Question 21) All the energy comes from producers, the flow of energy usally goes like this Sun - Producer (which is usually a plant)- Consumer (This one is usually a herbivore) - Consumer (This one is usually a Carnivore) - decomposer
Question 22) A producer is a organism that get its energy from the sun and doesn't need to look for it's food like a consumer does.They are usually one of the first things on the food web since it is a plant.
Question 23) If producers were removed from the food web the whole world would fall apart since that is the source where all other foods come from. For example, this is a food web, grass - deer - wolves, if the grass disappeared then the deer would have no more food, and would die off, if the deer dies off the wolves would have no food and they would die off.
Question 24) A consumer is an organism that looks for its own food. They can get there food from a producer (then it will be a herbivore) or from other consumers (then it is a carnivore)
Question 27) A decomposer is an organism that helps to have our earth clean and eat things like dead plants and animals. Some examples are like mushrooms, bacteria, moss.
Hope these answers help :)