Inorganic ionsAQA A-Level Biology: Mind map

Exam questions on Inorganic ions

1. Blood plasma contains sodium ions at a concentration of about 140 mmol dm⁻³, whereas free iron ions are present at less than 0.02 mmol dm⁻³. Most of the iron in blood is found inside red blood cells, as part of haemoglobin.
   A person's diet is deficient in iron. Explain why this reduces the amount of oxygen their blood can carry.2 marks
2. During a 400 m sprint, a runner's muscle cells respire anaerobically and produce lactic acid. The pH of the muscle cell cytoplasm falls from 7.1 to 6.6 by the end of the race.
   Explain why the pH of the muscle cell cytoplasm falls during the sprint.2 marks
3. A grower finds that tomato plants given a nutrient solution that lacks phosphate ions grow slowly, make few new cells and have small roots. Radioactively labelled phosphate ions (³²P) are then supplied to a healthy group of plants to find out where phosphorus is used.
   Explain why a lack of phosphate ions reduces the growth of the plants.3 marks