In the sentence "the new bakery opens <u>in</u> a week" you only have the preposition IN. A prepositional phrase consists of preposition plus a noun, pronoun or gerund working as the object.
So, the prepositional phrase is "in a week", the object of the preposition is "week" (a noun) which is pre-modified by the indefinite article "a".
Answer:Like all nouns, a gerund phrase can function as a subject, an object, or a complement within a sentence. For example: Eating blackberries quickly is a bad idea. ... (The gerund phrase is the direct object of the verb "hates.")
