Molecular Genetics Practice Test

12th Standard Zoology — Molecular Genetics: Online Practice Test

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Hershey and Chase experiment with bacteriophage showed that

A.Protein gets into the bacterial cells B.DNA is the genetic material C.DNA contains radioactive sulphur D.Viruses undergo transformation

DNA and RNA are similar with respect to having

A.Thymine as a nitrogen base B.A single-stranded helix shape C.Nucleotides containing sugars, nitrogen bases and phosphates D.The same sequence of nucleotides for the amino acid phenylalanine

An mRNA molecule is produced by

A.Replication B.Transcription C.Duplication D.Translation

The total number of nitrogenous bases in human genome is estimated to be about

A.3.5 million B.35000 C.35 million D.3.1 billion

E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two generations. What density distribution of DNA would you expect in this experiment?

A.One high and one low density band B.One intermediate density band C.One high and one intermediate density band D.One low and one intermediate density band

What is the basis for the difference in the synthesis of the leading and lagging strands of DNA molecules?

A.Origin of replication occurs only at the 5' end of the molecules B.DNA ligase works only in the 3' to 5' direction C.DNA polymerase can join new nucleotides only to the 3' end of the growing strand D.Helicases and single-strand binding proteins work only at the 5' end

Which of the following is the correct sequence of events with reference to the central dogma?

A.Transcription, Translation, Replication B.Transcription, Replication, Translation C.Duplication, Translation, Transcription D.Replication, Transcription, Translation

Which of the following statements about DNA replication is not correct?

A.Unwinding of DNA molecule occurs as hydrogen bonds break B.Replication occurs as each base is paired with another exactly like it C.Process is known as semi-conservative replication because one old strand is conserved in the new molecule D.Complementary base pairs are held together with hydrogen bonds

Which of the following statements is not true about DNA replication in eukaryotes?

A.Replication begins at a single origin of replication B.Replication is bidirectional from the origins C.Replication occurs at about 1 million base pairs per minute D.There are numerous different bacterial chromosomes, with replication occurring in each at the same time

Q10

The first codon to be deciphered was __________ which codes for ________.

A.AAA, proline B.GGG, alanine C.UUU, Phenylalanine D.TTT, arginine

Q11

Meselson and Stahl's experiment proved

A.Transduction B.Transformation C.DNA is the genetic material D.Semi-conservative nature of DNA replication

Q12

Ribosomes are composed of two subunits; the smaller subunit of a ribosome has a binding site for _________ and the larger subunit has two binding sites for two __________.

A.mRNA, tRNA B.tRNA, mRNA C.tRNA, rRNA D.rRNA, tRNA

Q13

An operon is a

A.Protein that suppresses gene expression B.Protein that accelerates gene expression C.Cluster of structural genes with related function D.Gene that switches other genes on or off

Q14

When lactose is present in the culture medium

A.Transcription of lac y, lac z, lac a genes occurs B.Repressor is unable to bind to the operator C.Repressor is able to bind to the operator D.Both (a) and (b) are correct

Q15

Who coined the term "gene" in 1909 to refer to the discrete determiners of inherited characteristics?

A.Wilhelm Johannsen B.Gregor Mendel C.Walter Sutton D.George Beadle

Q16

Which organism was used by George Beadle and Edward Tatum in the early 1940s to propose the one gene-one enzyme hypothesis?

A.Escherichia coli B.Neurospora crassa C.Streptococcus pneumoniae D.Drosophila melanogaster

Q17

In the transformation experiments of Avery, Macleod, and McCarty, the transforming ability of the heat-killed S-strain extract was lost only when treated with which enzyme?

A.Protease B.RNase C.DNase D.Amylase

Q18

Which radioactive isotopes were used by Alfred Hershey and Martha Chase in 1952 to selectively label viral proteins and DNA?

A.14C and 15N B.3H and 14C C.35S and 32P D.15N and 32P

Q19

What is the primary chemical difference between the pentose sugar ribose found in RNA and deoxyribose found in DNA?

A.Deoxyribose has one less carbon atom than ribose B.Deoxyribose has one less oxygen atom than ribose C.Deoxyribose has one more hydroxyl group than ribose D.Deoxyribose is a hexose sugar while ribose is a pentose sugar

Q20

A nucleoside is converted into a nucleotide when a phosphate group is covalently attached to which carbon of the pentose sugar?

A.1' carbon B.2' carbon C.3' carbon D.5' carbon

Q21

Who first coined and used the term "RNA world" in 1986 to hypothesize that RNA was the first genetic material on Earth?

A.Walter Gilbert B.Leslie Orgel C.Francis Crick D.Carl Woese

Q22

Approximately how many base pairs of DNA are wrapped around a single histone octamer to form a typical nucleosome in eukaryotes?

A.100 bp B.140 bp C.200 bp D.340 bp

Q23

The 30 nm chromatin fiber is stabilized by H1 interactions and forms a solenoid structure containing how many nucleosomes per turn?

A.Two nucleosomes B.Four nucleosomes C.Six nucleosomes D.Eight nucleosomes

Q24

Given that Escherichia coli has approximately 4.6 x 10^6 base pairs and replicates in 18 minutes, what is its average rate of polymerization?

A.500 bp/sec B.1000 bp/sec C.2000 bp/sec D.5000 bp/sec

Q25

In prokaryotes, which specific subunit of the RNA polymerase holoenzyme is responsible for recognizing the promoter sequence on DNA?

A.Alpha subunit B.Beta subunit C.Omega subunit D.Sigma subunit

Q26

What is the name of the AT-rich promoter region found in eukaryotes, which is also referred to as the Goldberg-Hogness box?

A.Pribnow box B.TATA box C.Shine-Dalgarno sequence D.Solenoid box

Q27

The point mutation causing sickle cell anemia involves a single base substitution in the sixth codon of the beta-globin gene, changing it from:

A.GTG to GAG B.GAG to GTG C.GUG to GAG D.GAG to GUG

Q28

What is the name of the prokaryotic ribosome binding site located at the 5' end of mRNA that base-pairs with 16S rRNA?

A.TATA box B.Pribnow box C.Shine-Dalgarno sequence D.Kozak sequence

Q29

Which is the largest known human gene, consisting of approximately 2.4 million bases?

A.Insulin B.Hemoglobin C.Dystrophin D.Actin

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About this Molecular Genetics test

This free online practice test covers Molecular Genetics from the 12th Standard Zoology (Samacheer Kalvi) syllabus. Choose the number of questions and an optional time limit, then answer and submit — everything is checked in your browser, with the correct answers and a worked explanation shown at the end. For the full solutions to every question in this set, see the solved MCQs page.

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