Amoeba is an example of a unicellular organism. It carries out movement, intake of food, gaseous exchange, and excretion within a single cell.

Unicellular organisms perform all basic functions within a single cell, whereas multicellular organisms distribute these functions among millions of specialized cells.

Other methods include storing food in cool, dark places to minimize exposure to light and heat, using opaque or UV-blocking packaging materials, and adding chelating agents to bind metal ions that can catalyze oxidation reactions.

Storing food in air-tight containers prevents exposure to oxygen, which is necessary for the oxidation process, thereby slowing down the rancidity of fats and oils.

Antioxidants are added to foods containing fats and oils to prevent oxidation by neutralizing free radicals, thus slowing down the process of rancidity.

Fats and oils become rancid due to oxidation, which alters their chemical composition, leading to changes in smell and taste.