Life Processes MCQ
1. Which of the following statements about the autotrophs is incorrect?
(a) They synthesise carbohydrates from carbon dioxide and water in the presence of sunlight and chlorophyll
(b) They store carbohydrates in the form of starch
(c) They convert carbon dioxide and water into carbohydrates in the absence of sunlight
(d) They constitute the first trophic level in food chains
Ans. (c) They convent carbon dioxide and water into carbohydrates in the absence of sunlight.
2. In which of the following groups of organisms, food material is broken down outside the body and absorbed?
(a) Mushroom, green plants, Amoeba
(b) Yeast, mushroom, bread mould
(c) Paramecium, Amoeba, Cuscuta
(d) Cuscuta, lice, tapeworm
Ans. (b) Yeast, mushroom, bread mould
Explanation: All of them are saprotrophs. In saprotrophic mode of nutrition, food material is broken down outside the body and absorbed.
3. Select the correct statement
(a) Heterotrophs do not synthesise their own food
(b) Heterotrophs utilise solar energy for photosynthesis
(c) Heterotrophs synthesise their own food
(d) Heterotrophs are capable of converting carbon dioxide and water into carbohydrates
Ans. (a) Heterotrophs do not synthesise their own food.
Explanation: Heterotrophs depend on other organisms for food.
4. Which is the correct sequence of parts in human alimentary canal?
(a) Mouth →stomach →small intestine →oesophagus →large intestine
(b) Mouth →oesophagus →stomach →large intestine →small intestine
(c) Mouth →stomach →oesophagus →small intestine →large intestine
(d) Mouth →oesophagus →stomach →small intestine →large intestine
Ans. (d) Mouth →oesophagus →stomach →small intestine →large intestine
5. If salivary amylase is lacking in the saliva, which of the following events in the mouth cavity will be affected?
(a) Proteins breaking down into amino acids
(b) Starch breaking down into sugars
(c) Fats breaking down into fatty acids and glycerol
(d) Absorption of vitamins
Ans. (b) Starch breaking down into sugars
Explanation: Salivary amylase converts starch into sugar. Digestion of proteins and fats does not take place in mouth, hence options (a) and (c) are incorrect.
6. The inner lining of stomach is protected by one of the following from hydrochloric acid. Choose the correct one
(a) Pepsin
(b) Mucus
(c) Salivary amylase
(d) Bile
Ans. (b) Mucus
Explanation: Mucus protects the inner lining of stomach from hydrochloric acid.
7. Which part of alimentary canal receives bile from the liver?
(a) Stomach
(b) Small intestine
(c) Large intestine
(d) Oesophagus
Ans. (b) Small intestine
Explanation: Bile from gall bladder goes to small intestine through hepatopancreatic duct.
8. A few drops of iodine solution were added to rice water. The solution turned blueblack in colour. This indicates that rice water contains
(a) complex proteins
(b) simple proteins
(c) fats
(d) starch
Ans. (d) Starch
Explanation: Starch makes a dark blue complex with iodine. This is the most often used test to check the presence of starch in something.
9. In which part of the alimentary canal food is finally digested?
(a) Stomach
(b) Mouth cavity
(c) Large intestine
(d) Small intestine
Ans. (d) Small intestine
Explanation: Partial digestion of food takes place in mouth and stomach. Digestion does not happen in large intestine. It is the small intestine, where digestion is completed.
10. Choose the function of the pancreatic juice from the following
(a) trypsin digests proteins and lipase carbohydrates
(b) trypsin digests emulsified fats and lipase proteins
(c) trypsin and lipase digest fats
(d) trypsin digests proteins and lipase emulsified fats
Ans. (d) Trypsin digests proteins and lipase emulsified fats
Explanation: Trypsin completes the digestion of protein. Lipase digests emulsified fat to convert it into fatty acids and glycerol.
11. When air is blown from mouth into a test-tube containing lime water, the lime water turned milky due to the presence of
(a) oxygen
(b) carbon dioxide
(c) nitrogen
(d) water vapour
Ans. (b) Carbon dioxide
Explanation: Carbon dioxide reacts with limewater Ca(OH)2 to form calcium carbonate which makes the lime water milky.
