Which structure is primarily responsible for the excretion of waste in a cell?

The lysosome is primarily responsible for the excretion of waste in a cell. It acts as the digestive system of the cell, containing enzymes that break down waste materials, cellular debris, and foreign pathogens. This process helps maintain the cell's health by recycling components and removing potentially harmful substances.

When the lysosome digests unwanted materials, it can either re-utilize these components for cellular processes or expel the remaining waste products from the cell. This function is crucial for cellular homeostasis and overall organism health, as it prevents the accumulation of toxic substances. The other structures mentioned do not play a direct role in waste excretion: ribosomes are involved in protein synthesis, the Golgi apparatus is responsible for sorting and packaging proteins for secretion, and mitochondria are the powerhouses of the cell, generating energy.