Biological Flashcards

A mutation that converts a codon to a stop codon is best described as a:

Answer: Nonsense mutation

A nonsense mutation changes an amino acid codon to a premature stop codon, resulting in a truncated, usually nonfunctional protein.

Which of the following is an example of negative feedback in the human body?

Answer: High blood glucose triggering insulin release to lower glucose

Insulin release in response to high blood glucose reduces glucose levels, which then signals decreased insulin release—a classic negative feedback loop.

Which of the following correctly pairs an organelle with its function?

Answer: Peroxisome — breakdown of fatty acids and detoxification of H2O2

Peroxisomes contain oxidative enzymes for fatty acid beta-oxidation and catalase to decompose the resulting hydrogen peroxide.

What is the significance of the ABO blood group system in pharmacology and medicine?

Answer: Mismatched transfusions trigger complement-mediated hemolysis

Transfusing incompatible ABO blood types causes recipient antibodies to activate complement, lysing donor red blood cells and potentially causing fatal hemolytic transfusion reactions.

Which property of DNA allows it to serve as a template for its own replication?

Answer: Complementary base pairing between antiparallel strands

Complementary base pairing (A-T, G-C) between antiparallel strands means each strand can serve as a precise template for synthesizing a new complementary strand.

Which type of epithelium lines the alveoli to facilitate gas exchange?

Answer: Simple squamous epithelium

Simple squamous epithelium is extremely thin, providing a minimal diffusion distance for O2 and CO2 exchange between alveolar air and blood.

What is the function of the myelin sheath surrounding axons?

Answer: Increases the speed of action potential conduction via saltatory conduction

Myelin insulates axon segments, forcing action potentials to jump between nodes of Ranvier (saltatory conduction), dramatically increasing transmission speed.