Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions for Biology

Though the conflict between humans and wildlife started with the evolution of man, the intensity of conflict has increased due to the activities of modern man. Justify your answer with suitable examples.

World’s most problematic aquatic weed is ______.

Which of the following exhibits biomagnification?

Which one of the following impurities is easiest to remove from wastewater?

Algal blooms impart a distinct colour to water due to ______.

What is cultural eutrophication?

Name an industry which can cause both air and thermal pollution and as well as eutrophication.

What is an algal bloom?

What do you understand by biomagnification?

What are the three major kinds of impurities in domestic wastewater?

Is it true that if the dissolved oxygen level drops to zero, the water will become septic. Give an example which could lower the dissolved oxygen content of an aquatic body.

How has DDT caused decline in bird population?

Observe figure and answer the following questions.

Biomagnification of DDT in an aquatic food chain

1. What ecological term is used to describe the DDT accumulation at different trophic levels?
2. List any one effect of DDT accumulation on birds
3. Will DDT accumulation lead to eutrophication?
4. Does it affect the BOD?
5. Name disease caused by accumulation of any heavy metal.

A true breeding pea plant, homozygous dominant for inflated green pods is crossed with another pea plant with constricted yellow pods (ffgg). With the help of Punnett square show the above cross and mention the results obtained phenotypically and genotypically in F₁ generation.

There was a loss of biodiversity in the ecosystem due to a new construction project in that area. What would be its impact on the ecosystem? State any three.

List any three major causes of loss of biodiversity.

Can we use slurry of human excreta instead of cowdung slurry to produce biogas in a typical biogas plant? Support your answer giving reasons.

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

Name any two biodiversity hot spots in India.

What would be the best method to measure the total population density of the number of fishes in river and why?