The walls of xylem cells are lignified (strengthened with a substance called lignin ). This allows the xylem to withstand pressure changes as water moves through the plant.
The cell membrane is flexible because of the presence of oil like substances called phospholipids, which gives it a fluid nature. While as the cell walls are rigid because of the presence of the thick layers of the substances like cellulose in plants, chitin in fungi and peptidoglycon in bacteria.
Answer:
Protein.
Explanation:
Pathogens may be defined as the disease causing organism and capable of inducing immune response in the organisms. The organisms that can acts as pathogen are virus, bacteria and nematodes.
Different experiments have been performed to find the infectious agent. The digestion of trypsin protect the animals from the disease. This means the infectious agent must be protein as the protein digestion disrupts the pathogenicity of the organism.
Thus, the answer is protein.
Insufficient nutrient, lack of water, no sunlight, climate change, pollution
