Then the things that eat green plants would die, and so would the things that eat them. This would continue forever until there was nothing left alive on earth. There's a nice thought :)
there would be no exchange of gases
The answer would depend on their relative sizes and the food pyramid.
The pyramid would collapse.
we will die and only microbes will survive
The chloroplasts would produce less energy.
If there were no green plants there would be no nitrogen cycle.If there were no green plants, the nitrogen that most organisms need wouldn't be transferred to all living things. Nitrogen is in green plants first, and then the herbivores, omnivores, and carnivores get it by eating the plants or eating the animals that eat those plants. Without green plants, those animals wouldn't really have anything to get the nitrogen from. Nitrogen is crucial to all plants in making amino acids and proteins which they need to survive, so there would be no life on Earth.
what would happen to plants nutrition if plants did not have roots
The chloroplasts would produce more energy.
The chloroplasts would produce more energy.
The plants will tend to grow lanky and weak, while the leaves will turn yellowish.
That honor should probably go to the phytoplankton, minute photosynthetic plants that provide food for krill, and oxygen for the world.
The chloroplasts would produce more energy.