Answer:
A feedback loop is a biological occurrence where the output of a system amplifies the system (positive feedback) or inhibits the system (negative feedback).
Explanation:
Example, during blood clotting, a cascade of enzymic proteins acitvates each other, leading to the formation of fibrin clot that prevents further blood loss.
First-pass effect.
The first-pass effect involves drugs that are given PO and absorbed from the small intestine directly into the portal venous system, which delivers the drug molecules to the liver. Once in the liver, enzymes break the drug into metabolites; they may become active or may be deactivated and readily excreted from the body. A large percentage of the oral dose is usually destroyed and never reaches tissues. Oral dosages account for this phenomenon to ensure an appropriate amount of the drug in the body to produce a therapeutic action. Passive diffusion is the major process through which drugs are absorbed into the body. Active transport is a process that uses energy to actively move a molecule across a cell membrane and is often involved in drug excretion in the kidney. Glomerular filtration is the passage of water and water-soluble components from the plasma into the renal tubule.
1. The right answer is in a discontinuous manner.
During DNA replication, the DNA polymerase synthesizes complementary DNA by mating on both strands, since the two strands are antiparallel, the replication is bidirectional, which means that one of the two strand is synthesized in a direction opposite to that of the direction of the enzyme, to do this, the DNA polymerase is obliged to synthesize DNA in the form of small fragments which are called Okazaki fragments, and its synthesized discontinuously (these fragments are not glued together by phosphodiester liasons, it is only after that another enzyme will intervene to ligate these fragments (DNA ligase).
