Question Video: Identifying the Movement of Ions from a High to Low Concentration into a Root Hair Cell | Nagwa Question Video: Identifying the Movement of Ions from a High to Low Concentration into a Root Hair Cell | Nagwa

Question Video: Identifying the Movement of Ions from a High to Low Concentration into a Root Hair Cell Biology • Second Year of Secondary School

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The diagram shows a simplified outline of a root hair cell and the movement of calcium ions from the soil into it. What process is being shown by the movement of calcium ions in the diagram?

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Video Transcript

The diagram shows a simplified outline of a root hair cell and the movement of calcium ions from the soil into it. What process is being shown by the movement of calcium ions in the diagram? (A) Active transport, (B) diffusion, (C) osmosis, (D) biosynthesis, or (E) chemosynthesis.

Mineral ions are essential for many different plant functions. For example, calcium ions play an important structural role in plant cell walls and cell membranes. Generally, plants absorb these ions through their roots from soil, and many plants have specialized root hair cells to aid in this absorption. There are two main ways that root cells can take up these ions from soil: either passively or actively.

When a particular ion is in a higher concentration in the soil than in the root hair cell, it will passively move down its concentration gradient into the root without requiring any extra input of energy from the plant itself. This process is called diffusion. The ion continues to passively spread out by diffusion until there is an approximately equal concentration of this particular ion in both areas.

Alternatively, if the concentration of this ion is higher in the root hair cell than in the soil, as we have illustrated in this pink diagram on the right, the uptake of this particular ion must be done actively. This process is called active transport. Active transport requires an input of energy to move ions from an area of low concentration in the soil to an area of high concentration in the root hair cell.

The question asks us to determine the process being shown by the movement of calcium ions in the diagram provided to us in the image on the far left. We can see that calcium ions, which are represented as red circles, are in a far higher concentration in the soil than they are in the root hair cell.

As the arrows show calcium ions moving into the root hair cells from the soil from an area of high to low concentration, we can work out the correct answer to this question. We know that moving particles from an area of high to low concentration does not require an input of energy, so it is a passive process. Therefore, the correct answer to this question is (B) diffusion.

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