Home Subjects NEET Zoology

NEET Zoology

Zoology questions for NEET UG — Animal Kingdom, Human Physiology, Genetics, Evolution.

273 Q 6 Topics Take Test
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Difficulty: All Easy Medium Hard 201–210 of 273
Topics in NEET Zoology
Q.201 Medium Human Physiology
In the cardiac cycle, ventricular repolarization is represented by which wave on an ECG?
A P wave
B QRS complex
C T wave
D U wave
Correct Answer:  C. T wave
EXPLANATION

The T wave represents ventricular repolarization. The QRS complex represents ventricular depolarization, while P wave represents atrial depolarization.

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Q.202 Medium Human Physiology
Which of the following statements about myelin sheath is correct?
A It is formed by neurons themselves
B It increases the speed of action potential propagation
C It is present uniformly along the entire axon
D It prevents action potentials from occurring
Correct Answer:  B. It increases the speed of action potential propagation
EXPLANATION

Myelin sheath, formed by oligodendrocytes in CNS and Schwann cells in PNS, increases conduction velocity by enabling saltatory conduction.

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Q.203 Medium Human Physiology
During inspiration, the external intercostal muscles contract. What is the primary consequence of this action?
A Decrease in thoracic cavity volume
B Increase in intrapleural pressure
C Increase in intrapulmonary pressure
D Increase in thoracic cavity volume
Correct Answer:  D. Increase in thoracic cavity volume
EXPLANATION

Contraction of external intercostal muscles elevates the ribs and sternum, increasing thoracic cavity volume, which decreases intrapulmonary pressure and causes air to flow in.

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Q.204 Medium Human Physiology
A patient suffers from thyroid deficiency. Which of the following metabolic changes would NOT be expected?
A Decreased metabolic rate
B Increased oxygen consumption
C Weight gain
D Reduced heat production
Correct Answer:  B. Increased oxygen consumption
EXPLANATION

Thyroid hormone deficiency decreases metabolic rate and oxygen consumption. Increased oxygen consumption would not occur; rather, it would decrease significantly.

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Q.205 Medium Human Physiology
In the cardiac cycle, the S3 heart sound is associated with:
A Rapid ventricular filling in early diastole
B Closure of atrioventricular valves
C Closure of semilunar valves
D Atrial contraction
Correct Answer:  A. Rapid ventricular filling in early diastole
EXPLANATION

S3 occurs during rapid ventricular filling phase (early diastole) when blood rapidly enters the ventricle. It's normal in young individuals but may indicate heart failure in older patients.

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Q.206 Medium Human Physiology
Which of the following statements about the lymphatic system is correct?
A Lymph flows from tissues into lymphatic capillaries and eventually returns to venous circulation via the thoracic duct
B Lymph contains a higher protein concentration than blood plasma
C Lymph nodes filter lymph but do not contain immune cells
D The lymphatic system has a central pumping organ like the heart
Correct Answer:  A. Lymph flows from tissues into lymphatic capillaries and eventually returns to venous circulation via the thoracic duct
EXPLANATION

Lymph drains from tissue spaces into lymphatic capillaries, passes through lymph nodes for filtration and immune response, and returns to the bloodstream via the thoracic duct into the left subclavian vein.

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Q.207 Medium Human Physiology
A patient experiences persistent hyperglycemia despite normal insulin levels. Which condition is most likely?
A Type 2 diabetes mellitus (insulin resistance)
B Type 1 diabetes mellitus
C Hypoglycemia
D Insulinoma
Correct Answer:  A. Type 2 diabetes mellitus (insulin resistance)
EXPLANATION

In Type 2 diabetes, normal or elevated insulin fails to lower blood glucose due to peripheral tissue insulin resistance, often caused by impaired receptor signaling or GLUT4 translocation defects.

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Q.208 Medium Human Physiology
Which protein in red blood cells is responsible for the chloride shift mechanism?
A Band 3 protein (anion exchanger)
B Glycophorin A
C Spectrin
D Aquaporin-1
Correct Answer:  A. Band 3 protein (anion exchanger)
EXPLANATION

Band 3 protein (anion exchanger 1) facilitates the exchange of Cl- for HCO3- across the RBC membrane, allowing CO2 transport as bicarbonate in blood.

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Q.209 Medium Human Physiology
In the digestive system, which hormone stimulates the pancreas to release bicarbonate-rich secretions?
A Secretin
B Cholecystokinin
C Gastrin
D Motilin
Correct Answer:  A. Secretin
EXPLANATION

Secretin, released by duodenal S cells in response to chyme acidity, specifically stimulates pancreatic ductal cells to secrete bicarbonate, neutralizing stomach acid.

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Q.210 Medium Human Physiology
Which of the following correctly describes the relationship between the parasympathetic nervous system and heart rate?
A Acetylcholine decreases heart rate by hyperpolarizing sinoatrial node cells
B Norepinephrine increases heart rate through sympathetic stimulation
C The vagus nerve inhibits ventricular contraction only
D Parasympathetic activity increases cardiac output during exercise
Correct Answer:  A. Acetylcholine decreases heart rate by hyperpolarizing sinoatrial node cells
EXPLANATION

Parasympathetic acetylcholine activates M2 muscarinic receptors on pacemaker cells, increasing K+ efflux and decreasing Ca2+ influx, causing hyperpolarization and reduced heart rate.

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