What do you think will happen if all the plants on earth disappeared?

if all the plants on Earth died so with the people when green plants make food they give off oxygen this is a gas that all animals must breathe in order to stay alive without plants and animals would have no oxygen to breathe and would die

well since animals need to feed off each other and some animals eats plants so if the animal that eats plants will be gone, and then the animals that eat animals will be gone and we wont survive because no trees and no food