Neural control and coordination practice · Mixed difficulty

Option C (Spinal cord) is correct because the spinal cord serves as the primary control center for most reflex actions, enabling rapid responses to stimuli.

Option C (Sympathetic nervous system; adrenaline and noradrenaline) is correct because the sympathetic nervous system and these hormones are responsible for the fight-or-flight response.

Option B (Both Assertion and Reason are true but Reason is not the correct explanation of Assertion) is correct because while both statements are true, the pons being a link between the upper brain and spinal cord is not directly explained by its role in breathing regulation.

Option C is correct because the cornea lacks blood vessels, minimizing the risk of immune rejection after transplantation.

The correct answer is C (Brain) because a reflex arc is a direct pathway from sensory neuron to motor neuron (or interneuron) bypassing the brain for a quick response.

Option D (Brain) is correct because multipolar neurons, which have one axon and multiple dendrites, are predominantly found in the brain and spinal cord.

Option D (It is located on the membrane which forms partition between scala media and scala tympani) is correct because the organ of Corti resides on the basilar membrane, which separates the scala media and scala tympani.

Option B (Opening of voltage gated $\mathrm{Na}^{+}$channel) is correct because the influx of sodium ions through voltage-gated sodium channels causes depolarization of the neuron.

Option D (Film) is correct because the retina in the eye functions similarly to the film in a camera, capturing the image.

Option B (I, II and III) is correct because each neuron has a cell body, a single axon, and a variable number of dendrites.

Option D (Axon) is correct because Schwann cells form a myelin sheath around the axon of a neuron, providing insulation and increasing the speed of nerve impulse transmission.

Option D (II, III and IV) is correct because Nissl's granules are irregular masses of ribosomes and ER, are granular bodies, and synthesize proteins.

Option D (Spherical) is correct because the adult human eyeball is approximately spherical in shape.

Option A (10 pairs) is correct because frogs have 10 pairs of cranial nerves.

Option A ($3N{a^ + }$ out for $2{K^ + }$ in) is correct because the sodium-potassium pump transports 3 sodium ions out of the cell for every 2 potassium ions it transports into the cell.

Option B is correct because the valve of Vieussens is a band of fibers that connects the corpora quadrigemina to the cerebellum.

Option C (The nociceptors of the skin are bare nerve endings) is correct because nociceptors, which detect pain, are indeed free nerve endings in the skin.

Option C (Non-myelinated nerve fibres do not posses nodes of Ranvier) is correct because nodes of Ranvier are gaps in the myelin sheath, which is absent in non-myelinated fibers.

Option D ($N{a^ + }$ ions from extracellular fluid to intracellular fluid) is correct because during an action potential, sodium ions rush into the cell, causing depolarization.

Option A (If both the assertion and the reason are true and the reason is a correct explanation of the assertion) is correct because in myelinated nerve fibers, the impulse jumps from one node of Ranvier to another due to ion exchange occurring only at the nodes.

Option C (Dopamine) is correct because Parkinson's disease is caused by the degeneration of dopamine-producing neurons in the brain.

Option A (More ${Na}^{+}$pumped out than ${K}^{+}$ions taken in) is correct because the sodium-potassium pump actively transports 3 sodium ions out for every 2 potassium ions in.

Option D (Both (a) and (c)) is correct because the fight and flight response is mediated by the sympathetic nervous system.

Option C (Hydra) is correct because Hydra possesses a nerve net, a simple nervous system without a centralized brain.

Option A (If both the assertion and the reason are true and the reason is a correct explanation of the assertion) is correct because Vitamin A deficiency does cause night blindness, and this is because Vitamin A is a precursor to retinal, a component of visual pigments.

The correct answer is A (A functional unit consisting of a receptor neural pathway and an effector neuron) because it accurately describes the components and function of a reflex arc.

Option A (Cell body) is correct because dendrites transmit impulses towards the cell body (soma) of the neuron.

Option C (Blind spot) is correct because the blind spot is the area where the optic nerve leaves the eye, and therefore has no photoreceptor cells.