The occular, or eye piece, has a magnification power of 10x. If the 10x low-power objective were in place, the magnification would be multiplicative.

Optical transmission is the amount of light that passes through a laboratory specimen. It can be used to measure the concentration of components in the specimen. Optotype is the variable-sized type used in testing visual acuity. Visual acuity is a measure of the resolving power of the eye; the smallest type that can be seen at a distance. The index of refraction is defined as the speed of light in a vacuum divided by the speed of light in a medium. 

The resolving power of a light microscope is the smallest structure that can be seen, approximately 1 micrometer (a millionth of a meter) by the microscope.

Light microscopes use lenses that range from 4x to 100x, are made of glass, and focus and magnify light rays.

The diaphragm regulates the amount of light that passes through an object being magnified. The iris controls the diameter of the beam of light entering the lens. The fine focus is used to move the objectives (lenses) to view objects clearly. The occulars are the lenses that one would look into to view the object. 

Electron microscopes use beams of electrons instead of light. The electrons are focused by magnetic fields rather than by lenses.

A phase plate is used with a light microscope to view details of objects characterized by differences in refractive index and, as such, have a difference in brightness or color. Tissues deep within the body can be imaged using the technique of multiphoton microscopy, in which photons are directed into tissues by an infrared laser. The reticle is a tiny grid pattern inserted into the eyepiece lens. It is used to make measurements of objects seen through the lens. 

The incorrect answer is retraction electron microscope. Transmission electron microscope is the simplest type by using a high voltage electron beam to formulate an image. Scanning electron microscopes produces an image through a scanning electron beam. Reflection electron microscopes use an electron beam that scatters when it hits a specimen, the image is then compiled from the scattered electron pattern. Scanning transmission electron microscopes uses a thin ray of electrons that scatters through the specimen to resolve the image. 

Typically, the secondary antibody is designed to have either a fluorescent or colorimetric tag to allow for detection. The primary antibody binds to the protein of interest, but (usually) does not have its own tag. The protein samples have already been properly separated during electrophoresis. Noise is blocked via various methods, but not by the secondary antibody. The secondary antibody does not influence the binding of the primary antibody. 

The correct answer is Western blot. Western blots utilize antibodies to detect specific proteins in a cell lysate. Northern blots detect specific RNA within a sample, whereas Southern blots detect specfic DNA sequences within a sample. An EMSA detects whether or not a protein is active, and therefore can bind a specific sequence of DNA.  

After proteins are run on an SDS-PAGE gel and separated by size, they are transferred to a nitrocellulose membrane. This exposes the proteins so that an antibody can recognize and bind to the protein of interest. Once the antibody is bound, a fluorescent secondary conjugated antibody will facilitate the visualization of the protein of interest. 

The major difference between ELISA and western blot is the fact that ELISA detects naive protein in its original conformation, while western requires denaturation of the protein by SDS-PAGE prior to detection. This makes western blotting more stringent and better for quantification, although both assays can quantitatively assess protein levels if done properly. 

SDS-PAGE requires that proteins are denatured before they are run through the gel, typically by the addition of detergents and then heating the sample. Since the protein has four subunits that are all different molecular weights, we would see four distinct bands that represent the four subunits. If the subunits had the same molecular weight, we would only see one band.