HorthooZ – Kerala GK, PSC Questions & Onam Quiz

Q1 Multiple Choice Question

During the generation of a neuronal action potential, the rapid depolarization phase is caused by voltage-gated opening of:

A Voltage-gated Sodium channels (causing rapid influx of Na+ into the axoplasm) B Chloride channels (causing Cl- influx) C Voltage-gated Potassium channels (causing K+ efflux) D Calcium ATPase pump actively pumping Ca2+ out

Q2 Multiple Choice Question

During which phase following an action potential is it completely physiologically impossible for a neuron to fire another action potential, no matter how strong the incoming stimulus is?

A Threshold resting state B Relative Refractory Period C Absolute Refractory Period (due to complete inactivation of voltage-gated Na+ channel inactivation gates) D Hyperpolarization phase alone

Q3 Multiple Choice Question

An Inhibitory Postsynaptic Potential (IPSP) hyperpolarizes the postsynaptic neuronal membrane, driving it away from threshold, primarily by opening transmitter-gated channels for:

A Sodium ion (Na+) influx exclusively B Calcium ion (Ca2+) influx exclusively C Hydrogen ion (H+) influx D Chloride ion (Cl-) influx or Potassium ion (K+) efflux

Q4 Multiple Choice Question

Why is corneal transplantation (keratoplasty) in humans rarely rejected by the recipient's immune system compared to other organ transplants?

A The cornea lacks blood and lymphatic vessels (it is completely avascular) B The cornea contains excessive numbers of white blood cells C The cornea is composed solely of inorganic bone minerals D The optic nerve destroys all host antibodies

Q5 Multiple Choice Question

What is the anatomical distribution of Grey Matter (neuronal cell bodies) and White Matter (myelinated nerve tracts) in the human brain compared to the spinal cord?

A In both brain and spinal cord: White matter is strictly outside and Grey matter inside B In both brain and spinal cord: Grey matter is strictly inside and White matter outside C In the brain: Grey matter is outside, White matter is inside; In the spinal cord: White matter is outside, Grey matter is inside D In the brain: White matter is outside; In the spinal cord: White matter is inside

Q6 Multiple Choice Question

In the human cochlea, where along the basilar membrane are high-frequency (high-pitch) sound waves and low-frequency (low-pitch) sound waves detected respectively?

A High frequencies at the narrow, stiff base; Low frequencies at the wide, flexible apex B Both high and low frequencies are detected uniformly across the entire basilar membrane C High frequencies in the semicircular canals; Low frequencies in the eardrum D High frequencies at the apex; Low frequencies at the base

Q7 Multiple Choice Question

According to the trichromatic theory of color vision (Young-Helmholtz theory), human cone photoreceptors are uniquely sensitive to which three primary colors?

A Red, Yellow, and Blue B Violet, Indigo, and Blue C Red, Green, and Blue D Green, Yellow, and Orange

Q8 Multiple Choice Question

Far-sightedness (Hypermetropia), where incoming light rays focus behind the retina, is optically corrected using which type of lens?

A Convex lens (Converging lens) B Prism lens C Cylindrical lens D Concave lens (Diverging lens)

Q9 Multiple Choice Question

Vital involuntary autonomic activities such as heart rate, blood pressure, respiration, swallowing, coughing, and sneezing are controlled by which brainstem structure?

A Cerebrum B Corpus callosum C Cerebellum D Medulla oblongata

Q10 Multiple Choice Question

Which jelly-like transparent fluid fills the large posterior chamber of the human eye between the lens and the retina, preventing the eyeball from collapsing?

A Vitreous humor B Cerebrospinal fluid C Aqueous humor D Endolymph

Q11 Multiple Choice Question

Near-sightedness (Myopia), where parallel light rays converge in front of the retina, is optically corrected using which type of lens?

A Bifocal lens B Concave lens (Diverging lens) C Convex lens (Converging lens) D Cylindrical lens

Q12 Multiple Choice Question

Through which circular lymphatic/venous channel at the junction of the iris and cornea does aqueous humor continuously drain out of the anterior chamber of the eye?

A Canal of Schlemm (Scleral venous sinus) B Eustachian tube C Central retinal artery D Nasolacrimal duct

Q13 Multiple Choice Question

Which egg-shaped mass of grey matter acts as the major 'relay station' of the brain, filtering and routing all incoming sensory impulses (except olfaction) to the cerebral cortex?

A Medulla oblongata B Thalamus C Cerebellum D Hypothalamus

Q14 Multiple Choice Question

Which anatomical duct connects the middle ear cavity to the nasopharynx, functioning to equalize air pressure on either side of the tympanic membrane (eardrum)?

A Eustachian tube B Lachrymal duct C Auditory canal D Cochlear aqueduct

Q15 Multiple Choice Question

An age-related loss of elasticity in the eye's crystalline lens and weakening of ciliary muscles resulting in impaired near vision is called 'Presbyopia', typically corrected by:

A Contact prism B Bifocal lenses (invented by Benjamin Franklin) C Simple plane glass D Cylindrical lens alone

Q16 Multiple Choice Question

The genuine sensory organ of hearing, composed of hair cells resting upon the basilar membrane within the cochlea of the inner ear, is called the:

A Macula of saccule B Organ of Corti C Crista ampullaris D Otolith organ

Q17 Multiple Choice Question

What is the correct sequential order of the three tiny middle ear ossicles that amplify sound waves from the tympanic membrane to the oval window?

A Stapes → Incus → Malleus B Incus → Malleus → Stapes C Malleus → Stapes → Incus D Malleus (Hammer) → Incus (Anvil) → Stapes (Stirrup)

Q18 Multiple Choice Question

Prolonged severe deficiency of Vitamin A leading to dryness, keratinization of the conjunctiva (Bitot's spots), and ulceration of the cornea is clinically called:

A Trachoma B Presbyopia C Glaucoma D Xerophthalmia

Q19 Multiple Choice Question

When a photon of light strikes a rhodopsin molecule in retinal rod photoreceptors, the immediate photochemical reaction (discovered by George Wald) involves:

A Photoisomerization of 11-cis-retinal into all-trans-retinal B Irreversible destruction of the opsin apoprotein C Direct phosphorylation of opsin by ATP D Conversion of all-trans-retinal into 11-cis-retinol

Q20 Multiple Choice Question

A progressive neurodegenerative disorder of the elderly causing severe irreversible cognitive decline, confusion, and loss of memory is called:

A Paralysis of limbs due to myelin sheath breakdown in motor nerves B Progressive loss of memory due to amyloid plaque buildup and Acetylcholine deficiency C Loss of hearing due to rupture of the basilar membrane D Inability of lacrimal glands to produce tears

Nervous System & Sense Organs