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

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?

Non viral and non vector methods are sometimes used to transfer genes or alien DNA into a plant cell. Explain one such method used in genetic engineering.

"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 ______.

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

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

By using Punnett square depict the genotypes and phenotypes of test crosses (where green pod colour (G) is dominant over yellow pod colour (g)) in Garden pea with unknown genotype.

Which one of the following groups faces maximum threat of extinction? 

The sixth extinction in progress currently is different from all previous extinctions on earth as it is ______.

Observe the contents 1, 2, 3 and 4 of soil samples A, B and C shown in the graph. If the temperature and soil moisture of all soil samples are identical, which soil sample (s) will show faster decomposition?

1 indicates lignin content, 2 indicates chitin, 3 indicates nitrogen content, and 4 indicates sugar content

Can we call human evolution as adaptive radiation?

Name a genus of baculovirus.

Why are scared groves highly protected?

How do organic farmers control pests?