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Q. No.What prevents the atria and the ventricles from contracting at the same time?
1. Pacemaker cells located in the atria fire before the pacemaker cells in the ventricles.
2. It takes time for epinephrine to diffuse from the atria to the ventricles to trigger contraction
3. The electrical signal generated in the right atrium is delayed at the AV node before passing to the ventricles.
4. The Na+ channels responsible for initiating ventricular contraction are inactivated and need to return to activated configuration to the electrically stimulated.
Subtopic: Human Heart: Gross Anatomy | Human Heart: Cardiac Cycle | Rhythmic Excitation of Human Heart: Part 1 | Rhythmic Excitation of Human Heart: Part 2 |
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The percentage of blood (by volume) occupied by corpuscles in two animals (1 and 2) which can survive at low as well as high altitudes is shown in the table:
Mark the correct interpretation:
1. Animal 1 is poorly adapted at high altitude as compared to animal 2
2. Animal 2 is poorly adapted at high altitude as compared to animal 1
3. Affinity of Hb for oxygen in animal 1 is higher at lower altitude
4. Hb of animal 2 shows higher affinity for oxygen as compared to animal 1
| Animal | Altitude | Corpuscles (%) |
| Animal 1 | Sea level | 34 |
| Animal 2 | Sea level | 33 |
| Animal 1 | 4700 m | 50 |
| Animal 2 | 4700 m | 34 |
Mark the correct interpretation:
1. Animal 1 is poorly adapted at high altitude as compared to animal 2
2. Animal 2 is poorly adapted at high altitude as compared to animal 1
3. Affinity of Hb for oxygen in animal 1 is higher at lower altitude
4. Hb of animal 2 shows higher affinity for oxygen as compared to animal 1
Subtopic: Blood: General Description & RBC: Part 1 | Blood: General Description & RBC: Part 2 | Blood: General Description & RBC |
67%
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One of the main advantages of a closed over an open circulatory system is:
1. The use of a heart to create pressure gradients necessary for blood flow
2. The ability to direct the flow of blood to certain tissues
3. The ability of respiratory pigment to transport O2
4. The ability to return blood to the heart
1. The use of a heart to create pressure gradients necessary for blood flow
2. The ability to direct the flow of blood to certain tissues
3. The ability of respiratory pigment to transport O2
4. The ability to return blood to the heart
Subtopic: Human Heart: Double Circulation |
From NCERT
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If there is a blockage between the AV node and AV bundle, how will this affect the appearance of the ECG?
1. PR interval would be smaller
2. QRS interval would be longer
3. There would be more P-waves than QRS complexes
4. There would be more QRS complexes than P-waves
1. PR interval would be smaller
2. QRS interval would be longer
3. There would be more P-waves than QRS complexes
4. There would be more QRS complexes than P-waves
Subtopic: ECG & Coronary Artery Disease |
59%
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Characteristics features of different blood vessels in the body are shown. A, B and C represent:
1. A = Total area, B = Velocity, C = Blood pressure
2. A = Blood pressure, B = Velocity, C = Total area
3. A = Velocity, B = Total area, C = Blood pressure
4. A = Total area, B = Blood pressure, C = Velocity
1. A = Total area, B = Velocity, C = Blood pressure
2. A = Blood pressure, B = Velocity, C = Total area
3. A = Velocity, B = Total area, C = Blood pressure
4. A = Total area, B = Blood pressure, C = Velocity
Subtopic: Blood: General Description & RBC: Part 1 | Blood: General Description & RBC: Part 2 | Blood: General Description & RBC |
56%
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The mammalian heart beat:
1. Stops when the nerve supply to the heart is cut
2. Originates at AV-node
3. Decreases when stretch receptors in the vena cava are stimulated
4. Slows down when the activity in the vagus nerve increases
1. Stops when the nerve supply to the heart is cut
2. Originates at AV-node
3. Decreases when stretch receptors in the vena cava are stimulated
4. Slows down when the activity in the vagus nerve increases
Subtopic: Regulation of Cardiac Activity |
53%
From NCERT
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If a molecule of CO2 released into the blood of a human foetus is exhaled through the mouth of the mother, it will not travel through the:
1. Right atrium of mother
2. Right atrium of foetus
3. Left ventricle of mother
4. Left ventricle of foetus
1. Right atrium of mother
2. Right atrium of foetus
3. Left ventricle of mother
4. Left ventricle of foetus
Subtopic: Human Heart: Double Circulation |
51%
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If it was possible to genetically engineer humans to be able to run long distances faster at high altitudes, which of the following would not help?
1. Increasing the thickness of cellular lining of the alveoli
2. Decreasing the average size of the alveoli
3. Increasing the amount of Hb in each RBC
4. More than one options as mentioned above
1. Increasing the thickness of cellular lining of the alveoli
2. Decreasing the average size of the alveoli
3. Increasing the amount of Hb in each RBC
4. More than one options as mentioned above
Subtopic: Regulation of Cardiac Activity |
59%
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Assertion (A): RBCs contain a red-colored complex protein called hemoglobin.
Reason (R): RBCs are devoid of nucleus in most of the mammals and are biconcave in shape.
1. Both (A) and (R) are true and (R) is the correct explanation of (A).
2. Both (A) and (R) are true, but (R) is not the correct explanation of (A).
3. (A) is true, but (R) is false.
4. (A) is false, but (R) is true.
Reason (R): RBCs are devoid of nucleus in most of the mammals and are biconcave in shape.
1. Both (A) and (R) are true and (R) is the correct explanation of (A).
2. Both (A) and (R) are true, but (R) is not the correct explanation of (A).
3. (A) is true, but (R) is false.
4. (A) is false, but (R) is true.
Subtopic: Blood: General Description & RBC |
88%
From NCERT
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Assertion (A): 'O' group individuals are called universal donors.
Reason (R): Group 'O' blood can be donated to persons with any other blood group.
1. Both (A) and (R) are true and (R) is the correct explanation of (A).
2. Both (A) and (R) are true, but (R) is not the correct explanation of (A).
3. (A) is true, but (R) is false.
4. (A) is false, but (R) is true.
Reason (R): Group 'O' blood can be donated to persons with any other blood group.
1. Both (A) and (R) are true and (R) is the correct explanation of (A).
2. Both (A) and (R) are true, but (R) is not the correct explanation of (A).
3. (A) is true, but (R) is false.
4. (A) is false, but (R) is true.
Subtopic: Blood: Blood Group (A,B,O) |
86%
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