Name two carbohydrates that serve as food reserves in yeast.

Glycogen and trehalose are indeed the two carbohydrates that serve as food reserves in yeast. Glycogen is a polysaccharide that functions as a form of energy storage in many organisms, including yeast. It can be broken down into glucose units when energy is needed.

Trehalose, a disaccharide, acts as a reserve carbohydrate as well and is particularly important for yeast and other microorganisms, especially in stress conditions. It helps in protecting cellular structures during dehydration and other stress situations while also serving as an energy source.

The other options consist of carbohydrates that are not primarily used by yeast for energy storage. For instance, sucrose and glucose are simple sugars that can be utilized as immediate sources of energy but do not function as storage polymers in yeast. Similarly, fructose and lactose do not serve as primary reserves in yeast. Lastly, while starch and cellulose are important carbohydrates in the plant kingdom, yeast typically does not store energy in these forms. Thus, glycogen and trehalose stand out as the correct answer for food reserves in yeast.