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42 questions · timed · auto-graded

Question 12 Marks
The below diagramatic sketch shows the stratisfication of pond ecosystem. Considering it, name X and Y.
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Question 32 Marks
Frame any two food chain patterns from the given organisms. Each chain must contain a minimum of four organisms.
Diatoms, Hawk, Rabbit, Vallisneria Stoke, guppies, grass, snake, large fishes, grasshopper, crane.
Answer
  1. Diatom → Guppies → Large fishes → Crane
  2. Grass → Rabbit → Snake → Hawk
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Question 42 Marks
According to ten percent law, how many Joules of energy does the individuals at the fourth tropic level will receive; if the individuals at first trophic level receives 1000 Joules of energy?
Answer
Organism at T4 level will receive 0.1 Joule of energy as per ten percent law.
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Question 52 Marks
Nutrients are retained in the ecosystem. Discuss how and name the process through which it is achieved?
Answer
Nutrients will retain in the ecosystem through biogeo chemical cycles. Various nutrients present in soil and atmosphere enter the organism at various trophic levels through food and other process and are cycled back to their origin. Thus the nutrients are not lost but retained in the ecosystem.
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Question 62 Marks
Define
  1. Hydrosere
  2. Xerosere
Answer
  1. Hydrosere: Succession of plants in a freshwater ecosystem.
  2. Xerosere: Succession of plants in areas with minimal amount of water.
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Question 72 Marks
Define plant succession.
Answer
Successive replacement of one type of plant community by the other of the same area/place is known as plant succession.
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Question 82 Marks
Which kind of organisms constitutes the pioneer community and climax community of a Hydrosere succession?
Answer
Phytoplanktons from the pioneer community and a variety of trees makes the climax community of a Hydrosere
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Question 92 Marks
Ecosystem management – comment on the statement.
Answer
Ecosystem management is a process that integrates ecological, socio-economic and institutional factors into a comprehensive strategy in order to sustain and enhance the quality of the ecosystem to meet current and future needs
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Question 102 Marks
What is meant by Ecosystem resilience?
Answer
Ecosystem is damaged by disturbances from fire, flood, predation, infection and drought, etc. removing a great amount of biomass. However, the ecosystem is endowed with the ability to resist the damage and recover quickly. This ability of an ecosystem is called ecosystem resilience or ecosystem robustness.
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Question 112 Marks
Mention the four categories of ecosystem services.
Answer
  1. Provisioning services
  2. Cultural services
  3. Supporting services
  4. Regulating services
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Question 122 Marks
What are Blue carbon ecosystems?
Answer
Seagrasses and mangroves of Estuarine and coastal ecosystems are the most efficient in carbon sequestration. Hence, these ecosystems are called “Blue carbon ecosystems”.
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Question 142 Marks
Name the type of ecosystem that exhibits the following types of the pyramid.
  1. Inverted pyramid of biomass
  2. Spindle-shaped pyramid of number
Answer
  1. Pond ecosystem
  2. Forest ecosystem.
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Question 152 Marks
Biogeochemical cycle comprises both gaseous cycle and sedimentary cycle. How they differ from one another?
Answer
  1. The components of gaseous cycle are placed in an atmosphere
    E.g: Oxygen in air
  2. whereas in sedimentary cycle, the components are present in/on Earth.
    E.g: Phosphorous in rocks.
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Question 162 Marks
What is pyramid of biomass?
Answer
A graphical representation of the amount of organic material (biomass) present at each successive trophic level in an ecosystem is called pyramid of biomass.
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Question 172 Marks
Why do we obtain an inverted pyramid in a parasite ecosystem?
Answer
The pyramid of number in a parasite ecosystem is always inverted, because it starts with a single tree. Therefore there is gradual increase in the number of organisms in successive trophic levels from producer to tertiary consumers.
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Question 182 Marks
What is Eltoian pyramid?
Answer
Eltonian pyramid or Ecological pyramid is a graphic representation of the trophic structure and function at successive trophic levels of an ecosystem.
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Question 192 Marks
Define food web.
Answer
The interlocking pattern of a number of food chain form a web-like arrangement called food web. It is the basic unit of an ecosystem, to maintain its stability in nature.
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Question 202 Marks
Rearrange the components of the ecosystem and frame a food chain. Also mention the type of food chain.
Hawk, Earthworm, Animal excreta and Blackbird.
Answer
Animal excreta → Earthworm → Blackbird → Hawk. It is a detritus food chain.
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Question 212 Marks
Which is the first link in a grazing food chain and a detritus food chain?
Answer
  1. The first link of grazing food chain is plants (Producers).
  2. The first link of detritus food chain is dead remains and excreta of plants and animals.
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Question 232 Marks
Define food chain.
Answer
The movement of energy from producers upto top carnivores is known as food chain, i.e., in any food chain, energy flows from producers to primary consumers, then from primary consumers to secondary consumers, and finally secondary consumers to tertiary consumers. Hence, it shows linear network links.
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Question 242 Marks
State the ten percent law.
Answer
Ten percent law states that during transfer of food energy from one trophic level to other, only about 10% stored at every level and rest of them (90%) is lost in respiration, decomposition and in the form of heat.
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Question 252 Marks
State the first law of thermodynamics.
Answer
First law of thermodynamics states that energy can be transmitted from one system to another in various forms. Energy cannot be destroyed or created. But it can be transformed from one form to another. As a result, the quantity of energy present in the universe is constant.
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Question 262 Marks
What is energy flow?
Answer
The transfer of energy in an ecosystem between trophic levels can be termed as energy flow. It is the key function in an ecosystem. Energy flow is always unidirectional in an ecosystem.
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Question 272 Marks
Name the category of organisms that occupy the first tropic level (T1) and fourth tropic level (T4) in an ecosystem.
Answer
Producers (autotrophs) occupy the first tropic level (T4) whereas the fourth tropic level (T4) is occupied by Tertiary Consumers (Secondary carnivore).
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Question 282 Marks
State the role of herbivores and microconsumers in a terrestrial ecosystem.
Answer
  1. Herbivores acts as primary consumers of producers (Plants).
  2. Microconsumers decomposes the dead remains and excreta of plants and animals.
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Question 292 Marks
Write the name of four important aspects of ecosystem.
Answer
  1. Productivity
  2. Energy flow
  3. Decomposition
  4. Nutrient cycling
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Question 302 Marks
Expand GPP and define it.
Answer
Gross Primary Productivity (GPP) is the total amount of food energy or organic matter or biomass produced in an ecosystem by autotrophs through the process of photosynthesis is called gross primary productivity.
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Question 312 Marks
How Net Primary Productivity can be derived?
Answer
Net Primary Productivity (NPP) is derived by the difference between Gross primary productivity (GPP) and respiration.
NPP = GPP – Respiration
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Question 322 Marks
What is meant by productivity of an ecosystem?
Answer
The rate of biomass production per unit area in a unit time is called productivity. It can be expressed in terms of gm /m2/year or Kcal/m2/ year.
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Question 332 Marks
Define Grey carbon and Black carbon.
Answer
Grey carbon – carbon stored in fossil fuel (coal, oil and biogas deposits in the lithosphere). Black carbon – carbon emitted from gas, diesel engine and coal fired power plants.
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Question 342 Marks
Pointout the factors that affects the photosynthetically active radiation.
Answer
PAR is not always constant because of clouds, tree shades, air, dust particles, seasons, latitudes and length of the daylight availability.
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Question 352 Marks
What do you mean by PAR? Mention its significance.
Answer
The amount of light available for photosynthesis of plants is called Photosynthetically Active Radiation (PAR) which is between the range of 400-700 mm wave length.
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Question 362 Marks
What is standing crop?
Answer
The amount of living materials present in a population at any given time is known as standing crop, which may be expressed in terms of number or biomass per unit area.
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Question 372 Marks
How will you define decomposers?
Answer
Decomposers are organisms that decompose the dead plants and animals to release organic and inorganic nutrients into the environment which are again reused by plants.
Example: Bacteria, Actinomycetes and Fungi.
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Question 382 Marks
Name the macro consumers and micro consumers.
Answer
  1. Macro consumers are herbivores, carnivores and omnivores.
  2. Micro consumers are decomposers.
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Question 392 Marks
What are biotic components?
Answer
Biotic (living) components includes all living organisms like plants, animals, fungi and bacteria. They form the trophic structures of any ecosystem.
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Question 402 Marks
Define ‘Standing state’ with regard to ecosystem.
Answer
The total inorganic substances present in any ecosystem at a given time is called standing quality (or) standing state.
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Question 412 Marks
Mention any two climatic factors and edaphic factors of an ecosystem.
Answer
  1. Climatic factors: Light and Air.
  2. Edaphic factors: Soilwaer and pH of soil.
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Question 422 Marks
According to A.G. Tansley, what is an ecosystem?
Answer
A.G. Tansley (1935), who defined ecosystem as ‘the system resulting from the integration of all the living and non-living factors of the environment.
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[ 2 Marks Questions ] - BIO BOTANY STD 12 Questions - Vidyadip