Ecosystems Quiz - ICSE Class 8 Science

Free practice quiz: Ecosystems (ICSE Class 8 Science). 52 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

Sample questions

1. Which of the following best describes a producer in an ecosystem?

   1. An organism that consumes other organisms for energy.
   2. An organism that converts light energy into chemical energy.
   3. An organism that breaks down dead organic matter.
   4. An organism that occupies the highest trophic level.
   Show answer

   Answer: B. An organism that converts light energy into chemical energy.

   Producers, such as plants and algae, are autotrophs that produce their own food through photosynthesis, converting light energy into chemical energy in the form of organic compounds. Consumers eat other organisms, decomposers break down dead matter, and apex predators are at the top of the food chain.

2. What is the primary function of scavengers in an ecosystem?

   1. To convert light energy into chemical energy
   2. To consume living organisms
   3. To feed on dead or decaying organisms
   4. To break down organic matter into inorganic nutrients
   Show answer

   Answer: C. To feed on dead or decaying organisms

   Scavengers, like vultures and hyenas, play a role in cleaning up the environment by consuming the carcasses of dead animals. While decomposers also break down dead matter, scavengers are typically larger animals that consume larger pieces of dead organic material.

3. What is the term for the organisms that consume dead or decaying organic matter in an ecosystem?

   1. Producers
   2. Primary consumers
   3. Secondary consumers
   4. Decomposers
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   Answer: D. Decomposers

   Decomposers, such as bacteria and fungi, break down dead organisms and waste products, returning essential nutrients to the ecosystem.

4. The process of denitrification in the nitrogen cycle results in:

   1. Conversion of ammonia to nitrates
   2. Release of nitrogen gas back into the atmosphere
   3. Absorption of nitrogen by plants
   4. Formation of organic nitrogen compounds
   Show answer

   Answer: B. Release of nitrogen gas back into the atmosphere

   Denitrification is carried out by denitrifying bacteria, which convert nitrates (NO3-) in the soil back into atmospheric nitrogen gas (N2), completing the nitrogen cycle.

5. Which process in the nitrogen cycle converts nitrates back into atmospheric nitrogen?

   1. Nitrification
   2. Assimilation
   3. Denitrification
   4. Ammonification
   Show answer

   Answer: C. Denitrification

   Denitrification is the microbial process of reducing nitrate or nitrite to gaseous nitrogen (N2 or N2O), thereby returning nitrogen to the atmosphere.

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