This free quiz has 12 real AQA A-level Biology exam questions on ATP, water and inorganic ions (27 marks, about 35 minutes). It marks itself: the 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 3.1.6–3.1.8)
how ATP is made by ATP synthase
the products of ATP hydrolysis
how the structure of ATP differs from a DNA nucleotide
why water's heat capacity and latent heat of vaporisation matter
why water uptake by a plant may not equal transpiration
iron ions in red blood cells, and hydrogen ions and pH
describing patterns in ion concentrations from a bar chart
five properties of water, and the roles of iron, sodium and phosphate ions (5 marks each)
How to use it
Write each answer in full before you open the mark scheme. Name the enzymes ATP hydrolase and ATP synthase precisely, and say energy is released, not produced. For each property of water, say why it matters to living organisms, not just what it is.
Where students lose marks (from AQA examiners’ reports and mark schemes)
Each point below is followed by wording that gained marks.
ATP structure. Knowledge of ATP's structure was often limited. Students wrote adenine instead of adenosine with three phosphates, labelled the sugar “pentose” instead of ribose, or mentioned glycosidic or hydrogen bonds. Many thought adenosine is a base.
✔ Gains credit: ATP is made of adenine, ribose and three phosphate groups (or adenosine and three phosphates).
Energy is released, not produced. Many answers lost marks by saying ATP “produces”, “makes” or “creates” energy, even when the rest of the answer was good.
✔ Gains credit: hydrolysis of ATP releases (provides) energy for other reactions, such as forming peptide bonds between amino acids.
ATP hydrolase and hydrolysis. Asked how phosphate is released from ATP, some students wrote about ATP synthase and making ATP instead. Many didn't say the reaction is hydrolysis, and “hydrolysis of a hydrogen bond” was rejected.
✔ Gains credit: phosphate is released from ATP in a hydrolysis reaction catalysed by ATP hydrolase (ATPase).
Phosphorylation. Saying “phosphate is used to phosphorylate the enzyme” wasn't enough. Far fewer students said phosphorylation makes substances more reactive, and some said it makes cells more reactive.
✔ Gains credit: the phosphate attaches to other substances (phosphorylation), making them more reactive or changing their shape.
Heat capacity vs latent heat. Only 32% scored all three marks when asked for properties of water. Students wrote “latent heat capacity”, left out “high” or “large”, or gave physics definitions without saying why each property matters.
✔ Gains credit: water has a high heat capacity, so it buffers changes in temperature; it has a large latent heat of vaporisation, so evaporation provides a cooling effect.
Water as a metabolite. Almost as many students said water is produced in photosynthesis as said it is used. Others said water is used in respiration, or gave “condensation” and “hydrolysis” as properties of water.
✔ Gains credit: water is a metabolite: it is used in photosynthesis and hydrolysis and produced in respiration.
Sodium ion gradients. Most linked sodium ions to co-transport, but far fewer explained how the sodium gradient is set up, and some confused the direction ions move in the Na⁺–K⁺ pump. Very few mentioned ions affecting osmosis.
✔ Gains credit: sodium ions are moved out of cells by active transport (the Na⁺–K⁺ pump), creating a sodium concentration gradient used in co-transport of glucose or amino acids; ions also affect water potential.
Keep practising
The other AQA 3.1 self-marking quizzes: Carbohydrates · Lipids · Proteins · Enzymes · Nucleic acids
Next, topic 3.2: the cell structure 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.