Questions on Energy Flow in Ecosystems
Multiple-Choice Questions: Energy Flow in Ecosystems
1. What is the main source of energy for almost all ecosystems?
A) Water
B) Moon
C) Wind
D) Sun
E) Soil
2. In an ecosystem, producers are organisms that:
A) Consume other organisms
B) Absorb nutrients from the soil
C) Feed on dead organisms
D) Convert solar energy into chemical energy
E) Live only in aquatic environments
3. Which group is classified as primary consumers?
A) Herbivores
B) Carnivores
C) Omnivores
D) Decomposers
E) Fungi
4. What best describes the flow of energy in an ecosystem?
A) Circular and infinite
B) Recycled continuously
C) Unidirectional and decreasing
D) Bidirectional
E) Always increasing
5. Which of the following best describes a trophic level?
A) The number of organisms in a population
B) A group of organisms sharing the same function in the food chain
C) A layer of soil nutrients
D) A level of oxygen concentration
E) A species’ ability to reproduce
6. What is the role of decomposers in energy flow?
A) They store energy
B) They eliminate energy waste
C) They create energy
D) They recycle nutrients back into the ecosystem
E) They consume primary producers
7. Which of the following is a tertiary consumer?
A) Grass
B) Rabbit
C) Snake
D) Hawk
E) Fungi
8. How much energy is transferred from one trophic level to the next?
A) 100%
B) 50%
C) 25%
D) 10%
E) 1%
9. What happens to the energy not transferred to the next trophic level?
A) It is destroyed
B) It is recycled
C) It is converted into matter
D) It is stored in the environment
E) It is lost as heat
10. What is an energy pyramid used to represent?
A) Biomass distribution in soil
B) Number of individuals at each level
C) Energy flow and loss at different trophic levels
D) Food preferences of organisms
E) Population growth over time
11. Why are there typically fewer organisms at higher trophic levels?
A) Less oxygen is available
B) Energy availability decreases
C) They reproduce more slowly
D) Predators avoid them
E) Their habitats are smaller
12. The first trophic level in an ecosystem is always:
A) Decomposers
B) Primary consumers
C) Secondary consumers
D) Producers
E) Carnivores
13. Which term best describes organisms that can make their own food using sunlight?
A) Heterotrophs
B) Carnivores
C) Herbivores
D) Autotrophs
E) Omnivores
14. What happens to biomass and energy as you move up an energy pyramid?
A) Both increase
B) Both remain constant
C) Biomass increases, energy decreases
D) Biomass decreases, energy increases
E) Both decrease
15. Which of the following best illustrates energy loss in an ecosystem?
A) Photosynthesis
B) Cellular respiration and heat release
C) Water evaporation
D) Carbon fixation
E) Nutrient cycling
16. Which type of organisms can be both primary and secondary consumers?
A) Carnivores
B) Herbivores
C) Decomposers
D) Omnivores
E) Producers
17. In which trophic level would foxes usually be classified?
A) Producers
B) Primary consumers
C) Secondary or tertiary consumers
D) Decomposers
E) Autotrophs
18. What is the ultimate fate of all energy in ecosystems?
A) It is stored in organisms permanently
B) It is lost to space
C) It is recycled by decomposers
D) It is lost as heat
E) It remains constant
19. What process in plants is essential for capturing energy from the sun?
A) Respiration
B) Photosynthesis
C) Fermentation
D) Nitrogen fixation
E) Digestion
20. Which of the following accurately represents the correct order of energy flow in a typical food chain?
A) Producer → Decomposer → Consumer
B) Consumer → Producer → Sun
C) Sun → Producer → Primary Consumer → Secondary Consumer
D) Secondary Consumer → Primary Consumer → Producer
E) Producer → Consumer → Sun
Answer Key with Explanations
1. D – The sun is the main energy source for most ecosystems, driving photosynthesis.
2. D – Producers (like plants) convert solar energy into chemical energy through photosynthesis.
3. A – Primary consumers are herbivores that eat producers.
4. C – Energy flows in one direction through an ecosystem and decreases at each trophic level.
5. B – A trophic level is a step in a food chain representing a level of energy consumption.
6. D – Decomposers break down dead organisms and recycle nutrients back to the ecosystem.
7. D – A hawk is a tertiary consumer, feeding on secondary consumers like snakes.
8. D – Only about 10% of the energy is passed to the next trophic level; the rest is lost.
9. E – Most of the energy is lost as heat through metabolism and respiration.
10. C – An energy pyramid shows the energy flow and loss across different trophic levels.
11. B – Less energy is available at higher trophic levels, supporting fewer organisms.
12. D – Producers, like plants, make up the first trophic level.
13. D – Autotrophs can produce their own food, usually via photosynthesis.
14. E – Both biomass and energy decrease at each successive trophic level.
15. B – Cellular respiration releases energy as heat, contributing to energy loss.
16. D – Omnivores eat both plants and animals, making them primary and secondary consumers.
17. C – Foxes typically feed on herbivores, placing them at secondary or tertiary levels.
18. D – Energy eventually exits the ecosystem as heat and cannot be recycled.
19. B – Photosynthesis allows producers to capture and convert solar energy.
20. C – Energy flows from the sun to producers to primary consumers to secondary consumers.
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