Answer: For detection and confirmation of HIV antibodies in blood samples.
Explanation: As the name implies ELISA( Enzyme-linked immunosorbent assay) is the first test widely used for determining the presence of HIV in a person's serum because of its high sensitivity. In an ELISA, a person's serum is diluted 400 times and applied to a plate to which HIV antigens are attached. If antibodies to HIV are present in the serum, they may bind to these HIV antigens. The plate is then washed to remove all other components of the serum. A specially prepared "secondary antibody" (an antibody that binds to other antibodies) is then applied to the plate, followed by another wash. This secondary antibody is chemically linked in advance to an enzyme.
Thus, the plate will contain enzyme in proportion to the amount of secondary antibody bound to the plate. A substrate for the enzyme is applied, and catalysis by the enzyme leads to a change in color or fluorescence. ELISA results are reported as a number; the most controversial aspect of this test is determining the "cut-off" point between a positive and a negative result. A cut-off point may be determined by comparing it with a known standard. Unknown samples that generate a stronger signal than the known or control sample or are called "positive" while those that generate weaker signal are "negative".
The principle of progression talks about the requirement to increment or increase gradually the difficulty of workload. This way of workout will increase the physical strength and body stamina. If a person wants to develop more power on his legs, the frequency, time, difficulty or intensity of workout should be lengthen or increased because this will progress the muscle.
Answer:
True
Explanation:
Among young children “friendship” is often based on proximity, such as they live next door, attend the same school, or it refers to whomever they just happen to be playing with at the time
