,BIOL251/BIOL 251 Module 8 Exam | Human Anatomy &
Physiology I w/ Lab | Portage Learning | Q & A | 2026/2027
(PDF)
**1. Which of the following is NOT classified as a special sense?**
A) Vision
B) Hearing
C) Touch
D) Equilibrium
Correct Answer: Touch
Rationale: The special senses include vision, hearing, equilibrium (balance), taste (gustation), and smell
(olfaction). Touch is considered a general sense because its receptors are widely distributed throughout
the skin and body rather than being localized to a single specialized organ.
**2. The process of converting a sensory stimulus into an electrical signal within a receptor cell is
called:**
A) Sensation
B) Perception
C) Transduction
D) Adaptation
Correct Answer: Transduction
Rationale: Transduction is the conversion of a stimulus (such as light, sound, or chemicals) into an
electrical signal (action potential) in a sensory receptor. Sensation is the conscious awareness of a
stimulus, and perception is the interpretation of that sensation.
**3. The outermost layer of the eye, composed of the sclera and cornea, is the:**
A) Vascular tunic
,B) Fibrous tunic
C) Nervous tunic
D) Retinal layer
Correct Answer: Fibrous tunic
Rationale: The eye has three distinct layers (tunics). The outermost fibrous tunic consists of the white
sclera posteriorly and the transparent cornea anteriorly. The vascular tunic (uvea) is the middle layer,
and the nervous tunic is the retina.
**4. Which structure controls the amount of light entering the eye by adjusting the size of the pupil?**
A) Lens
B) Cornea
C) Iris
D) Retina
Correct Answer: Iris
Rationale: The iris is the colored part of the eye containing smooth muscle that adjusts pupil diameter to
regulate light entry. The lens focuses light, the cornea refracts light, and the retina detects light.
**5. The middle layer of the eye, containing blood vessels, the ciliary body, and the iris, is the:**
A) Fibrous tunic
B) Nervous tunic
C) Vascular tunic
D) Scleral layer
Correct Answer: Vascular tunic
, Rationale: The vascular tunic (uvea) is the middle layer of the eye. It contains the choroid (blood supply),
the ciliary body (which produces aqueous humor and controls lens shape), and the iris (which regulates
light entry).
**6. The innermost layer of the eye, which contains the photoreceptors, is the:**
A) Sclera
B) Choroid
C) Retina
D) Cornea
Correct Answer: Retina
Rationale: The retina is the innermost nervous tunic of the eye and contains the photoreceptors (rods
and cones) that detect light and initiate visual signals. The sclera and cornea form the outer fibrous
layer, and the choroid is part of the vascular layer.
**7. Rods are primarily responsible for:**
A) Color vision
B) Bright light vision
C) Dim light vision
D) High visual acuity
Correct Answer: Dim light vision
Rationale: Rods function in low-light (night) vision and are more sensitive to light than cones. They do
not detect color and provide low-resolution vision. Cones are responsible for color vision and high visual
acuity in bright light.
**8. Cones are primarily responsible for:**
A) Dim light vision
B) Color vision and high visual acuity
Physiology I w/ Lab | Portage Learning | Q & A | 2026/2027
(PDF)
**1. Which of the following is NOT classified as a special sense?**
A) Vision
B) Hearing
C) Touch
D) Equilibrium
Correct Answer: Touch
Rationale: The special senses include vision, hearing, equilibrium (balance), taste (gustation), and smell
(olfaction). Touch is considered a general sense because its receptors are widely distributed throughout
the skin and body rather than being localized to a single specialized organ.
**2. The process of converting a sensory stimulus into an electrical signal within a receptor cell is
called:**
A) Sensation
B) Perception
C) Transduction
D) Adaptation
Correct Answer: Transduction
Rationale: Transduction is the conversion of a stimulus (such as light, sound, or chemicals) into an
electrical signal (action potential) in a sensory receptor. Sensation is the conscious awareness of a
stimulus, and perception is the interpretation of that sensation.
**3. The outermost layer of the eye, composed of the sclera and cornea, is the:**
A) Vascular tunic
,B) Fibrous tunic
C) Nervous tunic
D) Retinal layer
Correct Answer: Fibrous tunic
Rationale: The eye has three distinct layers (tunics). The outermost fibrous tunic consists of the white
sclera posteriorly and the transparent cornea anteriorly. The vascular tunic (uvea) is the middle layer,
and the nervous tunic is the retina.
**4. Which structure controls the amount of light entering the eye by adjusting the size of the pupil?**
A) Lens
B) Cornea
C) Iris
D) Retina
Correct Answer: Iris
Rationale: The iris is the colored part of the eye containing smooth muscle that adjusts pupil diameter to
regulate light entry. The lens focuses light, the cornea refracts light, and the retina detects light.
**5. The middle layer of the eye, containing blood vessels, the ciliary body, and the iris, is the:**
A) Fibrous tunic
B) Nervous tunic
C) Vascular tunic
D) Scleral layer
Correct Answer: Vascular tunic
, Rationale: The vascular tunic (uvea) is the middle layer of the eye. It contains the choroid (blood supply),
the ciliary body (which produces aqueous humor and controls lens shape), and the iris (which regulates
light entry).
**6. The innermost layer of the eye, which contains the photoreceptors, is the:**
A) Sclera
B) Choroid
C) Retina
D) Cornea
Correct Answer: Retina
Rationale: The retina is the innermost nervous tunic of the eye and contains the photoreceptors (rods
and cones) that detect light and initiate visual signals. The sclera and cornea form the outer fibrous
layer, and the choroid is part of the vascular layer.
**7. Rods are primarily responsible for:**
A) Color vision
B) Bright light vision
C) Dim light vision
D) High visual acuity
Correct Answer: Dim light vision
Rationale: Rods function in low-light (night) vision and are more sensitive to light than cones. They do
not detect color and provide low-resolution vision. Cones are responsible for color vision and high visual
acuity in bright light.
**8. Cones are primarily responsible for:**
A) Dim light vision
B) Color vision and high visual acuity
