Sub-topic: Surface Area to Volume Ratio
Question to ponder: What is surface area to volume ratio?
- When we are hungry or thirsty, we will try to drink or eat large portion of drinks or food. This is to satisfy our hunger. Notice that some people will actually use a large plate and a large glass when they are hungry? Why do they do this?
- This is the same with our body as well as for plants! In previous topic, you have learned about active transport. The absorption of nutrients in root hairs and in the small intestine of humans are good examples to demonstrate surface area to volume ratio. In order to maximize the absorption of nutrients as well a for efficient absorption process, organisms will need to have a large surface area to volume ratio.
- Since cells are limited in how large they can be.
This is because the surface area and volume ratio does not stay the same as their size increases. Because of this, it is harder for a large cell to pass materials in and out of the membrane, and to move materials through the cell.
Small intestine
- The small intestine is used for re-absorption of nutrients. Instead of having a smooth surface, to maximize absorption as well as to make the absorption more efficient, the small intestine's wall is covered with villi. These villi looks like carpet wool. These villi increases the surface area of the intestine, so that more nutrients can be absorbed into the body. We say that the surface area to volume ratio is high. This can be shown by the diagram below. Glucose and amino acids are absorbed into the blood capillaries while fats are absorbed into the lacteal. *please see the related video at active transport page.
1.1 Proving that the smaller the cell is, the larger the surface area to volume ratio is! |
1.2 Explanation on the surface area to volume ratio, and why is it important in cell. |
TcNMA <3
Thinking time: Think of our own body! Why are our bodies made up of tiny cells instead of just one large cell?
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