Question

Pheromones are airborne compounds detected through the sense of smell. During the mating season, female deer emit a pheromone that is sexually enticing to male deer, who perceive it through olfaction.

Why do only certain cells in the male deer receive pheromone signals, while the pheromones are exposed to all cells in the male deer?

(A) All cells contain the intra- and extra-cellular receptors necessary to stimulate a signal transduction pathway.

(B) Only certain cells in the male (particularly cells involved in the sex response) have receptors that bind to the female deer pheromone.

(C) Temporal isolation causes the receptors to only be active during mating season to maximize cell energy efficiency.

(D) Cell reception is different from organ processing of chemical signals.

Answer 1

Consider the concept of cell signaling and how it relates to pheromone detection.

Complete step-by-step Answer: Pheromones are a type of chemical communication used by many animals, including deer, to communicate with each other. Pheromones are released into the air and are detected by other animals through olfaction.

The female deer pheromone that triggers a sex response in male deer is called estrone. Estrone is a steroid hormone that is produced by the ovaries of female deer during mating season. When estrone is released into the air, it is detected by odorant receptors on the olfactory cells of male deer.

The odorant receptors on the olfactory cells of male deer are specialized to bind to estrone. When an estrone molecule binds to an odorant receptor, it triggers a signal transduction pathway that leads nerve impulse formation. This nerve impulse is then transmitted to the brain, where it is interpreted as a signal that a female deer is nearby and ready to mate.

The brain interprets the nerve impulse as a signal to release gonadotropin-releasing hormone (GnRH). Gonadotropin-releasing hormone (GnRH) circulates in the bloodstream to reach the pituitary gland, prompting the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH and FSH then travel in the bloodstream to the testes, where they trigger the synthesis of testosterone. Testosterone is responsible for the many physiological and behavioral changes that occur in male deer during mating season, such as increased heart rate, increased alertness, and increased aggression. Testosterone also stimulates the production of sperm.

The entire process of pheromone detection and response is a complex one that is essential for deer reproduction. By understanding how pheromones work, scientists can develop new methods for managing deer populations and preventing the spread of deer-borne diseases.

Hence the correct answer is Option B

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Note:**** Only certain cells in the male deer have odorant receptors that bind to the female deer pheromone. These cells are situated in the olfactory epithelium, which is the inner lining of the nasal cavity. When a male deer breathes in the pheromones emitted by a female deer, they attach to the scent receptors found on the olfactory cells. This initiates a series of processes in a signal transduction pathway that ultimately results in the creation of a nerve impulse, which is subsequently sent to the brain. The brain interprets the nerve impulse as a signal that a female deer is nearby and ready to mate, triggering physiological and behavioral changes in the male deer.