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 enzyme unwinds the DNA double helix ahead of the replication fork?
Answer: Helicase
Helicase breaks hydrogen bonds between base pairs and unwinds the double helix, creating the replication fork for DNA synthesis.
The Hardy-Weinberg equilibrium requires which of the following conditions?
Answer: Random mating within the population
Hardy-Weinberg equilibrium requires random mating, no selection, no mutation, no genetic drift, and no gene flow.
Which molecule acts as the final electron acceptor in aerobic cellular respiration?
Answer: Oxygen
Oxygen is the terminal electron acceptor in the electron transport chain, combining with electrons and H⁺ to form water.
Nondisjunction during meiosis I results in which outcome?
Answer: All daughter cells receive abnormal chromosome numbers
When homologous chromosomes fail to separate in meiosis I, all four resulting gametes receive an abnormal number of chromosomes.
In an enzyme-substrate interaction, what does the Michaelis constant (Km) represent?
Answer: Substrate concentration at half-maximal velocity
Km is the substrate concentration at which the reaction rate is half of Vmax, indicating the enzyme's affinity for its substrate.
Which process allows RNA to be synthesized from a DNA template?
Answer: Transcription
Transcription uses RNA polymerase to synthesize an RNA strand complementary to the DNA template strand.
T lymphocytes mature and become immunocompetent in which organ?
Answer: Thymus
T cells originate in bone marrow but migrate to the thymus where they undergo positive and negative selection to become mature, self-tolerant T lymphocytes.