Text Book Back Questions and Answers - Chapter 10 Neural Control and Coordination 11th Biology Zoology Guide Samacheer Kalvi Solutions - SaraNextGen [2024-2025]

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On April 24, 2024, 11:35 AM

Neural Control and Coordination
Text Book Back Questions and Answers
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Question 1.
Which structure in the ear converts pressure waves to action potentials?
(a) Tympanic membrane
(b) Organ of Corti
(c) Oval window
(d) Semicircular canal
Answer:
(b) Organ of Corti
Question 2.
Which of the following pairings is correct?
(a) Sensory nerve - afferent
(b) Motor nerve - afferent
(c) Sensory nerve - ventral
(d) Motor nerve - dorsal
Answer:
(a) Sensory nerve - afferent
Question 3.
During synaptic transmission of nerve impulse, neurotransmitter $(P)$ is released from synaptic vesicles by the action of ions $(Q)$ ? Choose the correct $P$ and $Q$ ?
(a) $\mathrm{P}=$ Acetylcholine, $\mathrm{Q}=\mathrm{Ca}^{+}$
(b) $\mathrm{P}=$ Acetylcholine, $\mathrm{Q}=\mathrm{Na}^{+}$
(c) $P=G A B A, Q=\mathrm{Na}^{+}$
(d) $P=$ Cholinesterase, $Q=C a^{+}$
Answer:
(a) $\mathrm{P}=$ Acetylcholine, $\mathrm{Q}=\mathrm{Ca}^{+}$
Question 4.
Examine the diagram of the two cell types $A$ and $B$ given below and select the correct option?

(a) Cell-A is the rod cell found evenly all over retina
(b) Cell-A is the cone cell more concentrated in the fovea centralis
(c) Cell-B is concerned with colour vision in bright light
(d) Cell-A is sensitive to bright light intensities
Answer:
(c) Cell-B is concerned with colour vision in bright light
Question 5.
Assertion: The imbalance in concentration of $\mathrm{Na}^{+}, \mathrm{K}^{+}$and proteins generates action potential.
Reason: To maintain the unequal distribution of $\mathrm{Na}^{+}$and $\mathrm{K}^{+}$, the neurons use electrical energy.
(a) Both Assertion and Reason are true and Reason is the correct explanation of the Assertion.
(b) Both Assertion and Reason are true but the Reason is not the correct explanations of Assertion.
(c) Assertion is true, but Reason is false.
(d) Both Assertion and Reason are false.
Answer:
(a) Both Assertion and Reason are true and Reason is the correct explanation of the Assertion.
Question 6.
Which part of the human brain is concerned with the regulation of body temperature?
(a) Cerebellum
(b) Cerebrum
(c) Medulla oblongata

(d) Hypothalamus
Answer:
(a) Cerebellum
Question 7.
The respiratory centre is present in the
(a) Medulla oblongata
(b) Hypothalamus
(c) CerebeLlum
(d) Thalamus
Answer:
(a) Medulla oblongata
Question 8.
Match the following human spinal nerves in column-I with their respective number in column-II and choose the correct option?

(a) (P-i v),(Q-i i),(R-i),(S-i i)
(b) ( $P-i i i),(Q-i),(R-i i),(S-i v)$
(c) $(P-i v),(Q-i),(R-i i),(S-i i i)$
(d) $(P-i i),(Q-i v),(R-i),(S-i i)$
Answer:
(a) (P-iv) (Q-iii) (R-i) (S-ii)

Question 9.
Which of the following cranial nerve controls the movement of eye ball ?
(a) Trochlear nerve
(b) Optic nerve
(c) Olfactory nerve
(d) Vagus nerve
Answer:
(a) Trochlear nerve
Question 10.
The abundant intracellular cation is
(a) $\mathrm{H}^{+}$
(b) $\mathrm{K}^{+}$
(c) $\mathrm{Na}^{+}$
(d) $\mathrm{Ca}^{+*}$
Answer:
(b) $\mathrm{K}^{+}$
Question 11.
Which of the following statement is wrong regarding conduction of nerve impulse?
(a) In a resting neuron, the axonal membrane is more permeable to $\mathrm{K}^{+}$ions and nearly impermeable to $\mathrm{Na}$; ions.
(b) Fluid outside the axon has a high concentration of $\mathrm{Na+}$ ions and low concentration of $\mathrm{K}^{+}$, in a resting neuron.
(c) lonic gradients are maintained by $\mathrm{Na}-\mathrm{K}$ pumps across the resting membrane, which transport $3 \mathrm{Na}^{+}$ions outwards for $2 \mathrm{~K}^{+}$into the cell.
(d) A neuron is polarized only when the outer surface of the axonal membrane 

Answer:
(d) Its pathways always involve four neurons
Question 15.
When the potential across the axon membrane is more negative than the normal resting potential, the neuron is said to be in a state of
(a) Depolarization
(b) Hyperpolarization
(c) Repolarization
(d) Hypopolarization
Answer:
(b) Hyperpolarization
Question 16.
Why is the blind spot called so?
Answer:
Slightly below the posterior pole of the eye, the optic nerve and the retinal blood vessels enter the eye. This region is devoid of rods and cones. Hence, this region is called blind spot.
Question 17.
Sam's optometrist tells him that his intraocular pressure is high. What is this condition called and which fluid does it involve?
Answer:
The aqueous humour present in between iris and lens and the cornea and iris is produced and drained at the same rate, maintaining a constant intra ocular pressure of about $16 \mathrm{~mm} \mathrm{Hg}$. Any block in the canal of schlemm increases the intra ocular pressure of aqueous humour. This condition is called 'Glaucoma'. Due to pressure, optic nerve and the retina are compressed. This leads to blindness.
Question 18.
Why are we getting running nose while crying?
Answer:
When we cry, the tears come out of the tear glands under the eyelids and drain through the tear duct that empty into the nose. It mixes with mucus there and the nose runs.
Question 19.
The action potential occurs in response to a threshold stimulus; but not at subthreshold stimuli. What is the name of the principle involved?
Answer:
All or none principle.
Question 20.
Pleasant smell of food urges Ravi to rush into the kitchen. Name the parts of the brain involved in the identification of food and emotional responses to odour?
Answer:
Olfactory nerve carries the sense of smell to the sensory strip present in the cerebrum. The sensory areas are present in the parietal lobe of the cerebrum. The stimuli of smell reaches the mammillary bodies present in the hypothalamus. This produces olfactory reflexes and emotional responses to odour.
Question 21.
Cornea transplant in humans is almost never rejected. State the reason?
Answer:
Cornea does not have blood vessels. Hence there is no possibility of rejection when cornea is transplanted from one person to another person.
Question 22.
At the end of repolarization, the nerve membrane gets hyperpolarized. Why?
Answer:
At the end of repolarization, the membrane potential inside the axolemma becomes negative due to the efflux of $\mathrm{K}^{+}$ions. When it becomes more negative than the resting potential $-70 \mathrm{mV}$ to about $-90 \mathrm{mV}$, it becomes hyperpolarised.
Question 23.
Label the parts of the neuron?

Answer:

1. Nucleolus
2. Node of Ranvier
3. Dendrite
4. Myelin sheath
5. Axon
6. Nucleus
Question 24.
The choroid plexus secretes cerebrospinal fluid. List the function of it?
Answer:
Cerebro spinal fluid provides buoyancy to the central nervous system.
1. It acts as a shock absorber for the brain and spinal cord.
2. It nourishes the brain cells by transporting food and oxygen.
3. It carries harmful metabolic wastes from the brain to the blood.
4. It maintains a constant pressure inside the cranial vessels.
Question 25.
What is the ANS controlling centre? Name the parts that are supplied by the ANS?
Answer:
Hypothalamus is the ANS controlling centre. The Autonomic neural system innervates smooth muscles, glands and cardiac muscle.
Question 26.
Why the limbic system is called the emotional brain? Name the parts of it?

Answer:
The limbic system is a set of components located on both side of the thalamus present in the inner part of the cerebral hemisphere. It includes the olfactory bulbs, cingulate gyrus, mammillary body, amygdala, hippocampus and hypothalamus. The limbic system plays a primary role in the regulation of pleasure, pain, anger, fear, sexual feeling, affection and memory. Hence it is called emotional brain.
Question 27.
Classify receptors based on type of stimuli?
Answer:

Question 28.
Name the first five cranial nerves, their nature and their functions?
Answer:

Question 29.
The sense of taste is considered to be the most pleasurable of all senses? Describe the structure of the receptor involved with a diagram?
Answer:
Gustatory receptor: The sense of taste is considered to be the most pleasurable of all senses. The tongue is provided with many small projections called papillae which give the tongue an abrasive feel. Taste buds are located mainly on the papillae which are scattered over the entire tongue surface.
Most taste buds are seen on the tongue few are scattered on the soft palate, inner surface of the cheeks, pharynx and epiglottis of the larynx. Taste buds are flask-shaped and consist of $50-100$ epithelial cells of two major types.
Gustatory epithelial cells (taste cells) and Basal epithelial cells (Repairing cells). Long microvilli called gustatory hairs project from the tip of the gustatory cells and extends through a taste pore to the surface of the epithelium where they are bathed by saliva.

Gustatory hairs are the sensitive portion of the gustatory cells and they have sensory dendrites which send the signal to the brain. The basal cells that act as stem cells, divide and differentiate into new gustatory cells. 

Question 30.
Describe the structures of olfactory receptors?
Answer:
The smell receptors are excited by air borne chemicals that dissolve in fluids. The yellow coloured patches of olfactory epithelium form the olfactory organs that are located on the roof of the nasal cavity.

The olfactory epithelium is covered by a thin coat of mucus layer below and olfactory glands bounded connective tissues, above. It contains three types of cells: supporting cells, Basal cells and millions of pin shaped olfactory receptor cells (which are unusual bipolar cells).
The olfactory glands and the supporting cells secrete the mucus. The unmyelinated axons of the olfactory receptor cells are gathered to form the
filaments of olfactory nerve [cranial nerve-l] which synapse with cells of olfactory bulb.
The impulse, through the olfactory nerves, is transmitted to the frontal lobe of the brain for identification of smell and the limbic system for the emotional responses to odour.
In-Text Questions Solved
Question 1.
Can you state why some areas of the brain and spinal cord are grey and some are white?
Answer:Some areas of the brain and spinal cord are grey due to the presence of nonmyelinated nerve cells. The white matter has myelinated nerve cells with myelin sheath made of fat.
Question 2.
Human brain is formed of a large number of parts like cerebrum, thalamus, hypothalamus, pons, cerebellum and medulla oblongata. Each part performs some specialized function and all the parts are essential for the survival of a person. Discuss the following statements:
(a) Thalami are called relay centres of the brain.
(b) Damage to medulla may cause the death of organism.
Answer:
(a) Thalamus is composed of grey mater which serves as a relay centre for impulses between the spinal cord, brain stem and cerebrum. Thus acting as a major coordinating centre for sensory and motor signaling. Within the thalamus, information is sorted and edited and plays a key role in learning and memory.
(b) Medulla contains vital centres that control cardio vascular reflexes, respiration and gastric secretions. Therefore, damage to medulla may cause the death of an organism.
Question 3.
Your friend is returning home after his visit to USA. All at home are waiting for
his arrival. How would you feel? State the division of ANS that predominates and mention few changes that take place in your body?
Answer:
I would feel excited. Sympathetic neural system of the ANS predominates and the various changes taking place inside the body includes; excess secretion of "adrenaline" to the blood stream from the medulla of the adrenal gland. This in turn, dilates pupil, inhibits salivation, accelerates heartbeat, inhibites digestion, etc.
Question 4.
Name the parts of the organ of equilibrium involved in the following functions?
(a) Linear movement of the body.
(b) Changes in the body position.
(c) Rotational movement of the head.
Answer:
(a) The utricle and saccule are two membranous sacs, found nearest the cochlea and contain equilibrium receptor regions called maculae that are involved in detecting the linear movement of the head.
(b) Two fluids, perilymph and endolymph, respond to the mechanical forces, during changes occurring in body position and acceleration.
(c) The anterior, posterior and lateral canals detects the rotational movement of the head.