Class VII, NCERT (CBSE) Science
Chapter 2, Nutrition in animals
Class 7, CBSE Science | Chapter-2, Nutrition in Animals | NCERT Solutions for Science Textbook Exercise
Q.1: What is mastication?
Solution: Mastication is a process in which chewing of food and mixing of saliva with it is done in mouth.
Q.2: What is the role of tongue in our mouth?
Solution: The tongue has following roles in our mouth:
=> It helps in talking.
=> It helps in mixing of saliva with the food during mastication.
=> It helps to swallow the food.
=> It gives us sensation of taste of food.
Q.3: What is peristalsis?
Solution: The powerful muscles in oesophagus gently push food down to the stomach in a wave - like action, called peristalsis.
Q.4: What are secreted inside the stomach?
Solution: Gastric juice is secreted by the walls of stomach which contains HCl and Pepsin.
Q.5: What are the functions of HCl and Pepsin in stomach?
Solution: Functions of HCl:
=> It helps to kill the germs present in the food.
=> After mixing with the food it makes an acidic medium which is essential for the activation of pepsin enzyme
Functions of Pepsin:
=> Pepsin digests protein into peptides.
Q.6: Which enzyme is secreted in small intestine?
Solution: Maltase and Trypsin.
Q.7: What is secreted from liver?
Solution: Bile juice is secreted from liver.
Q.8: What is egestion?
Solution: The process by which the faecal matter is removed through the anus from time to time is called egestion.
Q.9: What is digestion?
Solution: Digestion is a process which include crushing of the food into smaller particles by chewing and then breakdown of its complex components into simpler substances with the help of enzymes in a liquid medium which can be absorbed by our body.
Q.10: Write short notes (1 or 2 sentences) on -
(a) Pancreas (b) Liver (c) Oesophagus (d) Remination or Rumination (e) Pseudopodia
(a) Pancreas: Pancreas is a large cream coloured gland located or present just below the stomach. Pancreatic juice acts on carbohydrates and protein and changes them into simpler forms.
(b) Liver: Liver is a reddish brown gland present in the upper part of our abdomen on the right side. It is the largest gland in our body. It secretes bile juice stored in sac - like structure called gall bladder.
(c) Oesophagus: It is along, narrow, muscular tube which directly leads to the stomach. It is about 25 cm long and passes downwards through the neck, the thorax and the abdominal cavity.
(d) Rumination: A process in which partially digested food returns to the mouth in small lumps and the animal chews it. This type of process is called Remination or Rumination and such types of animals are called Ruminants.
(e) Pseudopodia: The unicellular organism like amoeba constantly changes its shape and position. It catches food by pushing out a finger - like projection called Pseudopodia.
Q.11: What are digestive enzymes?
Solution: There are different types of enzymes which are used for the digestion of different food materials like - carbohydrates, fats, protein etc. The process of digestion involves the association of several catalytic organic compounds. These are amylase, pepsin, lipase, tripsin etc. These organic compounds are known as digestive enzymes.