Biological Flashcards

Which of the following best describes a competitive inhibitor of an enzyme?

Answer: It competes with substrate for the active site and its effect can be overcome by excess substrate

Competitive inhibitors bind the active site reversibly; increasing substrate concentration displaces the inhibitor and restores enzyme activity.

During which stage of cellular respiration is the most ATP produced per glucose molecule?

Answer: Oxidative phosphorylation

Oxidative phosphorylation via the electron transport chain generates approximately 32–34 ATP molecules, far more than earlier stages.

Which hormone stimulates the reabsorption of sodium in the distal tubule of the nephron?

Answer: Aldosterone

Aldosterone, produced by the adrenal cortex, promotes Na⁺ reabsorption and K⁺ secretion in the distal tubule and collecting duct.

What is the role of telomerase in cancer cells?

Answer: It adds telomeric sequences to chromosome ends, enabling indefinite replication

Cancer cells overexpress telomerase, which lengthens telomeres after each division, preventing replicative senescence and allowing unlimited proliferation.

Which of the following correctly describes the process of translation?

Answer: mRNA codons are read by tRNA anticodons to assemble a polypeptide

Translation occurs at ribosomes where tRNA anticodons recognize mRNA codons and deliver amino acids to build a polypeptide chain.

Which cells of the immune system are primarily responsible for antibody production?

Answer: Plasma cells (differentiated B cells)

Plasma cells are terminally differentiated B lymphocytes that secrete large quantities of antigen-specific antibodies.

In which phase of mitosis do chromosomes align at the cell's equatorial plate?

Answer: Metaphase

During metaphase, spindle fibers attach to kinetochores and align chromosomes along the metaphase plate for equal distribution.