Science (English Medium) कक्षा १२ - CBSE Important Questions

What is an age-pyramid?

Mention any two examples where the organisms involved are commercially exploited in agriculture.

What is commensalism?

What is brood parasitism? Explain with the help of an example.

Write the best method to measure the population density of a single Banyan tree in comparison to Partlzenium weeds in a forest by an ecologist. Explain and justify your answer.

“It is often said that the pyramid of energy is always upright. On the other hand, the pyramid of biomass can be both upright and inverted.” Explain with the help if examples and sketches.

How are productivity, gross productivity, net primary productivity and secondary productivity interrelated ?

The primary productivity in an ecosystem is expressed as ______.

1. gm^-2 yr^-1
2. gm^-2 yr
3. Kcal m^-2 yr^-1
4. Kcal m^-2

Assertion (A): Decomposition process is slower if detritus is rich in lignin and cutin.

Reason (R): Decomposition is largely an oxygen requiring process.

List any four techniques where the principle of ex-situ conservation of biodiversity has been employed.

Identify ‘a’ and ‘b’ in the figure given below representing proportionate number of major vertebrate taxa.

Why should we conserve biodiversity ? How can we do it?

'in-situ' Conservation can help endangered/threatened species. Justify the statement.

Name and describe any three causes of bio-diversity losses.

Explain the concept of "co-extinction" by taking two examples.

List any three major causes of loss of biodiversity.

Enlist two criteria that are used to identify a region for maximum protection as 'Biodiversity hotspots'.

"Forests provide intangible benefits to us." Explain by taking three different areas, how.

The IUCN Red Data List (2004) in the last 500 years documents the extinction of nearly 784 species including ______.

What is ferromagnetism?