Animals & Nature · Unit 14

Ecosystems and Biodiversity

Niches, symbiosis, energy flow and why variety matters

An ecosystem is a set of relationships, and the useful question about any species is not what it is but what it does and what depends on it doing that.

The unit covers niches and competition, symbiosis in its several forms, energy and nutrient flow, the world's biomes, and why biodiversity matters practically rather than sentimentally.

This unit breaks down into 20 short steps and 118 questions, starting at difficulty 2 and building to 4. Below you can see exactly what it covers, how the path is structured, and worked examples with explanations.

Steps: 20
Questions: 118
Difficulty: 2-4

What this unit covers

Biomes of the World
Biodiversity and Invasive Species
Energy and Nutrient Flow
Niches and Competition
Living Together

Where this fits

Best after What Animals Eat and Habitats and Homes.

Where people slip

Two species cannot occupy exactly the same niche in the same place indefinitely. One outcompetes the other or they diverge, which is why apparently similar species always differ on closer inspection.

How the unit is structured

Ecosystems and Biodiversity runs as 20 short steps that unlock in order. 15 are practice rounds and 5 are challenge rounds that pull together everything before them. Questions start at difficulty 2 and climb to 4 as you progress.

Step 1 · easierStep 20 · harder

Challenge rounds

Example questions

30 real questions from this unit, with the answer and the reason behind it, grouped by what they practise. There are 118 in the unit altogether.

Biodiversity and Invasive Species

Multiple choiceLevel 2
1. What can happen if one species disappears from an ecosystem?
- Other species that depend on it can be affectedcorrect
- Nothing ever changes
- All other species die at once
- The habitat disappears instantly
Other species that depend on it can be affected, sometimes in surprising ways.
Sort into groupsLevel 2
2. Sort each item as living or non-living in an ecosystem.
Answer: Oak tree = Living; Badger = Living; River water = Non-living; Sunlight = Non-living
Ecosystems combine both kinds of component.
Build the sentenceLevel 3
3. Build a sentence about the roles species play.
Answer: Every species has a role in its ecosystem
Every species has a role in its ecosystem.
Choose all that applyLevel 3
4. Which reduce biodiversity? Pick all that apply.
- Habitat destructioncorrect
- Pollutioncorrect
- Invasive speciescorrect
- Planting native wildflowers
Habitat loss, pollution and invasive species all reduce variety.
Fact or fibLevel 3
5. An ecosystem with more species is generally better able to recover from disturbance.
Answer: True
True. Diversity spreads risk across many species.
Put in orderLevel 3
6. Put these stages of succession on bare rock in order.
Answer: Lichens colonise bare rock -> Thin soil forms -> Grasses and small plants grow -> Shrubs and trees establish
Lichens break rock down, soil forms, small plants arrive, then shrubs and trees.

Biomes of the World

Choose all that applyLevel 2
7. Which are living parts of an ecosystem? Pick all that apply.
- Plantscorrect
- Animalscorrect
- Fungicorrect
- Rocks
Plants, animals and fungi are all living components.
True or falseLevel 2
8. A pond can be an ecosystem all by itself.
Answer: True
True. Ecosystems range from a puddle to a whole forest.
Multiple choiceLevel 2
9. What does the word biotic mean?
- The living parts of an ecosystemcorrect
- The rocks and soil
- The temperature
- The rainfall
Biotic refers to the living parts of an ecosystem.
Multiple choiceLevel 3
10. Why do different regions of the world hold different kinds of life?
- Climate and soil differ from place to placecorrect
- Animals choose by preference alone
- All places are identical
- Humans decide everything
Temperature, rainfall and soil differ, so different species can survive in each place.
Type the answerLevel 3
11. What word describes the non-living parts of an ecosystem such as water and rock?
Answer: abiotic
Abiotic factors are the non-living conditions.
Choose all that applyLevel 3
12. Which events start succession? Pick all that apply.
- A wildfirecorrect
- A retreating glaciercorrect
- A new lava flowcorrect
- A quiet summer afternoon
Fire, landslides, glacier retreat and volcanic flows all clear ground.

Energy and Nutrient Flow

True or falseLevel 2
13. Energy is lost as heat at every step of a food chain.
Answer: True
True, which is why food chains are short.
Multiple choiceLevel 2
14. Where does nearly all energy in an ecosystem come from?
- The Suncorrect
- The soil
- The wind
- The Moon
Sunlight captured by plants powers almost every food chain.
Choose all that applyLevel 3
15. Which cycle round an ecosystem again and again? Pick all that apply.
- Watercorrect
- Carboncorrect
- Nitrogencorrect
- Sunlight energy
Water, carbon and nitrogen all cycle, while energy flows through once.
Multiple choiceLevel 3
16. What do plants do with sunlight?
- Make their own food from air and watercorrect
- Store it as electricity
- Turn it into soil
- Give it back unchanged
They use it to make sugars from carbon dioxide and water.
Type the answerLevel 3
17. What is the process plants use to capture energy from sunlight?
Answer: photosynthesis
Photosynthesis makes sugars and releases oxygen.
Choose all that applyLevel 3
18. Which processes return carbon to the atmosphere? Pick all that apply.
- Respirationcorrect
- Decompositioncorrect
- Burning fuel or woodcorrect
- Photosynthesis
Respiration, decomposition and burning all release carbon dioxide.

Living Together

Choose all that applyLevel 2
19. Which are parasites? Pick all that apply.
- Tickcorrect
- Fleacorrect
- Tapewormcorrect
- Earthworm
Ticks, fleas and tapeworms all live at the expense of a host.
Type the answerLevel 2
20. What is a relationship where both species benefit called?
Answer: mutualism
Mutualism is a two-way benefit.
Match the pairsLevel 3
21. Match each relationship to its description.
Answer: Mutualism = Both species benefit; Parasitism = One benefits, one is harmed; Predation = One eats the other; Competition = Both want the same resource
Relationships differ in who benefits and who is harmed.
Multiple choiceLevel 3
22. What is symbiosis?
- A close relationship between two speciescorrect
- A fight between animals
- A seasonal migration
- A kind of habitat
A close, long-term relationship between two different species.
True or falseLevel 3
23. Oxpeckers eat ticks from the skin of large mammals.
Answer: True
True. The bird gets food and the mammal loses parasites.
Choose all that applyLevel 3
24. Which are mutualisms? Pick all that apply.
- Bees pollinating flowerscorrect
- Cleaner fish removing parasitescorrect
- Gut microbes aiding digestioncorrect
- A tapeworm in an intestine
Pollination, cleaning stations and gut microbes all benefit both partners.

Niches and Competition

Choose all that applyLevel 2
25. Which are part of a species niche? Pick all that apply.
- What it eatscorrect
- When it is activecorrect
- Where it shelterscorrect
- Its name in English
Food, timing of activity, shelter and interactions all form the niche.
Multiple choiceLevel 2
26. What is a niche in ecology?
- The role a species plays in its ecosystemcorrect
- A hole in a rock
- A kind of nest
- A group of predators
A niche is the role a species plays, including what it eats, where it lives and when it is active.
Type the answerLevel 2
27. What word describes the job or role a species has in its ecosystem?
Answer: niche
A niche covers food, timing, space and interactions.
True or falseLevel 3
28. Two species living in the same habitat can have different niches.
Answer: True
True. They may feed on different things or be active at different times.
Choose all that applyLevel 3
29. Which are often described as keystone species? Pick all that apply.
- Sea ottercorrect
- Beavercorrect
- Grey wolfcorrect
- House sparrow
Sea otters, beavers and wolves all reshape their ecosystems.
Multiple choiceLevel 3
30. What does the word habitat mean in ecology?
- The place where a species livescorrect
- What an animal eats
- How fast an animal runs
- A group of animals
A habitat is the place where a particular animal or plant lives.

Where these questions come from. Each unit starts as a plan of the concepts it should cover and the difficulty it should span. Questions are written against that plan with AI assistance, then checked by a validator that rejects anything without a single defensible answer, an explanation, or plausible wrong options. How we write questions sets out the whole process, and corrections are fixed in the bank and reach the site and the app the same day.

How you practise

This unit mixes 9 different question formats, so you are recalling and applying rather than recognising the same layout every time.

Build the sentence
Choose all that apply
Fact or fib
Match the pairs
Multiple choice
Put in order
Sort into groups
True or false
Type the answer

Practise Ecosystems and Biodiversity

118 questions across 20 steps. Start with step one and crawl at your own pace.

Play this unit

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