Control and coordination — AS & A Level Biology (9700) questions by topic
The sliding filament model, neuromuscular junctions and temperature effects on muscle contraction define this topic: explaining the need for many mitochondria in presynaptic knobs and sarcomeres, labelling regions of striated muscle from an electron micrograph, and suggesting how age-related fibre differences affect contraction strength. Explain, suggest and identify lead the command words, and explain wants ATP's specific use, such as myosin head detachment, stated precisely.
With 20 real questions from 2023 to 2025 papers, marks here run from 6 to 15, so every answer requires sustained, multi-point detail rather than a single fact. Practising full mechanism explanations with instant marking is well suited here, since a missing membrane reference in a depolarisation answer, or a contradictory statement about ATP's role, is caught immediately.
What examiners look for
- A frequent error names the actin binding site as an active site, which is not the correct term.
- Answers sometimes contradict themselves by stating ATP is needed for cross-bridge formation as well as for its established roles.
- Depolarisation explanations often omit any reference to the membrane, losing the point about depolarisation not occurring.
- General accounts of the sliding filament mechanism that are not adapted to the specific question asked gain no credit.
- Strong answers name the specific proteins and ions involved, link mitochondrial ATP production to acetylcholine synthesis and myosin head detachment, and explain reduced transmission speed through the absence of saltatory conduction.
May–June 2025, Paper 41
The presence of gibberellins in a plant cell leads to the expression of genes involved in stem elongation. Describe how gibberellin causes stem elongation in plants.
Answer this question and get it marked →During the course of an action potential, the potential difference across a neurone membrane changes. Table 10.1 shows the potential difference across the neurone membrane at…
Answer this question and get it marked →May–June 2025, Paper 42
An axon membrane is described as being at its resting potential when an action potential is not occurring. Describe and explain how a resting potential of an axon membrane is…
Answer this question and get it marked →May–June 2025, Paper 43
Most carnivorous mammals need to move to hunt their prey. Outline why a carnivorous mammal makes more use of its nervous system, rather than its endocrine system, when it hunts.
Answer this question and get it marked →May–June 2025, Paper 44
Fig. 8.1 is a transmission electron micrograph (TEM) of striated muscle. Three regions are visible: a light-coloured region (P), a medium-coloured region (Q), and a darker region…
Answer this question and get it marked →May–June 2024, Paper 41
Humans detect the sweet taste of sucrose sugar using chemoreceptor cells in taste buds on the tongue. The red admiral butterfly, Vanessa atalanta, detects sucrose using…
Answer this question and get it marked →May–June 2024, Paper 42
Fig. 8.1 is a diagram of a sensory neurone, showing cell A at one end, the cell body, the myelin sheath, and structure B at the other end. Name the type of cell represented by…
Answer this question and get it marked →October–November 2024, Paper 41
Different species of animal have neurones with different characteristics. Fig. 1.1 is a diagram of a motor neurone of a rat and a motor neurone of a snail. The rat motor neurone…
Answer this question and get it marked →October–November 2024, Paper 42
Fig. 8.1 is a diagram of a motor neurone. On Fig. 8.1, label X points to a cell located along the axon, and label Y points to a part within the cell body. Label Z points to a…
Answer this question and get it marked →October–November 2024, Paper 43
Different species of animal have neurones with different characteristics. Fig. 1.1 is a diagram of a motor neurone of a rat and a motor neurone of a snail. The rat motor neurone…
Answer this question and get it marked →The leaves of Mimosa pudica plants are made of a number of structures known as pinnae. The pinnae fold when the leaf is touched. This closes the leaf. Fig. 4.1 shows an open leaf…
Answer this question and get it marked →February–March 2023, Paper 42
Fig. 7.1 represents a synapse between a chemoreceptor cell from a human taste bud and a dendrite of a sensory neurone. Different concentrations of sodium chloride solution were…
Answer this question and get it marked →Fig. 9.1 is a diagram of a relaxed sarcomere in striated muscle, with Z-lines, an M-line, an A-band and two I-bands marked. On Fig. 9.1, use label lines and letters to label an…
Answer this question and get it marked →May–June 2023, Paper 41
Sweet peas are garden plants that vary in height. - Tall sweet peas grow to 200 cm in height. - Dwarf sweet peas grow to 30 cm in height. - Tall sweet peas contain a dominant Le…
Answer this question and get it marked →May–June 2023, Paper 42
A striated muscle cell (muscle fibre) will contract when stimulated by a motor neurone at a neuromuscular junction. Air temperature can affect the temperature of striated muscle…
Answer this question and get it marked →May–June 2023, Paper 43
Sarcomeres are the functioning units of the myofibrils of the muscle fibres (muscle cells) of striated muscle. The arrival of an action potential at the sarcoplasmic reticulum of…
Answer this question and get it marked →Dopamine is a neurotransmitter released in some synapses in the brain. The release and action of dopamine is similar to that of acetylcholine. Fig. 9.1 is a diagram of a brain…
Answer this question and get it marked →October–November 2023, Paper 41
When an impulse arrives at a neuromuscular junction, it stimulates a muscle fibre of striated muscle to contract. Outline the similarities in structure between a neuromuscular…
Answer this question and get it marked →October–November 2023, Paper 42
There are many mitochondria located in the presynaptic knobs of neuromuscular junctions and in the sarcomeres of muscle fibres of striated muscle. Explain the need for many…
Answer this question and get it marked →October–November 2023, Paper 43
When an impulse arrives at a neuromuscular junction, it stimulates a muscle fibre of striated muscle to contract. Outline the similarities in structure between a neuromuscular…
Answer this question and get it marked →Other AS & A Level Biology topics
- Biological molecules (115)
- Cell structure (98)
- Transport in plants (91)
- Transport in mammals (77)
- Cell membranes and transport (67)
- Nucleic acids and protein synthesis (63)
- Practical skills (61)
- Enzymes (59)
- The mitotic cell cycle (58)
- Gas exchange (53)
- Infectious disease (49)
- Immunity (42)