NEET BIOLOGY

Detailed explanation-1: -Why is digestion important? Digestion is important for breaking down food into nutrients, which the body uses for energy, growth, and cell repair. Food and drink must be changed into smaller molecules of nutrients before the blood absorbs them and carries them to cells throughout the body.

Detailed explanation-2: -Once there is a concentration gradient to drive diffusion, the nutrients need a path across the membrane. Fats and fat soluble nutrients can move directly across the lipid membrane. Water, gasses, and other very small molecules can diffuse through the pores of the cell.

Detailed explanation-3: -Chemical digestion must occur because macromolecules such as proteins are too large to be readily absorbed (d). The small intestine can only absorb the monomers, or building blocks, of these large molecules. Proteins must therefore be chemically digested into amino acids, which are then absorbed by the mucosa.

Detailed explanation-4: -Nutrients need to be separated from food to be passed through the digestive epithelium to be utilised. If not broken down, large molecules produce toxic substances that pass through the epithelium of the digestive tract and are utilised by the cells. This can be lethal to the cells.