The elodea is getting the carbon dioxide from its environment like when underwater animals breathe out carbon dioxide the plants will use that carbon dioxide. The plants can also get the carbon dioxide from the atmosphere which can "dissolve" in water.
I am not sure but here is a link to help you :)
https://www.ncbi.nlm.nih.gov/pubmed/22322095
Scoville units is the scale used to determine how "hot" a pepper is.
A sweet bell pepper, which isn't spicy at all, has a ranking of 0.
The Carolina Reaper, one of the hottest peppers in the world, has a ranking of up to 2,200,000.
You have rods and cones in your eye. Cones detect colour and fine detail. Rods are used for monochrome vision; usually, monochrome vision is used in poorly lit, dark environments. Rods and cones are both in the retina of the eye.
Cones = Colour. CC is a good mnemonic.
