CBSE Class 12 Biology HOTs Ecosystem

CBSE Class XII Biology HOTs Questions Database for chapter Ecosystem. Based on CBSE and CCE guidelines. The students should practice these HOTs Questions to gain perfection which will help him to get more marks in CBSE examination. Based on CBSE and CCE guidelines. Based on the same pattern as released by CBSE every year. CBSE releases HOTs Questions every year. These papers are released prior to the CBSE board examinations so that students can do practice. databse of 1 marks, 2 marks, 3 marks and 5 marks questions.



Q.1) How does the man made ecosystem differ from the natural ecosystem? 

Ans1) Man made ecosystem Natural ecosystem Under regular control not under the control of man And monitored by man


Q.2) Detritus contribute to the biogeochemical cycles, how? 1

Ans2) By the decomposition of detritus, the simple minerals are released into the atmosphere & from there it come back to the earth.

Q.3) Can temperature regulate the rate of decomposition how? 1

Ans3) High temperature favours decomposition and low temperature inhibits decomposition.

Q.4) The detritus food chain and grazing food chain differ. How? 1

.Ans4) Detritus food chain begins from the dead and decaying matter while grazing food chain starts from the green plants(Producers).

Q.5) "The Green Revolution has been achieved due to the use of improved crop varieties and agrochemicals, but it is still not enough to feed the growing population". Suggest a suitable method of agriculture to meet the demand. 1

Ans5) Vegetation changes in turn change the food and shelter for various types of animals. As a result the foresaid changes happen.

Q.6) A species of Solanum is intolerant to salty soil. How will you make the species tolerant to the given abiotic stress?. 1

Ans6) In burnt out forests and flooded lands some soil or sediment is present. There is no need for soil to be formed.

Q.7) Why do we use GM to create tailor made plants?. 1

Ans7) The reservoir of gaseous cycle exists in the atmosphere and for the sedimentary cycle it is located in earth's crust.

2 marks


Q.1) "Flow of energy is unidirectional but nutrient flow is in a cycle" Give reason2
Ans.1) Energy flow is always from the sun to 'producers' and to the different trophic levels. so it is unidirectional. But the nutrients are moving from the living to non-living and vice-versa.
Q.2) "Decomposition is an oxygen requiring process" comment. 2
Ans2) Detritus is rich in nitrogen and sugars. For oxidation of nitrogen and sugars oxygen is required by a class of aerobic microbes.
Q.3) Some organisms are called top carnivores. Why? Give some examples. 2
Ans3) Top carnivores do not have direct predators. so they are referred to as top carnivores eg: Man, Lion, Tiger etc.
Q.4) Given below is the primary hydrarch succession. Bring out the missing sere stages in the process.
Ans4) A-Submerged plant stage, B-Reed swamp stage  C-scrub stage, D-Forest
Q.5) Given below is a simplified model of phosphorus cycle. Write down the natural reservoir of phosphorus and also the processes that put in phosphorus tothe soil.

Ans5) A. Rock minerals B. Weathering C. Decomposition


Q.1) Both carbon and phosphorus cycles are biogeochemical cycles but they differ in three aspects. List them. 3
1. Reservoir exists in atmosphere 1.Reservoir exists in earth's crust
Q.2) Ecosystems should carry a hefty price tag for its various services. Enlist six of them.
Ans2. Considerable inputs of carbon 2.Negligible inputs of phosphorus through rain fall.
through rainfall.



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