Mineral Nutrition (Cambridge O Level Biology)

Plants growing in soils lacking magnesium ions struggle to photosynthesise and therefore do not grow to their full potential.

Suggest an explanation why.

Fig. 1 shows the effect on crop yield (amount harvested) of using nitrogen-containing fertilisers.

Fig.1

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State one type of mineral ion, other than nitrate, that is required by a plant and explain its importance to the plant.

type of mineral ion ...........................................................
importance to plant ..........................................................

A student carried out an investigation into the effect of soil magnesium on plant growth.

In this investigation, the student set up two different environments as follows:

1. One plant was grown in sterile soil, provided with distilled water and placed in bright light.
2. One plant was grown in sterile soil, provided with magnesium dissolved in distilled water and placed in bright light.

Predict what the student will have observed after two weeks of growing in these conditions.

Explain your prediction from part (a).

When selecting the plants for the investigation in part (a), the student made sure that they picked plants with the same number of leaves.

Explain why this was necessary.

One method that can be used to show that photosynthesis has occurred is to test the leaves with iodine.

Explain how this shows that photosynthesis has occurred.