Model two cells as cubes. Cell P has sides of 2 µm, and cell Q has sides of 8 µm…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Model two cells as cubes. Cell P has sides of , and cell Q has sides of .
- Find the ratio of surface area to volume for each.
- How many times larger is the ratio of P than that of Q?
- Which cell can supply its inside more easily through its surface?
Need a reminder? The key ideaShow
Eukaryotic cells have a membrane-bound nucleus and membrane-bound organelles; prokaryotic cells have neither. Every cell has a plasma membrane, cytoplasm and ribosomes. Mycoplasma are about 0.3 µm long, bacteria 3 to 5 µm, a red blood cell about 7.0 µm. A cube of side s has surface area to volume 6/s.
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. P. per µm.
Step 2. Q. per µm.
Step 3. Compare. times.
Step 4. Which cell. P has four times as much surface for each unit of volume, so it is supplied more easily.
Answer: and per µm; times; cell P.
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