Biology Flashcards
7 cards from real PCAT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Biology flashcards as text
Which nitrogenous bases are classified as purines?
Answer: Adenine and guanine
Adenine and guanine are purines (double-ring structures), while cytosine, thymine, and uracil are pyrimidines (single-ring structures).
The conversion of pyruvate to acetyl-CoA occurs in which cellular location?
Answer: Mitochondrial matrix
Pyruvate is transported into the mitochondrial matrix where pyruvate dehydrogenase complex converts it to acetyl-CoA, CO₂, and NADH.
Which type of cell junction allows direct communication between adjacent cells via cytoplasmic channels?
Answer: Gap junctions
Gap junctions consist of connexin protein channels (connexons) that allow ions and small molecules to pass directly between neighboring cells.
In a food chain, approximately what percentage of energy is transferred from one trophic level to the next?
Answer: 10%
The 10% rule states that only about 10% of energy stored in one trophic level is transferred to the next; the rest is lost as heat.
Which region of an antibody is highly variable and responsible for antigen binding?
Answer: Variable region (Fab)
The Fab (fragment antigen-binding) region contains variable domains of both heavy and light chains that form the unique antigen-binding site.
Which process produces genetic variation by exchanging segments between homologous chromosomes during meiosis I?
Answer: Crossing over
Crossing over (recombination) occurs at chiasmata during prophase I, exchanging genetic segments between homologous chromosomes to increase genetic diversity.
Which neurotransmitter is primarily associated with the 'fight-or-flight' response and is released from the adrenal medulla?
Answer: Epinephrine
Epinephrine (adrenaline) is released from the adrenal medulla during sympathetic activation, increasing heart rate, blood pressure, and blood glucose.