In the human body, oxygen is absrobed by the lungs and nutrients are absorbed by the small intestine. in a single-celled organism, what this absorption directly involves

cell membrane

Explanation:

Single cell organisms like the bacteria depend mostly on diffusion for gaseous exchange. They take in food that does not require complex digestion processes. The cell membrane is selectively permeable and allows absorption of nutrients like glucose that have molecules of small size.

lysosomes contain a variety of enzymes, enabling the cell to break down various biomolecules it engulfs, including peptides, nucleic acids, carbohydrates, and lipids (lysosomal lipase). the enzymes responsible for this hydrolysis require an acidic environment for optimal activity. hope i !