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Course: MCAT > Unit 4

Lesson 1: Foundations of behavior passages

Feline night vision


Cats are carnivorous mammals that have adapted to become more efficient and skillful hunters. Most domesticated cats have long, thick whiskers that enhance their sense of touch and perception of depth, increased numbers of olfactory receptors to detect distinct scents, and ear flaps that move toward the source of a sound. Their adaptations have also given them excellent vision and an uncanny ability to see at night. They are able to see well in the dark because of a specialized membrane known as the tapetum lucidum - which humans do not have. The tapetum lucidum is homologous to a specialized structure in the human eye, known as the choroid. In humans, the choroid is darkly pigmented, while cats lack this dark pigment; resulting in a shiny reflective coating in the back of the eyeball. This coating allows stray light rays which may have passed through the retina to be reabsorbed after being reflected off of the tapetum lucidum (why a cat’s eyes glow at night when you stare directly at them). In contrast, any stray light rays in the human eyeball would be absorbed by the pigmented choroid. The tapetum lucidum is evolutionarily advantageous to a cat -it enhances night vision due to the reflective properties of the membrane and allows the cat to hunt in the dark.
A researcher is interested in exploring the differences between feline and human ability to see at night. He recruits ten cat owners and their domesticated cats, and places a piece of fish in a complex, dark maze for them to find. Each owner and cat enters the maze alone, and the researcher times how long it takes for the owners and cats to find the fish. The average group times to find the food are outlined in Table 1.
Table 1
GroupTime to find fish
Cats2.44 minutes
Humans6.32 minutes
Which of the following statements is correct? Cones are responsible for __ vision and are centered in the __; while rods are responsible for __ vision and are centered in the __. **
Choose 1 answer: