Which one of the following parts of human alimentary canal can be of maximum length ?
- A.Stomach
- B.Small intestine
- C.Large intestine
- D.Rectum
Correct answer
Explanation
The correct answer is B, Small intestine. At about 6 to 7 metres in an adult, the small intestine is by far the longest part of the alimentary canal.
The small intestine has three parts: the duodenum (about 25 cm, which receives bile from the liver and juice from the pancreas), the jejunum and the ileum. Most digestion is completed and almost all nutrients are absorbed here. Its inner wall carries millions of finger-like villi, and the cells on them carry microvilli, which together give an enormous surface area for absorption. The whole alimentary canal, from mouth to anus, is roughly 9 metres long, so the small intestine makes up most of it.
A is wrong because the stomach is a J-shaped bag only about 25 to 30 cm long, where protein digestion begins with pepsin and hydrochloric acid. C is wrong because the large intestine is wider but only about 1.5 metres long; it absorbs water and salts. D is wrong because the rectum is the short last part, about 12 cm, that stores faeces.
Exam tip: small intestine = longest part (about 6-7 m); large intestine = wider but shorter (about 1.5 m).
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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