Science (English Medium) कक्षा १२ - CBSE Important Questions for Biology

A team of students are preparing to participate in the interschool sports meet. During a practice session you find some vials with labels of certain cannabinoids.

1. Will you report to the authorities? Why?
2. Name of a plant from which such chemicals are obtained.
3. Write the effect of these chemicals on human body.

Suggest a method to ensure an anamnestic response in humans.

Enumerate four most common warning signs of drug and alcohol abuse amongst the youth.

A boy developed some allergic reactions when he straight entered into his air conditioned room after a game of football outside his house. Write any two symptoms that could be noticed in such condition. How does our body combat such conditions?

Epithelial lining of our intestine is considered as secondary lymphoid organ. Justify the statement.

State the medicinal value and the bioactive molecules produced by Streptococcus, Monascus and Trichoderma.

Identify ‘a’, ‘b’ and ‘c’ in the following table:

Identify 'A', 'B', 'C' and 'D' in the given table.
 

Given below is a list of six micro-organisms. State their usefulness to humans.

1. Nucleopolyhedrovirus
2. Saccharomyces cerevisiae
3. Monascus purpureus
4. Trichoderma polysporum
5. Penicillium notatum
6. Propionibacterium sharmanii

Explain the significant role of the genus Nucleopolyhedrovirus in an ecological sensitive area.

How do methanogens help to generate biogas?

Organic farmers prefer the biological control of diseases and pests to the use of chemicals for the same purpose. Justify

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

Study the given diagram of the Sewage Treatment  Plant (S.T.P.) and answer the question that follows:

1. Which one of the two 'S.T.P.' (A) or (B) will be more effective in treating the human excreta in municipal waste?
2. Write the steps followed in carrying the treatment of the sewage in step (Z), once the BOD of sewage is reduced significantly till it is passed on to the "anaerobic sludge digesters".

Name the drug a patient who has undergone a successful organ transplant, has to take all his/her life.

Farmers are often suggested to use the following organism in their crop land so as to improve the soil fertility. Explain.

Rhizobium

Farmers are often suggested to use the following organism in their crop land so as to improve the soil fertility. Explain.

Anabaena 

Given below are the list of the commercially important products and their source organisms. Select the option that gives the correct matches. 

Retroviruses have no DNA. However, the DNA of the infected host cell does possess viral DNA. How is it possible?

Rearrange the following in the correct sequence to accomplish an important biological reaction:

(a) In vitro synthesis of copies of DNA of interest

(b) Chemically synthesized oligonucleotides

(c) Enzyme DNA-polymerase

(d) Complementary region of DNA

(e) Genomic DNA template

(f) Nucleotides provided

(g) Primers

(h) Thermostable DNA-polymerase (from Thermus aquaticus)

(i) Denaturation of ds-DNA