Question

The fact that there are many more types of olfactory receptor neurons than types of color cones in vision indicates that:

A) each ORN can respond to only one specific odorant.
B) olfactory receptor neurons can be more narrowly tuned than cones.
C) olfactory receptor neurons can be more broadly tuned than cones.
D) the neural codes for odors and colors cannot be meaningfully compared.

Answer 1

The high number of olfactory receptor types compared to color cones suggests that olfactory receptors are broadly tuned, allowing detection of a diverse range of odors. Therefore, the correct option is C.

Step-by-step explanation:

The fact that there are many more types of olfactory receptor neurons (ORNs) than types of color cones in vision indicates that olfactory receptor neurons can be more broadly tuned than cones. This is because each olfactory sensory neuron expresses only one type of receptor protein, and these proteins are sensitive to specific odorants, allowing the system to distinguish a wide array of smells. Humans have about 350 olfactory receptor subtypes that combine to help us sense approximately 10,000 different odors, whereas vision is based on just three types of color cones.