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

Answer the following question.
State the importance of a Genetic code in protein biosynthesis.

Explain the process of aminoacylation of tRNA and its role in the process of translation.

Given below is a stretch of DNA showing the coding strand of a structural gene of a transcription unit?

5’-ATG ACC GTA TTT TCT GTA GTG CCC GTA CTT CAG GCA TAA-3’

1. Write the corresponding template strand and the mRNA strand that will be transcribed, along with its polarity.
2. If GUA of the transcribed mRNA is an intron, depict the sequence involved in the formation of mRNA/the mature processed hnRNA strand.
   i. In a bacterium
   ii. In humans
3. Upon translation, how many amino acids will the resulting polypeptide have? Justify.

Mention the evolutionary significance of the Homo erectus

At which stage during evolution did human use hides to protect their bodies and buried their dead?

Why is secondary immune response more intense than the primary immune response in humans?

Answer the following question:
The principle of vaccination is based on the property of the "memory" of the immune system. Taking one suitable example, justify the statement.

Answer the following question.
Differentiate between the roles of B-lymphocytes and T-lymphocytes in generating immune responses.

State the role of the thymus as a lymphoid organ. Name the cells that are released from it and mention their function.

Why is a malignant tumour considered to be more damaging than a benign tumour? Explain.

Name the type of association that the genus Glomus exhibits with higher plants.

Explain the process of sewage water treatment before it can be discharged into natural water bodies.

Answer the following question:
Why does 'Swiss Cheese' develop large holes?

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?

Why must a cell be made ‘competent’ in biotechnology experiments? How does calcium ion help in doing so?

Explain with the help of a suitable example the naming of a restriction endonuclease.

How are 'sticky ends' formed on a DNA strand? Why are they so called? 

Name two commonly used bioreactors.

State the role of “biolistic gun” in biotechnology experiments.

Name and explain the technique used for separating DNA fragments and making them available for biotechnology experiments.