A garden worm and a flat worm both live in moist environments and both exchange gases with their environments throught their skin. The garden worm has a circulatory system to move these gases around its body, the flatworm has no such system. Can you explain these observations given your knowledge of SA:V ratio?
**No worries people, i'm not asking for the answer, but what does this question mean? I found a garden worm in my backyard but i can't find a flatworm and i've been digging for one since this morning to find one. How do i observe it? Thank you ^ ^
2007-03-24 15:50:32 · 2 answers · asked by little.clown 2 in Science & Mathematics ➔ Biology
The question is all about substances diffusing through a surface membrane. If an organism doesn't have a circulatory system, it relies on diffusion to get every necessary nutrient to every cell in its body, and to remove wastes from every cell. Obviously, if you were a cell a long way away from the surface, you wouldn't have much hope of getting what you needed to stay alive. Imagine an organism shaped like a basketball - if it didn't have a circulatory system, there's no chance the cells in the middle would ever get any nutrients. If, however, you took the same volume of the basketball but squashed it so it now looked like a huge pancake, every cell is now pretty close to the surface, so they can all survive without the need for a circulatory system.
Moral of the story - for any given volume, if you have a shape (like a flatworm) which gives you a larger surface area, all your cells can get by with simple diffusion, and you don't need a circulatory system. If, however, you have a cylindrical shape (like a garden worm), you have cells in your middle which can't get enough nutrients without having them transported to them by a circulatory system.
Do a search on flatworms and you will probably find that the ones which live in your garden can only be seen under a microscope.
2007-03-24 16:35:58 · answer #1 · answered by SteveK 5 · 0⤊ 0⤋
Flatworms don't live in the ground to my knowledge. I believe they are mostly aquatic. Flatworms have a very large surface area to volume ratio.
2007-03-24 23:33:19 · answer #2 · answered by pathc22 3 · 0⤊ 0⤋