Biology Term 2 - Delhi Set 2 2021-2022 Science (English Medium) Class 12 Question Paper Solution

State the most important contribution of the following microbes for human welfare:

Monascus purpureus

State the most important contribution of the following microbes for human welfare:

Trichoderma Polysporum

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

State the mode of action of cocaine on the human body. Write the scientific name of the source plant it is obtained from.

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

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".

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.

What would be the best method to measure the total population density of a dense bacterial culture in a petridish and why?

Different types of antibodies are produced in our body by the B-lymphocytes in response to a pathogen that enters in our blood. Name any two antibodies produced and draw a schematic representation of an antibody molecule and label its four parts.

Why do doctors have to carry many tests for selecting a person to be a suitable donor for someone who is going for an organ transplant and not take the organ from just any body? Explain giving reason.

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

A cell-free method of amplifying DNA first developed in the mid 1980's revolutionised the field of biotechnology, Name the method and explain the basic steps of the technique involved.

Explain how recombinant human insulin was prepared in 1983 by Eli Lily an American company.

How does a gene therapy involving direct modification of the cells, in order to achieve a therapeutic goal is used in the treatment of ADA deficiency? Explain.

A host cell must be made competent, before it is able to receive an rDNA. Justify.

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

Name any two biodiversity hot spots in India.

Cloning of genes, play a very significant role in genetic engineering, helping the transfer of desirable foreign genes into different hosts. The scientists, to make this process easier and effective are creating engineered vectors in such a way that they help easy linking of foreign DNA and selection of recombinants from non-recombinants. 'pBR322' is one such engineered vectors developed by scientists. A diagram of an engineered vector pBR322 is given below:

1. Name the host for this cloning vector.
2. Identify 'Rop' and 'Ori' in the diagram from 'U', 'V', 'W', 'X', 'Y' and 'Z'. Write their functions.
3. Draw the fragments that will be formed by the action of 'Z' (marked in the diagram) on the specific site of the DNA segment given below:
   5' --- GTACGAATCCTGA --- 3'
   3' --- CATGCTTAGGACT --- 3'

The results of the study are depicted in the graph below:

1. How does the treatment with 2.5 mg/kg bring an effect on cholesterol metabolism when compared from 24 hours and 144 hours?
2. Write any two natural sources from where dsRNA molecule could be obtained for silencing the specific mRNA.
3. How is RNAi used in controlling the infection on the roots of tobacco plants by the nematode Meloidogyne incognitia?