1 - Habitants
From this term, it is understood that a habitant is someone or something that inhabits a habitat and lives there, in a sense.
2 - Ecosystem
An ecosystem is comprised of biotic and abiotic factors, for instance, rocks, organisms, trees, etc.
3 - Population
A population is the number of organisms in a species or total amount of something/someone in an ecosystem or community.
4 - Food Chain
A food chain represents a chain of how and where food flows within a small ecosystem or community. For instance, a basic food chain can be like this: Sun - Grass - Cow - Human - Decomposers
5 - Food Web
A food web is comprised of multiple food chains and animals/organisms. It depicts how and where energy travels in a more vast manner compared to a food chain.
Hope this helps!