Which organelle is NOT involved in the photosynthesis process?

Ribosomes are the organelles primarily responsible for protein synthesis in cells, translating messenger RNA into polypeptide chains. While they play a vital role in preparing the proteins needed for various cellular functions, ribosomes are not directly involved in the photosynthesis process.

Photosynthesis occurs mainly in chloroplasts, which contain chlorophyll and other pigments that capture light energy. Mitochondria, although known for their role in cellular respiration, support the overall energy balance in cells that perform photosynthesis by utilizing the products formed during photosynthesis. Plastids, of which chloroplasts are a specialized type, are also directly involved in the process as they help in the synthesis and storage of food materials.

Consequently, since ribosomes are dedicated to protein synthesis and do not participate in the capture and conversion of light energy or the biochemical reactions that comprise photosynthesis, they are the correct choice for the organelle not involved in this process.