Genetics MCQs with Solutions for NEET PG Biochemistry

Important MCQS with Solution 

Q1. All of the following are purine bases except

1. Adenine
2. Uric acid
3. Hypoxanthine
4. Uracil

Q2. The linkage present in a nucleotide is

1. a N glycosidic linkage
2. b a N glycosidic linkage
3. Phosphoester linkage
4. Acid anhydride linkage

Also read: Important Questions On Carbohydrate Metabolism

Q3. The linkage present in a monophosphate nucleotide is

1. a N glycosidic linkage
2. b N glycosidic linkage
3. Phosphoester linkage
4. Acid anhydride linkage

Q4. The linkage present between phosphate groups in a triphosphate nucleotide is

1. a N glycosidic linkage
2. b N glycosidic linkage
3. Phosphoester linkage
4. Acid anhydride linkage

Q5. The linkage present between individual nucleotides in a polynucleotide chain is

1. 3'5' phosphodiester linkage
2. b N glycosidic linkage
3. Phosphoester linkage
4. 5'3' phosphodiester linkage

Q6. Regarding DNA structure, which is true:

1. The double helical structure is stabilized by covalent bonds.
2. The individual strands are stabilized by 5'3' phosphodiester linkage.
3. The individual strands are stabilized by 3'5' phosphodiester linkage.
4. The term 5' end indicates that the 5' end is linked to the kinetochore.

Also read: Biochemistry Important Questions For NEET PG/FMG Exams

Q7. The most common form of DNA is

1. B DNA
2. Z DNA
3. A DNA
4. E DNA

Q8. The features of B DNA include all except

1. It is a right-handed helix.
2. One full turn of DNA has 10 nucleotides and measures 34A width 20A.
3. The major groove is equal to the minor groove in terms of width.
4. It is the form that is present under physiological conditions.

Q9. Denaturation of DNA is done by all except

1. Increasing the temperature
2. Increasing the salt concentration
3. Decreasing the salt concentrations
4. Formamide

Q10. The left-handed helix is seen in:

1. B DNA
2. Z DNA
3. A DNA
4. E DNA

Also read: Important Questions On Carbohydrate Chemistry

Q11. Which of the following is true about replication?

1. Conservative process
2. Bidirectional
3. Non conservation
4. Unidirectional

Q12. DNA Polymerase requires all except

1. RNA primer
2. 3' to 5' strand to act as a template
3. d NTP
4. 5' to 3' strand as a template

Q13. Replication fork includes all except?

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

Q14. Replication along lagging strand, true is:

1. Polymerase I synthesizes along 3' to 5' direction
2. Helicase and primase join to form primosome and moves along the lagging strand
3. Okazaki fragments are joined together by DNA helicase
4. DNA polymerase III removes RNA primer

Also read: Important Topics in Biochemistry for NEET-PG

Q15. Function of DNA polymerase b except:

1. Lagging strand synthesis
2. Leading strand synthesis
3. Okazaki fragment synthesis
4. RNA Primase

Q16. DNA polymerase with repair mechanism is?

1. DNA polymerase 1
2. DNA polymerase II
3. DNA polymerase III
4. DNA polymerase a

Q17. The True statement about telomerase are all except?

1. They are present at the ends of eukaryotic chromosome
2. Increased telomerase activity is associated with malignancy
3. DNA dependent RNA polymerase
4. DNA polymerase

Q18. The most common error in a DNA is

1. Base Excision
2. Pyrimidine dimer
3. Mismatch
4. DS DNA Break

Also read: Amino Acid Protein Chemistry

Q19. Base excision repair is done by

1. Apurinic endonuclease
2. DNA polymerase g
3. GATC Endonuclease
4. Ku helicase

Q20. Mismatch repair defect causes

1. HNPCC
2. Xeroderma pigmentosum
3. Fanconi's anaemia
4. Ataxia Telangiectasia

Q21. UV light damage to the DNA leads to

1. Purine dimers formed
2. DNA hydrolysis occurs
3. Specific endonuclease recognises the damage
4. Double stranded DNA Break occurs

Q22. Double stranded DNA break repair defect causes all except

1. Hereditary Non Polyposis Colon Cancer (HNPCC)
2. Ataxia Telangiectasia
3. Bloom's syndrome
4. Fanconi's syndrome

Q23. Cockayne syndrome is caused by the defect of

1. ds DNA Break Repair
2. Replication linked nucleotide excision repair.
3. Transcription linked nucleotide excision repair.
4. Mismatch repair

Also read: Recombinant DNA Technology

Q24. Severe combined immunodeficiency is caused by the defect of

1. Non-Homologous End Joining
2. Homologous DNA Repair
3. Transcription linked Nucleotide Excision Repair
4. Mismatch repair

Q25. Homologous DNA repair defect causes

1. Ataxia Telangiectasia
2. Lynch syndrome
3. Bloom syndrome
4. Fanconi's anaemia

Q26. All are the properties of genetic code except:

1. Universal
2. Degenerate
3. Non-overlapping
4. Ambiguous

Q27. No of possible codons

1. 64
2. 61
3. 20
4. 31

Also read: Properties of Genetic Code Mutation

Q28. The histone that is not present in a nucleosome is

1. H1
2. H2A
3. H2B
4. H3

Q29. No. of codons which code for an amino acid

1. 64
2. 61
3. 20
4. 31

Q30. Codon consists of:

1. 3 base pairs.
2. 2 base pairs
3. 5 base pairs
4. 3 nucleotides

Q31. Stop codon:

1. UAG
2. UCA
3. UAC
4. AUG

Also read: Hartnup Disease and Glycine Metabolic Effects

Q32. The amino acid which does not follow degeneracy of codon is:

1. Glycine
2. Glutamine
3. Tryptophan
4. Tyrosine

Q33. Wobble phenomenon explains which of the following:

1. Degeneracy
2. Unambiguity
3. Ambiguity
4. Punctuation

Q34. Transition mutation of GATCCT is:

1. GGTCCT
2. GTTCCT
3. GAACCT
4. GATACT

Also read: Mucopolysaccharides : Exceptions, Important Facts

Case-Based MCQs

Q. 40-year-old male who was diagnosed with rectal cancer. Left colectomy was carried out. A histopathologic diagnosis of poorly differentiated adenocarcinoma. Family history revealed the five family members were diagnosed with colorectal cancer, and two successive generations affected. All malignancies were diagnosed before 45 years of age. Microsatellite instability was detected on genetic analysis of tissue of the proband. It is caused by a defect of

1. Base Excision repair
2. Mismatch repair
3. Nucleotide Excision repair
4. ds DNA Break repair

Q. A 45-year-old male is detected to have fasting and postprandial hyperglycemia in the diagnostic range of diabetes. To understand his long-term glycemic control, he is asked to estimate his HbA1c. Chromatogram detects an abnormal hemoglobin peak, corresponding to Hb Bristol. His oxygen-carrying capacity is normal. Hb Bristol is an example of:

1. Silent Mutation
2. Acceptable mutation
3. Partially acceptable mutation
4. Nonsense mutation

Q. A 25-year-old male presents with a skin infection with yellowish crusts on the face. Impetigo was diagnosed, and Mupirocin ointment was prescribed. Mupirocin acts by

1. Inhibiting the binding of RNA polymerase to +1 site
2. Causing premature termination of mRNA synthesis
3. Causing premature termination of protein synthesis
4. Inhibiting translocation of ribosomes

Also read: INI-CET High Yield Questions For Biochemistry

Image-Based MCQ’s

Q. A family was reported with many cases of mental retardation and developmental delay. Some presented with retinitis pigmentosa. 3 neonatal deaths with lactic acidosis in the family forced them to consult a geneticist. A pedigree chart was drawn (attached). DNA was extracted from all affected members. PCRRFLP detected a point mutation (transversion) at one specific site. The explanation for variable presentation caused by a single mutation site is:

1. Phenotypic heterogeneity
2. Pleiotropy
3. Allelic heteroeneity
4. Heteroplasmy

Explanation

Phenotypic Heterogeneity:

• Multiple site mutations in a gene present with various presentations.
• Ex: Crigler Najjar Syndrome type 1 or 2 or sometimes mild rotor syndrome.

Pleiotropy:

• It is one mutation affecting multiple organs.
• Ex: Marfan's syndrome caused by fibrillin.

Allelic Heterogeneity:

• Multiple sites of mutation causing one presentation.
• Ex: Cystic Fibrosis (m/c cause is dF 508)

Q. True about the DNA defect observed in the image are all except

1. Caused by UV light.
2. Exonuclease is involved in the repair.
3. Defect of the repair causes Xeroderma Pigmentosum
4. Defect of the repair causes Cockayne syndrome

Also read: All About Vitamins - Important Information and Diseases

Q. In the image A denotes the wild-type allele. B is mutated. Identify the type of mutation.

1. Silent mutation
2. Point mutation
3. Acceptable mutation
4. Deletion

Q. Name X shown in the blue box, given the clue that it is an antibiotic, which inhibits the blue circle shown in the image.

1. Puromycin
2. Macrolide
3. Clindamycin
4. Chloramphenicol

Also read: Heme Synthesis Disorders

Important one-liners to remember 

• The most common error in DNA is base excision
• UV light damage to DNA causes pyrimidine dimer
• Ionisation radiation causes DNA break
• The linkage that is broken in base excision is b N glycosidic linkage
• The linkage that is cleaved in double-stranded DNA break is 3'5' phosphodiester linkage
• HbS mutation is an example of point mutation, transversion, missense, and partially acceptable mutations.
• Amino acids which do not follow degeneracy are: Methionine and Tryptophan
• Hb Milwaukee is an example of an acceptable mutation.
• In congenital methemoglobinemia histidine-F8 is replaced by tyrosine
• The instrument used for PCR is Thermocycler
• The enzyme used in conventional PCR is Taq DNA polymerase
• The enzyme used in LAMP PCR is BST or BSM DNA polymerase
• Real-time PCR quantifies in the Exponential or lag phase

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