incorrect — ecosystem includes both living community and non-living environment.
Q5 · Difficulty 1/3
Which of the following is an example of a density-dependent limiting factor?
- A volcanic eruption destroying habitat
- Competition for nesting sites among seabirds
- A sudden cold snap killing tropical fish
- Flooding from heavy rainfall
Show answer & explanation
✓ Answer: B — Competition for nesting sites among seabirds
Award 1 mark for competition for nesting sites among seabirds. This is density-dependent because the intensity of competition increases as population density increases. A is incorrect because volcanic eruptions affect populations regardless of density. C is incorrect because temperature extremes are density-independent abiotic factors. D is incorrect because flooding is a density-independent factor.
Q6 · Difficulty 1/3
Which of the following organisms in a Caribbean coral reef ecosystem is a primary consumer?
- Barracuda feeding on smaller fish
- Sea anemone capturing plankton
- Elkhorn coral with zooxanthellae
- Parrotfish feeding on algae
Show answer & explanation
✓ Answer: D — Parrotfish feeding on algae
Award 1 mark for parrotfish feeding on algae. Primary consumers are herbivores that feed on producers (plants/algae). A is incorrect because barracuda are tertiary consumers (carnivores eating other carnivores). B is incorrect because sea anemones are carnivores feeding on animals (secondary consumers). C is incorrect because coral with zooxanthellae are producers through photosynthesis.
Q7 · Difficulty 1/3
Scientists studying a small island in the Grenadines found that as the mongoose population increased, the population of ground-nesting birds decreased significantly. This is an example of which type of interaction?
- Commensalism
- Predation
- Parasitism
- Mutualism
Show answer & explanation
✓ Answer: B — Predation
Award 1 mark for predation. Predation occurs when one organism (mongoose) hunts and kills another (ground-nesting birds or their eggs) for food. D is incorrect because mutualism benefits both species. A is incorrect because commensalism benefits one species without affecting the other. C is incorrect because parasitism involves one organism living on or in another without immediately killing it.
Q8 · Difficulty 1/3
Which of these is a renewable energy source well suited to Caribbean islands?
- Coal
- Natural gas
- Solar
- Diesel
Show answer & explanation
✓ Answer: C — Solar
Solar energy is replaced continuously by sunlight, so it is renewable. Coal, natural gas and diesel are fossil fuels and are finite.
CXC CSEC Biology FAQ
What does the CXC CSEC Biology exam look like?
The CXC CSEC Biology exam is structured across 3 components. Paper 1 (Section A): 60 multiple-choice questions, 1 mark each. 75 minutes. Tests knowledge across the whole syllabus. Paper 2: Structured short-answer + 1 extended response question. Section A is compulsory; Section B has a choice. Approximately 2 hours 10 minutes. School-Based Assessment (SBA): Coursework component graded by the teacher, externally moderated. Worth ~20-30% of the final grade depending on subject. Total exam time: ~3.5 hours across Paper 1 and Paper 2 sittings.
Can I download a free CXC CSEC Biology past paper?
Real CXC past papers are published directly by CXC on their official website. Kramizo doesn't redistribute copyrighted past papers, but we do generate free AI-written practice papers in the exact same style — same command words, same difficulty tier, same mark conventions. Use this practice paper as warm-up, then time yourself on official past papers before exam day.
How is CXC CSEC Biology graded?
Grades: I (highest) to VI (lowest). A grade of III or above is typically required for further study. Kramizo's practice questions are tagged with difficulty 1-3 mapping roughly to the lower, middle, and top grade boundaries you'll encounter in the real exam.