Chlorophyll absorbs red and blue light. As a result, most green light is reflected and the plant appearance green.

For most plants, they will be fine with constant light exposure. Some crops can even increase their yields with the extra light. However, tomato and sweet pepper are two noticeable exceptions: constant exposure to light will damage their leaves, which can eventually kill the plant. However, it has showed that changing in temperature may help tomatoes to deal with the injuries.

This question is very interesting to NASA as well. How to maximize crop yields with limited resources will not only be important for human to go to other planets, it will help to feed people on Earth as well.

I've never done this experiment, but red light is useful for photosynthesis, although blue light is even more useful.

That's a popular science fair project.

Green leaves absorb red light, so the plants grow well in red light.