It because they give us oxygen and without oxygen we would all die from oxygen deprivation.
the process that gives us oxygen is photosynthesis
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The oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. This blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. From the left ventricle, the blood passes through the aortic valve to the aorta.
Binocular vision. Binocular vision is vision with two eyes, and the main cue for depth perception associated with binocular vision is retinal disparity. ... The disparity (difference) between these two retinal images (retinal disparity) can be used as a cue for depth/distance.
