Question 1

What is an ecosystem?

Accepted Answer

An ecosystem is a community of living organisms interacting with each other and their non-living environment.

Question 2

What is the difference between a producer and a consumer?

Accepted Answer

Producers make their own food through photosynthesis; consumers eat other organisms for energy.

Question 3

What is a food chain?

Accepted Answer

A food chain shows the transfer of energy from one organism to another in a sequence.

Question 4

What is the difference between biotic and abiotic factors?

Accepted Answer

Biotic factors are living components of an ecosystem (plants, animals, bacteria). Abiotic factors are non-living components (temperature, water, sunlight, soil).

Question 5

What happens to a food web if one species is removed?

Accepted Answer

Removing one species can cause a cascade effect — populations of prey may increase and predators may decrease, disrupting the balance.

Question 6

What percentage of energy is transferred from one trophic level to the next?

Accepted Answer

Only about 10% of energy is transferred from one trophic level to the next; the rest is lost as heat.

Question 7

What is the difference between a food chain and a food web?

Accepted Answer

A food chain is a single linear sequence of who eats whom. A food web is a more realistic network of interconnected food chains showing multiple feeding relationships.

Question 8

What are decomposers and why are they important?

Accepted Answer

Decomposers (bacteria, fungi) break down dead organisms and waste, recycling nutrients back into the soil so producers can use them again.

Question 9

What is a trophic level?

Accepted Answer

A trophic level is a feeding position in a food chain. Producers are at the first level; primary consumers (herbivores) are second; secondary consumers (carnivores) are third, and so on.

Question 10

What is carrying capacity?

Accepted Answer

Carrying capacity is the maximum population size that an ecosystem can sustainably support given available food, water, shelter, and other resources.

Question 11

What are limiting factors in a population?

Accepted Answer

Limiting factors are conditions that restrict population growth, such as food availability, predation, disease, and space.

Question 12

Describe the predator-prey relationship and how it affects population cycles.

Accepted Answer

When prey is abundant, predator populations grow. More predators reduce prey numbers, which then causes predator populations to decline. This creates cyclical population fluctuations.

Question 13

What is the difference between density-dependent and density-independent limiting factors?

Accepted Answer

Density-dependent factors (predation, disease, competition) become more intense as population grows. Density-independent factors (natural disasters, climate) affect populations regardless of their size.

Question 14

What is a biome?

Accepted Answer

A biome is a large geographic region characterized by specific climate, vegetation, and animal communities (e.g., rainforest, desert, tundra, grassland).

Question 15

Why is biodiversity important for ecosystem stability?

Accepted Answer

Greater biodiversity means more species filling different roles. If one species disappears, others can compensate, making the ecosystem more resilient to disturbances.

Question 16

What is an invasive species and how does it affect ecosystems?

Accepted Answer

An invasive species is a non-native organism introduced to an ecosystem where it has no natural predators. It can outcompete native species, disrupting food webs and reducing biodiversity.

Question 17

What is ecological succession?

Accepted Answer

Ecological succession is the gradual process by which an ecosystem changes over time. Primary succession starts on bare rock; secondary succession occurs after a disturbance in an existing ecosystem.

Question 18

In a forest ecosystem, wolves are removed by hunters. Predict the effects on the deer and plant populations.

Accepted Answer

Without wolves, deer populations would grow unchecked (no predator). Overgrazing by deer would then reduce plant populations, potentially damaging the entire ecosystem — a "trophic cascade."

Question 19

Why do energy pyramids always have fewer organisms at the top than at the bottom?

Accepted Answer

Because only ~10% of energy transfers between levels, there is far less energy available to support organisms at higher trophic levels. It takes many plants to support a few herbivores and even fewer carnivores.

Question 20

How do human activities like deforestation affect ecosystem balance?

Accepted Answer

Deforestation destroys habitats, reduces biodiversity, disrupts food webs, removes carbon sinks (increasing CO₂), causes soil erosion, and alters water cycles — all threatening ecosystem stability.

Ecosystems Answer Key

Prior Knowledge Questions

Activity A – Food Webs

Activity B – Population Dynamics

Activity C – Biomes and Biodiversity

Assessment Questions

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