Biochemistry Paper-2 (Supplementary), 2021 MBBS Batch ABVMU Lucknow

ATAL BIHARI VAJPAYEE MEDICAL UNIVERSITY, UTTAR PRADESH

MBBS 1st PROFESSIONAL SUPPLEMENTARY EXAMINATION

BIOCHEMISTRY - PAPER - II

TIME: 3 Hrs
Max. Marks: 100

Note: Attempt all questions. Answer Section - A and Section - B in separate answer books.

SECTION - A

PAPER CODE: 2322130003

Q.1 Long Answer (2 + 5 + 4 + 4 = 15 Marks)

Concerns about a 1-year-old girl’s development prompt the parents to bring her to the pediatrician. She was born at term and the delivery was uneventful. The baby is not meeting the expected milestones, according to the mother for an infant her age. She also mentions some hypopigmented patches on her skin and hair as well as an odd odour coming from her urine. The girl’s examination revealed some muscle hypotonia and microcephaly. The collected urine is found to have a “mousy” smell.

a) What is the most likely diagnosis?
b) What is the biochemical defect and how is it leading to this disease?
c) Why there is a development of hypopigmented patches and mousy odour in urine?
d) How can this abnormality be diagnosed and managed?

Q.2 Short Notes (within 500 words) (3 × 5 = 15 Marks)

a) Enlist the role of physicians towards society and community.
b) Write in brief about causes and treatment of Gout.
c) Write in brief about mechanisms of conversion of protooncogenes to oncogenes.

Q.3 Short Answer (within 100 words) (5 × 2 = 10 Marks)

a) How lead toxicity leads to anemia?
b) How Vitamin C plays an important role in synthesis of collagen?
c) How allopurinol is helpful in the management of gout?
d) Write in short about mechanism of nucleotide excision repair.
e) Write in brief about inhibitors of transcription.

Q.4 Multiple Choice Questions (1 × 10 = 10 Marks)

1. Hybridoma cells are grown in:
   a) HAT Medium
   b) DMEM Medium
   c) RPMI Medium
   d) Modified DMEM Medium

2. Transfection in recombinant DNA technology involves:
   a) Isolation of desired DNA
   b) Isolation of vectors
   c) Formation of chimeric DNA
   d) Uptake of chimeric DNA

3. A silent mutation is possible due to the following characteristics of the genetic code:
   a) Universality
   b) Unambiguity
   c) Non-overlapping
   d) Degeneracy

4. INCORRECT statement regarding Lesch-Nyhan syndrome
   a) Affects young boys
   b) Presents with gouty arthritis
   c) Enhanced reutilization of purine bases
   d) Bizarre behavior of self-mutilation

5. All of the following amino acids contribute to purine biosynthesis except:
   a) Glycine
   b) Aspartate
   c) Glutamine
   d) Cysteine

6. TIM-TOM proteins are associated with translocation of proteins of which organelle:
   a) Mitochondria
   b) Nucleus
   c) Peroxisome
   d) Lysosome

7. Select incorrect statement regarding Guthrie Test:
   a) The test can differentiate between congenital phenylketonuria (PKU) and maternal PKU
   b) It is a bacterial inhibition test
   c) β-2 Thienyl alanine is a growth inhibitor for bacteria
   d) Bacillus subtilis is grown in Petri dish

8. A chemical X converts DNA sequence from CAA to CAU.
   a) Meselson-Stahl experiment
   b) AMES Test
   c) Prausnitz-Kustner Test
   d) Indirect Coombs Test

9. Collagen present in skin is:
   a) Type I
   b) Type II
   c) Type III
   d) Type IV

10. CD4 T cells are generally restricted by:
    a) MHC class-I
    b) MHC class-II
    c) CD-1
    d) β2-microglobulin

SECTION – B PAPER CODE: 2322230003

Q.1 Long Answer Question (5 + 3 + 3 + 4 = 15 Marks)

At 12 weeks gestation, a 25-year-old Mediterranean woman visits her physician for the first time. She is worried about her unborn child and the possibility that she or her unborn child would inherit a "blood" ailment from her family because this is her first pregnancy. The patient recounts having slight anemia personally, but not to the same extent as her brother, who required repeated transfusions and passed away at age 10. The patient’s doctor informed her that she did not require iron supplementation in order to treat her anemia. The patient denies having any features of anemia. Her physical examination was in line with a 12-week pregnancy, and an ultrasound at the 12-week mark verified this.

Hemoglobin electrophoresis revealed increased hemoglobin A2 level (4.0 percent) and increased fetal hemoglobin level, a hypochromic, microcytic (small-sized red cell) anemia in the patient (hemoglobin, 9g/dL), a pattern that is in line with mild β-thalassemia. The diagnosis was given after the patient had chorionic villus sampling to determine if the fetus was impacted.

1. What is the molecular genetics behind this disorder?

2. Give reason why β-thalassemia is more commonly seen than α-thalassemia.

3. Why the patient in this case is suggested not to take iron supplements for her anemia?

4. Compare and contrast between anemia due to thalassemia and sickle cell anemia.

Q.2 Short Notes Questions (within 500 words) (3 x 5 = 15 Marks)

1. Write in brief about urea cycle and its disorders.

2. Compare and contrast between active immunity and passive immunity.

3. Compare and contrast the events of replication in prokaryotic and eukaryotic cells.

Q.3 Short Answer Questions (within 100 words) (5 x 2 = 10 Marks)

1. Write briefly about missense mutation using a suitable example.

2. What are glycosaminoglycans and what are their functions?

3. What is tolerance in immunology, and how is it necessary for normal immune function?

4. What are the biologically important products generated from tyrosine metabolism?

5. What is methemoglobinemia? What is the mechanism which protects against it under physiological conditions?

Q.4 Multiple Choice Questions (1 x 10 = 10 Marks)

1. One of the most effective amino acids contributing to the buffering action of proteins is:
   a) Histidine
   b) Arginine
   c) Lysine
   d) Methionine

2. Which compound of the urea cycle is synthesized in the mitochondria and transported out into the cytoplasm?
   a) Ornithine
   b) Citrulline
   c) Argininosuccinate
   d) Arginine

3. Elevated homocysteine levels are associated with the risk of:
   a) Bronchiectasis
   b) Nephrotic syndrome
   c) Coronary artery disease
   d) Diabetes mellitus

4. All of the following substances are synthesized from phenylalanine and tyrosine EXCEPT:
   a) Thyroid hormones
   b) Catecholamines
   c) Melanin
   d) Glucocorticoids

5. Ehlers-Danlos syndrome characterized by hypermobile joints and skin abnormalities is due to:
   a) Abnormality in gene for procollagen
   b) Deficiency of lysyl oxidase
   c) Deficiency of prolyl hydroxylase
   d) Deficiency of lysyl hydroxylase

6. All of the following are required for the hydroxylation of proline residues during collagen synthesis EXCEPT:
   a) Ascorbic acid
   b) Glutamate
   c) Ferrous ions
   d) Molecular oxygen

7. Selenocysteine is coded by:
   a) UGA
   b) UCA
   c) UAG
   d) UAA

8. The Creutzfeldt-Jacob disease attacks the:
   a) Heart
   b) Lungs
   c) Kidney
   d) Brain

9. Apart from proteins, which one of the following molecules also exerts enzymatic function:
   a) DNA
   b) RNA
   c) Carbohydrates
   d) Lipids

10. Tumor Marker for Ovarian Cancer is –
    a) β-human chorionic gonadotropin
    b) Alpha-Fetoprotein
    c) CA-125
    d) Carcinoembryonic Antigen

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