Class 10 Science

Life Processes NCERT Exemplar Problems

MCQ Part 1

Question 1: Which of the following statements about the autotrophs is incorrect?

  1. They synthesise carbohydrates from carbon dioxide and water in the presence of sunlight and chlorophyll
  2. They store carbohydrates in the form of starch
  3. They convert carbon dioxide and water into carbohydrates in the absence of sunlight
  4. They constitute the first trophic level in food chains

    Answer: (c) They convert carbon dioxide and water into carbohydrates in the absence of sunlight

Question 2: In which of the following groups of organisms, food material is broken down outside the body and absorbed?

  1. Mushroom, green plants, Amoeba
  2. Yeast, mushroom, bread mould
  3. Paramecium, Amoeba, Cuscuta
  4. Cuscuta, lice, tapeworm

    Answer: (b) Yeast, Mushroom, bread mould

Explanation: These are saprotrophs, and digestion in saprotrophs takes place before ingestion.

Question 3: Select the correct statement

  1. Heterotrophs do not synthesise their own food
  2. Heterotrophs utilise solar energy for photosynthesis
  3. Heterotrophs synthesise their own food
  4. Heterotrophs are capable of converting carbon dioxide and water into carbohydrates

    Answer: (a) Heterotrophs do not synthesize their own food

Explanation: Other options show features of autotrophic nutrition.

Question 4: Which is the correct sequence of parts in human alimentary canal?

  1. Mouth → stomach → small intestine → oesophagus → large intestine
  2. Mouth →oesophagus → stomach → large intestine → small intestine
  3. Mouth → stomach → oesophagus → small intestine → large intestine
  4. Mouth → oesophagus → stomach → small intestine → large intestine

    Answer: (d) Mouth → oesophagus → stomach → small intestine → large intestine

Question 5: If salivary amylase is lacking in the saliva, which of the following events in the mouth cavity will be affected?

  1. Proteins breaking down into amino acids
  2. Starch breaking down into sugars
  3. Fats breaking down into fatty acids and glycerol
  4. Absorption of vitamins

    Answer: (b) Starch breaking down into sugars

Explanation: Salivary amylase digests starch. Hence, its absence will hamper digestion of starch.

Question 6: The inner lining of stomach is protected by one of the following from hydrochloric acid. Choose the correct one

  1. Pepsin
  2. Mucus
  3. Salivary amylase
  4. Bile

    Answer: (b) Mucus

Question 7: Which part of alimentary canal receives bile from the liver?

  1. Stomach
  2. Small intestine
  3. Large intestine
  4. Oesophagus

    Answer: (b) Small intestine

Explanation: Bile comes to the small intestine through hepato-pancreatic duct.

Question 8: A few drops of iodine solution were added to rice water. The solution turned blue-black in colour. This indicates that rice water contains

  1. Complex proteins
  2. Simple proteins
  3. Fats
  4. Starch

    Answer: (d) Starch

Explanation: Starch makes a dark blue complex with iodine.

Question 9: In which part of the alimentary canal food is finally digested?

  1. Stomach
  2. Mouth cavity
  3. Small intestine
  4. Large intestine

    Answer: (c) Small intestine

Explanation: Major part of digestion takes place in small intestine, where digestion is completed. Digestion of starch takes place in mouth. Partial digestion of protein takes place in stomach. No digestion takes place in large intestine.

Question 10: Choose the function of the pancreatic juice from the following

  1. Trypsin digests proteins and lipase carbohydrates
  2. Trypsin digests emulsified fats and lipase proteins
  3. Trypsin and lipase digest fats
  4. Trypsin digests proteins and lipase emulsified fats

    Answer: (d) Trypsin digests proteins and lipase emulsified fats

Question 11: When air is blown from mouth into a test-tube (containing lime water), the lime water turned milky due to the presence of

  1. Oxygen
  2. Carbon dioxide
  3. Nitrogen
  4. Water vapour

    Answer: (b) Carbon dioxide

Explanation: Carbon dioxide reacts with limewater to form calcium carbonate. Insoluble calcium carbonate is responsible for appearance of white colour.