Which one of the following statements about lymph is correct?
- A.Lymph is formed due to leakage of blood through capillaries.
- B.Lymph contains blood cells such as RBC.
- C.Lymph is also circulated by the blood circulating heart.
- D.Lymph only transports hormones.
Correct answer
Explanation
The correct answer is A, Lymph is formed due to leakage of blood through capillaries. As blood flows through the thin-walled capillaries, part of its plasma, with small proteins and some white blood cells, leaks out into the spaces between cells. This tissue fluid bathes the cells, supplying food and oxygen and taking away wastes. The part of it that drains into lymphatic vessels is called lymph. Lymph flows slowly through the lymph vessels and lymph nodes and is finally poured back into the blood through the thoracic duct into a large vein near the heart. Lymph nodes filter it and add lymphocytes, which fight infection, and lymph from the intestine (the lacteals) carries absorbed fats. Option B is wrong because lymph has no red blood cells; it is colourless and contains mainly lymphocytes. Option C is wrong because the heart does not pump lymph; it moves by the squeezing of muscles and by valves in the vessels. Option D is wrong because lymph carries fats, proteins and white cells, not only hormones. Exam tip: lymph = plasma leaked from capillaries, no RBCs, returns to blood via the thoracic duct.
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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