AAMC MCAT Biological and Biochemical Foundations 3

Question 1

What is the final electron acceptor in the mitochondrial electron transport chain?

Accepted Answer

Oxygen (O2)

Answer

Molecular oxygen accepts electrons at Complex IV (cytochrome c oxidase), combining with protons to form water.

Question 2

Which hormone stimulates hepatic gluconeogenesis during fasting?

Accepted Answer

Glucagon

Answer

Glucagon, released by pancreatic alpha cells during fasting, activates cAMP pathways that upregulate gluconeogenesis to raise blood glucose.

Question 3

What distinguishes smooth muscle from skeletal muscle?

Accepted Answer

Smooth muscle lacks sarcomeres and is involuntarily controlled

Answer

Smooth muscle lacks organized sarcomeres and is regulated by the autonomic nervous system, making it involuntary.

Question 4

Which receptor type spans the membrane and has intrinsic kinase activity?

Accepted Answer

Receptor tyrosine kinase

Answer

Receptor tyrosine kinases (RTKs) phosphorylate tyrosine residues upon ligand binding, initiating downstream signaling cascades.

Question 5

What does the Hardy-Weinberg principle predict?

Accepted Answer

Allele and genotype frequencies in a non-evolving population remain constant

Answer

Hardy-Weinberg states that allele and genotype frequencies are stable in a large, randomly mating population with no selection, mutation, migration, or drift.

AAMC - Association of American Medical Colleges Practice Test

AAMC - Association of American Medical Colleges Practice Test

AAMC MCAT Biological and Biochemical Foundations 3