Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
Root hair cells have a long thin part that grows out between the grains of soil. How does this shape help the plant?
For a cube of side : surface area , volume , and the ratio of surface area to volume is . It falls as the cell grows.
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The shape. A long thin part has a lot of surface but little volume.
Step 2. Why it helps. Water and minerals enter through the surface. A large surface for the volume lets the cell take them in fast, and the thin part reaches into small spaces in the soil.
Answer: it gives a large surface area for its volume, so the cell takes in water and minerals quickly.
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