Species that arrive first in the newly created environment or available ecosystem are called PIONEER SPECIES
I'm 99.9% sure its lysosomes.
O2 (oxygen) is a covalent compound
In comparison they both show feeding relationship in an ecosystem.
In contrast, a food chain is a simple linear feeding relationship while a food web is a complex feeding relationship.
2) The arrows is to show the direction of the feeding relationship
wearing glass to protect from uv rays