Question 1: Which of the following statements about the autotrophs is incorrect?
They synthesise carbohydrates from carbon dioxide and water in the presence of sunlight and chlorophyll
They store carbohydrates in the form of starch
They convert carbon dioxide and water into carbohydrates in the absence of sunlight
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?
Mushroom, green plants, Amoeba
Yeast, mushroom, bread mould
Paramecium, Amoeba, Cuscuta
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
Heterotrophs do not synthesise their own food
Heterotrophs utilise solar energy for photosynthesis
Heterotrophs synthesise their own food
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?
Mouth → stomach → small intestine → oesophagus → large intestine
Mouth →oesophagus → stomach → large intestine → small intestine
Mouth → stomach → oesophagus → small intestine → large intestine
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?
Proteins breaking down into amino acids
Starch breaking down into sugars
Fats breaking down into fatty acids and glycerol
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
Pepsin
Mucus
Salivary amylase
Bile
Answer: (b) Mucus
Question 7: Which part of alimentary canal receives bile from the liver?
Stomach
Small intestine
Large intestine
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
Complex proteins
Simple proteins
Fats
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?
Stomach
Mouth cavity
Small intestine
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
Trypsin digests proteins and lipase carbohydrates
Trypsin digests emulsified fats and lipase proteins
Trypsin and lipase digest fats
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
Oxygen
Carbon dioxide
Nitrogen
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.