Science (English Medium) Class 12 - CBSE Question Bank Solutions for Biology

Organic farmer use Trichoderma as biological control agents. Explain.

Organic farmer use Baculovirus as biological control agents. Explain.

Read the paragraph given below and answer and questions that follow:

1. Taq polymerase after its discovery replaced E.coli DNA polymerase in PCR technique. Explain giving reasons why was the need felt for the change?
2. What is a primer and its importance in PCR?
3. Write the importance of PCR as a diagnostic tool.

Read the following paragraph and answer the questions that follow:

1. Name the human disease for which the gene therapy was used for the first time.
2. Explain the steps of gene therapy carried to cure the disease using the lymphocytes of the patient. Why is this therapy not a permanent cure of the disease?
3. Write the possible permanent cure of the disease by the gene therapy that is in progress. 

A Tight one-to-one relationship between many species of fig tree and certain wasps is an example of ______.

Assertion (A): Determining the sex of an unborn child followed by MTP is an illegal practice.

Reason (R): Amniocentesis is a practice to test the presence of genetic disorders also.

Assertion (A): Synthetic oligonucleotide polymers are used during Annealing in a PCR.

Reason (R): The primers bind to the double stranded DNA at their complementary regions.

1. Give an example of a genus of virus used as narrow spectrum insecticidal biocontrol agent.
2. How does its use serve as an aid in overall integrated pest management programme?

"Cattle and goats do not browse the Calotropis plant." Justify the statement giving reasons.

Write the scientific name of the source organism of the thermostable DNA polymerase used in PCR.

State the advantage of using Thermostable DNA polymerase.

"Biodiversity plays a major role in many ecosystem services that nature provides."

Describe any two broadly utilitarian arguments to justify the given statement.

"Biodiversity plays a major role in many ecosystem services that nature provides."

State one ethical reason for conserving biodiversity.

Bioreactors are the containment vehicles of any biotechnology-based production process. For large scale production and for economic reasons the final success of biotechnological process depends on the efficiency of the bioreactor.

Answer the following questions w.r.t. the given paragraph:

1. List the operational guidelines that must be adhered to so as to achieve optimisation of the bioreactor system. Enlist any four.
2. Mention the phase of the growth we refer to in the statement "Optimisation of growth and metabolic activity of the cells".
3. Is the biological product formed in the bioreactor suitable for the intended use immediate? Give reason in support of your answer.

Interaction between clown fish living among the stinging tentacles of sea anemone is an example of ______.

"Abingdon tortoise in Galapagos islands became extinct within a decade on introduction of goats in the island." Explain giving reason.

Many copepods live on the body surface of marine fish. This relationship is an example of ______.

"Some species of insects and frogs have evolved with various specific features that help them from being detected."

1. Justify the statement giving reasons.
2. Mention any two such features.

A pregnant human female was advised to undergo MTP. It was diagnosed that the fetus she was carrying had developed from a zygote having 45 chromosomes with only one X chromosome.

1. What is this condition called and how does it arise?
2. Why was she advised to undergo MTP?

A farmer grew 2 varieties of corn crops in fields A and B. He grew normal corn crops in field A and GM corn crops in field B. He observed corn borers attacked only in field A. To control it, spores of Bt were sprayed in field A.

1. Name the gene in the spores responsible for the control of this pest.
2. What effect will the spores of Bt have on the insect pest?
3. How has field B developed resistance against this pest?