Prepare for NEET Biology Biomolecules with MCQs & PYQs on NEET.GUIDE. Get free practice, previous year questions, and expert explanations of carbohydrates, proteins, and more.
A rare genetic disorder affects lipid metabolism by impairing the synthesis of plasmalogens. Which membrane component would be MOST directly affected?
Mitochondrial inner membrane
Nuclear envelope
Myelin Sheath
Lysosomal membrane
Which of the following is NOT a function of cardiolipin?
Stabilizing the structure of respiratory chain complexes
Facilitating mitochondrial cristae formation
Major component of cell membrane fluidity
Apoptosis regulation
Glycogen, the primary storage polysaccharide in animals, exhibits a highly branched structure. Which of the following best explains the significance of this branching for its function?
Branching increases the structural rigidity of glycogen, enabling it to form strong fibers.
Branching decreases the osmotic pressure exerted by glycogen within cells.
Branching facilitates the transport of glycogen across cell membranes.
Branching allows for rapid hydrolysis by providing multiple sites for enzyme action, crucial for quick energy release.
Agar, a polysaccharide extracted from certain red algae, is widely used as a solidifying agent in microbiological media. Which of the following structural features contributes most to agar's gelling properties?
High degree of branching similar to glycogen.
Presence of ฮฒ(1โ4) glycosidic linkages exclusively.
The presence of sulfated galactose residues and the formation of double helices.
Its ability to form highly crystalline structures similar to cellulose.
Hyaluronic acid, a glycosaminoglycan found in connective tissues, exhibits unique viscoelastic properties. Which combination of structural features contributes most significantly to these properties?
Branched structure with ฮฑ(1โ6) linkages, and high sulfate content.
Repeating disaccharide units containing glucuronic acid and N-acetylglucosamine, along with extensive hydration.
Linear structure with ฮฒ(1โ4) linkages, and hydrophobic interactions.
Presence of fucose residues and formation of triple helices.
A novel protein was discovered containing a unique amino acid with a side chain composed of a selenol group (-SeH). Compared to a cysteine residue (-SH) in a similar protein, this selenol-containing amino acid would MOST likely exhibit which property?
Increased reactivity towards oxidizing agents
Decreased reactivity towards oxidizing agents
Identical reactivity towards oxidizing agents
Formation of stronger disulfide bonds
Which amino acid substitution in a protein is MOST likely to disrupt a beta-sheet structure due to steric hindrance?
Glycine to Valine
Alanine to Glycine
Valine to Isoleucine
Serine to Threonine
The isoelectric point (pI) of a polypeptide with a high content of lysine and arginine residues would be expected to be:
Acidic
Neutral
Basic
Close to 7
A researcher isolates an enzyme from a thermophilic bacterium and finds that its activity dramatically decreases when incubated at 25ยฐC compared to its optimal temperature of 70ยฐC. This decrease in activity is MOST likely due to:
Increased substrate affinity at lower temperatures.
Changes in the enzyme's three-dimensional structure affecting the active site.
A decrease in the activation energy of the catalyzed reaction.
An increase in the concentration of competitive inhibitors at lower temperatures.
A novel organism is discovered that utilizes a unique metabolic pathway where the standard free energy change (Gยฐ) for the overall reaction is +25 kJ/mol. Which of the following strategies could this organism employ to make this pathway thermodynamically feasible?
Increase the concentration of products.
Decrease the concentration of reactants.
Couple the endergonic reaction to a highly exergonic reaction.
Decrease the temperature of the reaction.
