Important Questions for Class 12 Biology 1st Chapter Ecosystem MCQ, Very Short, Short Type, Long Type
CBSE Class 12 Important Questions for Class 12 Biology Class 14 Ecosystem all MCQ Type, Very Short Type, Assertion Reason Type, Case Study, Short Type and Long Type Questions with Answers by Expert. Important Questions for Section A, B, C, D Class 12 Biology Class 14.
- MCQs
(1) Which Pyramid is always upright, can never be inverted?
(a) Biomass
(b) Energy
(c) Number
(d) All the above
2) Assertion: Primary productivity varies in different types of ecosystems.
Reason: Primary productivity depends on a variety of environmental factors, availability of nutrients and photosynthetic capacity of plants
a.) Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
b.) Both Assertion and Reason are correct and Reason is not the correct explanation for Assertion.
c.) If assertion is true but the reason is false.
d.) If both assertion and reason are false.
(3) Assertion: Sun is the source of energy for all ecosystems on Earth
Reason: the deep-sea hydro-thermal ecosystem derives its energy from the sun.
a.) Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
b.) Both Assertion and Reason are correct and Reason is not the correct explanation for Assertion.
c.) If assertion is true but the reason is false.
d.) If both assertion and reason are false
(4) The rate of formation of new organic matter by consumers is called as
a.) Gross primary productivity
b.) Net primary productivity
c.) Secondary productivity
d.) Primary productivity
(5) Which of the following in an example of manmade ecosystem?
(a) Crop fields
(b) Grassland
(c) Wetland
(d) Estuary
(6) Primary consumers belong to which tropic level?
(a) 1st tropic level
(b) 2nd tropic level
(c) 3rd tropic level
(d) 4th tropic level
(7) Assertion: In primary succession in water, the pioneers arerooted-submerged plants
Reason: The succession is possible due to invasion of climax community members like phytoplankton in that area
a.) Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
b.) Both Assertion and Reason are correct and Reason is not the correct explanation for Assertion.
c.) If assertion is true but the reason is false.
d.) If both assertion and reason are false
(8) What is the movement of nutrient elements through the various components ofan ecosystem is called?
(a) Decomposition
(b) Nutrient cycling
(c) Mineralization
(d) Leaching
(9) The naturalreservoir of phosphorus is ____________
(a) Rocks
(b) shells, bones and teeth of animals
(c) Plants
(d) Bacteria
(10) Decomposition involves all the processes except
(a) fragmentation ofdetritus
(b) solubilization of phosphorous
(c) leaching
(d) catabolism
- Answer in one sentence
Q.1) Define: Stratification
Ans. Stratification refers to the vertical distribution of distinct species at various levels.
Q.2) What are decomposers?
Ans. Decomposers are organisms that break down complex organic materials into inorganic chemicals such as carbon dioxide, water, and nutrients.
Q.3) Which factors are considered the ecosystem AS a functional unit?
Ans. When considering the following features, the ecosystem’s components are considered to function as a unit: I productivity; (ii) decomposition; (iii) energy flow; and (iv) nutrient cycling.
Q.4) What is secondary productivity?
Ans. The rate at which consumers produce new organic matter is referred to as secondary productivity.
Q.5) What are decomposers?
Ans. Decomposers are organisms that break down complex organic materials into inorganic chemicals such as carbon dioxide, water, and nutrients.
Q.6) What do you mean by tropic levels?
Ans. According to their feeding connection with other organisms, organisms occupy a place in the natural environment or in a community. Organisms occupy a certain place in the food chain known as their trophic level based on the source of their nourishment or food.
- Answer in short
Q.1) Give detail explanation of functioning of an ideal ecosystem.
Ans. 1.) The autotrophs convert inorganic into organic material with the help of the sun’s radiant energy.
2.) Heterotrophs consume the autotrophs; and the dead matter decomposes and mineralizes, releasing it for reuse by the autotrophs, all of these events are repeated over and over again.
3.) Energy is dissipated and lost as heat to the environment in a unidirectional flow towards higher trophic levels.
Q.2) Explain humification and mineralization.
Ans. 1.) Humification results in the formation of humus, a dark-colored amorphous substance that is highly resistant to microbial action and decomposes at a very slow rate.
2.) It functions as a nutrition reservoir due to its colloidal structure.
3.) Some microorganism’s breakdown the humus further, resulting in the release of inorganic nutrients through a process known as mineralization.
Q.3) How is the ecosystem classified?
Ans. 1.) The terrestrial and marine ecosystems are two basic types of ecosystems.
2.) Terrestrial ecosystems include forests, grasslands, and deserts, whereas aquatic ecosystems include ponds, lakes, wetlands, rivers, and estuaries.
3.) Crop fields and aquariums are both examples of man-made ecosystems.
Q.4) Short note: Succession of Plants
Ans. 1.) The succession of plants is named hydrarch or xerarch depending on the nature of the habitat – whether it is water (or very wet places) or very dry areas.
2.) In moist locations, hydrarch succession occurs, with the successional series progressing from hydric to mesic environments.
3.) Xerarch succession, on the other hand, occurs in dry places and progresses from xeric to mesic circumstances.
4.) As a result, both hydrarch and xerarch successions result in mesic water conditions — neither too dry (xeric) nor too wet (mesic) (hydric).
Q.5) What are the major difference between primary and secondary succession?
Ans. 1.) Small phytoplankton are the pioneers in water’s primary succession, which are gradually replaced by rooted-submerged plants, rooted-floating angiosperms, free-floating plants, reedswamp, marsh-meadow, scrub, and finally trees.
2.) A forest would be the culmination once more. The sea body gradually transforms into land.
3.) The invasion of secondary succession species is determined by the state of the soil, the availability of water, the environment, as well as the seeds or other propagules present.
4.) Because the soil is already present, the pace of succession is significantly faster, and so the peak is achieved much sooner.
Q.6) Explain the detritus food chain?
Ans. 1.) The detritus food chain (DFC) starts with organic matter that has died.
2.) Decomposers, which are heterotrophic organisms such as fungi and bacteria, make up the majority of it.
3.) They get their energy and nutrients by decomposing decaying organic debris, also known as detritus.
4.) Saprotrophs are another name for these (sapro: to decompose).
5.) Decomposers produce digestive enzymes that break down dead and waste materials into simple, inorganic components that they may consume.
- Answer in brief
Q.1) What is succession?
Ans. 1.) All communities have one thing in common: their makeup and structure are always changing in response to changing environmental conditions.
2.) This transformation occurs in a systematic and sequential manner, paralleling changes in the physical environment.
3.) These changes eventually lead to a climax community, which is a community that is in close equilibrium with the environment.
4.) Ecological succession is the steady and reasonably predictable shift in a specific area’s species composition.
5.) During succession, certain species colonies an area and increase their population, while other species’ numbers drop and even perish.
6.) Succession is thus a process that begins in an area devoid of live beings – these could be regions where no living organisms have ever existed, such as bare rock, or areas where all living organisms have been lost.
7.) The first is referred to as main succession, whereas the second is referred to as secondary succession.
Q.2) With help of flow chart describe the decomposition cycle in a terrestrial ecosystem.
Ans.
Q.3) What is Primary productivity?
Ans. 1.) The amount of biomass or organic matter generated per unit area by plants during photosynthesis over time is referred to as primary production.
2.) It is measured in grammes per square meter (gm–2) or calories per square meter (kcal m–2). 3.) Productivity refers to the rate at which biomass is produced.
4.) To compare the productivity of different ecosystems, it is stated in units of gm–2 yr–1 or (kcal m–2) yr–1.
5.) Gross primary productivity (GPP) and net primary productivity (NPP) are two types of productivity (NPP).
6.) The rate at which organic matter is produced during photosynthesis determines an ecosystem’s gross primary productivity.
7.) Plants use a significant amount of GPP in their respiration.
8.) The net primary productivity (R) equals gross primary productivity minus respiration losses (NPP). NPP = GPP – R
Q.4) Explain the carbon cycle.
Ans. 1.) Carbon makes up 49% of the dry weight of living beings, making it the second most abundant element after water.
2.) When we look at the overall amount of carbon in the world, we find that 71% of it is dissolved in the oceans.
3.) The amount of carbon dioxide in the atmosphere is regulated by this marine reservoir.
4.) Fossil fuels also serve as a carbon storage facility. Carbon is cycled through the atmosphere, the seas, and living and dead species.
5.) According to one estimate, photosynthesis fixes 4 X103 kg of carbon in the biosphere each year.
6.) Through the respiratory actions of producers and consumers, a significant amount of carbon is released into the atmosphere as CO2.
7.) Decomposers add to the CO2 pool by digesting waste materials and dead organic matter on land and in the waters.
8.) A portion of the fixed carbon is lost to sediments and is no longer in circulation.
9.) Wood burning, forest fires, and organic matter combustion, fossil fuel combustion, and volcanic activity are all additional sources of CO2 release into the atmosphere.
10.) The carbon cycle has been greatly altered by human activity.
11.) Rapid deforestation and widespread fossil fuel combustion for energy and transportation have dramatically increased the rate of carbon dioxide release into the atmosphere.