Ecosystem

Describe the phosphorus cycle in an ecosystem. How does it differ from the carbon cycle with respect to (i) a gaseous phase and (ii) the reservoir involved?

Give one example each of an inverted pyramid of (i) number and (ii) biomass, and state why it is inverted.

Explain the flow of energy through an ecosystem with the help of a diagram. Why are ecological pyramids of energy always upright?

Explain the process of decomposition in an ecosystem, naming the steps involved (fragmentation, leaching, catabolism, humification, mineralisation).

What is ecological succession? Differentiate between primary and secondary succession. Describe the stages of hydrarch succession leading to a climax community.

Differentiate between gross primary productivity (GPP) and net primary productivity (NPP). Write the relationship between them.

What are ecosystem services? List any four services provided by a healthy forest ecosystem.

Why is the number of trophic levels in a food chain usually limited to 4 or 5?

How many marks is Ecosystem worth in the Class 12 board exam?

Around 6 marks of the 70-mark CBSE Biology theory paper, based on the official unit-wise weightage. Energy flow, ecological pyramids, nutrient cycles — draw them.

Is Ecosystem easy or hard?

It's rated medium — a moderate-difficulty chapter in Class 12 Biology. Most students need about 3 hours to cover it well.

What should I focus on in Ecosystem?

Going by the board papers themselves, the recurring areas are Nutrient Cycling, Ecological Pyramids, Energy Flow, Decomposition, Ecological Succession — that's where the marks actually sit.

What questions come from Ecosystem in board exams?

Between 2019–2024, CBSE board papers asked questions from this chapter on Nutrient Cycling, Ecological Pyramids, Energy Flow, Decomposition — 1- to 5-mark questions.