Overview of photosynthesis and ATPEdexcel International A Level Biology: Mind map

Exam questions on Overview of photosynthesis and ATP

1. Algae were supplied with water that contained the heavy isotope ¹⁸O (H₂¹⁸O) and with carbon dioxide that contained only the normal isotope ¹⁶O. The algae were illuminated and the oxygen gas that they released was collected and analysed.
   The experiment was repeated with water containing only ¹⁶O and carbon dioxide containing ¹⁸O. Predict where the ¹⁸O would be found. Explain your answer.2 marks
2. A hummingbird hovers in front of a flower while it feeds. Its flight muscles use ATP at a very high rate, but each muscle cell contains only enough ATP for a few seconds of activity.
   Explain how the hummingbird's muscles can keep contracting rapidly, although the amount of ATP in each cell is small.2 marks
3. Chloroplasts were isolated from leaf cells and placed in a suspension that contained ADP, inorganic phosphate and a compound that accepts hydrogen. When the suspension was illuminated, oxygen was released and ATP was formed. In darkness, neither oxygen nor ATP was produced.
   Explain these observations.3 marks