CBSE 2024-25 Competency-Based Questions With Answers: Assessment is vital in the learning process as it reinforces the knowledge of the students that they acquire during a course. These questions are crafted as they can help to evaluate the understanding of the students on various topics and subjects. The Central Board of Secondary Education has introduced competency-based questions for class 12 for the current academic session 2024-25. Students who want to excel in their exams and score well can go through this article. This article is going to help the students to prepare for the exam.
Multiple-Choice Questions
1. Which of the following occurs as a result of DNA replication being semi-conservative?
A)An AChromosome number becomes half in the gametes.
B)Each chromosome has half DNA and half RNA.
C)Parental characters are found in each chromosome.
D)Each new DNA strand has half the number of nucleotides compared to the parent DNA strand"
2. An organism has 6 X 109 bp in its DNA. Which of the following is likely to be closest in height to the length of its DNA molecule?
- A wardrobe: 2 m
- A tall tree: 20 m
- An A4 sheet: 20 cm
- A eukaryotic nucleus: 10-10 m
A)A Wardrobe
B)A tall tree
C)An A4 sheet
D)A eukaryotic nucleus
3. Which of the following is true about the structure of DNA and RNA?
P) The nitrogenous base is devoid of an OH group in DNA.
Q) The nitrogenous base of RNA gains the OH group lost by DNA.
R) The pentose sugar in RNA combines with an extra OH group.
S) The pentose sugar in DNA loses an OH group to form deoxyribose.
A)only P
B)only S
C)only R and S
D)only P and Q
4. Keratin is a common protein found in the human body with its gene on chromosome no. 12. Centromeres are constricted regions on the chromosome that help during cell division. In which of the following regions will the keratin gene and centromere be found?
| Option | Keratin | Centromere |
| P | euchromatin | euchromatin |
| Q | heterochromatin | heterochromatin |
| R | euchromatin | heterochromatin |
| S | heterochromatin | euchromatin |
A)P
B)Q
C)R
D)S
5. In Griffith's experiment, when he injected a mixture of heat-killed S strain (virulent) and live R bacteria (non-virulent), the mice died. What type of colony/ies would he observe when the bacteria from the dead mice would be plated on a culture medium?
A)Only rough colonies would be observed.
B)Only smooth colonies would be observed.
C)Both rough and smooth colonies would be seen.
D)Each colony would have a mix of both rough and smooth textures.
6. Given below are some statements about DNA replication.
DNA replication is semiconservative.
One of the DNA strands is replicated in a discontinuous fashion.
Each strand of parental DNA acts as a template for the new strand.
DNA replication shows a low level of accuracy.
Based on the statements, pick the correct option.
A)P and S are true and S is the reason for P
B)P and Q are true and Q is the reason for P
C)P and R are true and R is the reason for P
D)S and Q are true and Q is the reason for S
7. Two statements are given below - one is an Assertion (A) and the other is a Reason (R).
Assertion (A): DNA-dependent RNA polymerase catalyses polymerisation in the 5' to 3' direction.
Reason (R): The strand with 5' to 3' polarity is called the coding strand. Which of the following is correct?
A)Both A and R are true, and R is the correct explanation for A.
B)Both A and R are true, but R is not the correct explanation for A.
C)A is true, but R is false.
D)A is false, but R is true.
8. Which of the following statement/s are correct example/s of the degenerate feature of the genetic code?
UAA and UAG act as terminator codons.
CUA codes for leucine in bacteria as well as humans.
Valine is coded for by GUU and GUC.
A)only Q
B)only R
C)only P and Q
D)only P and R
Free Response Question/ Subjective Question
9. A DNA molecule is much longer than the length of the nucleus of a cell. Describe the organization of DNA inside a nucleus.
10. One strand of a DNA segment is made up of repeats of adenine and cytosine - 5' ACACACAC 3' Explain the formation of a dinucleotide (AC) and its base pair from nitrogenous bases.
- State TWO points of similarity between the process of replication and transcription in humans. Describe the fate of the products of replication and transcription for the following:
- location of the product/s
- lifespan of the product/s
In which phase/s of the cell cycle do these processes occur?
- Why is the enzyme ligase not required in DNA amplification using PCR? What will happen if DNA polymerase is used in PCR? Give a reason to support your answer. State one advantage of PCR over DNA replication. For any given sequence of nucleotides, DNA replication is faster than PCR. Justify.
- A DNA sequence consists of 35% cytosine nucleotides. What would be the percentage of adenine nucleotides in the same DNA sequence? Justify your answer. To get access to all the other questions and answers, students and learners can take a look at the FREE PDF that we are providing below. See the link.
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