A researcher is studying different types of cells. In which cell type will he/she encounter the highest number of lysosomes ?

The correct answer is (D) White blood cell. Lysosomes are membrane-bound organelles containing hydrolytic enzymes responsible for intracellular digestion and the breakdown of waste materials.

• White blood cells (WBCs): Particularly phagocytes like macrophages and neutrophils, WBCs are the body's primary defense against pathogens. They engulf bacteria and viruses through phagocytosis and require a high concentration of lysosomes to digest and destroy these foreign invaders.
• Pancreatic cells: These are specialized for secreting digestive enzymes and hormones, thus they are richer in Rough Endoplasmic Reticulum and Golgi bodies.
• Ovarian cells: These are involved in lipid/steroid hormone synthesis, requiring more Smooth Endoplasmic Reticulum.
• Muscle cells: In a runner, these cells prioritize energy production, meaning they contain a significantly higher density of mitochondria rather than lysosomes.

Consequently, cells with high phagocytic activity, like WBCs, possess the highest number of lysosomes.