NCERT NEET Biology English Medium Part-1 | Chapter 24 : Molecular basis of inheritance.

NCERT NEET Biology English Medium Part-1 | Chapter 24 : Molecular basis of inheritance.

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Question 1: In a polynucleotide chain, a nitrogenous base is linked to the OH of 1' C pentose sugar through which of the following bonds?

1. Phosphodiester linkage.
2. N-glycosidic linkage.
3. Phosphoester linkage.
4. Hydrogen bond.

Answer: b. N-glycosidic linkage.

Question 2: If a double-stranded DNA has 20 percent of cytosine, what will be the percentage of adenine in it?

1. 20 percent.
2. 30 percent.
3. 40 percent.
4. 60 percent.

Answer: b. 30 percent.

Question 3: The pitch of the DNA double helix is 3.4 nm. How many base pairs are present in each turn of the helix in a typical B-DNA?

1. 10 base pairs.
2. 11 base pairs.
3. 12 base pairs.
4. 9 base pairs.

Answer: a. 10 base pairs.

Question 4: Which of the following statements is incorrect regarding the structure of DNA proposed by Watson and Crick?

1. The two chains have anti-parallel polarity.
2. Adenine pairs with Thymine via three hydrogen bonds.
3. The backbone is constituted by sugar-phosphate.
4. The two chains are coiled in a right-handed fashion.

Answer: b. Adenine pairs with Thymine via three hydrogen bonds.

Question 5: Central dogma of molecular biology, which states that the genetic information flows from DNA to RNA to Protein, was proposed by?

1. James Watson.
2. Rosalind Franklin.
3. Francis Crick.
4. Erwin Chargaff.

Answer: c. Francis Crick.

Question 6: In some viruses, the flow of information is in reverse direction, that is, from RNA to DNA. Which enzyme catalyzes this reaction?

1. DNA dependent RNA polymerase.
2. RNA dependent DNA polymerase.
3. DNA dependent DNA polymerase.
4. RNA ligase.

Answer: b. RNA dependent DNA polymerase.

Question 7: The positively charged basic proteins that help in the packaging of DNA in eukaryotes are rich in which of the following amino acids?

1. Glutamate and Aspartate.
2. Lysine and Arginine.
3. Tryptophan and Tyrosine.
4. Valine and Leucine.

Answer: b. Lysine and Arginine.

Question 8: A typical nucleosome contains how many base pairs of DNA helix?

1. 100 bp.
2. 200 bp.
3. 300 bp.
4. 400 bp.

Answer: b. 200 bp.

Question 9: The chromatin that is loosely packed, stains light, and is transcriptionally active is referred to as?

1. Heterochromatin.
2. Euchromatin.
3. Centromere.
4. Telomere.

Answer: b. Euchromatin.

Question 10: In Griffith’s experiment, which of the following combinations injected into mice resulted in their death?

1. Live R strain.
2. Heat-killed S strain.
3. Heat-killed S strain + Live R strain.
4. Heat-killed R strain + Live S strain.

Answer: c. Heat-killed S strain + Live R strain.

Question 11: Who proved that the 'transforming principle' of Griffith's experiment was DNA and not protein or RNA?

1. Hershey and Chase.
2. Avery, MacLeod, and McCarty.
3. Meselson and Stahl.
4. Watson and Crick.

Answer: b. Avery, MacLeod, and McCarty.

Question 12: In the Hershey-Chase experiment, bacteriophages grown on radioactive phosphorus (32P) contained radioactive?

1. Protein.
2. DNA.
3. RNA.
4. Lipids.

Answer: b. DNA.

Question 13: Which of the following is not a required criterion for a molecule that can act as a genetic material?

1. It should be able to generate its replica.
2. It should be highly reactive and structurally unstable.
3. It should provide the scope for slow changes (mutation).
4. It should be able to express itself in the form of 'Mendelian Characters'.

Answer: b. It should be highly reactive and structurally unstable.

Question 14: RNA is more reactive and labile than DNA due to the presence of?

1. Uracil instead of Thymine.
2. 2'-OH group in every nucleotide.
3. Single-stranded nature.
4. Both a and b.

Answer: d. Both a and b.

Question 15: Which of the following is considered the first genetic material in the evolutionary timeline?

1. Protein.
2. DNA.
3. RNA.
4. Carbohydrate.

Answer: c. RNA.

Question 16: The experimental proof that DNA replicates semi-conservatively was first shown in?

1. Vicia faba.
2. Escherichia coli.
3. Streptococcus pneumoniae.
4. Drosophila melanogaster.

Answer: b. Escherichia coli.

Question 17: Meselson and Stahl used which heavy isotope to prove the semi-conservative nature of DNA replication?

1. 14C.
2. 15N.
3. 32P.
4. 35S.

Answer: b. 15N.

Question 18: Taylor and his colleagues used radioactive thymidine to prove semi-conservative replication in chromosomes of which plant?

1. Pisum sativum.
2. Vicia faba.
3. Oenothera lamarckiana.
4. Arabidopsis thaliana.

Answer: b. Vicia faba.

Question 19: The main enzyme responsible for DNA replication in prokaryotes is?

1. RNA polymerase.
2. DNA dependent DNA polymerase.
3. DNA ligase.
4. Helicase.

Answer: b. DNA dependent DNA polymerase.

Question 20: During DNA replication, the discontinuously synthesized fragments on the lagging strand are joined by?

1. DNA polymerase I.
2. DNA ligase.
3. Primase.
4. Helicase.

Answer: b. DNA ligase.

Question 21: Any mistake during DNA replication would result in?

1. Denaturation.
2. Mutation.
3. Transcription.
4. Recombination.

Answer: b. Mutation.

Question 22: In eukaryotes, the replication of DNA takes place at which phase of the cell cycle?

1. G1 phase.
2. S phase.
3. G2 phase.
4. M phase.

Answer: b. S phase.

Question 23: The failure of cell division after DNA replication results in?

1. Aneuploidy.
2. Polyploidy.
3. Haploidy.
4. Nullisomy.

Answer: b. Polyploidy.

Question 24: A transcription unit in DNA is defined primarily by three regions. Which of the following is not one of them?

1. A Promoter.
2. The Structural gene.
3. An Origin of replication.
4. A Terminator.

Answer: c. An Origin of replication.

Question 25: The strand of DNA which has the polarity 3' to 5' and acts as a template during transcription is called the?

1. Coding strand.
2. Non-template strand.
3. Template strand.
4. Sense strand.

Answer: c. Template strand.

Question 26: If the sequence of the coding strand in a transcription unit is 5'-ATCGCAT-3', what will be the sequence of the transcribed RNA?

1. 5'-UAGCGUA-3'.
2. 3'-UAGCGUA-5'.
3. 5'-AUCGCAU-3'.
4. 3'-AUCGCAU-5'.

Answer: c. 5'-AUCGCAU-3'.

Question 27: The promoter region in a transcription unit is located towards the?

1. 5' end of the template strand.
2. 3' end of the coding strand.
3. 5' end of the coding strand.
4. 3' end of the structural gene.

Answer: c. 5' end of the coding strand.

Question 28: A gene is strictly defined as the DNA sequence coding for?

1. tRNA only.
2. rRNA only.
3. mRNA only.
4. tRNA, rRNA, or a polypeptide.

Answer: d. tRNA, rRNA, or a polypeptide.

Question 29: The structural gene in a transcription unit is mostly polycistronic in?

1. Mammals.
2. Plants.
3. Bacteria.
4. Fungi.

Answer: c. Bacteria.

Question 30: In eukaryotes, the coding sequences or expressed sequences are called?

1. Introns.
2. Exons.
3. Cistrons.
4. Operons.

Answer: b. Exons.

Question 31: Which RNA polymerase is responsible for the transcription of 28S, 18S, and 5.8S rRNAs in eukaryotes?

1. RNA polymerase I.
2. RNA polymerase II.
3. RNA polymerase III.
4. Primase.

Answer: a. RNA polymerase I.

Question 32: In bacteria, the RNA polymerase requires which factor to transiently initiate transcription?

1. Rho factor.
2. Sigma factor.
3. Alpha factor.
4. Beta factor.

Answer: b. Sigma factor.

Question 33: The process of removing introns and joining exons in a defined order in hnRNA is called?

1. Capping.
2. Tailing.
3. Splicing.
4. Termination.

Answer: c. Splicing.

Question 34: During the capping of hnRNA, which unusual nucleotide is added to the 5' end?

1. Polyadenylate.
2. Methyl guanosine triphosphate.
3. Formyl methionine.
4. Pseudouridine.

Answer: b. Methyl guanosine triphosphate.

Question 35: In tailing of hnRNA, adenylate residues are added at the 3' end in a?

1. Template dependent manner.
2. Template independent manner.
3. Random manner.
4. Sequence specific manner via ligase.

Answer: b. Template independent manner.

Question 36: The presence of introns in split genes is considered reminiscent of?

1. Antiquity.
2. Advanced evolutionary stage.
3. Prokaryotic origin.
4. Viral insertion.

Answer: a. Antiquity.

Question 37: George Gamow argued that the genetic code should be made of a combination of how many nucleotides to code for 20 amino acids?

1. Two.
2. Three.
3. Four.
4. Five.

Answer: b. Three.

Question 38: Who synthesized RNA molecules with defined combinations of bases (homopolymers and copolymers) to decipher the genetic code?

1. Marshall Nirenberg.
2. Har Gobind Khorana.
3. Severo Ochoa.
4. Francis Crick.

Answer: b. Har Gobind Khorana.

Question 39: The Severo Ochoa enzyme is essentially a?

1. DNA dependent RNA polymerase.
2. Polynucleotide phosphorylase.
3. Peptidyl transferase.
4. Aminoacyl tRNA synthetase.

Answer: b. Polynucleotide phosphorylase.

Question 40: Which of the following is not a salient feature of the genetic code?

1. It is unambiguous and specific.
2. It is degenerate.
3. It is overlapping.
4. It is nearly universal.

Answer: c. It is overlapping.

Question 41: The codon AUG has dual functions. It codes for Methionine and also acts as a?

1. Stop codon.
2. Initiator codon.
3. Promoter codon.
4. Terminator codon.

Answer: b. Initiator codon.

Question 42: Which of the following sets represents the three stop codons?

1. UAA, UAG, UGA.
2. UAA, UAC, UAG.
3. UGA, UGG, UAA.
4. UAG, UCG, UGA.

Answer: a. UAA, UAG, UGA.

Question 43: A classical example of a point mutation resulting in a disease is?

1. Down's syndrome.
2. Turner's syndrome.
3. Sickle cell anemia.
4. Klinefelter's syndrome.

Answer: c. Sickle cell anemia.

Question 44: Insertion or deletion of one or two bases changes the reading frame from the point of insertion or deletion. This is known as?

1. Nonsense mutation.
2. Frameshift mutation.
3. Missense mutation.
4. Silent mutation.

Answer: b. Frameshift mutation.

Question 45: tRNA was previously known as sRNA, which stands for?

1. Soluble RNA.
2. Small RNA.
3. Structural RNA.
4. Synthetic RNA.

Answer: a. Soluble RNA.

Question 46: The secondary structure of tRNA has been depicted as looking like a?

1. L-shape.
2. Clover-leaf.
3. Hairpin loop.
4. Double helix.

Answer: b. Clover-leaf.

Question 47: The actual 3D structure of tRNA is a compact molecule that looks like?

1. An inverted L.
2. A clover-leaf.
3. A linear chain.
4. A circular loop.

Answer: a. An inverted L.

Question 48: The process of polymerization of amino acids to form a polypeptide is known as?

1. Transcription.
2. Translation.
3. Transformation.
4. Transduction.

Answer: b. Translation.

Question 49: The first phase of translation, where amino acids are activated and linked to their cognate tRNA, is called?

1. Peptidyl transfer.
2. Translocation.
3. Charging of tRNA.
4. Initiation.

Answer: c. Charging of tRNA.

Question 50: The cellular factory responsible for synthesizing proteins is the?

1. Lysosome.
2. Endoplasmic reticulum.
3. Ribosome.
4. Golgi apparatus.

Answer: c. Ribosome.

Question 51: In a bacterial ribosome, which rRNA acts as a catalyst (ribozyme) for the formation of the peptide bond?

1. 16S rRNA.
2. 23S rRNA.
3. 28S rRNA.
4. 18S rRNA.

Answer: b. 23S rRNA.

Question 52: The untranslated regions (UTRs) on an mRNA are located?

1. Only at the 5' end before the start codon.
2. Only at the 3' end after the stop codon.
3. At both 5' end before the start codon and 3' end after the stop codon.
4. Between the exons.

Answer: c. At both 5' end before the start codon and 3' end after the stop codon.

Question 53: During translation, the ribosome moves from?

1. Codon to codon along the mRNA.
2. 3' to 5' direction on mRNA.
3. Exon to intron.
4. Nucleus to cytoplasm.

Answer: a. Codon to codon along the mRNA.

Question 54: The regulation of gene expression in eukaryotes can be exerted at all of the following levels except?

1. Transcriptional level.
2. Processing level (splicing).
3. Transport of mRNA from nucleus to cytoplasm.
4. Replication level.

Answer: d. Replication level.

Question 55: In prokaryotes, the predominant site for control of gene expression is at the level of?

1. Initiation of transcription.
2. Termination of transcription.
3. RNA splicing.
4. Translation initiation.

Answer: a. Initiation of transcription.

Question 56: In the lac operon, what does the letter 'i' in the i gene stand for?

1. Inducer.
2. Inhibitor.
3. Initiator.
4. Intron.

Answer: b. Inhibitor.

Question 57: The z gene of the lac operon codes for which enzyme?

1. Permease.
2. Transacetylase.
3. Beta-galactosidase.
4. Repressor.

Answer: c. Beta-galactosidase.

Question 58: Which enzyme increases the permeability of the cell to beta-galactosides in the lac operon?

1. Beta-galactosidase.
2. Permease.
3. Transacetylase.
4. Ligase.

Answer: b. Permease.

Question 59: The inducer for the lac operon in E. coli is?

1. Glucose.
2. Galactose.
3. Lactose or allolactose.
4. cAMP.

Answer: c. Lactose or allolactose.

Question 60: Regulation of lac operon by a repressor is referred to as?

1. Positive regulation.
2. Negative regulation.
3. Feedback inhibition.
4. Allosteric regulation.

Answer: b. Negative regulation.

Question 61: The Human Genome Project (HGP) was officially launched in the year?

1988. 1988.
1989. 1990.
1990. 1992.
1991. 2003.

Answer: b. 1990.

Question 62: The HGP was closely associated with the rapid development of a new area in biology called?

1. Biotechnology.
2. Bioinformatics.
3. Biogeography.
4. Biosystematics.

Answer: b. Bioinformatics.

Question 63: Which of the following was not a primary goal of the Human Genome Project?

1. Identify all the approximately 20,000-25,000 genes in human DNA.
2. Determine the sequences of the 3 billion chemical base pairs that make up human DNA.
3. Clone human beings for therapeutic purposes.
4. Address the ethical, legal, and social issues (ELSI) that may arise from the project.

Answer: c. Clone human beings for therapeutic purposes.

Question 64: The method of sequencing the whole set of genome that contained all the coding and non-coding sequence, and later assigning different regions with functions is referred to as?

1. Expressed Sequence Tags (ESTs).
2. Sequence Annotation.
3. Microarray analysis.
4. DNA fingerprinting.

Answer: b. Sequence Annotation.

Question 65: For sequencing human DNA, the commonly used hosts for cloning were?

1. Bacteria and Yeast.
2. Viruses and Fungi.
3. Plants and Animals.
4. Plasmids and Cosmids.

Answer: a. Bacteria and Yeast.

Question 66: BAC and YAC stand for?

1. Bacterial Artificial Chromosome and Yeast Artificial Chromosome.
2. Bacterial Automated Cloning and Yeast Automated Cloning.
3. Basic Artificial Chromosome and Yeast Active Chromosome.
4. Bacterial Activated Clone and Yeast Activated Clone.

Answer: a. Bacterial Artificial Chromosome and Yeast Artificial Chromosome.

Question 67: The DNA sequencing process in HGP was based on the method developed by?

1. James Watson.
2. Frederick Sanger.
3. Alec Jeffreys.
4. Kary Mullis.

Answer: b. Frederick Sanger.

Question 68: The last human chromosome to be completely sequenced in May 2006 was?

1. Chromosome 1.
2. Chromosome X.
3. Chromosome Y.
4. Chromosome 21.

Answer: a. Chromosome 1.

Question 69: Single nucleotide polymorphisms (SNPs) are found at approximately how many locations in the human genome?

1. 1.4 million.
2. 2.4 million.
3. 3 billion.
4. 30,000.

Answer: a. 1.4 million.

Question 70: DNA fingerprinting involves identifying differences in some specific regions in DNA sequence called?

1. Euchromatin.
2. Repetitive DNA.
3. Promoters.
4. Exons.

Answer: b. Repetitive DNA.

Question 71: During density gradient centrifugation, the bulk DNA forms a major peak while repetitive DNA forms small peaks referred to as?

1. Minisatellites.
2. Macrosatellites.
3. Satellite DNA.
4. Microsatellites.

Answer: c. Satellite DNA.

Question 72: Satellite DNA does not generally code for proteins, but they form a large portion of the human genome and show a high degree of?

1. Transcription.
2. Mutation suppression.
3. Polymorphism.
4. Translation.

Answer: c. Polymorphism.

Question 73: The technique of DNA fingerprinting was initially developed by?

1. Kary Mullis.
2. Alec Jeffreys.
3. Frederick Sanger.
4. Francis Collins.

Answer: b. Alec Jeffreys.

Question 74: Alec Jeffreys used a satellite DNA as a probe that shows very high degree of polymorphism. It was called?

1. Single Nucleotide Polymorphism (SNP).
2. Variable Number of Tandem Repeats (VNTR).
3. Short Tandem Repeats (STR).
4. Restriction Fragment Length Polymorphism (RFLP).

Answer: b. Variable Number of Tandem Repeats (VNTR).

Question 75: In DNA fingerprinting, the separated DNA fragments are transferred to synthetic membranes, such as nitrocellulose or nylon. This technique is called?

1. Northern blotting.
2. Western blotting.
3. Southern blotting.
4. Eastern blotting.

Answer: c. Southern blotting.

Question 76: VNTR belongs to a class of satellite DNA referred to as?

1. Minisatellite.
2. Microsatellite.
3. Macromatellite.
4. Megasatellite.

Answer: a. Minisatellite.

Question 77: The size of VNTR varies generally from?

1. 0.1 to 20 kb.
2. 20 to 50 kb.
3. 50 to 100 kb.
4. 100 to 200 kb.

Answer: a. 0.1 to 20 kb.

Question 78: After hybridization with a VNTR probe in DNA fingerprinting, the autoradiogram gives many bands of differing sizes. These bands give a characteristic pattern for an individual except in the case of?

1. Siblings.
2. Fraternal twins.
3. Monozygotic (identical) twins.
4. Parent and offspring.

Answer: c. Monozygotic (identical) twins.

Question 79: Polymerase Chain Reaction (PCR) is utilized in DNA fingerprinting primarily to?

1. Digest the DNA.
2. Amplify the DNA.
3. Separate the DNA fragments.
4. Blot the DNA onto a membrane.

Answer: b. Amplify the DNA.

Question 80: Which of the following ratios remains constant for a particular species according to Chargaff’s rule?

1. A + C / T + G.
2. A + T / G + C.
3. A + G / T + C.
4. A / T.

Answer: c. A + G / T + C.

Question 81: The distance between two consecutive base pairs in a DNA helix is approximately?

3. 3.4 nm.
4. 0.34 nm.
5. 34 nm.
6. 20 nm.

Answer: b. 0.34 nm.

Question 82: In a 68 nm long DNA molecule, how many base pairs are present?

100. 100.
101. 200.
102. 300.
103. 400.

Answer: b. 200.

Question 83: If an E. coli with heavy DNA (15N) is allowed to grow in a medium containing normal 14N for 40 minutes, what will be the percentage of hybrid DNA?

1. 100%.
2. 50%.
3. 25%.
4. 75%.

Answer: b. 50%.

Question 84: The process of termination of transcription in bacteria is facilitated by?

1. Sigma factor.
2. Rho factor.
3. Core enzyme.
4. Operator.

Answer: b. Rho factor.

Question 85: The equivalent of a structural gene in a eukaryotic transcription unit is the?

1. Muton.
2. Recon.
3. Cistron.
4. Operon.

Answer: c. Cistron.

Question 86: The enzyme RNA polymerase III in eukaryotes is responsible for transcription of all except?

1. tRNA.
2. 5S rRNA.
3. snRNA.
4. hnRNA.

Answer: d. hnRNA.

Question 87: The presence of a nucleus in eukaryotes requires that mRNA is synthesized and processed in the nucleus and then transported to the cytoplasm. This primary transcript is called?

1. Mature mRNA.
2. hnRNA.
3. tRNA.
4. rRNA.

Answer: b. hnRNA.

Question 88: In the genetic code dictionary, how many codons code for amino acids?

64. 64.
65. 61.
66. 60.
67. 20.

Answer: b. 61.

Question 89: Valine replaces glutamic acid in sickle cell anemia due to a mutation in the beta-globin gene. The mutated codon in mRNA is?

1. GAG.
2. GUG.
3. UAA.
4. AUG.

Answer: b. GUG.

Question 90: Which sequence correctly depicts the hierarchy of DNA packaging in eukaryotes from smallest to largest?

1. DNA -> Nucleosome -> Chromatin -> Chromosome.
2. DNA -> Chromatin -> Nucleosome -> Chromosome.
3. Nucleosome -> DNA -> Chromatin -> Chromosome.
4. DNA -> Chromosome -> Chromatin -> Nucleosome.

Answer: a. DNA -> Nucleosome -> Chromatin -> Chromosome.

Question 91: Non-histone chromosomal (NHC) proteins are required for?

1. Primary packaging of DNA.
2. Formation of nucleosome core.
3. Higher level packaging of chromatin.
4. Replicating the DNA.

Answer: c. Higher level packaging of chromatin.

Question 92: The core of the nucleosome is made up of an octamer of histone proteins consisting of two molecules each of?

3. H1, H2A, H2B, H3.
4. H2A, H2B, H3, H4.
5. H1, H3, H4, H5.
6. H1, H2A, H3, H4.

Answer: b. H2A, H2B, H3, H4.

Question 93: In the process of translation, the bond formed between the carboxyl group of one amino acid and the amino group of the next is a?

1. Glycosidic bond.
2. Phosphodiester bond.
3. Peptide bond.
4. Hydrogen bond.

Answer: c. Peptide bond.

Question 94: The operon model for the regulation of gene expression was first elucidated by?

1. Watson and Crick.
2. Jacob and Monod.
3. Beadle and Tatum.
4. Meselson and Stahl.

Answer: b. Jacob and Monod.

Question 95: Which of the following conditions ensures that the lac operon is fully turned on?

1. Presence of glucose, absence of lactose.
2. Presence of lactose, absence of glucose.
3. Absence of both glucose and lactose.
4. Presence of both high glucose and high lactose.

Answer: b. Presence of lactose, absence of glucose.

Question 96: Repetitive DNA makes up a large portion of the human genome. What is its primary function?

1. Coding for essential metabolic enzymes.
2. Serving as origin of replication sites.
3. It has no direct coding function but sheds light on chromosome structure and evolution.
4. Transcribing into rRNA.

Answer: c. It has no direct coding function but sheds light on chromosome structure and evolution.

Question 97: How much of the human genome is estimated to code for proteins?

1. More than 50 percent.
2. Exactly 25 percent.
3. Less than 2 percent.
4. About 10 percent.

Answer: c. Less than 2 percent.

Question 98: The largest known human gene is?

1. Dystrophin.
2. Insulin.
3. Alpha-globin.
4. Beta-galactosidase.

Answer: a. Dystrophin.

Question 99: Chromosome 1 contains the highest number of genes. How many genes does it have?

231. 231.
232. 2968.
233. 31647.
234. 14000.

Answer: b. 2968.

Question 100: The Y chromosome has the fewest genes among human chromosomes. The number of genes on the Y chromosome is?

2968. 2968.
2969. 231.
2970. 14.
2971. 3000.

Answer: b. 231.

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