The list-of-statements biology item (options none, 1 only, 1 and 2, all) is usually decided by finding the clause whose direction is wrong. The examiner's favourite traps invert cause and effect, flip an increase for a decrease, or assert a proportionality that the data break. Check the direction of each clause against the real mechanism or the numbers and discard any that runs backwards, which often leaves none or one standing.
Trigger: an MCQ whose answer options are combinations of numbered statements.
Instances:
(i) reversed cause and effect: air entering the lungs is the result of the ribcage moving, not its cause.
(ii) reversed sign: hard exercise lowers pH through lactic acid, it does not raise it.
(iii) false proportionality: blood output is directly proportional to heart rate only if their ratio is constant, but the output peaks then falls, so it is not; and check any percentage exactly, 4.0 to 5.0 is 25 percent, not 20.
