NEET 2025 MCQ with Answer Explanation : “Ecosystem”.

Here below given some basic mcq’s of ecosystem with answer which is explained in details. Lets check one by one.

Question 1:
Which of the following is considered a primary consumer in an ecosystem?
(A) Lion
(B) Cow
(C) Eagle
(D) Snake

Answer: (B) Cow
Explanation:
Primary consumers are herbivores that directly depend on producers (plants) for their food. In this case, a cow feeds on grass and other plants, making it a primary consumer. Lions and eagles are carnivores (secondary or tertiary consumers), while snakes often feed on small animals, making them secondary or tertiary consumers depending on the food chain.

Question 2:
Which of the following statements is true regarding ecological pyramids?
(A) Pyramids of number are always upright.
(B) Pyramids of energy are always upright.
(C) Pyramids of biomass are always inverted.
(D) Pyramids of number are always inverted.

Answer: (B) Pyramids of energy are always upright.
Explanation:
Ecological pyramids represent the number, biomass, or energy at different trophic levels. The pyramid of energy is always upright because energy decreases at each successive trophic level due to the loss of energy in the form of heat during respiration and other metabolic activities. Pyramids of number and biomass can be either upright or inverted depending on the ecosystem.

Question 3:
Which of the following contributes the most to the total energy flow in an ecosystem?
(A) Herbivores
(B) Carnivores
(C) Primary producers
(D) Decomposers

Answer: (C) Primary producers
Explanation:
Primary producers, such as plants, algae, and some bacteria, form the base of the energy pyramid by converting solar energy into chemical energy through photosynthesis. This energy is then transferred to herbivores (primary consumers) and subsequently to higher trophic levels. The majority of the ecosystem’s energy originates from primary producers.

Question 4:
The primary productivity of an ecosystem is related to:
(A) Gross primary productivity
(B) Net primary productivity
(C) Secondary productivity
(D) Both (A) and (B)

Answer: (D) Both (A) and (B)
Explanation:
Primary productivity refers to the rate at which energy is converted by autotrophs (producers) into organic substances. Gross primary productivity (GPP) is the total amount of energy captured via photosynthesis. Net primary productivity (NPP) is the energy left after autotrophs have met their own energy needs (i.e., GPP minus the energy used for respiration). Both GPP and NPP contribute to the understanding of primary productivity in an ecosystem.

Question 5:
Which of the following is an example of a detritivore?
(A) Earthworm
(B) Snake
(C) Eagle
(D) Tiger

Answer: (A) Earthworm
Explanation:
Detritivores are organisms that feed on dead and decaying organic matter, helping to break it down and recycle nutrients. Earthworms, by consuming decaying matter in soil, are classic examples of detritivores. Snakes, eagles, and tigers are carnivores and do not feed on dead matter directly.

Question 6:
What is the role of decomposers in an ecosystem?
(A) Fix atmospheric nitrogen
(B) Convert organic material into inorganic nutrients
(C) Absorb sunlight for photosynthesis
(D) Help in pollination

Answer: (B) Convert organic material into inorganic nutrients
Explanation:
Decomposers, such as bacteria and fungi, break down dead organisms and organic waste into simpler inorganic compounds like nitrogen, phosphorus, and carbon. These nutrients are then recycled back into the ecosystem, allowing primary producers to reuse them.

Question 7:
The concept of “Ecological Niche” refers to:
(A) The number of species in an ecosystem
(B) The role a species plays in its ecosystem
(C) The physical space a species occupies
(D) The food chain in which a species participates

Answer: (B) The role a species plays in its ecosystem
Explanation:
An ecological niche is the role or function a species performs within its ecosystem, including how it interacts with other species, its habitat, and its feeding habits. It encompasses both the species’ physical environment and its interactions with other organisms.

Question 8:
In an aquatic ecosystem, the major primary producers are:
(A) Phytoplankton
(B) Zooplankton
(C) Small fish
(D) Fungi

Answer: (A) Phytoplankton
Explanation:
Phytoplankton are microscopic, photosynthetic organisms that float in the water column and are the primary producers in aquatic ecosystems. They capture sunlight and convert it into chemical energy, supporting the entire aquatic food web.

Question 9:
Which of the following is not a type of ecological pyramid?
(A) Pyramid of energy
(B) Pyramid of biomass
(C) Pyramid of numbers
(D) Pyramid of decomposition

Answer: (D) Pyramid of decomposition
Explanation:
Ecological pyramids are used to represent the relative amounts of energy, biomass, or number of organisms at each trophic level in an ecosystem. There is no such thing as a pyramid of decomposition. The recognized pyramids are those of energy, biomass, and numbers.

Question 10:
Which one of the following is an example of primary succession?
(A) Forest growing in an abandoned agricultural field
(B) Growth of lichens on a bare rock
(C) Regrowth of a forest after a wildfire
(D) Recovery of a coral reef after bleaching

Answer: (B) Growth of lichens on a bare rock
Explanation:
Primary succession occurs in areas that have not previously supported life, such as bare rock surfaces. Lichens are pioneer species that begin the process of soil formation, which eventually allows other plant species to establish themselves. The other examples relate to secondary succession.