Biomedical Sciences Flashcards
7 cards from real STP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Biomedical Sciences flashcards as text
During oxidative phosphorylation, at which complex does electron transport directly drive proton pumping into the intermembrane space?
Answer: Complexes I, III, and IV
Complexes I, III, and IV are proton pumps; Complex II does not translocate protons, and Complex V uses the proton gradient to synthesize ATP.
Which cell type is the primary source of IgE antibodies in an allergic response?
Answer: Plasma cells derived from B cells
B cells undergo class switching to IgE production upon IL-4 and IL-13 signaling, then differentiate into IgE-secreting plasma cells.
What does the Km value of an enzyme indicate?
Answer: The substrate concentration at half-maximum velocity
Km is the substrate concentration at which reaction velocity is half of Vmax, reflecting the enzyme's affinity for its substrate.
Which organelle contains enzymes that generate hydrogen peroxide and subsequently break it down with catalase?
Answer: Peroxisome
Peroxisomes use oxidases to generate H₂O₂ from fatty acid oxidation and other reactions, then neutralize it with catalase.
A researcher observes that a drug increases cAMP levels in cells. Which enzyme is most likely being inhibited?
Answer: Phosphodiesterase
Phosphodiesterase degrades cAMP; inhibiting it allows cAMP to accumulate, mimicking the effect of receptor activation.
Which DNA repair mechanism corrects base mismatches introduced during DNA replication?
Answer: Mismatch repair
Mismatch repair (MMR) recognizes and corrects nucleotide mismatches and small insertion/deletion loops arising during replication.
In flow cytometry, what does the FSC (forward scatter) parameter primarily indicate?
Answer: Cell size
Forward scatter correlates with cell size because larger cells deflect more laser light in the forward direction.