BIOD 152 MODULE 2 ACTUAL EXAM 2026/2027 | Portage Learning |
26 Questions with Rationales | Complete Answer Key | Pass
Guaranteed - A+ Graded
Q1 (Multiple Choice): Which type of sensory receptor responds to stimuli arising outside
the body, such as touch, pressure, or temperature changes in the external environment?
A. Interoceptors
B. Proprioceptors
C. Exteroceptors [CORRECT]
D. Nociceptors
Correct Answer: C
Rationale: Exteroceptors are sensory receptors that respond to external stimuli from
outside the body, including touch, pressure, temperature, and pain from the skin surface.
Interoceptors (A) detect stimuli from internal organs and viscera, such as blood
pressure changes or organ distension. Proprioceptors (B) are located in muscles,
tendons, and joints, providing information about body position and movement.
Nociceptors (D) are pain receptors that can be either exteroceptive (cutaneous pain) or
interoceptive (visceral pain), making this a functional classification rather than a
location-based one. Understanding receptor classification by location is fundamental to
organizing sensory information in the nervous system.
Q2 (Diagram Labeling): Image description: Cross-section of the eye showing anterior
and posterior segments with numbered structures.
,Label the following structures:
1. Transparent structure that refracts light entering the eye
2. Pigmented muscular structure that controls pupil size
3. Clear, watery fluid that fills the anterior chamber
4. Structure that changes shape to focus light on the retina
5. Gel-like substance that fills the posterior cavity
Correct Answer:
1. Cornea [CORRECT]
2. Iris [CORRECT]
3. Aqueous humor [CORRECT]
4. Lens [CORRECT]
5. Vitreous humor (vitreous body) [CORRECT]
Rationale:
1. Cornea: The transparent anterior portion of the fibrous tunic that refracts (bends)
light as it enters the eye. It provides approximately 65-75% of the eye's total
refractive power.
2. Iris: The colored, pigmented portion of the vascular tunic containing smooth
muscle (sphincter and dilator pupillae) that regulates pupil diameter and thus
light entry.
3. Aqueous humor: Produced by the ciliary body, this clear fluid fills the anterior and
posterior chambers, providing nutrients to avascular structures (cornea, lens)
and maintaining intraocular pressure.
4. Lens: The biconvex, transparent structure suspended by suspensory ligaments
from the ciliary body. It changes shape (accommodation) to fine-tune focus for
near or distant vision.
5. Vitreous humor: The gel-like substance filling the vitreous chamber (posterior
cavity), helping maintain eye shape and supporting the retina against the choroid.
Q3 (Short Answer): Explain the process of accommodation for near vision, including the
specific structures involved and their coordinated actions.
, Correct Answer: Accommodation for near vision involves three coordinated actions: [1]
The ciliary muscle contracts (via parasympathetic stimulation through CN III), [2]
causing the ciliary body to move forward and inward, [3] which relaxes tension on the
suspensory ligaments (zonular fibers), [4] allowing the elastic lens to become more
spherical (increased convexity), [5] thereby increasing refractive power to focus light on
the retina. Additionally, the eyes converge (medial rectus muscles contract) and pupils
constrict (miosis) to improve image clarity. [CORRECT]
Rationale: Accommodation requires understanding the anatomical relationships
between the ciliary body, suspensory ligaments, and lens. For distant vision, the ciliary
muscle is relaxed, tension on suspensory ligaments is high, and the lens is flattened
(less refractive power). For near vision, parasympathetic activation via the oculomotor
nerve (CN III) triggers ciliary muscle contraction, reducing suspensory ligament tension
and allowing the inherently elastic lens to recoil into a more convex shape. This
increases the lens's refractive power (measured in diopters). The near triad includes
accommodation, convergence, and pupillary constriction—all essential for clear near
vision. Loss of accommodation (presbyopia) occurs with age due to lens sclerosis.
Q4 (Clinical Scenario): A 68-year-old patient presents with gradual, painless vision loss
in both eyes. Examination reveals clouding of the lenses bilaterally. The patient reports
difficulty with night driving and seeing halos around lights. Which condition is most
likely, and which structural layer of the eye is primarily affected?
A. Glaucoma; neural tunic (retina)
B. Cataracts; vascular tunic (lens) [CORRECT]
C. Macular degeneration; fibrous tunic (cornea)
D. Diabetic retinopathy; neural tunic (retina)
26 Questions with Rationales | Complete Answer Key | Pass
Guaranteed - A+ Graded
Q1 (Multiple Choice): Which type of sensory receptor responds to stimuli arising outside
the body, such as touch, pressure, or temperature changes in the external environment?
A. Interoceptors
B. Proprioceptors
C. Exteroceptors [CORRECT]
D. Nociceptors
Correct Answer: C
Rationale: Exteroceptors are sensory receptors that respond to external stimuli from
outside the body, including touch, pressure, temperature, and pain from the skin surface.
Interoceptors (A) detect stimuli from internal organs and viscera, such as blood
pressure changes or organ distension. Proprioceptors (B) are located in muscles,
tendons, and joints, providing information about body position and movement.
Nociceptors (D) are pain receptors that can be either exteroceptive (cutaneous pain) or
interoceptive (visceral pain), making this a functional classification rather than a
location-based one. Understanding receptor classification by location is fundamental to
organizing sensory information in the nervous system.
Q2 (Diagram Labeling): Image description: Cross-section of the eye showing anterior
and posterior segments with numbered structures.
,Label the following structures:
1. Transparent structure that refracts light entering the eye
2. Pigmented muscular structure that controls pupil size
3. Clear, watery fluid that fills the anterior chamber
4. Structure that changes shape to focus light on the retina
5. Gel-like substance that fills the posterior cavity
Correct Answer:
1. Cornea [CORRECT]
2. Iris [CORRECT]
3. Aqueous humor [CORRECT]
4. Lens [CORRECT]
5. Vitreous humor (vitreous body) [CORRECT]
Rationale:
1. Cornea: The transparent anterior portion of the fibrous tunic that refracts (bends)
light as it enters the eye. It provides approximately 65-75% of the eye's total
refractive power.
2. Iris: The colored, pigmented portion of the vascular tunic containing smooth
muscle (sphincter and dilator pupillae) that regulates pupil diameter and thus
light entry.
3. Aqueous humor: Produced by the ciliary body, this clear fluid fills the anterior and
posterior chambers, providing nutrients to avascular structures (cornea, lens)
and maintaining intraocular pressure.
4. Lens: The biconvex, transparent structure suspended by suspensory ligaments
from the ciliary body. It changes shape (accommodation) to fine-tune focus for
near or distant vision.
5. Vitreous humor: The gel-like substance filling the vitreous chamber (posterior
cavity), helping maintain eye shape and supporting the retina against the choroid.
Q3 (Short Answer): Explain the process of accommodation for near vision, including the
specific structures involved and their coordinated actions.
, Correct Answer: Accommodation for near vision involves three coordinated actions: [1]
The ciliary muscle contracts (via parasympathetic stimulation through CN III), [2]
causing the ciliary body to move forward and inward, [3] which relaxes tension on the
suspensory ligaments (zonular fibers), [4] allowing the elastic lens to become more
spherical (increased convexity), [5] thereby increasing refractive power to focus light on
the retina. Additionally, the eyes converge (medial rectus muscles contract) and pupils
constrict (miosis) to improve image clarity. [CORRECT]
Rationale: Accommodation requires understanding the anatomical relationships
between the ciliary body, suspensory ligaments, and lens. For distant vision, the ciliary
muscle is relaxed, tension on suspensory ligaments is high, and the lens is flattened
(less refractive power). For near vision, parasympathetic activation via the oculomotor
nerve (CN III) triggers ciliary muscle contraction, reducing suspensory ligament tension
and allowing the inherently elastic lens to recoil into a more convex shape. This
increases the lens's refractive power (measured in diopters). The near triad includes
accommodation, convergence, and pupillary constriction—all essential for clear near
vision. Loss of accommodation (presbyopia) occurs with age due to lens sclerosis.
Q4 (Clinical Scenario): A 68-year-old patient presents with gradual, painless vision loss
in both eyes. Examination reveals clouding of the lenses bilaterally. The patient reports
difficulty with night driving and seeing halos around lights. Which condition is most
likely, and which structural layer of the eye is primarily affected?
A. Glaucoma; neural tunic (retina)
B. Cataracts; vascular tunic (lens) [CORRECT]
C. Macular degeneration; fibrous tunic (cornea)
D. Diabetic retinopathy; neural tunic (retina)
