BIOLOGY 1108 EXAM 4 REVIEW
QUESTIONS QUESTIONS AND
ANSWERS WITH DETAILED
SOLUTIONS – UPDATED 2026
VERSION GUARANTEED SUCCESS
What are hair cells and where are they located?
✔✔ Hair cells serve as the primary sensory receptors found within the organ
of Corti, which is situated inside the spiral-shaped cochlea of the inner ear.
What is the general function of these hair cells?
✔✔ They act as transducers that detect mechanical pressure waves and
convert them into chemical neurotransmitters; these signals then prompt
auditory neurons to transmit electrical impulses (action potentials) to the
brain.
How does the first step of hair cell activation occur?
✔✔ Initial activation begins when an incoming pressure wave physically
displaces or bends the stereocilia located at the apex of the hair cell.
What happens in the second step of the process?
✔✔ The movement of the stereocilia causes mechanically gated potassium
($K^+$) channels to pull open, allowing $K^+$ ions to flood into the cell from
the surrounding fluid.
What occurs during the third step of this cycle?
,✔✔ As the positively charged ions enter, the hair cell's membrane potential
becomes less negative, leading to a state of depolarization.
What is the fourth step in the signaling sequence?
✔✔ This change in voltage triggers the opening of voltage-gated calcium
($Ca^{2+}$) channels, resulting in an influx of $Ca^{2+}$ ions into the cell.
5th step of hair cell works
Neurotransmitters are released
6th step of hair cell works
Neurotransmitters bind to ligand gated channels in the dendrite region of the
auditory nerve (sensory neuron).
Select the true statements below. (transduction and photoreceptors)
Phototransduction is the translation of light (which is a physical stimulus =
electromagnetic radiation) into chemical signals (NTs), which are translated into
electrical signals (APs), which are then translated into chemical signals (NTs),
which are then translated into electrical signals (APs) sent to the thalamus/visual
cortex/brain.
Phototransduction involves photoreceptors, photoreceptor cells, bipolar neurons,
and ganglion neurons that wind together to form the optic nerve.
, Rods and cones are photoreceptor cells
Rhodopsin is a photoreceptor; it is embedded in the membrane of rod cells (which
are photoreceptor cells).
Rhodopsin is a G-protein coupled receptor
Humans have the greatest number of different photoreceptors.
False
Which sense in humans most closely resembles the ability of fish to detect the
movement of predators and/or prey.
Hearing and balance, which involve mechanically gated ion channels embedded in
sensory receptor cells (hair cells)
Sharks have receptors that can detect electrical charges in the water. They use this
ability to detect prey - they can actually detect the APs (electrical impulses) fired
by the muscles in fish swimming around them. The receptors embedded in the
electroreceptive cells found at the bottom of the ampullae de Lorenzini are:
Voltage gated Ca2+ ion channels
What are the 2 types of receptors - based on how they function?
Ion channel receptors
QUESTIONS QUESTIONS AND
ANSWERS WITH DETAILED
SOLUTIONS – UPDATED 2026
VERSION GUARANTEED SUCCESS
What are hair cells and where are they located?
✔✔ Hair cells serve as the primary sensory receptors found within the organ
of Corti, which is situated inside the spiral-shaped cochlea of the inner ear.
What is the general function of these hair cells?
✔✔ They act as transducers that detect mechanical pressure waves and
convert them into chemical neurotransmitters; these signals then prompt
auditory neurons to transmit electrical impulses (action potentials) to the
brain.
How does the first step of hair cell activation occur?
✔✔ Initial activation begins when an incoming pressure wave physically
displaces or bends the stereocilia located at the apex of the hair cell.
What happens in the second step of the process?
✔✔ The movement of the stereocilia causes mechanically gated potassium
($K^+$) channels to pull open, allowing $K^+$ ions to flood into the cell from
the surrounding fluid.
What occurs during the third step of this cycle?
,✔✔ As the positively charged ions enter, the hair cell's membrane potential
becomes less negative, leading to a state of depolarization.
What is the fourth step in the signaling sequence?
✔✔ This change in voltage triggers the opening of voltage-gated calcium
($Ca^{2+}$) channels, resulting in an influx of $Ca^{2+}$ ions into the cell.
5th step of hair cell works
Neurotransmitters are released
6th step of hair cell works
Neurotransmitters bind to ligand gated channels in the dendrite region of the
auditory nerve (sensory neuron).
Select the true statements below. (transduction and photoreceptors)
Phototransduction is the translation of light (which is a physical stimulus =
electromagnetic radiation) into chemical signals (NTs), which are translated into
electrical signals (APs), which are then translated into chemical signals (NTs),
which are then translated into electrical signals (APs) sent to the thalamus/visual
cortex/brain.
Phototransduction involves photoreceptors, photoreceptor cells, bipolar neurons,
and ganglion neurons that wind together to form the optic nerve.
, Rods and cones are photoreceptor cells
Rhodopsin is a photoreceptor; it is embedded in the membrane of rod cells (which
are photoreceptor cells).
Rhodopsin is a G-protein coupled receptor
Humans have the greatest number of different photoreceptors.
False
Which sense in humans most closely resembles the ability of fish to detect the
movement of predators and/or prey.
Hearing and balance, which involve mechanically gated ion channels embedded in
sensory receptor cells (hair cells)
Sharks have receptors that can detect electrical charges in the water. They use this
ability to detect prey - they can actually detect the APs (electrical impulses) fired
by the muscles in fish swimming around them. The receptors embedded in the
electroreceptive cells found at the bottom of the ampullae de Lorenzini are:
Voltage gated Ca2+ ion channels
What are the 2 types of receptors - based on how they function?
Ion channel receptors
