Grade 11 : Biology - Neural (Set 5) | Concept of Maths

Question 1

1. During the resting state of a neuron, the axonal membrane is characterized by:

A) High permeability to $Na^{+}$ and low permeability to $K^{+}$

B) Equal permeability to both $Na^{+}$ and $K^{+}$

C) Comparatively more permeable to $K^{+}$ and nearly impermeable to $Na^{+}$

D) Impermeable to both $Na^{+}$ and $K^{+}$

Answer

Correct Answer: C

Solution: In a resting neuron, the membrane is more permeable to potassium ions ($K^{+}$) and nearly impermeable to sodium ions ($Na^{+}$). This selectively permeable nature, maintained by the $Na^{+}-K^{+}$ pump (moving $3 Na^{+}$ out and $2 K^{+}$ in), establishes the resting membrane potential of approximately $-70\text{ mV}$.

Question 2

2. If a stimulus causes the membrane potential to shift from $-70\text{ mV}$ to $-55\text{ mV}$ (threshold), which event occurs immediately after?

A) Closure of Voltage-gated $K^{+}$ channels

B) Rapid opening of Voltage-gated $Na^{+}$ channels

C) Activation of the $Na^{+}-K^{+}$ ATPase pump

D) Efflux of $Cl^{-}$ ions from the axoplasm

Answer

Correct Answer: B

Solution: When the threshold stimulus ($-55\text{ mV}$) is reached, voltage-gated $Na^{+}$ channels open rapidly, allowing an influx of $Na^{+}$ ions down their electrochemical gradient, leading to depolarization.

Question 3

3. In an electrical synapse, the transmission of an impulse is:

A) Faster than a chemical synapse because the pre- and post-synaptic membranes are in very close proximity

B) Slower than a chemical synapse due to the absence of neurotransmitters

C) Dependent on the release of Acetylcholine into the synaptic cleft

Question 4

4. Which part of the human brain contains centers that control body temperature, urge for eating, and drinking?

A) Thalamus

B) Cerebellum

C) Pons

D) Hypothalamus

Answer

Correct Answer: D

Solution: The hypothalamus, located at the base of the thalamus, is the master regulator of homeostasis. It contains the thermoregulatory center and centers for hunger (feeding) and thirst (satiety).

Question 5

5. Identify the correct sequence of the reflex arc components:

A) Effector $\rightarrow$ Efferent neuron $\rightarrow$ CNS $\rightarrow$ Afferent neuron $\rightarrow$ Receptor

B) Receptor $\rightarrow$ Afferent neuron $\rightarrow$ CNS $\rightarrow$ Efferent neuron $\rightarrow$ Effector

C) Receptor $\rightarrow$ Efferent neuron $\rightarrow$ CNS $\rightarrow$ Afferent neuron $\rightarrow$ Effector

D) CNS $\rightarrow$ Receptor $\rightarrow$ Afferent neuron $\rightarrow$ Efferent neuron $\rightarrow$ Effector

Answer

Correct Answer: B

Solution: A reflex arc follows a specific unidirectional path: 1. Receptor (receives stimulus) 2. Afferent (Sensory) neuron (carries signal to CNS) 3. CNS (Interneuron processing) 4. Efferent (Motor) neuron (carries command to effector) 5. Effector (Muscle/Gland response).

Question 6

6. The 'Canal of Schlemm' is associated with which part of the human eye?

A) Retina

B) Vitreous chamber

C) Junction of Cornea and Sclera

D) Choroid

Answer

Correct Answer: C

Solution: The Canal of Schlemm is a vascular structure located at the iridocorneal angle (junction of cornea and sclera). It drains the aqueous humor from the anterior chamber into the blood, maintaining intraocular pressure.

Question 7

7. Rods contain a purplish-red protein called rhodopsin, which is a derivative of:

A) Vitamin A

B) Vitamin C

C) Vitamin D

D) Vitamin B12

Answer

Correct Answer: A

Solution: Rhodopsin (visual purple) is composed of opsin (a protein) and retinal (an aldehyde of Vitamin A). This is why Vitamin A deficiency leads to night blindness (Nyctalopia).

Question 8

8. In the human ear, the vibrations from the stapes are first transmitted to the:

A) Round window

B) Tympanic membrane

C) Scala tympani

D) Oval window

Answer

Correct Answer: D

Solution: Sound waves travel: Pinna $\rightarrow$ External auditory canal $\rightarrow$ Tympanum $\rightarrow$ Malleus $\rightarrow$ Incus $\rightarrow$ Stapes $\rightarrow$ Oval window (Fenestra ovalis) $\rightarrow$ Cochlear fluid.

Question 9

9. The part of the brain responsible for maintaining posture and equilibrium of the body is:

A) Cerebrum

B) Medulla oblongata

C) Cerebellum

D) Corpus callosum

Answer

Correct Answer: C

Solution: The cerebellum (part of the hindbrain) integrates sensory information from the vestibular system and proprioceptors to coordinate voluntary muscle movements, posture, and balance.

Question 10

10. Visual acuity (resolution) is highest at the:

A) Blind spot

B) Fovea centralis

C) Optic disc

D) Ora serrata

Answer

Correct Answer: B

Solution: The fovea centralis is a thinned-out portion of the macula lutea where only cones are densely packed. This area provides the sharpest vision and highest resolution.

Accepted Answer

Correct Answer: A

Solution: Electrical synapses allow direct flow of current between neurons via gap junctions. Because the distance is only about $0.2\text{ nm}$ (compared to $20-50\text{ nm}$ in chemical synapses), the transmission is significantly faster.

Grade 11 : Biology - Neural (Set 5) | Concept of Maths