Ecosystem MCQ Quiz in मल्याळम - Objective Question with Answer for Ecosystem - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

• An ecosystem is defined as the interaction of living organisms (biotic components) with each other and non-living (abiotic components) factors in the surrounding environment.
• It is the basic structural and functional unit of ecology.
• The term 'Ecosystem' was first coined by A.G.Tansley in 1935.
• Biotic components of an ecosystem refer to all living components and abiotic components include sunlight, temperature, humidity, atmospheric pressure, water, air, wind, soil, nutrients, etc.
• The ecosystem supports life systems and renders stability in the environment.
• It maintains a balance in nutrient cycling between biotic and abiotic components.
• Also maintains energy flow among the trophic levels.
• The types of ecosystems include- aquatic and terrestrial ecosystems.

Important Points

• Trophic levels are multiple steps in a food chain or ecological pyramid where food (or energy) is transferred from one organism to another.
• Based on the source of their nutrition or food, specific organisms occupy a specific place in the food chain.
• There are four types of trophic levels-
  • The First trophic level (T₁) - contained producers that produce their own food.
  • The Second trophic level (T₂) - is occupied by the primary consumers, i.e., herbivores.
  • The Third trophic level (T₃) - is occupied by the secondary consumers, i.e., the first carnivores.
  • The Fourth trophic level (T₄) - is occupied by the tertiary consumers, i.e., the second carnivores.
• The trophic level of lions in the forest ecosystem is T₄.
• In a food chain lion comes as tertiary consumers.
• Lions feed on secondary consumers like foxes, wild dogs, weasels, snakes, birds, etc.

Hence, the correct answer is option (2).

Concept:

• The transfer of food energy from producers (plants) through a series of organisms that consume and are consumed is termed the food chain.
• A food chain shows the linear movement of energy through a system by indicating the path of food from a producer to a final consumer.
• Food chains may have 3 to 5 trophic links with 15 to 20 species.
• The length of a particular food chain reflects the physical characteristics of a particular ecosystem.
• Within any ecosystem, there are 2 major food chains, such as the Grazing food chain and the Detritus food chain.
• The difference between these two food chains is the source of energy for the primary consumers.
• The grazing food chain starts with photosynthetic plants, while the detritus food chain starts with dead organic matter.
• Most of the natural ecosystems possess both grazing and detritus food chains.
• In terrestrial and shallow-water ecosystems grazing food chains dominate because a major proportion of the annual energy flow passes through this chain.
• In tidal marshes, almost 90% of the primary production is routed through the detritus food chains.

Explanation:

• Detritus food chains begin with dead organic matter and go from non-living organic matter to detrivores and their predators.
• Dead leaves → Woodlouse → Blackbird represents the detritus food chain.
• A large amount of organic matter is generated by the death of plants and their parts, animals, and their excretory products in all ecosystems.
• In these food chains, the flow of energy is not unidirectional. 
• The waste materials and dead organic matter in each of the trophic levels are recycled and returned as input to the dead organic matter at the base of the detritus food chains.

Additional Information

• Oaktree → Insects → Warbler and Grass → Rat → Snake → Eagle food chain represents the grazing food chain.
• Phytoplanktons → Zooplanktons → Small fish → Large fish food chain represents the aquatic grazing food chain.

Hence, the correct option is (3) Dead leaves → Woodlouse → Blackbird.

The correct answer is 50%

Explanation:

• Photosynthetically Active Radiation (PAR) is the range of solar radiation wavelengths from 400 to 700 nm that photosynthetic organisms can use for photosynthesis.
• PAR comprises a portion of the total incident solar radiation that reaches Earth.
• Of the incident solar radiation less than 50 percent of it is photosynthetically active radiation (PAR).
• Plants capture only 2-10 per cent of the PAR and this small amount of energy sustains the entire living world.

The correct answer is 10x(kcal m^-2)yr^-1

Explanation:

• In an ecosystem, Gross Primary Productivity (GPP) at the first trophic level is the total amount of energy produced through photosynthesis. Net Primary Productivity (NPP) is the energy that is left after subtracting the energy used by primary producers for respiration.
• Net Primary Productivity (NPP): Energy available after respiration by producers [ NPP = GPP - Respiration ]
• Gross Primary Productivity (GPP): Total energy produced.

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.

First trophic level (producers): NPP = 100x

• NPP at first trophic level would be the GPP for second trophic level.

Second trophic level (primary consumers/herbivores): GPP is 100x for second trophic level. 

• Energy available = 100x

Third trophic level (secondary consumers/carnivores): They receive about 10% of the energy from the second trophic level’s available energy.

• Energy available = ( 100x X 10% = 10x )

Concept:

• An ecological pyramid is a pictorial representation of the relationship between different organisms in an ecosystem.
• It is of three types: Pyramid of the number, Pyramid of biomass, and Pyramid of energy.
• The base of each pyramid represents the producers or the first trophic level while the apex represents the tertiary or top-level consumer.

Explanation:

The Limitations of an ecological pyramid are:

• It does not take into account the same species belonging to two or more trophic levels.
• It assumes a simple food chain, something that almost never exists in nature; it does not accommodate a food web.
• The saprophytes are not given any place in ecological pyramids even though they play a vital role in the ecosystem.
• Thereby, the correct option is ''all of them''

Important Points

• The pyramid of biomass in the sea or pond is generally inverted because the biomass of fishes far exceeds that of phytoplankton.  

• The pyramid of energy is always upright, can never be inverted, because when energy flows from a particular trophic level to the next trophic level, some energy is always lost as heat at each step.

Concept:

• An ecosystem refers to a geographic area where all organisms including plants and animals as well as abiotic factors such as climate and landscape work together.
• Thus an ecosystem comprises both biotic and abiotic factors.
• Ecosystems can range from very small to large-sized ecosystems encompassing the entire earth.
• In an ecosystem, the different species occupying particular habitat changes over time. This change is referred to as ecological succession.
• ​Ecological succession thus can be defined as the occurrence of a definite sequence of communities over a period of time in the same area.
• Ecological succession ultimately gives rise to a climax community.

Important Points

• Assertion - TRUE
  • A climax community is the final stage of ecological succession.
  • It represents a stable community.
  • It can be defined as an ecological community comprising all organisms - both plants and animals - that remain stable and exist in balance with their environment.
  • A climax community will not change as long as the climate and physiography remain the same.
  • Thus it can be said that a climax community is more or less stable with the climate.
• ​Reason - TRUE
  • A climax community is the final stage of ecological succession.
  • A climax community is characterized by dominant species. These species cannot be replaced by any other and remain fairly stable in the community.
  • A community begins with an invasion of a pioneer species. 
  • A pioneer species is one that first colonizes an area after disturbance.
  • These pioneer species are succeeded by other advanced complex species ultimately giving rise to the stable climax community.
  • In a climax community, species diversity remains the same because the species have successfully reproduced and do not allow invading species to thrive.
  • Thus these are the dominant species that provide stability to the climax community.

​

• Thus, both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).

So the correct answer is option 1.

The correct answer is 10%.Key Points

• The term "trophic level transfer efficiency" is the average amount of organic matter that is transferred from one trophic level to the next.
• This value is usually around 10%, meaning that only 10% of the organic matter from one level is transferred to the next level.
• Because energy is lost as metabolic heat when animals from one trophic level are consumed by species from the next, energy declines as it goes up the trophic levels.

Additional Information

• The food chain is a straight line made up of creatures in which energy and nutrients are passed from one to the next.
• When one creature eats another, this happens. 
• The decomposer organism comes at the end of the chain, having started with the producer organism. 

Key Points

• The biotic and abiotic factors of the ecosystem differ as the locations vary in space and time.
• The variations in the factors due to space results in spatial distribution pattern.
• Stratification is a type of such spatial pattern.
• The vertical distribution of different species at different levels is called stratification.
• For example in a forest, the trees occupy the higher strata, while grasses occupy the lowermost strata.

Additional Information

Fragmentation - 

• It is one of the steps of decomposition, where detritus is broken down into smaller particles by detritivores.

Humification -

• It is also one of the steps of decomposition in the ecosystem.
• It leads to the accumulation of humus, which undergoes very slow decomposition.
• Humus refers to the dark-coloured amorphous substance that is highly resistant to microbial action.

Primary production - 

• Primary productivity is defined as the amount of biomass produced per unit area over a time period by plants during photosynthesis.
• It depends on plant species inhabiting a particular area, availability of nutrients, light intensity, etc.
• Primary production is again defined in 2 ways:
  • Net primary productivity (NPP) - It is the amount of biomass available for the consumption of heterotrophs i.e., organic matter in excess of the respiratory utilization by the plants.
  • Gross primary productivity (GPP) - It is the rate of production of organic matter by photosynthesis per unit time including the photosynthate that is to be used in respiration.
  • They can be related by the equation: GPP - R = NPP, where R = Respiratory losses.

The correct answer is They considered the same species belonging to two or more trophic levels

Concept:

• Ecological pyramids are graphical representations that show the relative amounts of energy or matter contained within each trophic level in a given ecosystem.
• There are three main types of ecological pyramids: pyramid of numbers, pyramid of biomass, and pyramid of energy.
• There are certain limitations of ecological pyramids such as
  • It does not take into account the same species belonging to two or more trophic levels.
  • It assumes a simple food chain, something that almost never exists in nature
  • It does not accommodate a food web. 
  • Saprophytes are not given any place in ecological pyramids even though they play a vital role in the ecosystem.

Explanation:

• They do not include saprophytes (decomposers): This statement is correct. Ecological pyramids typically do not include decomposers because they break down dead organic matter and recycle nutrients back into the ecosystem, operating outside of the traditional trophic levels.
• Insect feeding on a big tree is an example of inverted pyramid of numbers: This statement is correct. In such a scenario, a single large tree supports numerous insects, resulting in an inverted pyramid of numbers where the number of primary consumers (insects) is greater than the number of producers (trees).
• The pyramid of biomass in a sea is inverted: This statement is correct. In marine ecosystems, the biomass of phytoplankton (producers) is less than the biomass of zooplankton (primary consumers), leading to an inverted pyramid of biomass.
• They considered the same species belonging to two or more trophic levels: This statement is incorrect. Ecological pyramids do not account for organisms that occupy multiple trophic levels. They assume a clear and distinct division between each level.

The correct answer is (A) - (IV), (B) - (II), (C) - (III), (D) - (I)

Explanation:

A. Standing state - 

• The amount of nutrients present in the soil at any given time in known as the standing state.
• The nutrients include carbon, nitrogen, phosphorus, calcium, etc.

B. Secondary productivity-

• It is defined as the rate of formation of new organic matter by consumers.

C. Standing crop - 

• Standing crop refers to the mass of living material at each trophic level at a particular time.
• It is measured as the biomass or number of organisms in that area.

D. Net Primary Productivity (NPP) - 

• It is the amount of biomass available for the consumption of heterotrophs i.e., organic matter in excess of the respiratory utilization by the plants.
• It can be expressed as: NPP = GPP - R, where GPP is Gross primary productivity and R denotes Respiratory losses.