When does the exponential growth of a population stop?

The image shows embryos of three vertebrate classes

Which of the following shows the correct order in which light information travels through the eye? (2 points) lens, pupil, retina, optic nerve pupil, lens, retina, optic nerve pupil, lens, optic nerve, retina lens, pupil, optic nerve, retina

Which best describes a gene? a. a sister chromatid b. a chromosome c. a tetrad d. a piece of a chromosome