P08

Biochemistry & Clinical Pathology

Biomolecules and metabolic pathways, clinical laboratory tests, normal values and their interpretation

46
questions
in this subject
0
cite a source
Act, Rule or reference
8
subtopics
covered

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Subtopics in this bank

Biomolecules, Bioenergetics and EnzymologyBlood chemistry normal valuesCarbohydrate metabolismHaematology testsIntermediary Metabolism and Biological Oxidation: Carbohydrate, Lipid and Amino Acid Pathways with Associated DisordersLiver function testsRenal function testsUrine analysis

Sample questions, with the reasoning

Every served question is explained like this — including why each wrong option is wrong.

A markedly raised erythrocyte sedimentation rate (ESR) most generally indicates:

  • A)Normal health
  • B)A specific diagnosis of tuberculosis
  • C)Blood group incompatibility
  • D)An ongoing inflammatory or chronic infective process

Why D is correct

Inflammation raises plasma fibrinogen and globulins, which make red cells stack into rouleaux and settle faster. The ESR is therefore a NON-SPECIFIC index: useful for detecting and monitoring inflammatory activity (TB, rheumatic diseases, chronic sepsis) but incapable of naming the disease.

AI fact-checked

A neutral (monoamino, monocarboxylic) amino acid such as alanine has an α-carboxyl group with pKa₁ = 2.3 and an α-amino group with pKa₂ = 9.7. What is its approximate isoelectric point (pI), and which species predominates there?

  • A)pI ≈ 6.0; the amino acid exists predominantly as the zwitterion (net charge zero).
  • B)pI ≈ 6.0; it exists predominantly as the fully protonated cation.
  • C)pI ≈ 12.0 (the sum of the two pKa values); predominantly the anion.
  • D)pI ≈ 3.5; predominantly the zwitterion.

Why A is correct

For an amino acid with no ionizable side chain the isoelectric point is the mean of the two pKa values flanking the zwitterion: pI = ½(2.3 + 9.7) = 6.0, at which the net charge is zero (zwitterion predominates).

AI fact-checked

All of the following amino acid residues are commonly utilized in the catalytic mechanisms of enzymes as covalent catalysis nucleophiles or general acid-base catalysts EXCEPT:

  • A)Serine
  • B)Leucine
  • C)Histidine
  • D)Cysteine

Why B is correct

Leucine is a purely hydrophobic, aliphatic amino acid with an isobutyl side chain that lacks any functional group capable of acting as a nucleophile, electrophile, or general acid-base catalyst under physiological conditions. It is typically buried in protein interiors or involved in hydrophobic interactions rather than active sites.

AI fact-checked

Practise P08 with real marking

46 questions · +1/−⅓ RRB-pattern marking · explanations after every answer. No sign-up needed.

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