Answer:
The answer is exogenous/non-self signals.
Explanation:
- All types of stimuli that trigger certain responses from cells are broadly classified into two categories:
- Self/ Endogenous Ligands
A ligand is a carrier molecule that can binds to a stimulus, thus, producing a signaling molecule. Ligands bind to specific receptors in or the surface of the cell.
Self/endogenous signals are signaling molecules produced by the body itself. They are part of normal cellular communication.
2. Non-self/Exogenous Ligands:
These are signals produced by a foreign source such as a pathogen or a drug administered into the body. Basically, any signal that is foreign to the body and not produced by the body itself are exogenous ligands. Exogenous ligands elicit an immune or allergic response in the body. When identified, these ligands and their source is attacked by the immune system.
Answer:
Salivary glands secrete salivary amylase, an enzyme that begins the breakdown of starch into glucose. Mucus moistens food and lubricates the esophagus. Bicarbonate ions in saliva neutralize the acids in foods
A - The alveoli have a membrane that is only one cell thick to allow for a short diffusion time to capillaries.
Answer:
Organism tend to adapt and evolve through natural selection.
Explanation:
Natural Selection can be described as a phenomenon by which those organisms are favored and selected by nature which are better adapted to live in an environment. These organism are able to reproduce and pass on their favorable traits to their offspring. Through natural selection, evolution occurs with the passage of time as those traits which are more suited to the ecosystem start existing in organisms.
