Plant mineral requirementsEdexcel A-Level Biology A: Mind map

Exam questions on Plant mineral requirements

1. A grower produces tomatoes in a greenhouse using hydroponics, in which the roots grow in a nutrient solution rather than soil. The solution must contain every essential mineral ion. A batch of plants was accidentally given a solution that contained no nitrate ions.
   The lower leaves of the plants given no nitrate turned yellow first, while the youngest leaves stayed green. Explain these observations.2 marks
2. A class investigates plant mineral deficiencies. Barley seedlings are grown for three weeks in four boiling tubes containing: a complete culture solution; a solution lacking nitrate; a solution lacking magnesium; and a solution lacking calcium. The same volume of solution is used in each tube and the tubes are kept in the same window.
   The students wrapped each tube in black paper. Suggest why.2 marks
3. A pot plant with soft, non-woody stems is left without water for a week on a sunny windowsill. Its leaves and stems droop. After it is watered, it gradually becomes upright again.
   Explain how water supports the stems of a non-woody plant such as this one.3 marks