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

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.

Cropland ecosystem is largest anthropogenic ecosystem characterized by less diversity and high productivity.

• Lichens produce small amounts of carbonic acids from their "roots" and these slowly dissolve the rock, releasing nutrients. Other nutrients are obtained from water-borne or air-borne particles of both organic and inorganic materials.
• The body of a lichen contains an alga; this is able to photosynthesize sugars, some of which are passed on to the fungal component of the lichen. In return the alga gets a tiny but significant amount of shelter within the tissues of the lichen.

The term ecosystem was first used in 1935 in a publication by British ecologist Arthur Tansley.