🩺 NEET🧬 Biology

Ecosystem

5 solved NEET Biology previous year questions on Ecosystem, each with the correct answer and a full explanation.

The rate of formation of new organic matter by rabbit in a grassland is called:

aNet productivity

bSecondary productivity

cNet primary productivity

dGross primary productivity

✓ Correct answer: b) Secondary productivity

ExplanationSecondary productivity is defined as the rate of formation of new organic matter by consumers.Since rabbit is consumer the rate of new organic matters is secondary productivity.

Which of the following would appear as the pioneer organisms on bare rocks?

aMosses

bGreen algae

cLichens

dLiverworts

✓ Correct answer: c) Lichens

ExplanationPioneer organisms are the first organisms to colonize a barren or disturbed environment, such as bare rocks, where no soil or vegetation exists initially.They play a crucial role in breaking down the rock surface and initiating the process of soil formation, which later supports more complex plant life.Lichens are the most common pioneer organisms on bare rocks.They consist of a symbiotic relationship between fungi and algae or cyanobacteria.Lichens are able to survive in harsh conditions and can gradually break down the rock surface to help form soil over time.Now, let's look at the other options: A - Mosses: Mosses can grow on bare rocks but generally come after lichens.They are not usually the first organisms to colonize bare rocks.B - Green algae: Green algae can grow on rocks, but they are more commonly found in aquatic environments or on moist surfaces, not typically as pioneer organisms on bare rocks.D - Liverworts: Liverworts are simple plants that can grow on moist, shaded rocks but are not typically the first to colonize bare rock surfaces compared to lichens.

Which of the following is not used for construction of ecological pyramids?

aFresh weight

bDry weight

cNumber of individuals

dRate of energy flow

✓ Correct answer: a) Fresh weight

ExplanationEcological pyramids are constructed using: Number of individuals, Biomass (dry weight), Rate of energy flow.Fresh weight is not used, because water content varies and gives misleading values.

Which one of the following statements for the pyramid of energy is incorrect?

aIts base is broad.

bIt shows energy content of different trophic level organisms.

cIt is inverted in shape.

dIt is upright in shape.

✓ Correct answer: c) It is inverted in shape.

ExplanationPyramid of energy shows the energy content at different trophic levels.Key features:1. Upright shape – because energy decreases at higher trophic levels due to losses as heat, respiration, and waste.2. Base is broad – representing the large energy available at the producer level.3. Energy content decreases as we move up the trophic levels.It is never inverted, unlike some pyramids of biomass or numbers in specific ecosystems.Answer: C. It is inverted in shape

In relation to Gross primary productivity and Net primary productivity of an ecosystem, which one of the following statements is correct? [NEET 2020]

aGross primary productivity is always less than Net primary productivity

bGross primary productivity is always more than Net primary productivity

cGross primary productivity and Net primary productivity are one and same

dThere is no relationship between Gross primary productivity and Net primary productivity

✓ Correct answer: b) Gross primary productivity is always more than Net primary productivity

ExplanationThe rate at which organic matter is produced during photosynthesis is known as gross primary productivity (GPP).A significant amount of GPP is used by plants in their respiration.Gross primary productivity minus respiration losses (R), is the net primary productivity (NPP).GPP – R = NPP As a result, GPP is always greater than NPP.

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