Fungi cannot produce their own food because they do not contain which of the following?

Fungi are classified as heterotrophs, which means they cannot produce their own food through photosynthesis like plants do. This is directly related to the absence of chlorophyll, the green pigment necessary for the photosynthesis process. Since fungi lack chlorophyll, they cannot convert sunlight into chemical energy, compelling them to obtain nutrients from external sources, such as decomposing organic matter.

In contrast, starch, cellulose, and protein do not directly influence the ability of fungi to produce food; rather, they can be found in the structure of fungi or their substrates. Starch and cellulose are types of carbohydrates, where starch is a storage form of energy in some plants and cellulose forms the structure of plant cell walls, and both are utilized by fungi for growth and metabolism. Proteins are essential for various metabolic processes, but their presence or absence does not affect the fundamental nutritional method of fungi compared to the necessity of chlorophyll for photosynthesis. Therefore, the inability of fungi to produce their own food is fundamentally due to the absence of chlorophyll.