Video Transcript
In plants, which of the following is an example of getting rid of excess minerals by shedding leaves? (A) Disposing of excess water, (B) disposing of excess calcium, (C) disposing of excess oxygen, or (D) none of the answers are correct.
Mineral ions tend to be absorbed from soil into a plant’s roots along with water into which these ions dissolve. They are then carried through xylem vessels to all other parts of the plant. Sometimes, the accumulation of these minerals can have toxic effects on plant cells, resulting in dangerous outcomes for the plant as a whole. This question is asking us to identify an example of a mineral that can be removed from plants by shedding leaves to avoid such toxic effects. Let’s take a look at an example.
Most plants require a mineral called calcium in fairly considerable amounts, as it plays an important structural role in plant cell walls and cell membranes. However, sometimes the soil plants grow in contains too much calcium. This results in the plant absorbing too much of this particular mineral, which can be toxic when allowed to accumulate.
Some plants, like this potato plant, can respond to this by restricting the accumulation of calcium to their leaves, roots, and tubers. The minerals are stored in these cells’ cytoplasm or vacuoles, where they can be converted into an insoluble crystal form. This can help to prevent these potentially toxic compounds from spreading to different parts of the plant and causing harmful effects. Calcium specifically is usually converted into insoluble crystals of calcium oxalate, which is sometimes called raphides. The plant parts that the insoluble crystals are stored in, like the leaves, can be easily shed, removing these toxic substances. Then, the plant can regrow new structures to replace those that were lost.
Now we can answer this question correctly. The option that gives an example of a mineral that can be excreted from a plant by shedding leaves is (B), disposing of excess calcium.
