Enzymes

Traps in Enzymes

• Uses an everyday idea instead of the biology
  Translate everyday words into the textbook definition before choosing. If the only reason an option attracts you is its name or looks, test it against the definition in the stem.
• Over-generalises a rule to all cases
  Absolute words (all, always, every, never) are rarely right in biology. Try to name one exception; if you can, reject the option.
• Thinks enzymes are used up or destroyed in the reaction
  A catalyst is unchanged at the end: the enzyme–substrate complex forms, the products leave, and the same active site takes the next substrate. Activity stops only if the enzyme is denatured (heat, extreme pH) or slowed (cold), never because it was used.
• Mixes up a pair of similar technical terms
  Make a two-column table for each confusable pair with one defining feature each, and a memory hook (aTLas holds the 'world' (skull) and nods; aXis lets you shake 'no'). Underline the defining feature the stem gives before you look at the options.
• Confuses food classes and their functions
  Carbohydrates and fats: energy. Proteins: growth and repair. Vitamins and minerals: protection (e.g. vitamin C → scurvy, iron → anaemia, iodine → goitre). Water and roughage are needed too. A balanced diet has all classes in the right proportions.
• Enzyme misconceptions
  Enzymes are protein catalysts, specific (lock and key), unchanged by reaction. High temperature denatures them; low temperature only slows them. Each has an optimum pH (pepsin ≈ 2, salivary amylase ≈ 7).
• Chooses a true but irrelevant statement
  Re-read the question word (why, which, where, what causes). An option can be a true fact and still be wrong because it answers a different question.