Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Problem:Passage: In plants and algae, photosynthesis takes place in organelles called chloroplasts. Chloroplasts contain stacks of membranes called thylakoids, which contain chlorophyll. Thylakoids are surrounded by a fluid-filled space called stroma. Answer: chloroplasts
Solution:
In plants and algae, photosynthesis takes place in which organelles?