Learn Hardcore German: Der Apotheker öffnet die Apotheke morgen früh. - The pharmacist opens the pharmacy tomorrow morning.

In German orthography, all nouns are capitalized—so Apotheker (pharmacist) and Apotheke (pharmacy) get initial capitals. öffnen is a verb, and verbs are written in lowercase.

Why is die Apotheke feminine while der Apotheker is masculine?

Every German noun has a grammatical gender (masculine, feminine, or neuter). der Apotheker (the pharmacist) is a masculine noun; die Apotheke (the pharmacy) is a feminine noun. You must match the definite article (der, die, das) to each noun’s gender.

What grammatical roles do der Apotheker and die Apotheke play, and which cases are they in?

der Apotheker is the subject performing the action, so it’s in the nominative case. die Apotheke is the direct object receiving the action, so it’s in the accusative case. You recognize accusative for a feminine singular noun because its article remains die in both nominative and accusative.

Why is öffnen in the present tense even though the action happens tomorrow, and how would I say it in the future tense?

German often uses the simple present tense with a time adverb (like morgen früh) to talk about scheduled future events. If you want the explicit future, use the auxiliary wird plus the infinitive:
Der Apotheker wird die Apotheke morgen früh öffnen.

Why is morgen früh placed at the end of the sentence? Can I move it elsewhere?

German main clauses follow the “verb-second” rule, but adverbials of time can appear early or late. Placing morgen früh at the end is perfectly normal for emphasis or style. You could also say:
Morgen früh öffnet der Apotheker die Apotheke.
Notice that the conjugated verb stays in the second position.

What’s the difference between öffnen and aufmachen?

Both mean “to open.”

öffnen is a non-separable, more formal verb.
aufmachen is a separable, more colloquial verb.
If you use aufmachen, the sentence becomes:
Der Apotheker macht die Apotheke morgen früh auf.

Why isn’t morgen capitalized in morgen früh?

Here morgen functions as an adverb meaning “tomorrow.” Adverbs are not capitalized. The noun der Morgen (“the morning”) would be capitalized, but that’s a different word/category.

How can I turn this statement into a yes/no question?

In German yes/no questions you invert the subject and the verb. So you’d say:
Öffnet der Apotheker die Apotheke morgen früh?