Question

which organelle contains a single membrane and modifies molecules?
mitochondria
nucleus
golgi apparatus
smooth endoplasmic reticulum

Explanation:

Mitochondria have a double - membrane. The nucleus has a nuclear envelope which is a double - membrane structure. The Golgi apparatus has a single membrane and modifies, sorts, and packages molecules. The smooth endoplasmic reticulum has a single membrane but its main functions are lipid synthesis and detoxification rather than modification as its primary role compared to the Golgi.

Answer:

Golgi apparatus