Questions & Answers about Мы любим биологию и литературу.
Why do the words for biology and literature end in -ю and -у instead of their dictionary endings?
Because they are the direct objects of the action (the things we love), they must be in the Accusative case. For feminine singular nouns, the dictionary ending -я changes to -ю (so биология becomes биологию) and the ending -а changes to -у (so литература becomes литературу).
Why does the verb любим end in -им and not -ем?
The dictionary form is любить (to love). Because it ends in -ить, it follows the second conjugation pattern. This means the мы (we) form takes the ending -им instead of the -ем ending you see on first conjugation verbs like знать (to know, which becomes мы знаем).
Would the endings be different if we were talking about loving living things instead of school subjects?
Not for feminine singular nouns! The rule for feminine words changing -а to -у and -я to -ю applies to both inanimate objects (like литература) and animate living beings (like changing сестра to сестру). The difference between living and non-living things in the Accusative case only matters for masculine nouns and plural nouns.