MCQ on Sensory Organs

🟢 Easy Level (1–20)

1. Which organ is responsible for vision?
   A) Ear
   B) Nose
   C) Eye ✅
   D) Skin
   Explanation: The eye is the sensory organ for vision.
2. Which part of the ear helps in maintaining balance?
   A) Cochlea
   B) Pinna
   C) Semicircular canals ✅
   D) Tympanic membrane
   Explanation: Semicircular canals detect rotational movements of the head.
3. Which sensory organ detects sound?
   A) Eye
   B) Skin
   C) Tongue
   D) Ear ✅
   Explanation: The ear detects sound waves and aids in hearing.
4. The colored part of the eye is called the:
   A) Lens
   B) Iris ✅
   C) Cornea
   D) Retina
   Explanation: The iris controls the size of the pupil and gives eye color.
5. Which organ helps in the sensation of taste?
   A) Tongue ✅
   B) Nose
   C) Skin
   D) Ear
   Explanation: The tongue contains taste buds for detecting flavors.
6. Which structure in the nose detects smell?
   A) Olfactory bulb ✅
   B) Nasal septum
   C) Sinuses
   D) Turbinates
   Explanation: The olfactory bulb processes smell signals.
7. Which layer of the eye contains photoreceptors?
   A) Sclera
   B) Retina ✅
   C) Cornea
   D) Iris
   Explanation: The retina contains rods and cones that detect light.
8. What part of the tongue is most sensitive to sweetness?
   A) Tip ✅
   B) Sides
   C) Back
   D) Middle
   Explanation: Sweet taste is primarily detected at the tip.
9. The transparent front part of the eye is the:
   A) Cornea ✅
   B) Iris
   C) Retina
   D) Lens
   Explanation: The cornea helps focus incoming light.
10. Which cells in the retina are responsible for color vision?
    A) Rods
    B) Cones ✅
    C) Bipolar cells
    D) Ganglion cells
    Explanation: Cones are sensitive to color and bright light.
11. The skin is the sensory organ for:
    A) Vision
    B) Hearing
    C) Touch ✅
    D) Smell
    Explanation: Skin detects touch, temperature, and pain.
12. The eardrum is also known as the:
    A) Pinna
    B) Tympanic membrane ✅
    C) Cochlea
    D) Oval window
    Explanation: It vibrates in response to sound waves.
13. Which taste cannot be detected by humans?
    A) Bitter
    B) Sweet
    C) Spicy ✅
    D) Umami
    Explanation: Spicy is sensed as pain, not taste.
14. Which part of the ear contains the organ of Corti?
    A) Outer ear
    B) Middle ear
    C) Inner ear ✅
    D) Eustachian tube
    Explanation: The organ of Corti is the hearing receptor inside the cochlea.
15. Which part of the eye focuses light onto the retina?
    A) Iris
    B) Cornea
    C) Lens ✅
    D) Sclera
    Explanation: The lens adjusts shape to focus light accurately.
16. The sense of smell is called:
    A) Gustation
    B) Olfaction ✅
    C) Tactile
    D) Audition
    Explanation: Olfaction is the detection of airborne molecules.
17. The pinna is a part of which organ?
    A) Eye
    B) Tongue
    C) Ear ✅
    D) Nose
    Explanation: The pinna collects sound waves and directs them into the ear.
18. Which part of the skin is rich in touch receptors?
    A) Epidermis
    B) Dermis ✅
    C) Hypodermis
    D) Subcutaneous tissue
    Explanation: The dermis contains touch, pressure, and pain receptors.
19. Which type of papillae contains most taste buds?
    A) Filiform
    B) Fungiform
    C) Foliate
    D) Vallate ✅
    Explanation: Vallate papillae have the highest concentration of taste buds.
20. The blind spot in the eye lacks:
    A) Blood vessels
    B) Ganglion cells
    C) Photoreceptors ✅
    D) Pigment
    Explanation: The optic disc lacks rods and cones, forming the blind spot.

🟡 Moderate Level (21–40)

21. Which part of the eye changes shape to focus on near or far objects?
    A) Iris
    B) Retina
    C) Lens ✅
    D) Cornea
    Explanation: The lens changes shape for accommodation.
22. Which cranial nerve is associated with hearing and balance?
    A) Trigeminal
    B) Facial
    C) Vestibulocochlear ✅
    D) Optic
    Explanation: The 8th cranial nerve carries auditory and balance information.
23. Which structure transmits vibrations from the eardrum to the inner ear?
    A) Cochlea
    B) Semicircular canals
    C) Auditory ossicles ✅
    D) Eustachian tube
    Explanation: The malleus, incus, and stapes conduct sound vibrations.
24. Which fluid fills the anterior chamber of the eye?
    A) Vitreous humor
    B) Aqueous humor ✅
    C) Synovial fluid
    D) Perilymph
    Explanation: Aqueous humor nourishes the cornea and lens.
25. Which receptors are responsible for detecting pain?
    A) Mechanoreceptors
    B) Thermoreceptors
    C) Nociceptors ✅
    D) Photoreceptors
    Explanation: Nociceptors respond to harmful stimuli.
26. Which part of the ear is connected to the pharynx?
    A) Eustachian tube ✅
    B) Cochlea
    C) Semicircular canals
    D) Auditory canal
    Explanation: It equalizes pressure between the ear and throat.
27. Which taste receptor detects umami?
    A) Glucose receptor
    B) Glutamate receptor ✅
    C) Salt receptor
    D) Bitter receptor
    Explanation: Umami taste detects amino acids like glutamate.
28. Which cells support photoreceptors in the retina?
    A) Bipolar cells
    B) Muller cells ✅
    C) Rods
    D) Cones
    Explanation: Muller cells provide structural and functional support.
29. How many semicircular canals are present in each ear?
    A) Two
    B) Three ✅
    C) Four
    D) Five
    Explanation: The three canals detect head movement in all planes.
30. Which part of the brain interprets visual information?
    A) Cerebellum
    B) Parietal lobe
    C) Occipital lobe ✅
    D) Temporal lobe
    Explanation: The occipital lobe processes signals from the eyes.
31. What causes the eye’s pupil to constrict?
    A) Dim light
    B) Parasympathetic stimulation ✅
    C) Sympathetic stimulation
    D) Distant vision
    Explanation: Parasympathetic nerves narrow the pupil in bright light.
32. Which part of the eye contains the highest density of cones?
    A) Retina
    B) Blind spot
    C) Fovea centralis ✅
    D) Iris
    Explanation: The fovea provides sharp central vision.
33. How many primary taste sensations are recognized by the tongue?
    A) 3
    B) 4
    C) 5 ✅
    D) 6
    Explanation: Sweet, sour, salty, bitter, and umami are the primary tastes.
34. Which eye structure helps drain excess aqueous humor?
    A) Iris
    B) Canal of Schlemm ✅
    C) Retina
    D) Cornea
    Explanation: The canal maintains intraocular pressure.
35. Where are olfactory receptors located?
    A) Tongue
    B) Nasal cavity roof ✅
    C) Sinuses
    D) Throat
    Explanation: The upper nasal cavity has olfactory receptor neurons.
36. Which part of the ear converts vibrations into nerve signals?
    A) Cochlea ✅
    B) Tympanic membrane
    C) Malleus
    D) Semicircular canal
    Explanation: The cochlea contains hair cells that convert vibrations into electrical impulses.
37. Which receptors detect changes in temperature?
    A) Thermoreceptors ✅
    B) Mechanoreceptors
    C) Chemoreceptors
    D) Nociceptors
    Explanation: Thermoreceptors respond to heat and cold.
38. Which fluid fills the posterior chamber of the eye?
    A) Perilymph
    B) Aqueous humor
    C) Vitreous humor ✅
    D) Cerebrospinal fluid
    Explanation: Vitreous humor maintains eye shape.
39. Which sensory receptor detects pressure and vibration?
    A) Ruffini corpuscle
    B) Pacinian corpuscle ✅
    C) Meissner’s corpuscle
    D) Merkel cells
    Explanation: Pacinian corpuscles respond to deep pressure.
40. Which structure maintains equilibrium during linear acceleration?
    A) Cochlea
    B) Semicircular canals
    C) Utricle and saccule ✅
    D) Oval window
    Explanation: These detect changes in head position relative to gravity.

🔴 Hard Level (41–50)

41. Which cranial nerve carries olfactory information?
    A) I – Olfactory ✅
    B) II – Optic
    C) V – Trigeminal
    D) VII – Facial
    Explanation: The olfactory nerve transmits smell signals.
42. The lens is held in place by:
    A) Iris muscles
    B) Suspensory ligaments ✅
    C) Ciliary body
    D) Retina
    Explanation: Zonules or suspensory ligaments connect the lens to the ciliary body.
43. Which part of the skin senses deep touch?
    A) Free nerve endings
    B) Meissner’s corpuscles
    C) Pacinian corpuscles ✅
    D) Thermoreceptors
    Explanation: Pacinian corpuscles detect deep pressure and vibration.
44. Which part of the eye is avascular?
    A) Retina
    B) Cornea ✅
    C) Choroid
    D) Iris
    Explanation: The cornea lacks blood vessels for transparency.
45. Which molecule binds odorants in the nasal cavity?
    A) Mucin
    B) Odorant-binding proteins ✅
    C) Albumin
    D) Enzymes
    Explanation: OBPs help transport odorants to receptors.
46. The ciliary body controls lens shape by:
    A) Pupil dilation
    B) Aqueous humor secretion
    C) Contracting and relaxing ✅
    D) Focusing light
    Explanation: It alters lens curvature for focusing.
47. Which part of the ear converts sound waves into electrical signals?
    A) Stapes
    B) Organ of Corti ✅
    C) Tympanic membrane
    D) Semicircular canal
    Explanation: The organ of Corti contains sensory hair cells.
48. Which papillae are most numerous but lack taste buds?
    A) Fungiform
    B) Foliate
    C) Filiform ✅
    D) Circumvallate
    Explanation: Filiform papillae are for texture, not taste.
49. The fovea centralis is located within the:
    A) Retina ✅
    B) Lens
    C) Cornea
    D) Choroid
    Explanation: It’s the area of sharpest vision.
50. Which nerve carries taste from the anterior 2/3 of the tongue?
    A) Glossopharyngeal
    B) Vagus
    C) Trigeminal
    D) Facial nerve ✅
    Explanation: The facial nerve (VII) transmits taste from the anterior tongue.