Which components in tree cells are indigestible to many insects and pathogens?

The correct choice identifies cellulose and lignin as the components in tree cells that are challenging for many insects and pathogens to digest. Cellulose is a complex carbohydrate that forms a significant part of the plant cell wall, providing structural support. Its molecular structure is resistant to enzymatic breakdown, making it difficult for many herbivorous insects to process. Insects that feed on plants have specialized adaptations, but many still struggle with digesting cellulose effectively.

Lignin, another key component, is a complex organic polymer found in the secondary cell walls of many plants. It provides rigidity and structural integrity, acting as a barrier to pests and pathogens. This makes it even harder for insects and many microorganisms to penetrate and feed on the plant tissues. The presence of cellulose and lignin contributes to the overall toughness of the plant, protecting it from herbivory and infection.

In contrast, fats, proteins, sugars, and starches are more easily digestible by many organisms, including insects, which can break them down and utilize them for energy. Minerals and salts, while essential for various plant functions, do not play a direct role in resistance against herbivores or pathogens in the same way that cellulose and lignin do. Thus, the presence of cellulose and lign