This set of Class 11 Biology Chapter 18 Multiple Choice Questions & Answers (MCQs) focuses on “ECG”.
1. What is the full form of ECG?
a) Electricity cardiac group
b) Electrocardio group
c) Electrocardium granules
d) Electrocardiogram
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Explanation: ECG stands for Electrocardiogram. ECG is a graphical representation of the electrical activity of the heart during a cardiac cycle. It is measured with the help of a machine called an electrocardiograph.
2. To measure ECG, usually how many electrodes are connected to a patient?
a) One
b) Two
c) Three
d) Four
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Explanation: To measure a standard ECG, a patient is connected to the machine with three electrical leads-one to each wrist and one to the left ankle. It continuously monitors heart activity.
3. Which of the following letters is marked incorrectly in the given diagram?
a) P & R
b) Q & T
c) T & S
d) T-wave
View Answer
Explanation: The correct representation of a standard ECG is given as follows:
Each peak in the ECG is identified with a letter from P to T that corresponds to a specific electrical activity of the heart.
4. Which of the following waves represent the excitation of the atria?
a) P-wave
b) QRS complex
c) T-wave
d) ST-segment
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Explanation: The P-wave represents the electrical excitation of depolarisation of the atria which leads to the contraction of both the atria. The T-wave represents the repolarisation of the ventricles.
5. Which of the following represents the depolarisation of the ventricles?
a) P-wave
b) T-wave
c) QRS complex
d) PQ interval
View Answer
Explanation: The QRS complex represents the depolarisation of the ventricles, which initiate the ventricular contraction. The contraction starts shortly after Q and marks the beginning of the systole.
6. The end of the T-wave marks the end of the systole.
a) True
b) False
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Explanation: The end of the T-wave marks the end of the systole. The T-wave represents the return of the ventricles from excited to normal state which is also known as repolarisation of the ventricles.
7. By counting the number of which of the following waves, the heartbeat of a person can be determined?
a) P-wave
b) QRS complex
c) ST-segment
d) PQ interval
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Explanation: By counting the number of QRS complexes that occur in a given period, one can determine the heartbeat rate of an individual. Any deviation from the shapes of the curve indicates a possible abnormality or a disease. Hence, it is of great clinical significance.
8. Which of the following represents the enlargement of auricles?
a) Enlargement of P-wave
b) Enlargement of QR segment
c) Depression of ST segment
d) Elevation of ST segment
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Explanation: Enlargement of auricles is represented by the enlargement of P-wave or sometimes the lengthening of PQ interval also represents the enlargement of auricles by rheumatic fever.
9. What does the depression of ST-segment depict?
a) Ischemia
b) Hypokalemia
c) Myocardial infarction
d) Acute heart attack
View Answer
Explanation: The depression of ST-segment shows Ischemia which means there is an insufficient supply of blood to the heart muscles or the weakening of the heart muscles.
10. Which of the following muscles have the longest refractive period?
a) Skeletal muscles
b) Smooth muscles
c) Cardiac muscles
d) Facial muscles
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Explanation: Cardiac muscles never show the property of summation or tetanus spasm as the muscles have the longest refractory period. Cardiac muscles also have the least latent period.
11. Angina pectoris is a symptom of myocardial infarction.
a) True
b) False
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Explanation: Angina pectoris is a symptom of myocardial infarction. Due to the weakening of heart muscles, the heart is not able to supply enough blood which causes severe pain called angina pectoris. If left untreated, tissues would be dead and that will cause myocardial infarction or acute heart attack.
12. What is meant by iso-volumetric systole?
a) The time duration between the closing and opening of AV valves
b) The time duration between the closing and opening of semilunar valves
c) The time duration between the closing of AV valves and opening of semilunar valves
d) The time duration between the closing of semilunar valves and the opening of AV valves
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Explanation: The time duration between the closing of AV valves and the opening of semilunar valves is known as iso-volumetric systole. The time duration between the closing of semilunar valves and the opening of AV valves is known as iso-volumetric diastole.
13. What is meant by AV block?
a) Impulse not reaching SA node
b) Impulse not reaching the AV node
c) Impulse not reaching Purkinje fibers
d) Impulse not generating in the heart
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Explanation: When the impulse is not reaching the AV node then this is known as AV block. When the impulse is not reaching the Purkinje fibers then it is called a Purkinje block.
14. What is the main symptom of heart failure?
a) Lung congestion
b) Vomiting
c) Yellowing of eyes
d) Pain in the chest
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Explanation: When the heart is not pumping sufficient blood according to the needs of the body organs then it leads to heart failure. Lung congestion is the main symptom of heart failure.
15. What is the full form of CAD?
a) Coronary artery disease
b) Carotid artery disorder
c) Carotid artery disease
d) Coronary angina disorder
View Answer
Explanation: CAD refers to coronary artery disease which is caused by atherosclerosis and arteriosclerosis. Atherosclerosis refers to the deposition of cholesterol, fat, calcium on the walls of coronary arteries while arteriosclerosis refers to the deposition of calcium which leads to the hardening of the arteries.
Sanfoundry Global Education & Learning Series – Biology – Class 11.
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