Olfactory receptors do/are NOT highly modified neurons. have cilia that bind odorous substances. number between 10,000 and 20,000.
The Correct Answer and Explanation is:
Correct answer: Olfactory receptors are NOT numbering between 10,000 and 20,000.
Explanation:
Olfactory receptors are specialized sensory cells responsible for detecting odors. They play a crucial role in the sense of smell by interacting with odor molecules in the air and sending signals to the brain. Let’s explore the three statements to determine which is not true.
- Olfactory receptors are highly modified neurons:
This statement is true. Olfactory receptor cells are actually specialized types of neurons. They are unique because they can regenerate throughout life, unlike most other neurons. These cells have direct contact with the external environment and transmit sensory signals from the nose to the brain’s olfactory bulb. - They have cilia that bind odorous substances:
This is also true. The cilia are hair-like projections on the dendritic end of olfactory receptor neurons. These cilia are covered with receptor proteins that bind to specific odor molecules. When an odor molecule binds to a receptor on the cilia, it triggers an electrical signal that is transmitted to the brain for interpretation. - They number between 10,000 and 20,000:
This is false. Humans have around 400 functional types of olfactory receptor genes, not 10,000 to 20,000. Although humans have millions of individual olfactory receptor cells in the nasal epithelium, the number of different receptor types is much lower. In comparison, some animals like dogs have over 1,000 types of olfactory receptors, giving them a much more acute sense of smell.
In conclusion, olfactory receptors are indeed specialized neurons with cilia that detect odor molecules, but the statement about their number being between 10,000 and 20,000 is incorrect when referring to the types of receptors. This makes it the correct answer to the question.
