I need help with this

A food chain is a environment/group of animals/plants that feed off each other’s energy

A food web is multiple food chains/environments that show how diverse the eating patterns of animals/plants are and how the energy is passed around.

Food webs and food chains are a lot alike, they both show energy being passed, both show animals consuming one another or plants, and both go in depth about the cycle of life.

The differences between the two are this: the food chain is a lot less informative, it partially shows what happens but a food web goes a little more in depth, food webs are generally larger than food chains, food chains don’t usually have too many predators while food webs might have multiple.

Summary:
Food webs are a large classification of the animals/plants/bacteria and there eating habits, energy flow and so on and so forth.
Food chains are a smaller classification of a few animals within an environment, and it shows their eating habits, energy flow as well.
Both are very good if you are looking to learn about animals, plants, energy or just environments and changes in general. It shows how reliant animals and plants are to one another and really shows how drastic changes can happen if said animal or plant is removed from an environment. All in all, food chains and food webs help us learn a lot.

The answer to the first one is barometer.