This free quiz has 10 real AQA A-level Biology exam questions on muscle contraction (24 marks, about 30 minutes). It marks itself: the two tick-box questions are marked for you, and for written answers you check your work against the real AQA mark scheme.
What the quiz covers (AQA 3.6.3)
the banding pattern of a sarcomere and how it changes when a myofibril contracts
the roles of ATP in muscle contraction
how calcium ions and tropomyosin control the formation of actinomyosin bridges
using actin and myosin interaction to explain how a mitochondrion is moved
how antagonistic muscles in the iris make the pupil constrict
where muscle fibres get ATP at very high effort, and staining evidence from trained mice
how glycogen concentration relates to the properties of fast and slow fibres (4 marks)
how creatine supplements and carbohydrate loading help different fibres in different exercise (5 marks)
How to use it
Write each written answer in full before you open the mark scheme, then tick only the points you really made. Say that muscles contract or relax, name the myosin head and the binding sites on actin, and write phosphocreatine in full. For the fibre-type questions, compare fast and slow fibres in the same sentence.
Where students lose marks (from AQA examiners’ reports and mark schemes)
Each point below is followed by wording that gained marks.
Contract and relax. Almost 40% of students scored zero on one iris question, often by describing the opposite action or not naming the muscles. Words such as “constrict”, “expand”, “widen”, “lengthen” and “shorten” were used instead of contract or relax.
✔ Gains credit: name each muscle and say whether it contracts or relaxes, e.g. the circular muscle contracts while the radial muscle relaxes.
Actin and myosin in the bands. Some students reversed the positions of actin and myosin, and confusion over the A band was common. Others named the bands and lines correctly but never said which filaments they contain.
✔ Gains credit: the light I band contains only actin, the H zone contains only myosin, and the darkest region is where actin and myosin overlap.
Binding sites, not active sites. A few students wrote “active site” instead of binding site, and many spent time on troponin, which is not on the current specification. Some wrote about calcium ions in synaptic transmission instead.
✔ Gains credit: with fewer calcium ions, less tropomyosin is moved from the binding sites on actin, so fewer actinomyosin bridges form.
The myosin head moves. Many students simply wrote that filaments “move” or mentioned a “power stroke” with no further detail. Others wrote “myofibril” instead of myosin, or left out the myosin “head”.
✔ Gains credit: the myosin head attaches to actin and bends (changes angle), pulling the actin filament; then the next myosin head attaches and bends.
Every role of ATP. Some answers left out actin, saying only that myosin was removed, and the role of ATP in moving calcium ions was rarely included. Weaker answers made incorrect links between ATP, calcium ions and tropomyosin.
✔ Gains credit: ATP is used to break actinomyosin bridges (detach myosin from actin), to move the myosin head, and for active transport of calcium ions back into the sarcoplasmic reticulum.
Compare fast and slow fibres. A significant minority described only one type of fibre, and many did not link fibre types to types of exercise, which capped them at 3 marks out of 5. “Working anaerobically” or “aerobically” was not accepted, and saying energy is “produced” was rejected.
✔ Gains credit: fast fibres contract quickly, are used for short, intense exercise such as sprinting and mainly use anaerobic respiration, whereas slow fibres contract slowly, are used for longer exercise such as a marathon and use aerobic respiration.
Glycogen, not glucagon. Weaker answers confused glycogen with glucagon, and mixed up glycolysis, glycogenolysis, glycogenesis and gluconeogenesis. Students who wrote “PCr” lost the mark, as abbreviations not used in the specification are not accepted.
✔ Gains credit: glucose is stored as glycogen (glycogenesis) and glycogen is hydrolysed to glucose (glycogenolysis) for respiration; creatine is used to form phosphocreatine, which combines with ADP to form ATP.
Keep practising
The other AQA 3.6 self-marking quizzes: Stimuli and receptors · Nervous coordination · Blood glucose · Kidney
Next, topic 3.7: the inheritance quiz
The AQA topic index
weekly AQA group classes: Year 12 on Tuesdays at 5.15pm, Year 13 on Wednesdays or Thursdays at 6.30pm
Questions © AQA, from past A-level and AS Biology papers, with their mark schemes and examiners’ reports.