CBSE Class 12 Biology Ecosystem (1). CBSE issues sample papers every year for students for class 12 board exams. Students should solve the CBSE issued sample papers to understand the pattern of the question paper which will come in class 12 board exams this year. The sample papers have been provided with marking scheme. It’s always recommended to practice as many CBSE sample papers as possible before the board examinations. Sample papers should be always practiced in examination condition at home or school and the student should show the answers to teachers for checking or compare with the answers provided. Students can download the sample papers in pdf format free and score better marks in examinations. Refer to other links too for latest sample papers.
1 What does the base tier of the ecological pyramid represent?
2 In the North East region of India, during the process of jhum cultivation, forests are cleared by burning and left for regrowth after a year of cultivation. How would you explain the regrowth of forest in ecological term?
3 Climax stage is achieved quickly in secondary succession as compared to primary succession. Why?
4 Why are oceans least productive?
5 Organisms at a higher trophic level have less energy available. Comment.
6 What are the shortcomings of ecological pyramids in the study of ecosystem?
7 How do you distinguish between humification and mineralisation?
8 List three parameters used for constructing ecological pyramids. Describe any one instance where the pyramid may look inverted.
9 Differentiate between a detritivore and a decomposer giving an example of each.
10 Construct an ideal pyramid of energy when 1,00,000 joules of sunlight is available. Label all its trophic levels.
11 Construct a pyramid of biomass starting with phytoplanktons. Label 3 trophic levels. Is the pyramid upright or inverted? Why?
12 Explain with the help of two examples how the pyramid of number and the pyramid of biomass can look inverted.
13 Justify the given statements:
a) Energy flow in an ecosystem is unidirectional
b) Secondary succession is faster than primary succession
14 What will happen to an ecosystem if:
a) All producers are removed
b) All organisms of herbivore level are eliminated
c) All top carnivore population is removed
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