In humans, the exit of partially digested food from the stomach into the small intestine is regulated by which one of the following structures/processes?
- A.Peristalsis
- B.Muscular walls of stomach
- C.Sphincter muscle
- D.Villi in small intestine
Correct answer
Explanation
The correct answer is C, Sphincter muscle. A ring of muscle at the lower end of the stomach, the pyloric sphincter, opens and closes to let food pass into the small intestine a little at a time. In the stomach, food is churned with hydrochloric acid, pepsin and mucus into a semi-liquid paste called chyme. The pyloric sphincter releases this chyme into the duodenum, the first part of the small intestine, in small amounts so that bile and pancreatic juice can act on it properly. NCERT's Class 10 chapter on life processes names this sphincter as the regulator of the stomach's exit. Option A is wrong because peristalsis is the wave-like contraction that pushes food along the gut; it moves food but does not control the gateway. Option B is wrong because the muscular walls of the stomach churn and mix food rather than regulate its exit. Option D is wrong because villi are finger-like projections that absorb digested food after it has already entered the small intestine. Exam tip: pyloric sphincter = stomach to duodenum gate; villi = absorption; peristalsis = movement along the gut.
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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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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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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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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