31 Years NEET Previous Year Questions: Ecosystem - 1 - NEET MCQ

NPP at first trophic level would be the GPP for second trophic level. NPP at second trophic level would be GPP for third trophic level. Therefore, 100x(kcal/m²/yr) would be GPP at second trophic level and 100x * 10% (kcal/m²/yr) i.e 10x(kcal/m²/yr) energy would be GPP at third trophic level.

(+, +) Mutualism : In this interaction, both the interacting species are benefitted.
(+, 0) Commensalism : Only one species is benefitted and the other species remains unharmed.
(−, 0) Amensalism : Neither species is benefitted. One remains unharmed and the other is harmed.
(+, −) Parasitism : One species is benefitted and other is negatively effected.

Let's evaluate each statement:
A. Detrivores perform fragmentation.
This statement is true. Detrivores, such as earthworms and beetles, break down detritus (dead organic material) into smaller pieces in a process called fragmentation.

B. The humus is further degraded by some microbes during mineralization.
This statement is true. Microbes, including bacteria and fungi, break down humus into inorganic nutrients in a process called mineralization.

C. Water-soluble inorganic nutrients go down into the soil and get precipitated by a process called leaching.
This statement is true. Leaching refers to the process where nutrients are washed away from the soil into lower layers or into bodies of water.

D. The detritus food chain begins with living organisms.
This statement is false. The detritus food chain begins with dead organic material or detritus, not living organisms.

E. Earthworms break down detritus into smaller particles by a process called catabolism.
This statement is false. The process by which earthworms break down detritus into smaller particles is called fragmentation, not catabolism. Catabolism refers to the breakdown of complex molecules in living organisms to form simpler ones, along with the release of energy.

Therefore, the correct answer is : Option D : A, B, C only.

In the equation GPP - R = NPP,
GPP stands for Gross Primary Productivity, NPP stands for Net Primary Productivity, and R represents the energy used by plants for their own metabolic processes, which is also known as Respiratory loss.

Algal bloom imparts a distinct colour to the water bodies. It causes deterioration of the water quantity and fish mortality.

• Decomposition is the process by which decomposers breakdown complex organic matter into inorganic substances.
• The rate of decomposition is controlled by chemical composition of detritus and climatic factors. Decomposition is slower if detritus is rich in lignin and chitin and quicker, if detritus is rich in nitrogen and water soluble substances like sugars.

Phosphorus cycle is a sedimentary cycle. Reservoir pool of phosphorus in ecosystem is the earth's crust or lithosphere. Weathering of rocks accelerate phosphorus cycle.

(Detritivores break down detritus into smaller particles) e.g. earthworm. This process is called fragmentation.

Two individuals that are competing for same resource can avoid competition by choosing different times for feeding or different foraging patterns.

In primary succession in water, the pioneers are the small phytoplanktons, which are replaced with time by rooted-submerged plants, rooted floating angiosperms followed by free-floating plants, then reed-swamp, marsh-meadow, scrub and finally trees.

• Productivity is the total amount of biomass or organic matter produced per unit area. Over a period of time by plants. This is also called Primary production.
• Productivity of consumer is called Secondary production.

Both hydrarch and xerarch succession lead to medium water condition called mesic condition. This condition is neither too dry nor too wet.

• The species that invade a bare area are called pioneer species.
• The individual transitional communities in an ecological succession are termed as seral stages or seral communities.

The amount of nutrients, such as carbon, nitrogen, phosphorus, calcium, etc., present in the soil at any given time, is referred to as the standing state.

The gross primary productivity of an ecosystem is the rate of production of organic matter during photosynthesis. Some of this organic matter is lost because of the respiration of plants. The remaining primary productivity is the net primary productivity.

Pyramid of biomass in an aquatic ecosystem (e.g., pond, sea) is usually inverted because the biomass of fishes exceeds the biomass of phytoplanktons.

The given data depicts the inverted pyramid of biomass, usually found in aquatic ecosystem. This can be understood by taking an example of a pond in which phytoplankton (10g) represents the producer. Small fishes (60g) feeding upon these phytoplankton represent primary consumers which are further eaten by the big fishes (120g) representing secondary consumers.

• Detrivores, (e.g. earthworm) break down detritus into smaller particles.
• The species that invade a bare area in succession are called pioneer species.
• The products of ecosystem processes are termed ecosystem services.
  Example: Healthy forest ecosystems purify air and water, mitigate droughts and floods, etc.
• Natality refers to the number of births during a given period in the population.

An abiotic factor relating to the physical or chemical composition of the soil found in a particular area.
Example: Very alkaline soil may be an edaphic factor limiting the variety of plants growing in a region. 

• Stratification is the occurrence of vertical zonation in the ecosystem & indicates the presence of favorable environmental conditions.
  Example: Trees occupy top vertical strata or layer of a forest, shrubs the second. Herbs & grasses occupy the bottom layers.
• It is absent or poor where environmental conditions are unfavorable.
  Example: Desert ecosystems have very few trees & shrubs.

Standing crop is the amount of living biomass in an ecosystem. It indicates the productivity & luxuriance of growth. It is expressed in the form of number or biomass of organisms per unit area

Gross Primary Productivity (GPP) is the rate of production of biomass or accumulation of energy by green plants per unit area per unit time. GPP depends on the chlorophyll content.

Secondary succession takes place in disturbed area having poor vegetation.

The given graph illustrates that population B got success in the grassy field in comparison to population A.

The gradual and predictable change, in the composition of species takes place in a given area during ecological succession.

Biomagnification means an increase in concentration of toxins through the trophic levels of a food chain.

Industrial melanism occured in England due to industrial revolution. It caused black coating of moths for the adaptation in the present environment.

• Carbon and Nitrogen are gaseous nutrient cycle.
• Sulphur and phosphorus are sedimentary nutrient cycle

Leghemoglobin prevents oxygen poisoning which causes inactivation of nitrogenase.

Biotic community is an association of individuals of different species living in the same habitat and showing functional interactions.