I NEED HELP!!!

[Fromage]

I have these exact same questions, and I'm having trouble answering them as well. For question 1, I answered "By increasing irradiance," but I am not sure if that's right...

For question 2, I think that the cycle of oxygen and carbon dioxide would slow down or halt, since the cycle is part of photosynthesis (since plants inhale carbon dioxide and exhale oxygen).

For question 3, I think animal life would definitely cease to exist without autotrophs because, obviously, they would have no source of food.

What do you guys think of these answers?? Am I on the right track?

[Condraz23]

Fromage, you are probably right. As for the second question, there would also be less oxygen and more carbon dioxide.