Neural Control and CoordinationNEET Zoology · Class 11 · NCERT Chapter 9

Solution

Parasympathetic neural signals, primarily through the vagus nerve, decrease heart rate and reduce cardiac output by increasing the refractory period of the sinoatrial node. NCERT XII chapter Neural Control and Coordination explains this effect, confirming option (a) as correct.

Solution

The hypothalamus is responsible for regulating body temperature, among other homeostatic functions. NCERT XII chapter Neural Control and Coordination highlights the hypothalamus's role in thermoregulation, so option (d) is correct.

Solution

The fight-or-flight reaction activates the adrenal medulla, leading to increased secretion of epinephrine and norepinephrine. This response prepares the body for rapid action by increasing heart rate, blood pressure, and energy availability, as described in NCERT XII Neural Control and Coordination, so option (c) is correct.

Solution

Fovea has highest visual acuity which has only cone cells and no rod cells.

Solution

Anterior horn cells are ventral horn cells of spinal cord which consists of motor neurons.

Solution

Frog or the vertebrates have myogenic heart having self contractile system or are autoexcitable; because of this condition, it will keep on working outside the body for some time.

Solution

Carotene is the source of retinal which is involved in formation of rhodopsin of rod cells. Retinal, a derivative of vitamin A, is the light-absorbing part of all visual photopigments.

Solution

Pre-synaptic membrane is involved in the release of neurotransmitter in the chemical synapse. The receptors sites for neurotransmitters are present on post-synaptic membrane.

Solution

Oligodendrocytes are neuroglial cells which produce myelin sheath in central nervous system while Schwann cell produces myelin sheath in peripheral nervous system.

Solution

Nissl bodies, found in the cytoplasm of neurons, are composed of free ribosomes and rough endoplasmic reticulum (RER). These structures are involved in protein synthesis, as described in NCERT XII Neural Control and Coordination, so option (d) is correct.

Solution

Oxidative phosphorylation occurs in the inner mitochondrial membrane, not the outer membrane. NCERT XII chapter Neural Control and Coordination describes the inner mitochondrial membrane as the site of the electron transport chain and ATP synthesis, so option (d) is incorrect.

Solution

Submetacentric chromosomes are not L-shaped; they have a centromere near the middle, making them slightly off-center. L-shaped chromosomes are acrocentric. NCERT XII chapter Neural Control and Coordination describes chromosome types and their centromere positions, so option (a) is incorrect.

Solution

Ref. XII NCERT Chapter- 15, Page No. 264

Solution

- Organ of Corti is located on the basilar membrane (iv).
- Cochlea is the coiled part of the labyrinth (ii).
- Eustachian tube connects the middle ear and pharynx (i).
- Stapes is attached to the oval window (iii).

Solution

The cockroach can survive for a few days without its head because the major part of its nervous system, including segmental ganglia, is situated along the ventral part of its body. This allows basic functions to continue even without the head, making option (c) correct.

Solution

Option (4) is the correct answer as impulse transmission across an electrical synapse is always faster than that across a chemical synapse. → Chemical synapses use chemicals for transmission which are known as neurotransmitters. → The membranes of presynaptic and postsynaptic neur ons are in close proximity in an electrical synapse. → In an electrical synapse, the transmission of the impulse occurs in the form of an electrical current from one neuron to the next neuron.

Solution

- A. Fovea - III. Point of greatest visual acuity or resolution.
- B. Iris - I. Visible coloured portion of eye that regulates diameter of pupil.
- C. Blind spot - IV. Point where optic nerve leaves the eyeball and photoreceptor cells are absent.
- D. Sclera - II. External layer of eye formed of dense connective tissue.

Solution

The limbic system and hypothalamus are responsible for regulating sexual behavior, emotions, and autonomic functions. NCERT XII chapter Neural Control and Coordination highlights the role of these structures in emotional and behavioral responses, so option (b) is correct.

Solution

Correct answer is option (1) because the correct pathway of conduction of action potential is SA → AV node → AV bundle → Bundle branches → Purkinje fibres

Solution

The correct answer is option (2) as A. Pons – Part of hindbrain, it connects different regions of the brain. B. Hypothalamus – Also have neuro secretory cells which secrete hormones. C. Medulla oblongata – Part of hindbrain which controls respiration and gastric secretions. D. Cerebellum – Part of hindbrain with convoluted surface which provides additional space for neurons, also regulates posture and balance.

Solution

The correct answer is option (3) as statement I is correct but statement II is incorrect. In human brain, a deep cleft divides the cerebrum longitudinally into two halves, which are termed as the left and right cerebral hemispheres. The cerebral hemispheres are connected by a tract of nerve fibres called corpus callosum. Three major regions make up the brain stem i.e. mid brain, pons and medulla oblongata. Cerebrum is a part of forebrain which does not form brain stem. Options (1), (2) and (4) are incorrect.

Solution

The correct answer is option no. (2) as A. P wave - III. Depolarisation of atria. B. QRS complex - II. Depolarisation of ventricles. C. T wave - IV. Repolarisation of ventricles. D. T-P gap - I. Heart muscles are electrically silent. - 79 - NEET (UG)-2024 (Code-Q1)

Solution

Normal cardiac activities of the heart are regulated intrinsically, i.e., auto regulated by specialised muscles (nodal tissue), hence the heart is called myogenic. A special neural centre in the medulla oblongata can moderate the cardiac function through autonomic nervous system.

Sympathetic nervous system can increase the rate of heartbeat, ventricular contraction and thereby cardiac output.

Parasympathetic neural signals decrease the rate of heartbeat, speed of conduction of action potential and thereby the cardiac output. Adrenal medullary hormones can also increase the cardiac output.

Solution

Normal cardiac activities of the heart are regulated intrinsically, i.e., auto regulated by specialised muscles (nodal tissue), hence the heart is called myogenic. A special neural centre in the medulla oblongata can moderate the cardiac function through autonomic nervous system.

Sympathetic nervous system can increase the rate of heartbeat, ventricular contraction and thereby cardiac output.

Parasympathetic neural signals decrease the rate of heartbeat, speed of conduction of action potential and thereby the cardiac output. Adrenal medullary hormones can also increase the cardiac output.