216 exam-style questions on Form and function with answers and explanations. Six real samples below — the full set is free with an account.
The 'induced fit' model of enzyme action states that:
Answer: The active site changes shape slightly as the substrate binds
In the induced fit model the active site is flexible and moulds around the substrate as it binds, straining bonds and lowering activation energy, unlike the older rigid lock-and-key idea.
The Bohr shift describes how increased carbon dioxide (and lower pH) causes haemoglobin to:
Answer: Release oxygen more readily
Higher CO2 and lower pH in active tissues lower haemoglobin's affinity for oxygen, shifting the dissociation curve right. This releases more oxygen exactly where respiration demands it.
Which structure initiates the heartbeat by acting as the heart's natural pacemaker?
Answer: Sinoatrial (SA) node
The sinoatrial node in the right atrium spontaneously generates electrical impulses that spread across the atria, setting heart rate. The AV node then relays the signal to the ventricles.
A defining property of a stem cell is that it
Answer: can self-renew and differentiate
Stem cells retain the capacity to divide (self-renew) and to differentiate; potency varies (totipotent, pluripotent, multipotent).
Active transport across a membrane requires
Answer: energy from ATP
Active transport moves substances against their concentration gradient using ATP and membrane pump proteins.
Facilitated diffusion differs from simple diffusion because it
Answer: uses membrane transport proteins
Facilitated diffusion is passive (down the gradient) but uses channel or carrier proteins for large or polar solutes.
216 Form and function questions — free with an account. Spaced repetition, streaks and full exam simulations included.
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