Gaokao Biology: Cell Biology and Metabolism Flashcards
7 cards from real GAOKAO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Gaokao Biology: Cell Biology and Metabolism flashcards as text
Osmosis is defined as the movement of water molecules across a semipermeable membrane from a region of:
Answer: High water potential to low water potential
Osmosis moves water from high water potential (low solute) to low water potential (high solute) across a semipermeable membrane until equilibrium is reached.
The chemiosmotic theory, proposed by Peter Mitchell, explains ATP synthesis through:
Answer: A proton gradient driving ATP synthase rotary mechanism
Mitchell's chemiosmosis theory states that the electron transport chain creates a proton (H⁺) gradient, and the potential energy of protons flowing back through ATP synthase drives ATP synthesis.
In C4 plants such as maize, carbon dioxide is first fixed in mesophyll cells into:
Answer: Oxaloacetate (OAA)
In C4 photosynthesis, PEP carboxylase in mesophyll cells fixes CO₂ onto PEP to form oxaloacetate (4C), which is transported to bundle sheath cells where CO₂ is released for the Calvin cycle.
Which nuclear event must occur before a cell can begin mitosis?
Answer: DNA replication (S phase)
DNA replication during S phase of interphase must be completed before mitosis can begin, ensuring each daughter cell receives a complete copy of the genome.
Allosteric regulation of enzymes refers to:
Answer: Regulation by molecules binding to sites other than the active site, causing conformational changes
Allosteric regulation occurs when effector molecules (activators or inhibitors) bind to allosteric sites, causing conformational changes that affect the active site's shape and activity.
What is the primary function of the nucleolus within the nucleus?
Answer: Synthesis and processing of ribosomal RNA (rRNA)
The nucleolus is the site of rRNA gene transcription and ribosomal subunit assembly; it disappears during mitosis and reforms after division.
In which stage of aerobic respiration is CO₂ directly released as a product?
Answer: Pyruvate oxidation and Krebs cycle
CO₂ is released during pyruvate oxidation (pyruvate → acetyl-CoA + CO₂) and during the Krebs cycle (at isocitrate dehydrogenase and α-ketoglutarate dehydrogenase reactions).