Answer:
I, II, III
Explanation:
A threshold stimulus is a stimulus that is capable to produce a response in excitable tissues such as neurons and muscle fibers. At threshold potential, the outward movement of K+ and inward movement of Na+ become equal to each other. When the potential exceeds the threshold potential, more and more Na+ enter the cell to depolarize it and to allow the opening of Na+ channels. Therefore, to fire an action potential, the threshold must be exceeded.
Conduction of action potential is all or none phenomenon which means that either it occurs or it does not occur. As an impulse is passed by each successive part of an exon, it enters the refractory period during which there is no conduction of nerve impulse. It ensures the one-way conduction of impulse from the cell body to the axon terminal only.
Answer:
Helper T cells are arguably the most important cells in adaptive immunity, as they are required for almost all adaptive immune responses. They not only help activate B cells to secrete antibodies and macrophages to destroy ingested microbes, but they also help activate cytotoxic T cells to kill infected target cells.
Explanation:
Helper T cells become activated when they are presented with peptide antigens by MHC class II molecules, which are expressed on the surface of antigen-presenting cells (APCs). Once activated, they divide rapidly and secrete cytokines that regulate or assist the immune response.
Vitamin B6 is essential for the synthesis of T cells. These cells form part of the immune system.
<h3>What is Vitamin B6?</h3>
Vitamin B6, also called pyridoxine, is a water-soluble micronutrient found in different types of foods.
Vitamin B6 is required to generate T cells and white blood cells (lymphocytes), which are cells of the immune system.
Vitamin B6 is also fundamental for the generation of interleukin-2, which is a molecule involved in immune responses.
Learn more about vitamins here:
brainly.com/question/1327898
Answer:
The correct answer is option c. "formation of protocells that use DNA to direct the polymerization of amino acids".
Explanation:
The polymerization of amino acids is a complex biological function that involves multiple proteins and cofactors working together at different locations in the cell. Even though there are some scientific advances in the production of synthetic protocells (cell like structures made from synthetic particles), the formation of protocells able to synthesize amino acids from DNA directly has not been accomplished.
