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Molecular Basis of Inheritance: NEET MCQ Questions [100+ Solved]

Below are the NEET MCQ questions on Class 12 Biology Chapter “Molecular Basis of Inheritance” based on the NCERT textbook. Solve the below free NEET mock test for a better understanding of the various topics. 100+ important MCQs (multiple choice questions) are given in this NEET question bank.

“Molecular Basis of Inheritance” is the 6th chapter in the unit “Genetics and Evolution” of class XII or class 12th Biology NCERT. Do note that NEET (which is conducted by NTA) is based on NCERT textbooks so they are a must-have. You can also download PDFs of NCERT textbooks.

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  1. In a DNA strand the nucleotides are linked together by?
    (a) glycosidic bonds
    (b) phosphodiester bonds
    (c) peptide bonds
    (d) hydrogen bonds

(b) phosphodiester bonds

  1. What determines the expression of the transgene in the target tissue in transgenics?
    (a) enhancer
    (b) transgene
    (c) promoter
    (d) reporter

(d) reporter

  1. E.coli with a mutated gene of the lac operon cannot grow in a medium containing only lactose for energy, why?
    (a) the lac operon is constitutively active in these cells
    (b) they cannot synthesize functional beta-galactosidase
    (c) in the presence of glucose, E.coli cells do not utilize lactose
    (d) they cannot transport lactose from the medium into the cell

(b) they cannot synthesize functional beta-galactosidase

  1. Holoenzyme RNA polymerase binds to a DNA sequence during transcription, causing the DNA to assume a saddle-like structure. This sequence is called?
    (a) AAAT box
    (b) TATA box
    (c) GGTT box
    (d) CAAT box

(b) TATA box

  1. Which of the following uses RNA as a template for synthesizing DNA?
    (a) DNA polymerase
    (b) RNA polymerase
    (c) Reverse transcriptase
    (d) DNA dependant RNA polymerase

(c) Reverse transcriptase

  1. AGTCTACCGATAGT is a short sequence of bases on one strand of DNA. What will be the corresponding base sequence in the new strand if this sequence serves as a template for the formation of a new strand of DNA?
    (a) AGTCTACCGATAGT
    (b) TCAGATGGCTATCA
    (c) TGATAGCCATCTGA
    (d) GACATCGATTCGAT

(b) TCAGATGGCTATCA

  1. Who postulated the one gene-one enzyme hypothesis?
    (a) Hershey and Chase
    (b) A. Garrod
    (c) Beadle and Tatum
    (d) R. Franklin

(c) Beadle and Tatum

  1. The Okazaki fragments in DNA chain growth
    (a) polymerize in the 3’ – to – 5’ direction and form a replication fork
    (b) prove the semi-conservative nature of DNA replication
    (c) polymerize in the 5’ – to – 3’ direction and explain 3’ – to – 5’ DNA replication
    (d) result in transcription.

(c) polymerize in the 5’ – to – 3’ direction and explain 3’ – to – 5’ DNA replication

  1. Eukaryotic cells have a nucleus that is considerably larger than the DNA molecule. How is the DNA accommodated here?
    (a) super-coiling in nucleosomes
    (b) DNase digestion
    (c) through the elimination of repetitive DNA
    (d) deletion of non-essential genes

(a) super-coiling in nucleosomes

  1. FOr the first time, where was the one gene-one enzyme relationship established?
    (a) Salmonella typhimurium
    (b) Escherichia coli
    (c) Diplococcus pneumoniae
    (d) Neurospora crassa

(d) Neurospora crassa

  1. Molecular basis of organ differentiation depends on the modulation in the transcription by what?
    (a) ribosome
    (b) transcription factor
    (c) anticodon
    (d) RNA polymerase

(d) RNA polymerase

  1. In which of the following pairs of codons is their function or the signal for the specific amino acid matched correctly?
    (a) GUU, GCU-Alanine
    (b) UAG, UGA-Stop
    (c) AUG, ACG-Start/Methionine
    (d) UUA, UCA-Leucine

(b) UAG, UGA-Stop

  1. Which of the following pairs of nitrogenous bases of nucleic acids is wrongly matched with its category?
    (a) Thymine, Uracil – Pyrimidines
    (b) Uracil, Cytosine – Pyrimidines
    (c) Guanine, Adenine – Purines
    (d) Adenine, Thymine – Purines

(d) Adenine, Thymine – Purines

  1. Haploids are more suitable for mutation studies than diploids. Why?
    (a) haploids are reproductively more stable than diploids
    (b) mutagens penetrate in haploids more effectively than diploids
    (c) haploids are more abundant in nature than diploids
    (d) all mutations, whether dominant or recessive are expressed in haploids

(d) all mutations, whether dominant or recessive are expressed in haploids

  1. What did T.O. Diener discover?
    (a) free infectious DNA
    (b) infectious protein
    (c) bacteriophage
    (d) free infectious RNA

(d) free infectious RNA

  1. Which of the following about genetic code is false?
    (a) It is nearly universal
    (b) It is degenerate
    (c) It is unambiguous
    (d) A codon in mRNA is read in a non-contiguous fashion

(d) A codon in mRNA is read in a non-contiguous fashion

  1. Where was semi-conservative replication of DNA first demonstrated?
    (a) Escherichia coli
    (b) Streptococcus pneumoniae
    (c) Salmonella typhimurium
    (d) Drosophila melanogaster

(a) Escherichia coli

  1. In whose experiments was DNA cracked and it was identified unequivocally that a genetic code is a triplet?
    (a) Hershey and Chase
    (b) Morgan and Sturtevant
    (c) Beadle and Tantum
    (d) Nirenberg and Mathaei

(d) Nirenberg and Mathaei

  1. There is one aspect of genetic code that is not apparent, and that is its being?
    (a) degenerate
    (b) ambiguous
    (c) universal
    (d) specific

(b) ambiguous

  1. What is the process through which the amount of DNA, RNA and protein at any given time, can be determined?
    (a) autoradiography
    (b) tissue culture
    (c) cellular fractioning
    (d) phase-contrast microscopy

(a) autoradiography

  1. Where are Balbiani rings found?
    (a) polysomes
    (b) polytene chromosomes
    (c) autosomes
    (d) nonsense chromosomes

(b) polytene chromosomes

  1. Cytosine and guanine are paired in a DNA helix by?
    (a) covalent bond
    (b) phosphate bond
    (c) three hydrogen bonds
    (d) two hydrogen bonds

(c) three hydrogen bonds

  1. During protein synthesis, which RNAs transport amino acids from the amino acid pool in the cytoplasm to the ribosome?
    (a) tRNA
    (b) mRNA
    (c) rRNA
    (d) hnRNA

(a) tRNA

  1. What is the structure of DNA?
    (a) linear
    (b) double helix
    (c) single helix
    (d) triple helix

(b) double helix

  1. Who discovered transposon?
    (a) Sutton
    (b) Strassburger
    (c) Fischer
    (d) B.Mc Clintock

(d) B.Mc Clintock

  1. There are 42 chromosomes in the root cells of wheat. How many chromosomes would the synergid cell have?
    (a) 7
    (b) 14
    (c) 21
    (d) 28

(c) 21

  1. What do Okazaki fragments form?
    (a) leading strand
    (b) lagging strand
    (c) non-sense strand
    (d) senseful strand

(b) lagging strand

  1. Who gave the wobble hypothesis?
    (a) F.H.C. Crick
    (b) Nirenberg
    (c) Holley
    (d) Khorana

(a) F.H.C. Crick

  1. Name one pair of the following terms or names that has the same meaning?
    (a) Gene pool-genome
    (b) Codon-gene
    (c) Cistron-triplet
    (d) DNA fingerprinting – DNA profiling

(d) DNA fingerprinting – DNA profiling

  1. Which of the following statements about t-RNA is true?
    (a) It binds with an amino acid at its 3′ end.
    (b) It has five double-stranded regions.
    (c) It had a codon at one end which recognizes the anticodon on messenger RNA.
    (d) It looks like a cloverleaf in the three-dimensional structure.

(d) It looks like a cloverleaf in the three-dimensional structure.

  1. What codon codes for the same information as UGC?
    (a) UGU
    (b) UGA
    (c) UAG
    (d) UGG

(a) UGU

  1. An organism’s protein synthesis comes to a halt at one point. Select any three codons from the following, any one of which could trigger this halt.
    (a) UUU, UCC, UAU
    (b) UUC, UUA, UAC
    (c) UAG, UGA, UAA
    (d) UUG, UCA, UCG

(c) UAG, UGA, UAA

  1. About how many nitrogenous bases are there in the human genome?
    (a) 3.5 million
    (b) 35 thousand
    (c) 35 million
    (d) 3.1 billion

(d) 3.1 billion

  1. Which of the following pairs is the correct match regarding the codon and amino acid coded by it?
    (a) UUA-valine
    (b) AM-lysine
    (c) AUG-cysteine
    (d) CCC-alanine

(a) UUA-valine

  1. Where does the TATA box of eukaryotic promotor lie?
    (a) about 25 bp upstream of the transcription start site
    (b) about 50 bp upstream of the transcription start site
    (c) about 75 bp upstream of the transcription start site
    (d) about 200 bp upstream of the transcription start site

(a) about 25 bp upstream of the transcription start site

  1. DNA extracted from eukaryotic cells contains 30 percent adenine bases. Approximately what percentage of this DNA contains cytosine?
    (a) 10%
    (b) 20%
    (c) 30%
    (d) 40%

(b) 20%

  1. a, b and c are three genes. The crossover between a and b is 20%, b and c is 28%, and a and c is 8%. What is the sequence of the genes on the chromosome?
    (a) b, a, c
    (b) a, b, c
    (c) a, c, b
    (d) None of these

(a) b, a, c

  1. What group of codons is called a degenerate codon?
    (a) UAA, UAG and UGA
    (b) GUA, GUG, GCA, GCG and GAA
    (c) UUC, UUG, CCU, CAA and CUG
    (d) UUA, UUG, CUU, CUC, CUA and CUG

(a) UAA, UAG and UGA

  1. In a prokaryotic cell, transcription is?
    (a) initiated at a promoter using one of three RNA polymerases (RNA polymerase II).
    (b) initiated at a start codon with the help of initiation factors and the small subunit of the ribosome.
    (c) initiated at a promoter and uses only one strand of DNA, the template strand, to synthesize a complementary RNA strand.
    (d) is terminated at stop codons.

(c) initiated at a promoter and uses only one strand of DNA, the template strand, to synthesize a complementary RNA strand.

  1. What would happen if the second codon of a polypeptide, UGC, was changed to UAG by a mutation in DNA?
    (a) Nothing. The ribosome would skip that codon and translation would continue.
    (b) Translation would continue, but the reading frame of the ribosome would be shifted.
    (c) Translation would stop at the second codon and no functional protein would be made.
    (d) Translation would continue, but the second amino acid in the protein would be different.

(c) Translation would stop at the second codon and no functional protein would be made.

  1. 66 codons are found in a functional piece of mRNA. This mRNA codes a protein that could have a maximum number of how many amino acids?
    (a) 22
    (b) 64
    (c) 65
    (d) 66

(c) 65

  1. What causes the polypeptide chain to terminate?
    (a) UUG, UAG and UCG
    (b) UAA, UAG and UGA
    (c) UUG, UGC and UCA
    (d) UCG, GCG and ACC

(b) UAA, UAG and UGA

  1. How can nucleotide arrangement in DNA be seen?
    (a) X-ray crystallography
    (b) electron microscope
    (c) ultracentrifuge
    (d) light microscope

(a) X-ray crystallography

  1. DNA polymerase is primarily responsible for what?
    (a) add nucleotides to the growing daughter strand.
    (b) seal nicks along the sugar-phosphate backbone of the daughter strand.
    (c) unwind the parent DNA double helix.
    (d) prevent reassociation of the denatured parent DNA strands.

(a) add nucleotides to the growing daughter strand.

  1. It appears that a lagging daughter strand of DNA is synthesized in the “wrong” direction. How is this synthesis accomplished?
    (a) ligating (connecting) short Okazaki fragments that are synthesized in short spurts in the “right” direction.
    (b) primase.
    (c) using multiple primers and DNA polymerase I.
    (d) Both (a) and (b)

(d) Both (a) and (b)

  1. DNA synthesis requires RNA primers because?
    (a) DNA polymerase can only add to an existing strand of nucleotides.
    (b) DNA polymerase can only add to an existing DNA strand.
    (c) DNA primase is the first enzyme in the replication complex.
    (d) All of the above

(a) DNA polymerase can only add to an existing strand of nucleotides.

  1. Where do repair and proofreading occur?
    (a) at any time during or after the synthesis of DNA.
    (b) only before DNA methylation occurs.
    (c) only in the presence of DNA polymerase.
    (d) only in the presence of an excision repair mechanism.

(a) at any time during or after the synthesis of DNA.

  1. Replication of DNA is an ____ process and _____ energy.
    (a) exergonic; does not require
    (b) endothermic; does require
    (c) endergonic; does require
    (d) endothermic; does not require

(c) endergonic; does require

  1. What do triplet UUU code for?
    (a) leucine
    (b) methionine
    (c) phenylalanine
    (d) glycine

(c) phenylalanine

  1. What is a false statement about DNA replication?
    (a) Okazaki fragments are the initiators of continuous DNA synthesis along the leading strand.
    (b) Replication forks represent areas of active DNA synthesis on the chromosomes.
    (c) Error rates for DNA replication are often less than one in every billion base pairings.
    (d) Ligases and polymerases function in the vicinity of replication forks.

(a) Okazaki fragments are the initiators of continuous DNA synthesis along the leading strand.

  1. Hershey and Chase’s experiments discovered that the mechanism of viral replication was that?
    (a) protein, not DNA, is the hereditary material.
    (b) DNA, not protein, is the hereditary material.
    (c) protein and DNA play an equal role in determining inheritance.
    (d) neither protein nor DNA play a role in determining inheritance.

(b) DNA, not protein, is the hereditary material.

  1. Which statement about the replication of DNA is false?
    (a) Many different enzymes are needed for the process to function properly.
    (b) Mistakes can be corrected at multiple steps in the process.
    (c) Uncorrected mistakes introduce mutations into the DNA base sequence.
    (d) Mistakes in the copying process are very common occurrences.

(d) Mistakes in the copying process are very common occurrences.

  1. Let us suppose that you chemically label both strands of a DNA molecule. Then, you allow unlabelled nucleotides are then used to replicate the DNA. Which of the following statements regarding the DNA molecules produced is false?
    (a) Both will have the chemical label.
    (b) One will have the chemical label, and the other will not.
    (c) One strand within each molecule will have the chemical label.
    (d) Assuming no replication errors, both molecules will be genetically identical.

(c) One strand within each molecule will have the chemical label.

  1. To produce a functioning protein from the information contained in a gene, the
    (a) DNA must be replicated.
    (b) information must be transcribed into mRNA and then translated into amino acids.
    (c) tRNA must be transcribed into rRNA and then translated into amino acids.
    (d) ribosome must be converted from rRNA into mRNA.

(b) information must be transcribed into mRNA and then translated into amino acids.

  1. Why is DNA acidic?
    (a) sugar
    (b) purine
    (c) phosphoric acid
    (d) pyrimidine

(c) phosphoric acid

  1. What is a nucleosome?
    (a) intron interrupted DNA
    (b) double-helix DNA
    (c) negatively charged DNA wrapped around positively charged histone octamer
    (d) satellite DNA

(c) negatively charged DNA wrapped around positively charged histone octamer

  1. How can genes be inactivated?
    (a) inaccurate removal of introns.
    (b) transposable genetic elements.
    (c) movement of genes to heterochromatic regions of the chromosome.
    (d) All of the above

(d) All of the above

  1. What is the mechanism of gene regulation that occurs after mRNA transcription but before mRNA is translated into protein?
    (a) mRNA splicing
    (b) DNA packing
    (c) Repressors and activators
    (d) Protein degradation

(a) mRNA splicing

  1. The genetic code degeneration is attributed to the?
    (a) third member of a codon
    (b) first member of a codon
    (c) second member of a codon
    (d) entire codon

(a) third member of a codon

  1. When adenine is replaced by guanine in a mutational event, it is a case of?
    (a) frameshift mutation
    (b) transcription
    (c) transition
    (d) transversion

(c) transition

  1. What is reverse transcriptase?
    (a) RNA dependent RNA polymerase
    (b) DNA dependent RNA polymerase
    (c) DNA dependent DNA polymerase
    (d) RNA dependent DNA polymerase

(d) RNA dependent DNA polymerase

  1. In higher organisms, Crossing over that results in genetic recombination occurs between?
    (a) sister chromatids of a bivalent
    (b) non-sister chromatids of a bivalent
    (c) two daughter nuclei
    (d) two different bivalents

(b) non-sister chromatids of a bivalent

  1. Short sequences of what are present in the telomeres of eukaryotic chromosomes?
    (a) thymine rich repeats
    (b) cytosine rich repeats
    (c) adenine rich repeats
    (d) guanine rich repeats

(c) adenine rich repeats

  1. Eukaryotic chromosomes
    (a) are circular and contain origin and terminator sequences.
    (b) are linear and have origins and telomeres.
    (c) contain coding and non-coding sequences.
    (d) Both (b) and (c)

(d) Both (b) and (c)

  1. The processes that result in the formation of mRNA from DNA and protein from mRNA are respectively
    (a) translation and transcription
    (b) transcription and replication
    (c) transcription and translation
    (d) replication and translation.

(c) transcription and translation

  1. What does structural gene ‘Z’ synthesize in lac operon?
    (a) b-galactosidase
    (b) galactosidase permease
    (c) galactosidase transacetylase
    (d) None of the above

(a) b-galactosidase

  1. For gene expression to occur, chromatin structure must be altered because?
    (a) condensed chromatin is replicated but not transcribed.
    (b) condensed chromatin makes most DNA sequences inaccessible to the transcription complex.
    (c) decondensed chromatin has more nucleosomes per DNA molecule.
    (d) heterochromatin is actively transcribed and euchromatin is not transcribed.

(b) condensed chromatin makes most DNA sequences inaccessible to the transcription complex.

  1. What is not expected to be found in prokaryotic DNA?
    (a) Millions of base pairs.
    (b) Histone proteins around which the DNA is coiled.
    (c) Functionally related genes grouped in the same section of DNA.
    (d) A majority of DNA that codes for protein or RNA.

(b) Histone proteins around which the DNA is coiled.

  1. Griffith’s experiments on Streptococcus pneumoniae were primarily designed to?
    (a) find a cure for pneumonia in humans.
    (b) prevent cancers caused by exposure to ultraviolet light.
    (c) determine if DNA is the hereditary material.
    (d) discover the molecular structure of DNA.

(a) find a cure for pneumonia in humans.

  1. In a DNA molecule, which of the following parts is held together by hydrogen bonds?
    (a) The carbons within the sugar-phosphate group.
    (b) The carbons within the nitrogen-containing bases.
    (c) Nucleotide bases on opposite strands of the helix.
    (d) Successive nucleotides within a single strand of the helix.

(c) Nucleotide bases on opposite strands of the helix.

  1. What is operon?
    (a) the sequence of three nitrogen bases determining a single amino acid.
    (b) a set of closely placed genes regulating a metabolic pathway in prokaryotes.
    (c) a segment of DNA specifying a polypeptide.
    (d) a gene responsible for switching on and switching off of other genes.

(b) a set of closely placed genes regulating a metabolic pathway in prokaryotes.

  1. Why was DNA first thought to be a poor candidate for the hereditary material?
    (a) Griffith’s experiments showed that protein, not DNA, caused the transformation.
    (b) viruses lack DNA yet still pass genetic information between generations.
    (c) DNA was believed to have a simple chemical structure with little variability.
    (d) the work of Hershey and Chase showed that protein was the genetic material.

(c) DNA was believed to have a simple chemical structure with little variability.

  1. Consider Griffith’s experiments on Streptococcus pneumoniae transformation. Consider extending these experiments by injecting live strain S bacteria and heat-killed strain R bacteria into a mouse. The mouse will _ and you will find live strain _ bacteria in its blood.
    (a) die; R
    (b) live; R
    (c) die; S
    (d) live; S

(c) die; S

  1. An enzyme, telomerase is a
    (a) simple protein
    (b) RNA
    (c) ribonucleoprotein
    (d) repetitive DNA

(c) ribonucleoprotein

  1. You are asked to help solve a murder. A sample of what they believe to be the killer’s DNA is brought to you from the crime scene for chemical analysis. Adenine, thymine, ribose, and uracil were detected in this sample, leading to the conclusion that it is?
    (a) pure DNA.
    (b) pure RNA.
    (c) probably a mixture of DNA and RNA.
    (d) probably a mixture of rRNA and mRNA.

(c) probably a mixture of DNA and RNA.

  1. A sequence of DNA reads GAGCCTATGCCAGTA before mutation. The sequence reads GAGCGTACGCCATTA after the mutation. Which explanation best describes how the DNA has changed?
    (a) There was a single base deletion.
    (b) There was a single base substitution.
    (c) There were multiple base deletions.
    (d) There were multiple base substitutions.

(d) There were multiple base substitutions.

  1. Experiments of Avery, McLeod, and McCarty demonstrated that DNA is the genetic material by demonstrating that?
    (a) both protein and DNA samples provided the transforming factor.
    (b) DNA was not complex enough to be the genetic material.
    (c) only samples with DNA provided activity.
    (d) even though DNA was molecularly simple, it provided adequate variation to act as the genetic material.

(c) only samples with DNA provided activity.

  1. What do Chargaff’s rules of base pairing state?
    (a) the ratio of purines to pyrimidines is roughly equal in all tested organisms.
    (b) the ratio of A to T is roughly equal in all tested organisms.
    (c) the ratio of A + T and G + C is roughly equal in all tested organisms.
    (d) Both (a) and (b)

(d) Both (a) and (b)

  1. When a steroid molecule binds to the _, a set of human genes are sequentially expressed.
    (a) messenger RNA
    (b) DNA sequence
    (c) ribosome
    (d) transfer RNA

(b) DNA sequence

  1. Removal of introns and joining the exons in a defined order in a transcription unit is called?
    (a) tailing
    (b) transformation
    (c) capping
    (d) splicing

(d) splicing

  1. In what we call the lac operon, what does “lac” refer to?
    (a) The number 1,00,000
    (b) Lactose
    (c) Lactase
    (d) Lac insect

(b) Lactose

  1. What does DNA fingerprinting refer to?
    (a) molecular analysis of profiles of DNA samples
    (b) analysis of DNA samples using imprinting devices
    (c) techniques used for molecular analysis of different specimens of DNA
    (d) techniques used for the identification of fingerprints of individuals.

(a) molecular analysis of profiles of DNA samples

  1. What happens in negative operon?
    (a) co-repressor binds with repressor
    (b) co-repressor does not bind with repressor
    (c) co-repressor binds with inducer
    (d) cAMP has a negative effect on the lac operon

(a) co-repressor binds with repressor

  1. How do we refer to genes that are responsible for turning on and off the transcription of a set of structural genes?
    (a) Operator genes
    (b) Redundant genes
    (c) Regulator genes
    (d) Polymorphic genes

(a) Operator genes

  1. Is transcription of operon still possible if the gene encoding the lac repressor is mutated so that it no longer binds the operator?
    (a) Yes, but only when lactose is present.
    (b) No, because RNA polymerase is needed to transcribe the genes.
    (c) Yes, because the operator will not be bound by the repressor and RNA polymerase can transcribe the lac operon.
    (d) No, because cAMP levels are low when the repressor is nonfunctional.

(c) Yes, because the operator will not be bound by the repressor and RNA polymerase can transcribe the lac operon.

  1. How common is it for an incorrect base to be replaced with another incorrect base during proofreading?
    (a) 1 in 10 bases
    (b) 1 in 100 bases
    (c) 1 in 1,000 bases
    (d) 1 in 10,000 bases

(d) 1 in 10,000 bases

  1. How does transcriptional regulation occur in prokaryotes?
    (a) a repressor binding an operator and preventing transcription.
    (b) an activator binding upstream from a promoter and positively affecting transcription.
    (c) different promoter sequences binding RNA polymerase more tightly, resulting in more effective transcriptional initiation.
    (d) All of the above

(d) All of the above

  1. When a signal molecule binds to a target cell, what is the first thing that happens?
    (a) A transcription factor acts on the DNA.
    (b) The signal molecule binds to RNA.
    (c) A new protein is made in the target cell.
    (d) The signal molecule binds to a receptor.

(d) The signal molecule binds to a receptor.

  1. What is the process of DNA amplification or multiplication for fingerprinting?
    (a) polymerase chain reaction
    (b) nesslerisation
    (c) Southern blotting
    (d) Northern blotting

(a) polymerase chain reaction

  1. Which enzymes are produced by lactose operon?
    (a) b-galactosidase, permease and glycogen synthetase.
    (b) b-galactosidase, permease and transacetylase.
    (c) Permease, glycogen synthetase and transacetylase.
    (d) b-galactosidase, permease and phosphoglucose isomerase.

(b) b-galactosidase, permease and transacetylase.

  1. Prokaryotes and eukaryotes both regulate gene expression through the?
    (a) control of mRNA translation.
    (b) breakdown of proteins formed by translation.
    (c) prevention of DNA uncoiling before transcription.
    (d) control of gene transcription.

(d) control of gene transcription.

  1. Satellite DNA
    (a) is classified into many categories such as micro-satellites, minisatellites, etc. based on the base composition length of segments and the number of repetitive units.
    (b) normally does not code for any protein.
    (c) shows polymorphism.
    (d) forms the basis of DNA fingerprinting.

(b) normally does not code for any protein.

  1. By studying the structure of DNA, we can understand three major properties of genes that are
    (a) They contain information, direct the synthesis of proteins, and are contained in the cell nucleus.
    (b) They contain nitrogenous bases, direct the synthesis of RNA, and are contained in the cell nucleus
    (c) They encode the organism’s phenotype, are passed on from one generation to the next and contain nitrogenous bases.
    (d) They contain information, replicate exactly, and change to produce a mutation.

(d) They contain information, replicate exactly, and change to produce a mutation.

  1. Gene regulation occurs at what level in prokaryotes?
    (a) transcription
    (b) translation
    (c) post-transcription
    (d) post-translation

(a) transcription

  1. The regulation of tryptophan synthesis in E. coli affects gene expression. This is an example of
    (a) translational control.
    (b) transcriptional control.
    (c) homeotic gene control.
    (d) breaking down mRNA molecules.

(b) transcriptional control.

  1. According to a recent analysis of the human genome, which of the following conclusions does not demonstrate our genetic connection with other, more primitive organisms?
    (a) Only 35,000 genes are required to make a human.
    (b) Human DNA contains hundreds of bacterial genes.
    (c) Numerous homeotic genes are shared among humans and other animals.
    (d) There are over 40 newly identified disease genes.

(d) There are over 40 newly identified disease genes.

  1. What causes the determination of one amino acid by more than one codon?
    (a) redundancy of genetic code.
    (b) continuous nature of genetic code.
    (c) punctuation in genetic code.
    (d) universal nature of genetic code.

(a) redundancy of genetic code.

  1. What would happen if a nucleotide without a hydroxyl group at the 3′ end were added to a PCR?
    (a) No additional nucleotides would be added to a growing strand containing that nucleotide.
    (b) Strand elongation would proceed as normal.
    (c) Nucleotides would only be added at the 5′ end.
    (d) T. aquaticus DNA polymerase would be denatured.

(a) No additional nucleotides would be added to a growing strand containing that nucleotide.

  1. What does SNP (pronounced snips) stand for?
    (a) small nuclear protein
    (b) single nucleotide particle
    (c) single nucleotide polymorphism
    (d) small nicking points

(c) single nucleotide polymorphism

  1. The process by which genetic information is transferred from DNA to RNA/RNA is formed from DNA?
    (a) transversion
    (b) transcription
    (c) translation
    (d) translocation

(b) transcription

  1. In humans, the hormone testosterone binds to specific proteins in cells, which then bind to specific DNA sites in cells. These proteins probably act to
    (a) help RNA polymerase transcribe certain genes.
    (b) alter the pattern of DNA splicing.
    (c) stimulate protein synthesis.
    (d) unwind the DNA so that its genes can be transcribed.

(a) help RNA polymerase transcribe certain genes.

  1. What is the name of the DNA site at which RNA polymerase binds during transcription?
    (a) enhancer
    (b) promoter
    (c) regulator
    (d) receptor

(b) promoter

  1. In prokaryotes, a GTP molecule is required for translation initiation in?
    (a) association of 50 S subunit of the ribosome with the initiation complex
    (b) formation of formyl-met-tRNA
    (c) binding of 30 S subunit of the ribosome with mRNA
    (d) association of 30S-mRNA with formyl-met-tRNA

(d) association of 30S-mRNA with formyl-met-tRNA

  1. As a ‘start’ or ‘stop’ codon, which of the following triplet codes is correctly matched with its amino acid specificity in protein synthesis?
    (a) UAC – Tyrosine
    (b) UCG – Start
    (c) UUU – Stop
    (d) UGU – Leucine

(a) UAC – Tyrosine

  1. tRNA takes part in?
    (a) the transfer of genetic code to the cytoplasm.
    (b) carry amino acids to ribosomes.
    (c) collection of RNA in ribosomes.
    (d) copy the genetic code from DNA in the nucleus.

(b) carry amino acids to ribosomes.

  1. Which enzymes are produced by lactose operon?
    (a) b-galactosidase, permease and glycogen synthetase.
    (b) b-galactosidase, permease and transacetylase.
    (c) Permease, glycogen synthetase and transacetylase.
    (d) b-galactosidase, permease and phosphoglucose isomerase.

(b) b-galactosidase, permease and transacetylase.

  1. In a gene encoding a polypeptide of 50 amino acids, what would happen if the 25th codon (UAU) was changed to UAA?
    (a) A polypeptide of 25 amino acids will be formed
    (b) A polypeptide of 24 amino acids will be formed
    (c) Two polypeptides of 24 and 25 amino acids will be formed
    (d) A polypeptide of 49 amino acids will be formed

(b) A polypeptide of 24 amino acids will be formed

  1. Where does protein synthesis occur?
    (a) on ribosomes present in cytosol as well as in mitochondria
    (b) only on ribosomes attached to the nuclear envelope and endoplasmic reticulum
    (c) only on the ribosomes present in the cytosol
    (d) on ribosomes present in the nucleolus as well as cytoplasm

(a) on ribosomes present in cytosol as well as in mitochondria

  1. At what step of translation is high energy of phosphate bonds not consumed?
    (a) Translocation
    (b) Amino acid activation
    (c) Peptidyl-transferase reaction
    (d) Aminoacyl tRNA binding to active ribosomal site

(d) Aminoacyl tRNA binding to active ribosomal site


Other Chapters:

Class 11

Class 12


Good luck Medicoholics! Until next time.

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