Four cells are found at different places in a root tip…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Four cells are found at different places in a root tip. Name the phase of growth that each cell belongs to.
- A small, square cell in a tight group, with a large nucleus and dense cytoplasm.
- A cell twice as long as its neighbour next to the tip, with a vacuole that is growing, and with new wall being laid down.
- A tall cell with a thick wall and a root hair, at its full size.
- A cell that is in the middle of mitosis.
Need a reminder? The key ideaShow
Growth is a permanent, irreversible increase in size, made by living cells using energy. Plant growth is open, because meristems keep adding cells. In a root the cells pass through three phases, from the tip: meristematic (small, dividing, large nucleus), elongation (vacuoles grow, cells enlarge, new wall) and maturation (full size, thick wall). Dry weight is a better measure than fresh weight, because the water content changes.
The worked solution
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. (a) Small, with a large nucleus and dense cytoplasm: the meristematic phase.
Step 2. (b) Growing vacuole, enlarging cell, new wall: the elongation phase.
Step 3. (c) Full size, thick wall, root hair: the maturation phase.
Step 4. (d) Only the cells of the meristematic zone divide, so it is in the meristematic phase.
Answer: (a) meristematic; (b) elongation; (c) maturation; (d) meristematic.
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