Which one of the following statements regarding Electrocardiogram is correct ?
- A.Electrocardiogram is graphical representation of electrical activity of cornea
- B.Electrocardiogram is graphical representation of activity of kidney
- C.Electrocardiogram is graphical representation of activity of brain
- D.Electrocardiogram is graphical representation of electrical activity of heart
Correct answer
Explanation
The correct answer is D, Electrocardiogram is graphical representation of electrical activity of heart. An ECG records the electrical signals that make the heart muscle contract with each beat.
Each heartbeat starts at the sino-atrial (SA) node, the natural pacemaker in the right atrium. The impulse spreads through the atria and then the ventricles, and electrodes on the chest, arms and legs pick it up. A normal ECG shows a P wave for atrial depolarisation, the QRS complex for ventricular depolarisation and a T wave for ventricular repolarisation. Doctors use it to find heart attacks, irregular rhythms and other heart disease. The machine is the electrocardiograph, developed by Willem Einthoven, who won the Nobel Prize in 1924.
A is wrong: the electrical activity of the eye's retina is recorded by an electroretinogram, not an ECG. B is wrong: the kidney is checked by tests and scans, not by an ECG. C is wrong: the electrical activity of the brain is recorded by an electroencephalogram (EEG).
Exam tip: ECG for heart, EEG for brain, EMG for muscles.
Practice Questions
View allThe fact that the planets move around the Sun, not in circles but in ellipses, was first demonstrated by
- A.Galileo
- B.Martin Luther
- C.Johannes Kepler
- D.Copernicus
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In 1609 Kepler showed that the planets move around the Sun in elliptical orbits, with the Sun at one focus of the ellipse.
Read the full explanation →Which one of the following statements is correct?
- A.Urea is produced in liver.
- B.Urea is produced in blood.
- C.Urea is produced from digestion of starch.
- D.Urea is produced in lung and kidney.
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Liver cells turn the toxic ammonia released from the breakdown of amino acids into urea through the ornithine cycle, also called the urea cycle.
Read the full explanation →Which one of the following is the correct sequence of passage of light in a compound microscope?
- A.Condenser-Objective lens-Eyepiece-Body tube
- B.Objective lens-Condenser-Body tube-Eyepiece
- C.Condenser-Objective lens-Body tube-Eyepiece
- D.Eyepiece-Objective lens-Body tube-Mirror
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Light passes through the condenser to the specimen, is picked up by the objective lens, travels up the body tube and reaches the eye through the eyepiece.
Read the full explanation →Which one of the following statements regarding haemoglobin is correct?
- A.Haemoglobin present in RBC can carry only oxygen but not carbon dioxide.
- B.Haemoglobin of RBC can carry both oxygen and carbon dioxide.
- C.Haemoglobin of RBC can carry only carbon dioxide.
- D.Haemoglobin is only used for blood clotting and not for carrying gases.
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It binds oxygen at its iron-containing haem groups and carries some carbon dioxide on its protein chains. Each haemoglobin molecule has four polypeptide chains and four haem groups, and each haem iron can hold one oxygen molecule, forming oxyhaemoglobin in the lungs.
Read the full explanation →Which one of the following statements regarding histone proteins is correct?
- A.Histones are proteins that are present in mitochondrial membrane.
- B.Histones are proteins that are present in nucleus in association with DNA.
- C.Histones are proteins associated with lipids in the cytosol.
- D.Histones are proteins associated with carbohydrates in the cytosol.
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They are the proteins around which DNA winds to form chromatin in the nucleus of eukaryotic cells. Histones are small basic proteins, rich in the positively charged amino acids lysine and arginine, which attract the negatively charged phosphate groups of DNA.
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