Molecular Biology Online Quiz Questions And Answers

16- Which ONE of the following is true concerning Antidiuretic hormone(ADH)?
1) Carbamazepine potentiates it's release
2) Ethanol potentiates it's release
3) It circulates in the blood bound to neurohypophysin
4) It is a cyclic octapeptide
5) It is synthesised in the posterior pituitary
Answers-1

17- Restriction enzymes:
1) Cut DNA
2) Join two pieces of DNA together
3) Synthesize DNA
4) Degrade DNA
5) Are involved in cell cycle arrest
Answers-1
Restriction enzymes cut DNA at sequences specific for each restriction enzyme, they are vital tools for molecular biology and molecular genetic research.

18- Reverse transcriptase-PCR is used to ampify:
1) Antibodies
2) DNA
3) RNA
4) Protein
5) Plasmids
Answers-3
Reverse transcriptase PCR is a means of amplifying RNA. The RNA is transcribed into complimentary DNA (cDNA) using the enzyme reverse transcriptase, the cDNA
is then amplified by conventional PCR.

19- The level of cellular telomerase activity will affect:
1) The rate of cell growth
2) Cell death
3) The number of cell divisions a cell is capable of undergoing
4) Cell survival
5) RNA synthesis
Answers-3
The telomere is a DNA sequence at the end of each chromosome which becomes progressively shorter with each division the cell undergoes. When it is reduced to a
critical length the cell is not capable of dividing, the enzyme telomerase is able to lengthen the telomere thus preventing this occurring.

20- Which of the following is activated by Cholera toxin?
1) Adenylate cyclase
2) Guanlyate cyclase
3) Peroxisome proliferator receptor (PPAR) gamma
4) Sodium/potassium ATPase
5) The glucose-sodium transporter
Answers-1
Cholera toxin activates adenylate cyclase with generation of cAMP.

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Molecular Biology Multiple Choice Questions And Answers

11- The thyroid hormone receptor is:
1) A gated ion channel
2) A cell surface receptor
3) A cytoplasmic protein
4) A G-protein coupled receptor
5) A nuclear receptor
Answers-5
The thyroid hormone receptor is a nuclear receptor. When it binds T3 it is able to bind to the thyroid hormone response element (TRE) in the promoter region of
thyroid hormone responsive genes and initiates transcription.

12- Proteins known as cyclins:
1) Regulate the menstrual cycle
2) Are differentially expressed throughout the cell cycle
3) Regulate antibody production
4) Regulate the cycling of receptors between the cell surface and the cytoplasm
5) Regulate DNA transcription
Answers-2
Cyclins are key regulators of the cell cycle, different cyclins are expressed at different stages of the cell cycle.

13- Which of the following is a glycoprotein hormone?
1) Growth hormone releasing hormone
2) Cortisol
3) Thyrotropin releasing hormone (TRH)
4) Thyrotropin (TSH)
5) Oxytocin
Answers-4
Thyrotropin is glycosylated, cortisol is a steroid hormone and the others are peptide hormones/neuropeptides which as a group are rarely glycosylated.

14- Which ONE of the following have their own self replicating DNA?
1) Golgi body
2) Lysosomes
3) mitochondria
4) Peroxisome
5) Rough Endoplasmic Reticulum
Answers-3
Abnormalities of Mitochondrial DNA are associated with inherited conditions such as Leber's OA, MELAS syndrome and DIDMOAD(Dr Vajira H. W. Dissanayake)

15- A Plasmid is best described as
1) a recombinant section of DNA
2) a small viral particle
3) bacterial DNA separate from the chromosome
4) consist of multiple copies of a single gene
5) having multiple origins of replication
Answers-3

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Molecular Biology Objective Type Questions And Answers

6- The Polymerase Chain Reaction (PCR) is used to amplify small amounts of DNA for further analysis. First the DNA double helix must be split into two strands. This is achieved by
1) alkali solution
2) centrifugation
3) DNA polymerase
4) heating to nearly 100°C
5) viral reverse transcriptase
Answers-4

7- Protein synthesis occurs within cells. A particular molecule that is produced in the nucleus initiates protein synthesis. This molecule matures in the cytoplasm and binds to the ribosome. This molecule is
1) messenger RNA
2) ribosomal RNA
3) RNA nucleotide
4) RNA polymerase
5) transfer RNA
Answers-1

8- Northern blotting is a technique that can be used to detect:
1) Antibodies
2) DNA
3) RNA
4) Protein
5) Plasmids
Answers-3
Northern blotting is a means of detecting RNA, frequently used to quantify specific mRNA transcript levels.

9- Which of the following statements regarding messenger RNA (mRNA) is correct?
1) mRNA never contains introns.
2) mRNA is translated into proteins in the nucleus.
3) mRNA contains the bases cytosine and thymine.
4) reverse transcriptase uses mRNA as a template to produce complementary DNA.
5) mRNA is used in the Southern blotting technique.
Answers-4

10- Transcription RNA (tRNA) has three bases specific for a particular amino acid with which it binds to messenger RNA (mRNA). This specific area of tRNA is called the
1) anticodon
2) codon
3) exon
4) intron
5) transposon
Answers-1

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23 Top Molecular Biology Objective Type Questions And Answers

1- Apoptosis is induced by:
1) Activation of caspases
2) The MAP kinase pathway
3) DNA synthesis
4) Antibodies
5) Necrosis
Answers-1

2- Phosphorylation of protein tyrosine residues is associated with:
1) Cell signalling pathways
2) Protein degradation
3) Alzheimer's disease
4) Protein synthesis
5) Creutzfeldt-Jacob Disease
Answers-1
Phosphorylation of specific tyrosine residues of components of cell signalling pathways is often a key event in the activation of the pathway.

3- Two strains of Escherichia coli are isolated and both are resistant to ampicillin. Strain A retains its resistance to amplicillin when grown form multiple generations in the absence of ampicillin. However strain B loses its resistance when grown in the absence of ampicillin. Which of the following best explains the loss of antibiotic resistance in strain B?
1) Changes in the bacterial DNA gyrase
2) Downregulation of the resistance gene
3) Loss of a plasmid containing the resistance gene
4) Mutations in the resistance gene
5) Transposition of another sequence into the resistance gene
Answers-3

4- Apoptosis is the process of programmed cell death and occurs in cells that have damaged DNA. A mediator of this process is a tumour suppressor gene that inhibits mitosis and promotes apoptosis. This gene is:-
1) bcl-2
2) caspases
3) fas (CD95)
4) p53
5) ras
Answers-4

5- Which of the following is an oncogene?
1) The N-Myc gene
2) The WT1 (first Wilm's tumour) gene
3) The Retinoblastoma gene
4) The WT2 (second Wilm's tumour) gene
5) The BCRabI translocation (Philadelphia chromosome)
Answers-1

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