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

Which of the following life processes is evolved around RNA?

In an mRNA molecule, untranslated regions (UTRs) are present at ______.

UTRs are the untranslated regions present on ______.

Which of the following statements is correct regarding ribosomes?

Regulation of gene expression occurs at the level of ______.

Which cellular process is shown below?

Which of the following are correct statements for a tRNA molecule?

1. It is an adapter molecule.
2. Previously called sRNA (soluble RNA)
3. tRNA has a codon loop that has bases complementary to the code,
4. it also has an amino acid accepter end to which it binds to amino acids. 
5. It is non-specific for each amino acid.

In case of polyembryony, if an embryo develops from the synergid and another from the nucellus which is haploid and which is diploid?

What is polyembryony and how can it be commercially exploited?

Which of the following is true with respect to AUG?

(a) Identify the polarity of x to x’ in the diagram below and mention how many more amino acids are expected to be added to this polypeptide chain.

(b) Mention the codon and anticodon for alanine.

(c) Why are some untranslated sequences of bases seen in mRNA coding for a polypeptide? Where exactly are they present on mRNA?

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

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

How does initiation of the translation process occur in prokaryotes? Explain.

Where are the untranslated regions located on mRNA and why?

Do you think that friends can influence one to take alcohol/drugs? If yes, how may one protect himself/herself from such an influence?

In your view, what motivates youngsters to take to alcohol or drugs and how can this be avoided?

Under polio prevention programme, infants in India were given polio vaccines on a large scale at regular intervals to eradicate polio from the country.

(a) What is a vaccine? Explain how does it impart immunity to the child against the disease.
(b) With the help of an example each, differentiate between active and passive immunity.

Name the pattern of inheritance where F₁ phenotype

resembles only one of the two parents.

Which of the following statements is correct about the role of regulatory proteins in transcription in prokaryotes?