Photosynthesis

Question 2

Explain why + what mineral ions do in plant growth

Answer 2

• Photosynthesis produces carbohydrates
• carbohydrates only contain carbon, hydrogen and oxygen, but the amino acids which make up proteins also contain nitrogen
• this means plants also need nitrogen which they take in the form of nitrate ions
• other chemicals in plants contain other elements e.g. chlorophyll molecules contain magnesium and nitrogen
• these additional nutrients are dissolved in water in the soil as mineral ions
• plants absorb these through their roots using active transport as the concentration of ions in the soil is lower than in the plant cells

Question 3

Briefly describe the practical investigating starch production in leaves

Answer 3

1. Destarch plant - leave in dark place for 24 hours - will ensure plant uses up existing stores of starch - this means all starch identified is as a result of the photosynthesis during the experiment
2. Place leaf into light for an hour, then put into boiling water (to remove waxy cuticle)
3. Place leaf into hot ethanol (not heated by Bunsen burner - ethanol is flammable). This removes chlorophyll, to lose green colour- so that it is easier to see iodine colour
4. Place leaf in water to soften, then onto a dish and put iodine solution on top