The oxygen that goes through alveoli and diffuses into blood capillaries. The oxygenated blood goes though aorta and is pumped by the heart and goes out through the vena cava to be distributed to the whole body. the deoxygenated blood comes back to the heart from the body and is pumped back towards the lungs. the carbon dioxide diffuses out of the blood capillaries and goes out of the body.
Answer:
Presence of specific antigen receptors on the surface of Immunocompetent B and T cells make them to generate immune response against specific antigens only.
Explanation:
The cellular and antibody-mediated immune responses are specific in nature. This means these immune responses are generated for particular foreign molecules or antigens only. These immune responses include B and T lymphocytes. Before T cells leave the thymus or B cells leave the red bone marrow, they develop immunocompetence. Immunocompetence is the ability to carry out adaptive immune responses. During this process. B cells and T cells make distinctive proteins and insert them into their plasma membranes. Some of these proteins function as antigen receptors capable of recognizing specific antigens. This is why the B and T cell-mediated third line of defense are specific in nature.
For example, antibody-mediated immune responses generate the memory cells for most previously encountered antigens to ensure the generation of more rapid and vigorous response during any further encounter with the same antigen.
<span>Two main characteristics that distinguish autotrophs from heterotrophs are:
A~ Autotrophs produce their own food by either chemosynthesis or photosynthesis. Heterotrophs do not produce their own food. Heterotrophs obtain their food by consuming autotrophs or heterotrophs.
B~ Autotrophs are at the primary level in a food chain and Heterotrophs are at the secondary level or tertiary level in a food chain.</span>
