Practise CAIE AS Biology 3.1 by explaining enzyme specificity and catalytic action, then interpreting investigations that track substrate or product change.
The diagram shows a simple metabolic pathway.
The letters W, X, Y and Z represent four different substances. At each step in the diagram the substrate undergoes a chemical reaction catalysed by an enzyme. The reaction produces the next substance in the pathway.
Which statements correctly describe the enzymes taking part in this metabolic pathway?
1 They are all globular proteins.
2 They all have the same tertiary structure.
3 They all contain hydrogen atoms in their structure.
1, 2 and 3
1 and 2 only
1 and 3 only
2 only
The diagram shows different molecules in a solution.
Which statement could explain what happens when some of the molecules are mixed together?
Molecule P forms an enzyme-substrate complex with the non-competitive inhibitor molecule Q .
Molecule Q binds to molecule P, increasing the activation energy.
Molecules R and S bind to the active site of molecule P .
Molecules S and R are the products of the breakdown of molecule P .
Influenza virus has an enzyme called neuraminidase which breaks down glycoproteins in the surface membrane of the cell that the virus will infect. The glycoprotein binds to the active site of neuraminidase by induced fit.
Which statements about the induced fit hypothesis of enzyme action are correct?
1 The active site must have the same shape as the substrate for them to bind together.
2 This enzyme is less likely to be affected by non-competitive inhibitors than an enzyme working by the lock-and-key mechanism.
3 The substrate is converted to product by specific R-groups in the active site just like the lock-and-key mechanism.
1 and 2
2 and 3
2 only
3 only