The smooth ER is especially abundant in cells that synthesize extensive amounts of ________________. nucleic acids toxins enzymes proteins Lipids

The smooth endoplasmic reticulum (smooth ER) is especially abundant in cells that synthesize extensive amounts of lipids.

The smooth ER is primarily involved in lipid synthesis and metabolism, as well as the detoxification of certain chemicals. For example, in liver cells, the smooth ER plays a key role in lipid metabolism and detoxification processes. In other cell types that require extensive lipid production, such as adrenal or gonadal cells, the smooth ER is also prevalent.

While the rough ER is associated with the synthesis of proteins due to the presence of ribosomes, the smooth ER is specifically tailored for lipid-related functions. Therefore, the correct answer to the question is lipids.