National 5 Biology - Unit 3 Questions
and Answers | Latest Version | 2025/2026
| Correct & Verified
What is a population?
✔✔A group of organisms of the same species living in the same area at the same time.
What is meant by biodiversity?
✔✔The variety of different species of living organisms in an ecosystem.
What is the term for the role an organism plays in an ecosystem?
✔✔Niche
Why is it important to maintain high biodiversity in an ecosystem?
✔✔It increases stability and resilience against changes or disease.
What happens if two species occupy the same niche?
✔✔They compete and one may be outcompeted and die out.
1
,What is a producer?
✔✔An organism that makes its own food using photosynthesis.
What is a consumer?
✔✔An organism that eats other organisms for energy.
What is a predator?
✔✔An animal that hunts and kills other animals for food.
What is a food web?
✔✔A network of interconnected food chains showing energy flow in an ecosystem.
What is the source of energy for most ecosystems?
✔✔Sunlight
What is a decomposer?
✔✔An organism that breaks down dead material to recycle nutrients.
2
, How is energy lost between each level of a food chain?
✔✔Through movement, heat, and undigested materials.
Why are food chains usually short?
✔✔Because too much energy is lost at each level.
What is a limiting factor?
✔✔A condition that restricts the growth or survival of an organism.
Give an example of a biotic factor.
✔✔Competition for food
Give an example of an abiotic factor.
✔✔Temperature
What is a quadrat used for?
✔✔To estimate population size of plants or slow-moving animals.
3
and Answers | Latest Version | 2025/2026
| Correct & Verified
What is a population?
✔✔A group of organisms of the same species living in the same area at the same time.
What is meant by biodiversity?
✔✔The variety of different species of living organisms in an ecosystem.
What is the term for the role an organism plays in an ecosystem?
✔✔Niche
Why is it important to maintain high biodiversity in an ecosystem?
✔✔It increases stability and resilience against changes or disease.
What happens if two species occupy the same niche?
✔✔They compete and one may be outcompeted and die out.
1
,What is a producer?
✔✔An organism that makes its own food using photosynthesis.
What is a consumer?
✔✔An organism that eats other organisms for energy.
What is a predator?
✔✔An animal that hunts and kills other animals for food.
What is a food web?
✔✔A network of interconnected food chains showing energy flow in an ecosystem.
What is the source of energy for most ecosystems?
✔✔Sunlight
What is a decomposer?
✔✔An organism that breaks down dead material to recycle nutrients.
2
, How is energy lost between each level of a food chain?
✔✔Through movement, heat, and undigested materials.
Why are food chains usually short?
✔✔Because too much energy is lost at each level.
What is a limiting factor?
✔✔A condition that restricts the growth or survival of an organism.
Give an example of a biotic factor.
✔✔Competition for food
Give an example of an abiotic factor.
✔✔Temperature
What is a quadrat used for?
✔✔To estimate population size of plants or slow-moving animals.
3
