Ecosystem: NEET PYQ, 2018–2026

Q1 · Botany · Ecosystem

Which term refers to the total biomass of living organisms present in an ecosystem at a given moment, as opposed to the rate at which that biomass is produced?

• AStanding crop
• BGross primary productivity
• CNet primary productivity
• DSecondary productivity

Q2 · Botany · Ecosystem

Which term denotes the rate at which consumers convert the food they ingest into new organic biomass?

• AGross primary productivity
• BNet primary productivity
• CStanding crop
• DSecondary productivity

Q3 · Botany · Ecosystem

In a shallow pond, the standing crop (biomass at a given moment) of phytoplankton is found to be smaller than the standing crop of zooplankton that feed on them. Which statement correctly explains this biomass inversion while the pyramid of net productivity for the pond remains upright?

• APhytoplankton are larger organisms than zooplankton, so they must have fewer individuals per unit area, which lowers their standing crop.
• BPhytoplankton have a very high rate of turnover, being grazed and replaced so quickly that a small standing crop supports a larger and longer-lived zooplankton standing crop, while their productivity per unit time is still greater than that of zooplankton.
• CZooplankton receive energy directly from sunlight through their own photosynthetic pigments, so their biomass exceeds that of phytoplankton.
• DDecomposers in the pond are removed from the pyramid, so the zooplankton standing crop appears larger when the bacterial biomass is subtracted.

Q4 · Botany · Ecosystem

Which group of organisms is NOT represented as a trophic level in an ecological pyramid?

• AProducers
• BPrimary consumers
• CDecomposers
• DTop carnivores

Q5 · Botany · Ecosystem

Detritus accumulates in waterlogged areas such as peat bogs much faster than it decomposes. Which statement best explains why peat, rather than mineral soil, forms in these conditions?

• ADecomposition is slowed because the anaerobic, waterlogged conditions limit the activity of aerobic decomposers, so detritus accumulates as partially decomposed organic material.
• BDecomposition is faster in waterlogged areas because the water carries oxygen to decomposers, so organic matter is destroyed quickly.
• CPeat forms because waterlogged soils lack nitrogen, which makes detritus indigestible to bacteria and fungi.
• DPeat forms because mineral particles in the soil adsorb all decomposers, which stops their activity completely.

Q6 · Botany · Ecosystem

In a grassland, the herbivore level assimilates 4,000 kJ m^-2 yr^-1 from the plants it eats, and its respiration over the year uses 2,500 kJ m^-2 yr^-1. What is the net secondary productivity of this herbivore level, which is the energy available to the next trophic level?

• A1,500 kJ m^-2 yr^-1
• B4,000 kJ m^-2 yr^-1
• C2,500 kJ m^-2 yr^-1
• D6,500 kJ m^-2 yr^-1

Q7 · Botany · Ecosystem

A bulbul in an orchard feeds on ripe guavas in the morning and on caterpillars that eat the guava leaves in the evening. In this ecosystem the bulbul functions as:

• Aa primary consumer only, because a species is fixed at one trophic level
• Ba secondary consumer only, because it eats animals as well as plants
• Ca primary consumer when it eats the fruit and a secondary consumer when it eats the caterpillars
• Da producer when it eats the fruit and a primary consumer when it eats the caterpillars

Q8 · Botany · Ecosystem

Decomposers are generally not shown as a separate bar in ecological pyramids because:

• Athey do not belong to one trophic level, since they feed on dead matter from all levels
• Bthey contain no energy and therefore have zero biomass
• Cthey are always fewer in number than producers
• Dthey only exist in aquatic ecosystems

Q9 · Botany · Ecosystem

In a grassland, the net primary productivity (NPP) is 60,000 kJ m^-2 yr^-1 after producer respiration is subtracted, and the gross primary productivity (GPP) is 100,000 kJ m^-2 yr^-1. Assume all of the NPP is eaten by primary consumers and that each trophic level passes on exactly 10 per cent of the energy it receives to the next level. How much energy reaches the secondary consumers per year?

• A6,000 kJ m^-2 yr^-1
• B1,000 kJ m^-2 yr^-1
• C600 kJ m^-2 yr^-1
• D60 kJ m^-2 yr^-1

Q10 · Botany · Ecosystem

In an ecosystem, the flow of energy is:

• Acyclic, returning to the producers
• Bunidirectional: from the sun to the producers and then to the consumers
• Cin both directions between producers and consumers
• Dfrom consumers to producers