Author: Joseph Baxter. Linear, quadratic and exponential functions have different graphs, equations, and characteristics. In this tutorial, compare the shape of linear, quadratic, and exponential curves on a graph, and explore how to identify a function as linear, quadratic, or exponential by examining x- and y-coordinates. (more)
The tier of cells at the back of the retina contains the light receptors, the rods and cones. Rods, which are far more numerous than cones, are responsible for our vision in dim light and are out of commission in bright light.
The retina contains 100 million rods and 7 million cones. The retina is lined with black pigment called melanin -- just as the inside of a camera is black -- to lessen the amount of reflection. The retina has a central area, called the macula, that contains a high concentration of only cones.