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NEET UG

NEET UG MCQ questions — Physics, Chemistry, Botany & Zoology for medical entrance.

258 Q 4 Subjects 12th (PCB)
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Difficulty: All Easy Medium Hard 221–230 of 258
Subjects in NEET UG
Q.221 Easy NEET Zoology Human Physiology
Which of the following hormones is primarily responsible for increasing blood glucose levels during the fasting state?
A Glucagon
B Insulin
C Oxytocin
D Thyroxine
Correct Answer:  A. Glucagon
EXPLANATION

Glucagon is secreted by alpha cells of pancreatic islets and increases blood glucose by promoting glycogenolysis and gluconeogenesis during fasting.

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Q.222 Easy NEET Zoology Human Physiology
Which structure in the kidney is responsible for ultrafiltration?
A Glomerulus
B Loop of Henle
C Collecting duct
D Distal convoluted tubule
Correct Answer:  A. Glomerulus
EXPLANATION

The glomerulus, a network of capillaries in the renal corpuscle, filters blood under hydrostatic pressure to produce the ultrafiltrate that forms the basis of urine.

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Q.223 Easy NEET Zoology Human Physiology
The phenomenon where a nerve impulse can jump from one node of Ranvier to the next is called:
A Saltatory conduction
B Continuous conduction
C Bidirectional conduction
D Synaptic transmission
Correct Answer:  A. Saltatory conduction
EXPLANATION

Saltatory conduction occurs in myelinated neurons where action potentials jump between nodes of Ranvier, increasing conduction velocity significantly compared to unmyelinated fibers.

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Q.224 Easy NEET Zoology Human Physiology
Which of the following enzymes is responsible for breaking down acetylcholine at the neuromuscular junction?
A Acetylcholinesterase
B Monoamine oxidase
C Catechol-O-methyltransferase
D Butyrylcholinesterase
Correct Answer:  A. Acetylcholinesterase
EXPLANATION

Acetylcholinesterase rapidly hydrolyzes acetylcholine in the synaptic cleft, terminating neuromuscular transmission and allowing muscle relaxation.

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Q.225 Easy NEET Zoology Human Physiology
The blood-brain barrier is primarily composed of which type of cell?
A Astrocytes and endothelial cells
B Microglia and oligodendrocytes
C Ependymal cells and pia mater
D Schwann cells and fibroblasts
Correct Answer:  A. Astrocytes and endothelial cells
EXPLANATION

The blood-brain barrier is formed by tight junctions between endothelial cells of brain capillaries, supported by astrocytes that regulate nutrient transport and maintain the barrier's integrity.

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Q.226 Easy NEET Zoology Human Physiology
Which hormone is primarily responsible for increasing blood glucose levels during the fight-or-flight response?
A Epinephrine
B Insulin
C Glucagon
D Thyroxine
Correct Answer:  A. Epinephrine
EXPLANATION

Epinephrine (adrenaline) is released by the adrenal medulla during stress and increases blood glucose by promoting glycogenolysis and inhibiting insulin secretion.

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Q.227 Easy NEET Zoology Human Physiology
During inspiration, the diaphragm contracts and moves:
A Upward
B Downward
C Laterally
D Anteriorly
Correct Answer:  B. Downward
EXPLANATION

Diaphragm contraction flattens it and moves downward, increasing thoracic cavity volume and decreasing intra-pulmonary pressure.

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Q.228 Easy NEET Zoology Human Physiology
Which structure in the brain is responsible for maintaining body equilibrium and balance?
A Cerebrum
B Cerebellum
C Medulla oblongata
D Hypothalamus
Correct Answer:  B. Cerebellum
EXPLANATION

The cerebellum coordinates voluntary movements and maintains body balance through proprioceptive feedback.

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Q.229 Easy NEET Zoology Human Physiology
The cardiac cycle duration in a normal adult is approximately:
A 0.4 seconds
B 0.8 seconds
C 1.2 seconds
D 1.6 seconds
Correct Answer:  B. 0.8 seconds
EXPLANATION

A complete cardiac cycle takes approximately 0.8 seconds at a heart rate of 72 beats per minute.

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Q.230 Easy NEET Zoology Human Physiology
Which enzyme initiates protein digestion in the stomach?
A Lipase
B Pepsin
C Trypsin
D Amylase
Correct Answer:  B. Pepsin
EXPLANATION

Pepsin is a protease secreted by gastric glands that begins protein digestion in the acidic environment of the stomach.

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