Homework help

JJtheunicycle · January 12, 2009, 9:08pm

For my science class I have to design an experiment to answer the question: How does carbon dioxide cycle through living systems?

Im given the following:

4 test tubes
Water
1 plastic straw and cotton
Bromothymol blue
Elodea
1 small aquatic snail
And a light or dark cabinet

Use your knowledge of plants and animals to design a controlled experiment that will test your hypothesis for the question we are investigating. Think about what will happen to the color of the BTB under each light condition. After you make an experiment make a hypothesis for each tube in light and dark conditions.

Ummm I’ve got no idea how to do this. Any help would be wonderful. I think Im supposed to put the snail in a tube and the elodea in another tube, then test how much co2 there is with the BTB. Maybe?

Rezinha · January 12, 2009, 9:15pm

Oh, I thought it would be some punnet squares

JJtheunicycle · January 12, 2009, 9:40pm

Heres my idea let me know if it will work or not.

Tube 1. Put the snail in one tube with BTB. I think the snail should produce co2 turning the BTB yellow. In light and dark.

Tube 2. The elodea in another tube and blow into the tube (making c02/making BTB yellow) in the light I think the elodea will use the c02 to make oxygen and the BTB will become blue again. I think the elodea will create co2 in the dark though because it cant do its thingy.

Tube 3. Control

Tube 4. Mehh.

Will that all work?

maestro8 · January 12, 2009, 10:48pm

Why don’t you try it and find out for yourself?

After all, that is the point of an experiment, no?

JJtheunicycle · January 13, 2009, 6:07am

I was actually really hoping maestro would show up in this thread. Thanks maestro

catinabag1 · January 13, 2009, 6:09am

he always shows up when he’s needed most

maestro8 · January 13, 2009, 9:08am

So far in this thread, I’ve read a bit of a hypothesis, a bit of an experimental plan… it really doesn’t look like you need any help. Just run the experiment!

Part of experimental science is practice. Experiments aren’t easy, especially when you’re doing something you’ve never done before. So… just go for it! You’ll learn more than you set out to learn, I guarantee.

My only advice is to take good notes. Keep a watch and a notebook handy, and write down everything you do and when you do it… step by step. If you have access to a thermometer and/or hygrometer? (measures humidity) write those numbers down too. Remember scientist types love numbers, so any numbers you can capture are good (how big is the snail? how large is the test tube?).