Molecular Basis of Inheritance

CBSE Class 12 Biology · every board question from this chapter, 2023–2026 · 61 of them repeated across years

• In a human, the average gene consists of (i) bases and the largest known human gene contains (ii) bases. Select the correct…2026
• To separate repetitive DNA from bulk genomic DNA, which of the following method is used?2026asked 2×
• A DNA molecule is 160 base pairs long. It has 30 % Guanine. How many Adenine bases are present in this DNA molecule?2026asked 3×
• Taylor and colleagues performed an experiment on which of the following organisms to provide proof for semi-conservative…2026
• Choose the correct statements: (i) Polycistronic mRNA is generally found in eukaryotes. (ii) The RNA polymerase II transcribes…2026asked 3×
• Four different transcription units are shown below. Choose the option with the correct image.2026
• A bacterium having radioactive thymidine in its DNA is allowed to multiply in a medium having non-radioactive thymidine for two…2026
• Two plants whose DNA has been sequenced are2026
• Which of the following is used to visualize DNA bands under UV light after gel electrophoresis?2026asked 3×
• C-peptide of human insulin is:2026
• The smallest part of DNA molecule that can be changed by point mutation is:2026
• Messelson and Stahl's experiment carried out centrifugation in CsCl 2 density gradient to separate:2026
• In RNAi, genes are silenced using which of the following biomolecules?2026asked 2×
• A gene having non-coding introns and coding exons is known as:2026
• A DNA molecule is 140 base pairs long. It has 20 % thymine. How many guanine bases are present in the molecule?2026
• Assertion: Repetitive sequences make up a very large portion of human genome. Reason (R): Repetitive sequences do not have direct…2026asked 3×
• Assertion: DNA cannot pass through cell membrane of a bacterial cell. Reason (R): DNA is a hydrophilic molecule.2026asked 3×
• Assertion: Repetitive sequences are stretches of DNA sequences that are thought to have no direct coding functions. Reason (R):…2026asked 2×
• The diagram below shows the sequence of amino acids in part of haemoglobin molecule. (i) If the base T is substituted with A, in…2026asked 2×
• One of the salient features of the genetic code is that it is nearly universal from bacteria to humans. Mention two exceptions to…2026
• What is meant by translation in protein synthesis? Explain charging of tRNA (aminoacylation of tRNA) and mention its importance…2026asked 3×
• Construct a complete transcription unit with promoter and terminator on the basis of the hypothetical coding strand given below:…2026asked 3×
• Draw a labelled diagram of a 'replicating fork' showing the polarity. Why does DNA replication occur within such 'fork'?2026asked 2×
• What is a genetic code? Why did scientists feel the need to propose a genetic code? Genetic code is said to be 'Universal'. Why?2026asked 3×
• Read the following passage and answer the questions that follow: Gene expresses itself in a cell system as a protein/enzyme. How…2026asked 3×
• Read the following passage and answer the questions that follow: The process of copying genetic information from template strand…2026asked 3×
• (i) Describe the series of experiments conducted by Frederick Griffith. Comment on the significance of the result obtained. (ii)…2026asked 2×
• The following questions are based on the classic experiment conducted by Hershey and Chase. (i) Why were bacteriophages chosen by…2026
• (i) Watson and Crick's discovery of double helical structure was based on which two findings. Also mention the name of the…2026asked 2×
• Observe the segment of mRNA given below and answers the questions given below: (i) Explain and illustrate the steps involved to…2026asked 2×
• (i) Identify the structure shown above and name the process taking place. (ii) Write the source of energy for the process and…2026
• Describe how the lac operon operates both in the presence and absence of an inducer in E. coli. OR (i) Differentiate between…2026
• The RNA triplet UAG acts as a stop codon which terminates the synthesis of a polypeptide. Below is given a strand of DNA which…2025
• The region of chromatin that are actively transcribed are thought to be:2025
• The histone core in a nucleosome of chromatin thread is a/an:2025
• What are minisatellites?2025asked 2×
• In its extended 'beads-on-string' form of chromatin, the 'beads' in the string represent:2025
• Cistron is a segment of DNA coding for a:2025
• Choose the correct option that indicates the enzyme, ribozyme in bacteria that acts as a catalyst.2025
• In its extended 'beads-on-string' form of chromatin, the 'string' in the 'beads-on-string' represent:2025
• The process of splicing in eukaryotes represents the dominance of the:2025
• In E. coli, a DNA sequence that specifies where RNA polymerase will bind and initiate transcription of a gene is:2025
• In its extended 'beads-on-string' form of chromatin, the 'beads' are composed of:2025
• Regulation of lac operon by repressor is referred to as:2025
• The simplest definition of a gene in eukaryotes is - A unit of DNA that has information to mainly specify the synthesis of:2025
• The approach of sequencing the whole set of genome, including all the coding and non-coding sequences in HGP is:2025
• The substrate used during DNA replication by the enzyme DNA-dependent DNA polymerase is:2025
• SNPs in Human Genome Project refers to:2025
• During the process of transcription, after binding to a promoter, RNA polymerase catalyses and makes the bases in the template…2025
• The approach used in HGP of identifying all the genes that are expressed as RNA is referred to as:2025
• Some of the important goals of HGP are given below. Choose the correct goal of HGP.2025
• In molecular biology, who proposed that genetic information flows in one direction?2025
• The phosphoester linkage in the nucleotides is between2025
• Given below is a heterogeneous RNA formed during Eukaryotic transcription: How many introns and exons respectively are present in…2025asked 3×
• If the sequence of bases in DNA is ATTCGATG, then the sequence of bases in the transcript will be:2025
• In a DNA, the percentage of thymine is 20. What is the percentage of guanine in it?2025
• In a translational unit UTRs are present at:2025
• Use the given information to select the amino acid attached to the 3' end of tRNA during the process of translation, if the…2025
• Use the given information to select the amino acid attached to the 3' end of tRNA during the process of translation, if the…2025
• Use the given information to select the amino acid attached to the 3' end of tRNA during the process of translation, if the…2025
• 'AGGTATCGCAT' is a sequence from the coding strand of a gene. What will be the corresponding sequence of the transcribed mRNA?2025
• Study the items of Column-I and those of Column-II: Choose the option that correctly matches the items of Column-I with those of…2025asked 3×
• Isolation of DNA from a fungal cell can be achieved by using:2025
• Isolation of DNA from a bacterial cell can be achieved by using:2025
• Removal of RNA polymerase-III from nucleoplasm of a eukaryotic cell will affect the transcription of which of the following?2025
• The sequence of nitrogenous bases in a segment of a coding strand of DNA is 5' - AATGCTAGGCAC - 3'. Choose the option that shows…2025asked 3×
• Which enzyme(s) will be produced in a bacterial cell in which 'UAG' is inserted in the 'lac-y gene' due to mutation? Choose the…2025
• The correct depiction of the experiment performed by Matthew Meselson and Franklin Stahl to prove that DNA replicates…2025asked 3×
• If Meselson and Stahl's experiment is continued for 80 minutes (till III generation) then what would be the ratio of DNA…2025asked 3×
• What would happen if a gene encoding a polypeptide of 50 amino acids, 25^ th Codon (UAU) is mutated to "UAA"?2025
• During gel electrophoresis migration of DNA fragments leading to their separation takes place on the agarose gel. Choose the…2025
• Isolation of DNA from a plant cell can be achieved by using:2025
• The correct depiction of the centrifugation step of the experiment conducted by Alfred Hershey and Martha Chase on using…2025
• In a DNA, percentage of thymine is 20. What is the percentage of Guanine?2025
• Assertion: Scaffold proteins are non-histone chromosomal proteins. Reason (R): They are rich in lysine and arginine.2025
• Assertion: One of the property of genetic code is degeneracy. Reason (R): Some amino acids can be coded by more than one codon.2025asked 2×
• Assertion: Replication of DNA takes place in S phase of the cell cycle. Reason (R): DNA replication and cell division cycle…2025asked 2×
• Study the given molecular structure of double-stranded polynucleotide chain of DNA and answer the questions that follow. How many…2025asked 3×
• Given below are the diagrammatic representations of the replicating fork of DNA in E. coli. Study the diagrams and answer the…2025asked 3×
• Assume that the given mRNA (start site is not depicted) is theoretically translated in two reading frames. Translation starting…2025asked 3×
• Write the scientific name of the source organism of the thermostable DNA polymerase used in PCR. State the advantage of using…2025
• Construct and label a transcription unit from which the RNA segment given below has been transcribed. Write the complete name of…2025
• The base sequence in one of the strands of DNA is: 'TAGCATGAT' Give the base sequence of its complementary strand. How are these…2025
• A segment of DNA, 'TTG AGG GGG ATG' was translated into an oligopeptide with the amino acids, Lysine - Serine - Proline -…2025
• Explain how the addition of lactose in the medium regulates the switching on of the lac operon in bacteria.2025asked 3×
• Study the given below single strand of deoxyribonucleic acid depicted in the form of a "stick" diagram with 5' - 3' end…2025asked 3×
• Study the diagram given below and answer the questions that follows: Identify the structure shown in the above figure. Identify…2025asked 3×
• The process of copying the genetic information from one strand of DNA into RNA is termed as transcription. The principle of…2025asked 3×
• Write the features a molecule should have to act as a genetic material. In the light of the above features, evaluate and justify…2025asked 2×
• The type of bond represented by the dotted line '-----' in a schematic polynucleotide chain is:2024asked 3×
• A DNA fragment has 2500 nucleotides, out of which 240 are Guanine. How many bases having double hydrogen bonds between them does…2024
• How many base pairs will be there in 20 nucleosomes in a DNA double helix?2024
• A DNA fragment has 2000 nucleotides, out of which 140 are Adenine. How many bases does this DNA segment possess that have triple…2024
• A DNA fragment has 3000 nucleotides, out of which 160 are Guanine. How many bases having double hydrogen bonds between them does…2024
• You know that there are twenty different types of naturally occurring amino acids and four different types of bases in the DNA. A…2024
• Which was the last of the 24 human chromosome to be completely sequenced?2024
• Listed below are some amino acids and their corresponding mRNA codons: Select the DNA sequence that would code for the following…2024
• Which one of the following statements is correct in the context of observing DNA separation by agarose gel electrophoresis?2024asked 2×
• In the double helical structure of DNA molecule, the strands are:2024asked 3×
• In a 'transcription unit', the 'terminator' is located towards the:2024asked 3×
• Which of the options has correct identification of 'P', 'Q' and 'R' in the illustration of 'Central Dogma' given below?2024asked 3×
• In an experiment, E. coli is grown in a medium containing ^14 NH 4 Cl. ( ^14 N is the light isotope of Nitrogen) followed by…2024asked 3×
• The commonly used vector for human genome sequencing was/were:2024
• Match the following genes of the lac operon listed in column 'A' with their respective products listed in column 'B': Select the…2024asked 3×
• For the replication of the first recombinant DNA, Stanley Cohen and Herbert Boyer used the DNA polymerase of:2024
• If the sequence of nitrogen bases of the coding strand in a transcription unit is 5^′ - ATGAATG - 3', the sequence of bases in…2024asked 3×
• Assertion: Primary transcripts in eukaryotes are subjected to splicing to remove the introns. Reason (R): Primary transcripts…2024asked 3×
• Assertion: RNA is unstable and can mutate at a faster rate. Reason (R): The presence of 2' - OH group in every nucleotide of RNA…2024asked 3×
• Assertion: The sugar-phosphate backbone of two chains in DNA double helix show anti-parallel polarity. Reason (R): The…2024
• Assertion: In molecular diagnosis, single stranded DNA or RNA tagged with radioactive molecule is called a probe. Reason (R): A…2024asked 3×
• If the base adenine constitutes 31% of an isolated DNA fragment, then write what will be the expected percentage of the base…2024asked 3×
• Given below is an illustration of the experiment performed by Louis Pasteur. Explain the experiment and its conclusion.2024
• 5^′-G^ A A T T C-3^′ 3^′-C T T A A G-5^′ Name the restriction enzyme that recognises the given specific sequence of bases. What…2024
• Consider the given data of a hypothetical small portion of mRNA that codes for a functional polypeptide chain and answer the…2024asked 3×
• Name and write two characteristics of the type of DNA that forms the basis of DNA fingerprinting technique. Mention any two…2024asked 2×
• Identify the picture given below and name the tool under which it was viewed. What do the dark spots represent in the picture?…2024
• (i) Write the karyotype and the genetic disorder of an individual who has developed from a zygote formed from an 'XX' egg…2024asked 2×
• Explain the process by which amino acid gets attached to the tRNA molecule during translation process. How does the translation…2024
• Why does DNA replication occur within a replication fork and not in its entire length simultaneously? "DNA replication is…2024asked 3×
• Explain the processing of heterogeneous nuclear RNA (hnRNA) into a fully functional mRNA in eukaryotes. Where does this…2024asked 2×
• Study the steps shown below, that are carried during a specific technique: Identify the steps 'A' and 'D' in the diagram. What…2024
• Generally, in eukaryotic cells the average length of a transcription unit along a DNA molecule is about 8,000 nucleotides, so the…2024
• Answer the following questions that are based on "Hershey and Chase" experiment using E. coli and bacteriophage: (i) Why did they…2024
• Study the schematic diagram given below and answer the questions that follow: (i) Identify the polarity from 'X' to ' X ' in the…2024asked 3×
• Natural selection operates in different ways in nature. (i) Identify the type of natural selection depicted in the graph above.…2024asked 2×
• Given below is a list of steps Meselson and Stahl carried out in their experiment to prove that DNA replication is…2023asked 2×
• Identify the region 'X', the factor 'Y' and the enzyme 'Z' involved in the process of transcription in prokaryote as shown in the…2023asked 3×
• Identify the element used by Hershey and Chase to label the protein in their experiment, from the following options:2023
• Study the DNA profiles obtained as a result of DNA fingerprinting of a child 'X' and three individuals 1, 2 and 3. Which one of…2023asked 2×
• Which of the following samples of DNA in the table given below will give the desired result during polymerase chain reaction?2023
• DNA profiles of the child and three individuals 1, 2 and 3 who claim to be the parents of the child are given below. Select the…2023
• Assertion: For sequencing, the total DNA from a cell is isolated and converted into random fragments. Reason (R): DNA is a very…2023
• Assertion: For DNA sequencing, the total DNA from a cell is isolated and converted into random fragments of relatively smaller…2023
• Assertion: In an operon, the regulator and operator genes are not associated with the constitutive genes. Reason (R):…2023
• State the principle involved in separation of DNA fragments using gel electrophoresis. How are DNA fragments visualised once they…2023
• Write the scientific name of the source organism of the themostable DNA polymerase used in PCR. State the advantage of using…2023
• (i) How many types of RNA polymerases are there in a eukaryote cell? Mention which one of them transcribes hnRNA. (ii) Write the…2023asked 3×
• Human Genome Project (HGP) was a mega project launched in the year 1990 with some important goals. Enlist any four prime goals of…2023asked 3×
• Gene expresses itself in a cell system as a protein/enzyme. How does an expression of gene occur in a cell system and when does…2023asked 3×
• (i) Draw a labelled diagram of a replication fork in a prokaryote indicating the process of DNA replication. (ii) Differentiate…2023
• (i) How and why is charging of tRNA essential in the process of translation? (ii) State the function of ribosome as a catalyst in…2023
• Meselson and Stahl carried out an experiment to prove the nature of DNA replication. Recall the experiment and answer the…2023asked 2×
• Name and describe the steps involved in the technique widely used in forensics that serves as the basis of paternity testing in…2023
• Protein synthesis requires the services of all three types of RNAs, namely t-RNA, m-RNA and r-RNA. Explain the role of each of…2023asked 2×

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