Ecosystem MCQ for various competative exams

1.

Which of the following best defines an ecosystem?

a) A community of organisms and their physical environment

b) A group of individuals of the same species

c) A single organism and its habitat

d) A complex food web

Answer: a) A community of organisms and their physical environment

2.

What is the primary source of energy in most ecosystems?

a) Sunlight

b) Fossil fuels

c) Wind

d) Geothermal energy

Answer: a) Sunlight

3.

Which term refers to the role of an organism in an ecosystem?

a) Niche

b) Habitat

c) Trophic level

d) Adaptation

Answer: a) Niche

4.

What are decomposers in an ecosystem?

a) Organisms that break down dead organic matter

b) Primary producers

c) Carnivorous animals

d) Photosynthetic plants

Answer: a) Organisms that break down dead organic matter

5.

What is the process by which plants convert sunlight into chemical energy?

a) Photosynthesis

b) Respiration

c) Transpiration

d) Evaporation

Answer: a) Photosynthesis

6.

Which of the following is an abiotic factor in an ecosystem?

a) Temperature

b) Herbivores

c) Predators

d) Decomposers

Answer: a) Temperature

7.

What is the term for the variety of different species in an ecosystem?

a) Biodiversity

b) Population density

c) Ecological succession

d) Trophic level

Answer: a) Biodiversity

8.

Which of the following is an example of a natural ecosystem?

a) A farm

b) A city park

c) A zoo

d) A forest

Answer: d) A forest

9.

What is the primary source of carbon in most ecosystems?

a) Atmosphere

b) Plants

c) Rocks

d) Water

Answer: b) Plants

10.

What is the process by which nitrogen is converted into a usable form by bacteria?

a) Nitrogen fixation

b) Photosynthesis

c) Cellular respiration

d) Transpiration

Answer: a) Nitrogen fixation

11.

Which of the following is an example of a keystone species?

a) Bees

b) Grasshoppers

c) Wolves

d) Rabbits

Answer: c) Wolves

12.

What is the term for the transfer of energy between trophic levels in a food chain?

a) Energy flow

b) Food web

c) Trophic cascade

d) Food chain

Answer: a) Energy flow

13.

Which of the following is a renewable resource?

a) Natural gas

b) Coal

c) Solar energy

d) Petroleum

Answer: c) Solar energy

14.

What is the main factor responsible for the loss of biodiversity?

a) Habitat destruction

b) Climate change

c) Pollution

d) Overhunting

Answer: a) Habitat destruction

15.

Which of the following is an example of a biotic factor in an ecosystem?

a) Temperature

b) Rainfall

c) Plants

d) Rocks

Answer: c) Plants

16.

What is the term for the process of a species gradually changing over time?

a) Evolution

b) Succession

c) Adaptation

d) Speciation

Answer: a) Evolution

17.

Which of the following is a threat to marine ecosystems?

a) Overfishing

b) Deforestation

c) Desertification

d) Acid rain

Answer: a) Overfishing

18.

What is the role of a producer in an ecosystem?

a) Convert sunlight into chemical energy

b) Decompose dead organic matter

c) Prey on other organisms

d) Regulate the ecosystem

Answer: a) Convert sunlight into chemical energy

19.

What is the term for the process of gradual change in an ecosystem over time?

a) Ecological succession

b) Trophic level

c) Biotic interaction

d) Nutrient cycling

Answer: a) Ecological succession

20.

What is the importance of maintaining a balanced ecosystem?

a) Sustains biodiversity and ecological services

b) Increases global warming

c) Promotes pollution

d) Enhances habitat destruction

Answer: a) Sustains biodiversity and ecological services