Science (English Medium) कक्षा १२ - CBSE Important Questions

Differentiate between the genetic codes given below:
Unambiguous and Universal

Differentiate between the genetic codes given below:
Degenerate and Initiator

Answer the following question.
List the two methodologies which were involved in the human genome project. Mention how they were used.

Answer the following question.
Describe the structure and function of a t-RNA molecule. Why is it referred to as an adapter molecule?

Answer the following question.
Explain the process of splicing of hn-RNA in a eukaryotic cell.

The human chromosome with the highest and least number of genes in them are respectively ______.

Which of the following amino acid residues will constitute the histone core?

(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?

Observe the segment of mRNA given below.

(a) Explain and illustrate the steps involved to make fully processed hnRNA?

(b) Gene encoding RNA Polymerase I and III have been affected by mutation in a cell. Explain its impact on the synthesis of a polypeptide, stating the reasons.

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

Where are the untranslated regions located on mRNA and why?

Explain the process of binding of ribosomal units to mRNA during protein synthesis.

A short piece of DNA, having 20 base pairs, was analyzed to find the number of nucleotide bases in each of the polynucleotide strands. Some of the results are shown in the table.

How many nucleotides containing Adenine were present in strand 2?

What is the smallest part of a DNA molecule that can be changed by a point mutation?

• Assertion: Ribosomal RNA is synthesized in the nucleus of the cell.
• Reason: It is translated with the enzyme RNA polymerase III.

The image below shows the result of plating bacteria in a chromogenic medium after incorporating the gene of interest in the plasmid. Some plates had blue colonies; some plates had white colonies. A single bacterium extracted from Plate I, II, and III is shown below:

On the basis of your observations:

1. Identify the plate(s) which is/are white. Give a reason.
2. Identify the plate(s) which is/are blue. Give a reason.

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.

Write the probable differences in eating habits of Homo habilis and Homo erectus.

Explain co-evolution with reference to parasites and their hosts.

How did Darwin explain adaptive radiation ? Give another example exhibiting adaptive radiation.