NEET > Ecology and Environment

Explore popular questions from Ecology and Environment for NEET. This collection covers Ecology and Environment previous year NEET questions hand picked by popular teachers.


Q 1.    

Correct4

Incorrect-1

Which ecosystem has the maximum biomass{tex}?{/tex}

A

Grassland ecosystem

B

Pond ecosystem

C

Lake ecosystem

Forest ecosystem

Explanation

Q 2.    

Correct4

Incorrect-1

The primary producers of the deep-sea hydrothermal vent ecosystem are

A

green algae

chemosynthetic bacteria

C

blue-green algae

D

coral reefs.

Explanation

Hydrothermal vents are cracks in the ocean floor that emit jets of hot water loaded with minerals and chemosynthetic bacteria. These bacteria are autotrophs that oxidise hydrogen sulphide in vent water to obtain energy which is used to produce organic material. These chemosynthetic bacteria are the primary producers and form the base of vent food webs. All vent animals ultimately depend on bacteria for food.

Q 3.    

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Incorrect-1

Which of the following would appear as the pioneer organisms on bare rocks{tex}?{/tex}

A

Mosses

B

Green algae

Lichens

D

Liverworts

Explanation

The bare rocky habitat is extremely hostileto living beings. There is no water, as thesubstratum does not absorb rain water. There is nonutrient holding mechanism. Plants cannot growon these rocks. The first inhabitants or pioneers ofsuch a habitat are usually lichens as they areresistant to desiccation and extreme temperatures.

Q 4.    

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Incorrect-1

Which one of the following is a characteristic feature of cropland ecosystem{tex}?{/tex}

A

Absence of weeds

B

Ecological succession

C

Absence of soil organisms

Least genetic diversity

Explanation

Cropland ecosystem is an artificial or man-made terrestrial ecosystem which is created and maintained by human beings for their maximum benefits. Therefore, they will have least genetic diversity.

Q 5.    

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Incorrect-1

The term ecosystem was coined by

A

E. Haeckel

B

E. Warming

C

E.P.Odum

A. G. Tansley.

Explanation

The term ecosystem was coined by A.G.Tansley in {tex} 1935 . {/tex}

Q 6.    

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Incorrect-1

Most animals that live in deep oceanic waters are

A

tertiary consumers

detritivores

C

primary consumers

D

secondary consumers.

Explanation

Benthos is the community of organisms which live on, in, or near the sea bed, also known as the benthic zone. As no light is available at this zone of sea, the energy source for deep benthic ecosystems is often organic matter from higher up in the water column which drifts down to the depths.
This dead and decaying matter sustains the benthicorganisms, and therefore, most organisms in benthiczone {tex} i e , {/tex} in deep oceanic waters, are scavengers ordetritivores

Q 7.    

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Incorrect-1

During ecological succession

A

the numbers and types of animals remain constant

B

the changes lead to a community that is in near equilibrium with the environment and is called pioneer community

the gradual and predictable change in species composition occurs in a given area

D

the establishment of a new biotic community is very fast in its primary phase.

Explanation

Biotic or écological succession is the natural development of a series of biotic communities at the same site, one after the other tilla climax community develops which does not change further because it is in perfect harmony with the environment of the area. The change is orderly and sequential. There is a parallel change in the physical environment.During an ecological succession, the number and types of animals goes on increasing with time. The community that is in near equilibrium with the environment is called climax community. The establishment of a new biotic community is slow in its primary phase but gradually becomes fast in its secondary phase.

Q 8.    

Correct4

Incorrect-1

In which of the following both pairs have correct combination{tex}?{/tex}

A

Gaseous nutrient cycle : Nitrogen and Sulphar sedimentary nutrient cycle: Carbon and Phosphorus

B

Gaseous nutrient cycle : Sulphar and Phosphorus sedimentary nutrient cycle: Carbon and Nitrogen

Gaseous nutrient cycle : Carbon and Nitrogen sedimentary nutrient cycle: Sulphar and Phosphorus

D

Gaseous nutrient cycle : Carbon and Sulphar sedimentary nutrient cycle: Nitrogen and Phosphorus

Explanation

Biogeochemical cycles are of two types: gaseous and sedimentary. In gaseous nutrient cycles, the materials involved in circulation between biotic and abiours components of biosphere are gases or vapours and the reservoir pool is atmosphere or hydrosphere, e.g. carbon, hydrogen, oxygen, nitrogen, water. In sedimentary nutrient cycles, materials involved in circulation between biotic and abiotic components of biosphere are non-gaseous and the reservoir pool is lithosphere, e.g.,phosphorus, calcium, magnesium. Sulphur has both sedimentary and gaseous nutrient cycles.

Q 9.    

Correct4

Incorrect-1

The mass of living material at a trophic level at a particular time is called

A

net primary productivity

standing crop

C

gross primary productivity

D

standing state.

Explanation

Standing crop is the total amount of living material in a specified population at a particular time, expressed as biomass (standing biomass) or its equivalent in terms of energy. The standing crop may vary at different times of the year; for example, in a population of deciduous trees between summer and winter.

Q 10.    

Correct4

Incorrect-1

Vertical distribution of different species occupying different levels in a biotic community is known as

A

zonation

B

pyramid

C

divergence

stratification.

Explanation

Q 11.    

Correct4

Incorrect-1

Secondary succession takes place on/in

A

newly created pond

B

newly cooled lava

C

bare rock

degraded forest.

Explanation

Secondary succession (subsere) is thebiotic succession that occurs in an area whichbecome secondarily bare due to the destruction ofcommunity previously present there. Secondarysuccession starts from previously built up substratawith already existing living matter. The action ofany external force, such as a sudden change in
climatic factors, biotic intervention, fire, etc., had resulted in the destruction of previous community. Thus, area became devoid of living matter but its substratum, is built up. It has organic matter, so is biologically fertile and thus the successions are comparatively more rapid.

Q 12.    

Correct4

Incorrect-1

Most animals are tree dwellers in a

A

temperate deciduous forest

tropical rainforest

C

coniferous forest

D

thorn woodland.

Explanation

Tropical rainforests have a very denseplant cover. They also experience a large amountof precipitation, thus the forest floor is alwaysdamp. Thus, the conditions there have led animalsto get adapted to arboreal habitats. Most animalsfound there are tree dwellers as almost every spaceon the forest floor is occupied by the vegetation.

Q 13.    

Correct4

Incorrect-1

In an ecosystem the rate of production of organic matter during photosynthesis is termed as

A

secondary productivity

B

net productivity

C

net primary productivity

gross primary productivity.

Explanation

The amount of energy accumulation in green plants as biomass or organic matter per unit area over a time period is known as primary productivity. The rate of total capture of energy, or the rate of total production of organic material (biomass), is known as gross primary productivity.

Q 14.    

Correct4

Incorrect-1

Match the following and select the correctoption.

A

A-i B-ii C-iii D-iv

B

A-iv B-i C-iii D-ii

C

A-iii B-ii C-iv D-i

A-ii B-i C-iv D-iii

Explanation

Q 15.    

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Incorrect-1

Given below is a simplified model of phosphorus cycling in a terrestrial ecosystem with four blanks (A-D). Identify the blanks.

A

A - Rock minerals
B - Detritus
C - Litter fall
D - Producers

B

A - Litter fall
B - Producers
C - Rock minerals
D - Detritus

A - Detritus
B - Rock minerals
C - Producers
D - Litter fall

D

A - Producers
B - Litter fall
C - Rock minerals
D - Detritus

Explanation

Q 16.    

Correct4

Incorrect-1

If 20{tex}\ \mathrm { J } {/tex} of energy is trapped at producer level, then how much energy will be available to peacock as food in the following chain{tex}?{/tex}
Plant → Mice → Snake → Peacock

0.02{tex}\ \mathrm { J } {/tex}

B

0.002{tex}\ \mathrm { J } {/tex}

C

0.2{tex}\ \mathrm { J } {/tex}

D

0.0002{tex}\ \mathrm { J } {/tex}

Explanation

Herbivores are eaten by primary carnivores. Only 10{tex} \% {/tex} of the herbivores productivity is utilized for raising productivity of primary carnivores. The rest is consumed in ingestion, respiration, maintenance of body heat and other activities. Higher carnivores similarly are able to retain only 10% of energy present in primary
carnivores. It is called 10{tex} \% {/tex} law which was proposedby Lindemann. Accordingly, if plant trapped 20{tex} \mathrm { J } {/tex} ofenergy, mice will have {tex} 2 \mathrm { J } , {/tex} snake will have 0.2{tex} \mathrm { J } {/tex} andhence, peacock will have 0.02{tex} \mathrm { J } {/tex} of energy.

Q 17.    

Correct4

Incorrect-1

Natural reservoir of phosphorus is

rock

B

fossils

C

sea water

D

animal bones.

Explanation

The reservoir pool of phosphorus is in phosphate rocks while the cycling pool is soil and water for terrestrial and aquatic ecosystems respectively. Small amount of phosphate is always being added to the cycling pool through weathering of rocks. Phosphate is generally found in soil in combination with calcium, iron and aluminium.Atmosphere or gaseous cycle is absent. Phosphate circulates in the abiotic environment in lithosphere as well as hydrosphere.

Q 18.    

Correct4

Incorrect-1

Secondary productivity is rate of formation of new organic matter by

consumers

B

decomposers

C

producers

D

parasites.

Explanation

The rate of photosynthesis of organic matter by the consumers is known as secondary productivity. It depends upon the loss while transferring energy containing organic matter from the previous trophic level plus the consumption due to respiration and predation. Therefore, net productivity decreases with each trophic level.

Q 19.    

Correct4

Incorrect-1

Which one of the following processes during decomposition is correctly described{tex}?{/tex}

A

Catabolism - Last step in the decomposition under fully anaerobic condition

B

Leaching - Water soluble inorganic nutrients rise to the top layers of soil

Fragmentation - Carried out by organisms such as earthworm

D

Humification - Leads to the accumulation of a dark coloured substance humus which undergoes microbial action at a very fast rate.

Explanation

Decomposition is the process in which decomposers break down complex organic matter into inorganic substances like carbon dioxide, waterand nutrients. The important steps in the process of decomposition are fragmentation, leaching,catabolism, humification and mineralisation. Detritivores (e.g., earthworm) break down detritus into smaller particles. This process is called fragmentation. By the process of leaching, water-soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts.Bacterial and fungal enzymes degrade detritus into simpler inorganic substances. This process is called as catabolism. Humification and mineralisation occur during decomposition in the soil.Humification leads to accumulation of a dark coloured amorphous substance called humus that undergoes decomposition at an extremely slow rate.undergoes decomposition at an extremely slow rate.and release of inorganic nutrients occur by the process known as mineralisation.

Q 20.    

Correct4

Incorrect-1

Which two distinct microbial processes are responsible for the release of fixed nitrogen as dinitrogen gas {tex} \left( \mathrm { N } _ { 2 } \right) {/tex} to the atmosphere{tex}?{/tex}

A

Aerobic nitrate oxidation and nitrite reduction

B

Decomposition of organic nitrogen and conversion of dinitrogen to ammonium compounds

C

Enteric fermentation in cattle and nitrogen fixation by Rhizobium in root nodules of legumes

Anaerobic ammonium oxidation and denitrification.

Explanation

Denitrification is a chemical process in which nitrates in the soil are reduced to molecular nitrogen {tex} \left( \mathrm { N } _ { 2 } \right) {/tex} which is released into the atmosphere. It is done by denitrifying bacteria like Peudomonas denitificans. Anaerobic oxidation of ammonium (NH{tex} _{ 4 } {/tex}) also releases nitrogen in the atmosphere.

Q 21.    

Correct4

Incorrect-1

Which of the following is a primary consumer in maize field ecosystem{tex}?{/tex}

Grasshopper

B

Wolf

C

Phytoplankton

D

Lion

Explanation

Primary consumers are herbivorous organisms that feed on producers. Carnivores are termed secondary, tertiary etc., consumers depending upon their position in food chain. In food chain on land, grasshoper is a herbivore (primary consumer) while wolf and lion are carnivores. Phytoplanktons are producers in aquatic food chains.

Q 22.    

Correct4

Incorrect-1

When man eats fish which feeds on zooplanktons which have eaten small plants, the producer in this chain is

small plants

B

fish

C

{tex}\mathrm {m a n} {/tex}

D

zooplankton.

Explanation

The transfer of food energy from producers to consumers through a series of organisms with repeated eating and being eaten is known as food chain. Green plants are always the first link of food chain because they alone are capable of synthesizing organic food by using light energy by photosynthesis. The logical sequence of a food chain is :

Q 23.    

Correct4

Incorrect-1

Which one of the following is not a gaseous biogeochemical cycle in ecosystem{tex}?{/tex}

A

Sulphur cycle

Phosphorus cycle

C

Nitrogen cycle

D

Carbon cycle

Explanation

Biogeochemical cycles are of two types: gaseous and sedimentary. In gaseous nutrient cycles, the materials involved in circulation between biotic and abiours components of biosphere are gases or vapours and the reservoir pool is atmosphere or hydrosphere, e.g. carbon, hydrogen, oxygen, nitrogen, water. In sedimentary nutrient cycles, materials involved in circulation between biotic and abiotic components of biosphere are non-gaseous and the reservoir pool is lithosphere, e.g.,phosphorus, calcium, magnesium. Sulphur has both sedimentary and gaseous nutrient cycles.

Q 24.    

Correct4

Incorrect-1

Identify the possible link "A" in the following food chain.
Plant → Insect → "A" → Eagle

A

Rabbit

B

Wolf

Cobra

D

Parrot

Explanation

Q 25.    

Correct4

Incorrect-1

Given below is an imaginary pyramid of numbers. What could be one of the possibilities about certain organisms at some of the different levels{tex}?{/tex}

Level {tex} \mathrm { PC } {/tex} is "insects" and level {tex} \mathrm { SC } {/tex} is "'small insectivorous birds".

B

Level {tex} \mathrm { PP } {/tex} is "phytoplanktons" in sea and "whale" on top level TC

C

Level one PP is "pipal trees" and the level {tex} \mathrm { SC } {/tex} is "sheep".

D

Level {tex} \mathrm { PC } {/tex} is "rats" and level {tex} \mathrm { S } \mathrm { C } {/tex} is "cats".

Explanation