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Meaning of an ecosystem - class-XI

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Which of the following is an advantage of depredation 

  1. It serves as conduits for energy transfer across tropic levels

  2. It keeps population of organism of lower trophic level under control

  3. Predators help in maintain species diversity in a community, by reducing the intensity of competition among competing prey species

  4. All of these


Correct Option: D
Explanation:

Most pastures are already under substantial grazing pressure, in effect forcing sheep to steeper and less productive pastures. An important long-term goal is to improve forage conditions for native prey species to help reduce depredation pressures on domestic stock.

So, the correct option is 'All of these'.

The concentration of polychlorinated biphenyls (PCB, an organochloride contaminant) in many fish populations has been declining, since a ban on their production was instituted in the late 1970s. PCBs remain a potential problem, however, because they are lipophilic and are known to biomagnify. Based on this knowledge, 

What type of fish expected to be safest for human consumption?

  1. Piscivorous fish species (i.e., which eat other fish)

  2. Benthivorous fish species (i.e., which eat invertebrates on the lake bottom)

  3. Small (young) fish

  4. Fish species with high fat content


Correct Option: C
Explanation:

Heavy metals and persistent pesticides (e.g., organochlorine of chlorinated hydrocabons like DDT) pass into food chain and increase in amount per unit weight of organisms with the rise in trophic level due to their accumulation in fat, This phenomenon is called biomagnification. Therefore, lower the trophic level of fish (such as small fish), lesser will be the biomagnification and hence safer it will be for consumption.

Which of the following best describes a tropical region?

  1. Hot and humid

  2. Moderately hot, heavy rainfall

  3. Cold and humid

  4. Hot and dry


Correct Option: A
Explanation:

Mainly climate in tropical regions is hot and humid. It sees rainfall and high temperatures during summers. 

So, option A is the correct answer.

Which of the following belongs to the category of primary consumers?

  1. Snakes

  2. Water insects

  3. Eagle 

  4. Cattle


Correct Option: D
Explanation:

The consumers in an ecosystem are heterotrophs, mostly animals which feed on other organisms. Consumers are also called as phagotrophs, as they ingest food. Consumers can be first order consumers, e.g., herbivores, cattle, rabbit, deer, insects like grasshopper etc. They feed on producers. Primary carnivores are second order consumers. They feed on herbivores. Secondary carnivores are third order consumers which feed on primary carnivores. For example, Small fish and water insects like scavenger beetles that feed on the crustaceans. 

Thus, the correct answer is option D.

Identify which one of the following is an example of incomplete ecosystem?

  1. Grassland

  2. Cave

  3. River

  4. Wetland


Correct Option: B
Explanation:

An ecosystem is a segment of nature or biosphere consisting of a community of living beings and the abiotic or physical environment, both interacting and exchanging materials between them. An ecosystem which lacks one or the other component is called as an 'Incomplete ecosystem', e.g., sea bottom and caves where sunlight may not reach and consequently photoautotrophs or green plants may not flourish; freshly formed rain water pond where plants may not have well settled and a pond formed in rains may be temporary also.

Thus, the correct answer is option B.

Trophic levels are formed by

  1. Organisms linked in food chain

  2. Only plants

  3. Only animals

  4. Only carnivores


Correct Option: A
Explanation:

Food chain is the sequence of organisms through which food and energy is passed in an ecosystem with the members of trophic level. Trophic level is the hierarchical levels in an ecosystem which consists organism

If bamboo plant is growing in a far forest then what will be its trophic level?

  1. First

  2. Second

  3. Third

  4. Fourth


Correct Option: A
Explanation:

Trophic levels are steps or divisions of food chain characterised by the specific method of obtaining food. Producers belong to first trophic level, herbivores to second trophic level and carnivores to third trophic level. Bamboo plant, which is a producer will belong to first trophic level. It will capture solar energy for other organisms living in the forest. Thus, the correct answer is option A.

The zooplanktonic forms are

  1. Primary consumers

  2. Secondary consumers

  3. Carnivores

  4. Primary producers


Correct Option: A
Explanation:

In a pond or lake ecosystem, zooplanktons (ciliates, flagellates, rotifers, small crustaceans, like Cyclops and Daphnia larvae) are directly dependent on phytoplanktons. Thus, the correct answer is option A.

A rat feeding upon potato tuber is

  1. Producer

  2. Carnivore

  3. Decomposer

  4. Primary consumer


Correct Option: D
Explanation:

Rat is a herbivore animal, who used to eat plant products. The potato plant is a producer who trap solar energy and produces food (carbohydrates), which are stored in potato tubers. The rat cannot produces their own food by the use of solar energy and hence, feeds on potato tuber for his life processes.

Thus, the correct answer is option D.

Trophic levels in a food chain are formed by

  1. Producers

  2. Consumers

  3. Decomposers

  4. All of the above


Correct Option: D
Explanation:
A food chain is series of plants/animals which are interrelated in the form of organism being eaten as food by the other. Trophic levels in a food chain are formed by producers, consumers and decomposers. In the given food chain, plants are producers. The animals eating plants are called as primary consumers and animals eating primary consumers are called as secondary consumers. Decomposers are those which decomposes the waster organic matter and release energy back in the environment.
Thus, the correct answer is 'All of the above.'

Food web is constituted by

  1. Various interlinked food chains in a community

  2. Relationship between animals and plants

  3. Relationship between organisms and their environment

  4. Relationship between animals, plants and microbes


Correct Option: A
Explanation:
A food chain is series of plants/animals which are interrelated in the form of organism being eaten as food by the other. Food web is constituted by various interlinked and interdependent food chains in a community. It is also called as consumer-resource system. Ecosystem consists of living organisms and their abiotic environment. 
Thus, the correct answer is 'Various interlinked food chains in a community.'

A food chain can have trophic levels

  1. Three or four

  2. Three

  3. Two

  4. One


Correct Option: A
Explanation:

Food chain in an ecosystem is defined as the passage of food from one trophic level to the next higher trophic level. The transfer of food from one trophic level to the next level results in the passage of energy through these trophic levels. A food chain can have 3 or 4 trophic levels. Plants are producers which are present in first trophic level. Primary consumers are second trophic levels which eat plants. They are herbivores. Secondary consumer are present make third trophic level. They eat primary consumers and are carnivores. Tertiary or top consumer make fourth trophic level. They are carnivores

Thus, the correct answer is 'Three or four.'

Food levels of an ecosystem are known as

  1. Producer levels

  2. Herbivore levels

  3. Consumer levels

  4. Trophic levels


Correct Option: D
Explanation:

A food chain is series of plants/animals which are interrelated in the form of organism being eaten as food by the other. A food chain consists of producers abd consumers. In the given food chain, plants are producers. They are present in the first trophic level. It is also called as T$ _1$ trophic level. The animals eating plants are called as primary consumers. They are herbivores and occupy the second trophic level in an ecosystem. It is also called as T$ _2$ trophic level. Animals eating primary consumers are called as secondary consumers. They occupy the third trophic level in an ecosystem. It is also called as T$ _3$ trophic level. 

Thus, the correct answer is 'Trophic levels.'

In general, food webs consist of producers, consumers, and decomposers.

  1. True

  2. False

  3. Either

  4. Neither


Correct Option: A
Explanation:
Food web is an interconnected network of many food chains. In a food web, an organism occupies more than one trophic level. It may feed on different organisms of lower trophic levels and may get eaten itself by organisms of higher trophic levels. Food chain in turn, is a series of organisms which eat one and get eaten by other. A food chain comprises of different organisms at subsequent trophic levels. Autotrophs being producers occupy the lowest trophic level while consumers and decomposers occupy higher trophic levels. So, a food web consists of producers, consumers and decomposers with each occupying a particular trophic level.
Hence, the statement given in the question is correct.
So, the correct answer is 'True'.

Food web ensures survival of all types of trophic levels.

  1. True

  2. False

  3. Either

  4. Neither


Correct Option: A
Explanation:
Food web is a mesh like network of food chains which are interconnected. In a food web, an organism occupies more than one trophic level. It feeds on the organisms of lower trophic levels and is also eaten by other organisms of higher trophic levels. Thus all organisms at different trophic levels get food in a food web which ensures their survival. 
Hence, the statement given in the question is correct.
So, the correct answer is 'True'.

An example of a producer in the aquatic food web would be

  1. Duckweed

  2. Ducks

  3. Fish

  4. Insects


Correct Option: A
Explanation:
Producers are the green plants which convert light energy into chemical energy and prepare their own food. They are autotrophic component of an ecosystem. They are green plants and are photosynthetic. Their kind varies with the type of ecosystem. In an aquatic ecosystem, producers will be aquatic plants. For example, Duckweed also known as water lenses. These are flowering aquatic plants which keep floating on the surface of water. Since these plants are photosynthesising, they are producers in an aquatic food web.
So, the correct answer is 'Duckweed'.

Organisms of a higher trophic level which feed on several types of organisms belonging to a lower trophic level constitute the

  1. food web

  2. ecological pyramid

  3. ecosystem

  4. food chain


Correct Option: A
Explanation:
A. Food web is an interconnected network of many food chains. An organism occupies more than one trophic level in a food chain. It feeds on different organisms of lower trophic levels and may be eaten by other organisms of higher trophic levels.
B. An ecological pyramid is the diagrammatic representation of the relationship between numbers, biomass and energy content of producers and consumers in an ecosystem.
C. The ecosystem is the community of organisms which interact with each other and with their surroundings or environment.
D. A food chain is a series of organisms which eat one and get eaten by others.
So, the correct answer is 'Food web'.

Trophic levels are formed by-

  1. only plants

  2. only animals

  3. only carnivores

  4. organisms linked in food chain


Correct Option: D
Explanation:
A trophic level is the position of an organism in a food chain. A food chain starts with producers which are green plants and occupy the lowest trophic level. The highest trophic level is occupied by carnivores which feed on lower trophic levels for energy. A simple food chain is represented as:
Plant ---> Herbivore ---> Carnivore
Hence, trophic levels are formed by different organisms linked in a food chain.
So, the correct answer is 'organisms linked in the food chain'.

Each step in a food chain is called a

  1. trophical level.

  2. consumer level.

  3. food web.

  4. producer.


Correct Option: A
Explanation:
A. Trophic level is the position of an organism that it occupies in a food chain. Simply, trophic level is each step in a food chain representing producers and consumers.
B. Consumer levels represent heterotrophs that feed on producers and occupy higher trophic levels in a food chain.
C. Food web is an interconnected network of food chains.
D. Producers are the green plants that convert light energy into chemical energy and prepare their food. 
So, the correct answer is 'trophical level'.

Which pair is not correctly related?

  1. GPP - Photosynthetic organisms

  2. Middle strata of forest ecosystem - Shrubs

  3. Abundance of decomposers - Sea surface

  4. Flow of energy - Always unidirectional


Correct Option: C
Explanation:

A. Gross primary productivity (GPP) is a term used to describe the rate at which plants and other photosynthetic organisms produce organic compounds in an ecosystem. Hence 'GPP - Photosynthetic organisms' are related to each other.

B. Stratification is the layering of habitats within an ecosystem with the presence of distinctive physical and biological boundaries between the strata (layers). In a temperate deciduous forest, you typically have 5 vertical layers: the canopy layer, the sapling layer, the shrub layer, the herbaceous layer, and the moss layer. Hence 'Middle strata of forest ecosystem - Shrubs' are related to each other.
C. The cycling of materials such as carbon, water, and other nutrients is mainly dependent upon soil-dwelling decomposer organisms such as bacteria fungi, earthworms, and insects. Bacteria and fungi are the most abundant of the microbial decomposers. Hence the sea surface is not a decomposer 'Abundance of decomposers - Sea surface' are not related to each other.
D. The flow of energy in food chains is unidirectional. The energy which passes to the herbivores does not come back to the autotrophs. The energy that is captured by the autotrophs does not revert back to the Sun. Hence 'Flow of energy - Always unidirectional' are related to each other.
So the answer is option C 'Abundance of decomposers - Sea surface'. 

Which one occupies more than one trophic level in a pond ecosystem?

  1. Zooplankton

  2. Phytoplankton

  3. Fish

  4. Frog


Correct Option: C
Explanation:

A fish consuming phytoplanktons occupies primary consumer level while when consuming another small fish, it occupies secondary consumer level. So, a fish can occupy more than one trophic level in a pond ecosystem.

So, the correct answer is option C, fish.

Grass $\rightarrow$ Goat $\rightarrow$ Man  $\rightarrow$
In above food chain man is

  1. Top consumer

  2. Secondary consumer

  3. Primary consumer

  4. Producer


Correct Option: B
Explanation:

A trophic level is a group of organisms within an ecosystem which occupy the same level in a food chain. There are five main trophic levels within a food chain, each of which differs in its nutritional relationship with the primary energy source. The primary energy source in any ecosystem is the Sun. Primary producers are usually plants and algae, which perform photosynthesis in order to manufacture their own food source. Primary producers make up the first trophic level. The second trophic level consists of herbivores, these organisms gain energy by eating primary producers and are called primary consumers. Trophic levels three, four and five consists of carnivores and omnivores. Trophic level three consists of carnivores and omnivores (Example: Man) which eat herbivores; these are the secondary consumers. 

So, the correct answer is 'Secondary consumer'.

Which of the following trophics level is occupied by man feeding on curd?

  1. $T _2$

  2. $T _3$

  3. $T _4$

  4. $T _1$


Correct Option: B
Explanation:

A man feeding on curd occupied the third trophic level. Here, the grasses are at the first trophic level, the cow/buffalo who feeds on grasses is at the second trophic level. The curd is prepared by the milk of cow/buffalo by the action of bacteria, but the energy of the milk is getting transferred to the man, so man is at the third trophic level.

Hence, the correct answer is 'T$ _{3}$'

Food web usually exists in ecosystem which

  1. Is based on order of preference

  2. Consists of several interconnected food chain

  3. May include organism occupying different tropic levels

  4. More than one option is correct


Correct Option: D
Explanation:

Food web represents an interconnection of many food chains in an ecosystem and that is the reason in a food web, there can be organisms occupying different trophic level at the same time. For example, in a food web, a crow can be at the second trophic level or at the fourth trophic level.

Hence, the correct answer is 'More than one option is correct'

The trophic level of lion in a forest ecosystem is:

  1. $T _3$

  2. $T _4$

  3. $T _2$

  4. $T _1$


Correct Option: A

Food web contains many _______.

  1. Primary consumers

  2. Secondary consumers

  3. Tertiary consumers

  4. Food chains


Correct Option: A

A food web is

  1. Like a food chain

  2. A set of interconnected food chains, illustrating the tropic relationships among species

  3. The set of prey species that are consumed by animals in an ecosystem

  4. The tropic (feeding) levels that can be observed in an ecosystem


Correct Option: B

When number of food chains is interlocked this is called

  1. food link

  2. food chain

  3. food web

  4. pyramid


Correct Option: C

Trophic levels are formed by 

  1. Only plants

  2. Only carnivores

  3. Only animals

  4. Organisms linked in food chain


Correct Option: D
Explanation:

The trophic level is the sequential arrangement of several organisms on the basis of the number, energy flow, and biomass present at the different level. Food chains start at trophic level 1 with primary producers, such as plants, move to herbivores at level 2, predators at level 3 and finish with carnivores or apex predators at level 4 or 5. Thus, the correct answer is option D.

Vultures in an ecosystem are 

  1. Predators

  2. Scavangers

  3. Consumers

  4. Top carnivores


Correct Option: B
Explanation:

Vultures are scavenging birds that feed on dead animals. Vultures do not kill their own prey, they feed on dead animals. As scavengers, vultures play an important role in the ecosystem by decomposing the dead animal matter, cleaning the environment and reducing the spread of diseases.

What is true about any ecosystem?

  1. It is self regulatory

  2. It is self sustained

  3. Top carnivores have climax trophic level position

  4. All of the above


Correct Option: D
Explanation:
  • Ecosystems are said to be self-regulating or self-sustained in that each contains feedback mechanisms, which function to maintain the components of the system in one or other of its equilibrium states.
  • An equilibrium state demonstrates the stability of ecosystems. Even in these stable states, the components of ecosystems are in dynamic exchanges, and these exchanges involve the build-up of energy or materials, which cycle the ecosystem either within a single equilibrium or between various equilibrium states. 
  • It is the adaptive capacity of ecosystems, that have provided both the stability and the enormous range of diversity on earth.
  • Food chains start at trophic level 1 with primary producers such as plants, moved to herbivores at level 2, predators at level 3 and finish with carnivores or apex predators at level 4 or 5.
    Thus, the correct answer is option D.

If bamboo plant is growing in a forest, then what will be the trophic level of it?

  1. First trophic level $(T _1)$

  2. Second trophic level $(T _2)$

  3. Third trophic level $(T _3)$

  4. Fourth trophic level $(T _4)$


Correct Option: A
Explanation:

Trophic structure of an ecosystem is a type of producer-consumer arrangement, in which each food level is called as trophic level and the graphical representation of the trophic structure of ecosystem constitutes ecological pyramids. The green plants are producers and represent the first trophic level. So, bamboo plant is in the first trophic level.

Which one of the following types of organisms occupy more than one trophic level in a pond ecosystem?

  1. Frog

  2. Phytoplankton

  3. Fish

  4. Zooplankton


Correct Option: C
Explanation:

Fishes occupy more than one trophic level because some feed only on phytoplanktons and zooplankton, while other feeds on algae or other food sources across various strata of the water body  

So, the correct answer is 'Fish'

Organisms of a higher trophic level which feed on several types of organisms belonging to a lower trophic level constitute the

  1. Food web

  2. Ecological pyramid

  3. Ecosystem

  4. Food chain


Correct Option: A
Explanation:
A network of food chains or feeding relationships in which organisms of higher trophic level feeds on more than one type of consumers. 

In an ecosystem, trophic level of man is

  1. Producer

  2. Herbivore

  3. Omnivore

  4. Carnivore


Correct Option: C
Explanation:

An omnivore is an organism, that regularly consumes a variety of material, including plants, animals, algae, and fungi. Human beings are omnivores. People eat plants, such as vegetables and fruits. Human beings eat animals, cooked as meat or used for products like milk or eggs. Human eats fungi, such as mushrooms. We also eat algae, in the form of edible seaweeds, such as nori, which are used to wrap sushi rolls, and sea lettuce, eaten in salads. Both omnivores and carnivores, meat eaters, are at the third trophic level. Carnivores and omnivores are secondary consumers.

More than one interconnected food chain in a region forms

  1. Ecological pryamid

  2. Food web

  3. Food chain

  4. None of the above


Correct Option: B
Explanation:

food web is a natural interconnection between the food chains. Each living thing in an ecosystem is part of multiple food chains. Each food chain is one possible path that energy and nutrients may take as they move through the ecosystem. All of the interconnected and overlapping food chains in an ecosystem make up a food web.

Therefore, the correct answer is option B.

A group of interconnected food chains is called as a

  1. Food cycle

  2. Complex food chain

  3. Pyramid of energy

  4. Food web


Correct Option: D
Explanation:

A food web consists of all the food chains in a single ecosystem. Each living thing in an ecosystem is part of multiple food chains. Each food chain is one possible path that energy and nutrients may take as they move through the ecosystem. All of the interconnected and overlapping food chains in an ecosystem make up a food web.

Trophic levels are formed by_______________

  1. Plants only

  2. Animals only

  3. Carnivores only

  4. Organisms linked in food chain


Correct Option: D
Explanation:

  • The trophic level of an organism is the position it occupies in a food chain. A food chain represents a succession of organisms that eat another organism and are, in turn, eaten by others. 
  • Food chains start at trophic level 1 with primary producers such as plants, move to herbivores at level 2, predators at level 3 and finish with carnivores or apex predators at level 4 or 5.

Therefore, the correct answer is option D.

Organisms of the same trophic level are______________

  1. Deer and honey bee

  2. Cheetah and grasshopper

  3. Snake and earthworm

  4. Crow and cow


Correct Option: A
Explanation:

  • Herbivores are at the second level of the food chain and mainly eat plants. Herbivores are considered primary consumers and are the first consumers on the food chain. 
  • The honey bee is a herbivore and therefore lives purely on the nutrients from plants. 
  • Deer are also herbivores, they eat plants and grasses. So, they belong to the same trophic level.

Therefore, the correct answer is option A.

Food webs can be constructed to describe

  1. The species interactions

  2. The species separation

  3. The species union

  4. None of these


Correct Option: A
Explanation:

Food webs can be constructed to describe the species interactions. The fundamental purpose of food webs is to describe feeding relationship among species in a community.

Trophic levels in ecosystem is formed by

  1. Ony bacteria

  2. Only plants

  3. Only herbivores

  4. Organisms linked in food chain


Correct Option: D
Explanation:

The food chain is the series or linear link of different organisms through which the nutrients flow from one level to another. The trophic levels are denoted by the flow of energy from one level to the next level. The levels in any ecosystem is known by the organisms which are connected with each other by the transfer of energy.

So, the correct answer is option D. 

Which of the following trophic levels includes a bird feeding on both insects and berries?

  1. Primary consumer

  2. Secondary consumer

  3. Tertiary consumer

  4. Both A and B

  5. Both A and C


Correct Option: D
Explanation:

Primary consumers are the organisms that feed on producers. Since the bird is feeding on berries (producer), it is a primary consumer. The organisms that feed on primary consumers are termed as secondary consumers. Since the bird is feeding on insects (primary consumer), it is a secondary consumer as well. This makes option D correct answer. 

All of the following organisms are correctly paired with their trophic level except

  1. Tree- producer

  2. Hawk- primary consumer

  3. Fungi- detritivore

  4. Fox- secondary consumer

  5. Grasshopper- primary consumer


Correct Option: B
Explanation:
The tree is a producer. Producers are any kind of green plant. Green plants make their food by taking sunlight and using the energy to make sugar.
Hawk is a tertiary consumer which eats secondary consumers like hawks eat owls in a food chain. 
Fungi is a detritivore. They are heterotrophs that obtain nutrients by consuming detritus.
Fox is a secondary consumer. They eat primary consumers. They are carnivores (meat-eaters) and omnivores (animals that eat both animals and plants).
Grasshopper is a primary consumer. They are animals that eat primary producers.
Therefore, the correct answer is option B.

Which of the following best describes the trophic level within an ecosystem?

  1. Size of food eaten at that level

  2. Nutrient source of the organisms in each level

  3. Stages in ecological succession

  4. Habitats of the organisms within that level

  5. Elevation above sea level


Correct Option: A
Explanation:

An ecosystem is made up of organisms that differ in the energy source that they depend on upon and how they provide energy for other organisms in the food web. The steps of the nutritive food chain in the ecosystem is known as trophic levels. In other words, it is the position that an organism occupies in a food chain depending on what it eats, and what eats it.

The base of the food web in marine ecosystem is

  1. Phytoplankton

  2. Zooplankton

  3. Kelp

  4. Fish

  5. Whales


Correct Option: A
Explanation:

Phytoplanktons are the major producers and constitute the base of five level food web of the marine ecosystem. They convert chemical energy into the usable form of energy. Zooplanktons and other herbivores feed on phytoplanktons and these herbivores are themselves eaten by higher level consumers. Fishes and whales occupy higher level as consumers. Kelps occupy the base of the food web in kelp beds only. The correct answer is option A.

Which of the following limits the number of trophic levels maintained by an ecosystem?

  1. The number of species

  2. The population size

  3. The loss of potential energy

  4. The number of individuals

  5. The hours of sunshine


Correct Option: C
Explanation:

With each trophic level, only 10% potential energy is transferred and 90% is lost as heat in respiration. The longer the food chain, the lesser is the energy transfer efficiency. To increase the energy transfer efficiency, food chains must be smaller with a limited number of trophic levels. Thus, the correct answer is C.

All organisms that feed at each other link in a food chain comprise a ______.

  1. food pyramid

  2. energy pyramid

  3. trophic level

  4. calorie

  5. biomass


Correct Option: C

Which of the following is false?

  1. Quantity of biomass in trophic level at a particular period is called as standing crop.

  2. The energy content in trophic level is determined by considering a few individuals of a species in that trophic level.

  3. The succession that occurs in newly cooled lava is called as primary succession.

  4. Rate of succession is faster in secondary succession.

  5. Phytoplanktons are the pioneers in the aquatic ecosystem.


Correct Option: B
Explanation:

Trophic level refers to each levels in the  ecological pyramid and is designated as per their position in the food chain. The trophic level starts from 1 -which represents the primary producers and it moves upto  primary consumers- level 2, secondary consumers -level 3 and tertiary consumers at level 4 or 5. In an aquatic ecosystem, the phytoplanktons are the pioneers and primary producers along with the algae and cyanobacteria. Standing crop refers to the mass of living material present at a trophic level at a particular time. The ecological succession takes place from primary to secondary and reaches a climax stage. primary succession refers to the ecological succession that takes place where no living organisms ever existed. for eg. the sucession that occurs in a newy cooled lava.  Moreover, it has been seen that the rate of succession is faster in secondary than the primary succession as soil is already present in case of secondary succession.

In a food chain, deer is eaten by lion and deer east vegetation. Which one of the statements given is true?
(P) Lion is second order consumer and deer is first order consumer.
(Q) Lion is predator and deer is prey.
(R) Lion is first order consumer and deer is second order consumer.
(S) Lion is third order consumer and deer is second order consumer.

  1. Only (P) and (Q)

  2. Only (Q) and (R)

  3. Only (P) and (S)

  4. Only (P) and (R)


Correct Option: A
Explanation:

In a food chain where a deer feeds on producers and lion feeds on the deer then, the deer is a first order consumer and the lion is a second order consumer, and as the lion feeds in the deer, lion is the predator and the deer is the prey. 

Thus, the correct answer is option A. 

If a grassland food chain is linked to the food chain in the forest. It can be termed as

  1. Ecosystem

  2. Food chain

  3. Food web

  4. None of the above


Correct Option: C

Which of the following statement defines the difference between the food chain and food web?

  1. Food chain demonstrates the interdependence.

  2. Food web demonstrates the interlinked food chain.

  3. Food chain is an exchange of energy.

  4. None of the above


Correct Option: B

A peacock eats snakes which eat frogs. These eat hoppers which in turn thrive on leaves of the plants. The peacock is

  1. Primary consumer

  2. Secondary consumer

  3. Decomposer

  4. Apex of the food pyramid


Correct Option: D
Explanation:

Apex of the food pyramid is the tip of the food pyramid. In the given food pyramid, peacock eats snakes which eat hoppers which in turn eats leaves of the plants. Hence, the peacock is the apex of food pyramid and plants are the base of the food pyramid.  Hoppers are primary consumer and snakes are secondary consumers of the given food pyramid.

Thus, the correct answer is 'Apex of the food pyramid.'

Extinction of a species in a food chain is compensated in

  1. Ecological pyramid

  2. Food web

  3. Food chain

  4. None of the above


Correct Option: B
Explanation:

Food web is interconnected food chains in an ecosystem. Extinction of a species in a food chain is compensated in food web. When a particular species in a food chain becomes extinct, it is compensated by the remaining generalized species at the same trophic level.

Thus, the correct answer is 'Food web.'

Which of the following statements about food chains are correct?
(a) Removal of 80% tigers resulted in increased growth of vegetation.
(b) Removal of most carnivores resulted in an increased population of deer.
(c) Length of the food chain is limited to 3-4 trophic levels due to energy loss.
(d) Length of the food chain may vary from 2-3 trophic levels.

  1. a, d

  2. a, b

  3. b, c

  4. c, d


Correct Option: C
Explanation:

In a food chain, the carnivores eat up herbivores, or in other words, the secondary consumers consume the primary consumers. So, we can say that if the number of carnivores decreases, the number of herbivores like deer go on decreasing as they will not get eaten up. So, removal of most of the carnivores will result in an increased population of deer. 

Apart from this, we also know that as we move from one tropic level to another, the amount of energy goes on decreasing. This is according to the 10% law according to which, at each trophic level, 10& energy is lost. So, each food chain is only 3-4 tropic levels long due to these energy losses. 
So, option b and c is the correct option.
So the correct option is C.

Networking of different food chains in an ecosystem provides

  1. Stability

  2. Instability

  3. Origin of new species

  4. None of the above


Correct Option: A
Explanation:

Food web is constituted by various interlinked food chains in a community. Networking of different food chains in an ecosystem provides stability to the ecosystem. Due to interconnecting food chains, relationships between the species remain constant over relatively long periods of time.

Thus, the correct answer is 'Stability.'

Which of the following occupies more than one trophic level in the same ecosystem at the same time?

  1. Sparrow

  2. Goat

  3. Frog

  4. Lion


Correct Option: A
Explanation:

In an ecosystem, there are various trophic levels. Each trophic level consists of a particular organisms. It consists of producers, consumers, decomposers. The first trophic level consists of producers such as plants. The second trophic level consists of primary consumers. The third trophic level consists of secondary consumers. There are certain organisms which occupy more than one trophic level in the same ecosystem at the same time. An example include sparrow. It feeds upon grains. Hence, it is called as primary consumer and occupies second trophic level. It also feeds upon insects. Hence, it is called as secondary consumer and occupies third trophic level.

Thus, the correct answer is 'Sparrow.'

Which of the following may occupy any trophic level in an ecosystem?

  1. Plankton

  2. Aquatic animals

  3. Decomposers

  4. Aquatic plants


Correct Option: B
Explanation:

There are various trophic levels in a food chain. The first trophic level consists of primary producers such as plant. The second trophic level consists of herbivores or primary consumers. The third trophic level consists of carnivores or secondary consumers. Decomposers are present at the top trophic level. Phytoplankton occupies the first trophic level in an ecosystem. The zooplankton feeding upon phytoplankton occupies the second trophic level in an ecosystem. Aquatic animals occupy any trophic level in an ecosystem. Aquatic animals such as zooplankton occupies first trophic level. Aquatic animals such as small fish occupies second trophic level. Aquatic animals such as large fish occupies third trophic level. The aquatic plants occupy first trophic level. 

Thus, the correct answer is 'Aquatic animals.'

A group of interconnected food chains is called

  1. complex food chain

  2. food web

  3. food cycle

  4. pyramid of biomass


Correct Option: B
Explanation:

A web of interconnected food chains is known as food web.

The food web has various interdependent food chains and establishes ecological balance.
So, the correct option is 'food web'.

Trophic levels are formed by:

  1. plants only

  2. animals only

  3. organisms linked in food chains

  4. top consumers in food chain


Correct Option: C
Explanation:

Trophic means food. The animals linked in the food chain form various trophic levels. A food chain is a series of organisms that eat and get eaten.

So, the correct option is 'organisms linked to the food chain'.

Which is not true about a complex food web?

  1. Populations tend to remain about the same size

  2. Energy levels remain about the same for all trophic levels

  3. Inputs are constant and outputs are minimal except for heat

  4. Most of the energy entering the system maintains the whole community


Correct Option: B
Explanation:

The amount of energy at each trophic level decreases as it moves through an ecosystem. As little as 10% of the energy at any trophic level is transferred to the next level; the rest is lost largely through metabolic processes as heat. Food webs illustrate how energy flows through ecosystems, including how efficiently organisms acquire and use it. Autotrophs, producers in food webs, can be photosynthetic or chemosynthetic. They use light energy to synthesize their own food, while chemoautotrophs use inorganic molecules. Heterotrophs cannot synthesize their own energy, but must obtain it from autotrophs in food webs.

So the correct option is 'energy levels remain about the same for all trophic levels.' 

If we weighed all of the organisms at each level of this food web, which would be the heaviest?

  1. Grass and trees

  2. Grasshoppers and squirrels

  3. Hawks and foxes

  4. All levels would weigh the same


Correct Option: A
Explanation:

A food web consists of all the food chains in a single ecosystem. Each living thing in an ecosystem is part of multiple food chains. Each food chain is one possible path that energy and nutrients may take as they move through the ecosystem. All of the interconnected and overlapping food chains in an ecosystem make up a food web.  An ecosystem cannot support a large number of omnivores without supporting an even larger number of herbivores, and an even larger number of autotrophs and hence the biomass of autotrophs will be the heaviest as it present in abundant amount..

So the correct option is 'grass and trees'.

Energy flow in an ecosystem begins with

  1. Omnivores

  2. Herbivores

  3. Decomposers

  4. Autotrophs


Correct Option: D
Explanation:

An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment, interacting as a system.  Sun is the source of energy fixed by the photoautotrophs, called primary producers, like green plants. Primary consumers absorb most of the stored energy in the plant through digestion, and transform it into the form of energy they need, such as adenosine triphosphate (ATP), through respiration. A part of the energy received by primary consumers, herbivores, is converted to body heat (an effect of respiration), which is radiated away and lost from the system. 

So the correct option is 'autotrophs'.

Humans and animals such as bears are biologically adapted to be

  1. Omnivores

  2. Herbivores

  3. Deteritivores

  4. Autotrophs


Correct Option: A
Explanation:

Omnivore is a consumption classification for animals that have the capability to obtain chemical energy and nutrients from materials originating from plant and animal origin. Often, omnivores also have the ability to incorporate food sources such as algae, fungi, and bacteria into their diet as well. Omnivores come from diverse backgrounds that often independently evolved sophisticated consumption capabilities. Although cases exist of herbivores eating meat and carnivores eating plant matter, the classification "omnivore" refers to the adaptations and main food source of the species in general. Various mammals are omnivores in the wild,  including humans and bear species.

So the correct option is 'omnivores'.

Of the total amount of energy that passes from one trophic level to another, about 10% is

  1. Respired and becomes heat

  2. Passed out as faeces or urine

  3. Stored as body tissue

  4. Recycled to autotrophs


Correct Option: C
Explanation:

The trophic level of an organism is the position it occupies in a food chain. The amount of energy at each trophic level decreases as it moves through an ecosystem. As little as 10 percent of the energy at any trophic level is transferred to the next level; the rest is lost largely through metabolic processes as heat. If a grassland ecosystem has 10,000 kilocalories (kcal) of energy concentrated in vegetation, only about 1,000 kcal will be transferred to primary consumers, and very little (only 10 kcal) will make it to the tertiary level. Energy pyramids such as this help to explain the trophic structure of an ecosystem.

So the correct option is 'Stored as body tissue'.

The interlocking pattern of various food chains is referred as food web.

  1. True

  2. False


Correct Option: A
Explanation:

In nature, some organisms operate in the ecosystem not just at a single trophic level but more than one trophic levels which means that it may derive its food from more than one source. The organism may get eaten itself by another organism of higher trophic level. It may also feed on different organisms of lower trophic levels. In this way, various food chains are linked together in an ecosystem and the intersection of these food chains form a complex network called food web. 

Hence, the statement given in the question is correct.
So, the correct answer is 'True'.

Trophic levels in ecosystem are formed by

  1. only bacteria

  2. only plants

  3. only herbivores

  4. organisms linked in food chain


Correct Option: D
Explanation:

Trophic levels in an ecosystem are formed by organisms linked in food chain. It starts from producer level and usually ends at secondary or tertiary consumer levels.

So, the correct answer is option D, organisms linked in food chain.

In an aquatic ecosystem , a mollusc typically belongs to

  1. $T _1$

  2. $T _2$

  3. $T _3$

  4. $T _4$


Correct Option: B
Explanation:

Mollusc constitutes the second largest phylum in the animal kingdom which includes a group of animals living on land, in marine water, and in fresh water. Mollusks include both herbivores and carnivores animal. They eat both plants and small animals. In an aquatic ecosystem, a mollusk acts as primary consumers, so it belongs to second trophic level (T2).

The study of food chains and food webs is observed in the phenomenon known as

  1. biological chain

  2. ecosystem

  3. biological magnification

  4. energy flow


Correct Option: C

In oceans, food web is involved in more species, than

  1. The Terrestrial Ecosystem

  2. The Estuaries

  3. The Mangroves

  4. All of Above


Correct Option: A

A dependent, on producers for their food is called

  1. Autotrophic organisms

  2. Heterotrophs

  3. Primary producers

  4. Sulphur and carbon


Correct Option: B

In which of the following countries Slow Food Movement took place to combat fast food?

  1. United States

  2. France

  3. Italy

  4. England


Correct Option: C

Tree $\rightarrow$ Caterpillar $\rightarrow$ Robin $\rightarrow$ Cat represents a food chain. In this food chain, if the tree can provide 100000 calories of energy, how much calories of energy will be available to the robin and the cat?

  1. 10000 and 1000 calories, respectively

  2. 1000 and 100 calories, respectively

  3. 1000 and 10000 calories, respectively

  4. 100 and 1000 calories, respectively


Correct Option: B
Explanation:
The amount of energy flow decreases with every successive trophic level and only 10% is passed to the next level as useable biological energy and the rest 90% is lost in the transfer. So, in the given case, 1,00,000 calories of energy  is with producer that is the tree and thus caterpillar will have 10,000, robin will have 1,000 and the energy available with cat will be 100 calories.
So, the correct answer is option B.

In an aqueous environment, microscopic animals and plants are collectively known as

  1. Herbivores

  2. Fauna and flora

  3. Planktons

  4. Symbionts


Correct Option: C
Explanation:

Planktons are the small or microscopic organisms that drift or swim weakly in a body of water, including bacteria, diatoms, jellyfish and various larvae. Plankton is an important food source for fish and other larger organisms. They cannot swim against a current.

Therefore, the correct answer is option C.

What is correct about food chain and food web?

  1. The food chain is a series of organisms feeding on one another, food web consists of a number of interlinked food chains.

  2. The food chain is a series of plants feeding on one another, food web consists of a number of interlinked chains.

  3. The food chain is a series of plant feeding, food web consists of a number of interlinked nets.

  4. The food chain is a series of plants feeding on one another, food web consists of a number of food.


Correct Option: A
Explanation:

  • A food chain is a linear path in which an organism gets food, it starts with plants and ends with animals. A network of many food chains is called a food web. 
  • A food web consists of all the food chains in a single ecosystem. Each living thing in an ecosystem is part of multiple food chains. 
  • Each food chain is one possible path that energy and nutrients may take as they move through the ecosystem. All of the interconnected and overlapping food chains in an ecosystem make up a food web.

Thus, the correct answer is option A.

The concept of trophic structure of a community emphasizes the

  1. prevalent form of vegetation

  2. keystone predator

  3. feeding relationships within a community

  4. effects of coevolution


Correct Option: C
Explanation:

The trophic structure in a community is the feeding relationships between species as the first level is occupied by producers and then primary and secondary consumers decomposers and so on have a successive trophic level. 

So, the correct option is 'feeding relationships within a community'.


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