Biology ICSE Class 7 Important Questions Chapter 6 Ingestion, Digestion, Absorption and Assimilation of Food
Extra Questions
Question 1.
Put the organs in the correct order to show the path of food.
Answer:
Mouth → oesophagus → small intestine → large intestine → anus.
This is the correct order of organs to show the path of food.
Question 2.
Draw diagram to show peristalsis through the oesophagus.
Answer:
Question 3.
What ¡s peristahis?
Answer:
The process by which the food passes from the pharynx to the stomach through the oesophagus by a series of contraction is known as peristalsis.
Question 4.
Answer:
Question 5.
What changes occur in food in the mouth ?
Answer:
he mouth is the first part of digestive system. It receives food and starts mechanical digestion.. The ingested food is first broken down in the mouth when it is chewed. Simultaneously it get mixed with the saliva. This process is called mastication cr mechanical digestion. It prepares the food for chemical digestion, that is, the digestion by action of enzyme. The teeth help chewing down the food. There are 4 kinds of teeth.
These are incisors, canines, premolars and molars, incisors are the cutting teeth. These help in biting and cutting the food. Canines are the tearing teeth that helps to tear and hold the food. Premolars and molars are the crushing and grinding teeth which helps in grinding the food.
When we chew the food it is mixed with saliva, secreted by salivary glands softens the food. Saliva contains an enzyme called salivary amylase also called ptyalin, acts on starch to convert it in to maltose.
Question 6.
Define nutrition. Name its steps in humans.
Answer:
The process by which organisms obtain and use food is known as nutrition.
In humans, it involves five steps –
- Ingestion
- Digestion
- Absorption
- Assimilation
- Egestion
Question 7.
What is egestion ?
Answer:
It is the last stage of nutrition in which the undigested, insoluble part of food is eliminated in the form of faeces from the body.
Question 8.
What is mastication or mechanical digestion ?
Answer:
The process of food getting mixed with saliva in the mouth is called mastication or mechanical digestion.
Question 9.
What constitutes our digestive system ?
Answer:
The digestive system consists of two parts –
(i) Alimentary canal – It is a long tube-like structure running from mouth to the anus. It consists of mouth, pharynx, oesophagus, stomach, small intestine, large intestine, rectum and anus.
(ii) Digestive glands – The glands associated with the alimentary canal are salivary glands, liver and pancreas.
Question 10.
What is homodont and hetcrodont dentition ?
Answer:
The condition of having one type of teeth is called homodent dentition as in frogs and fish. The condition of having different shapes and structure of teeth is called heterodent dentition as in humans, dog, cows, etc.
Question 11.
Why does the stomach not corrode when it secretes nearly 2 litres of hydrochloric acid every day ?
Answer:
To protect itself from the corrosive acid, the stomach lining has a thick coating of mucus which is produced every two weeks.
Question 12.
Show the path of food in the alimentary canaL
Answer:
Question 13.
What happens to food in the stomach ?
Answer:
Muscles of the stomach wall contract rhythmically, crushing and mixing the food with gastric juices, which is rich in hydrochloric acid. Gastric juice kills bacteria and helps in digestion of proteins by secreting two enzymes – pepsin and renin.
Question 14.
Name different digestive enzymes and their functions.
Answer:
Question 15.
What changes occur in food in the mouth ?
Answer:
The mouth is the first part of digestive system. It receive food and start mechanical digestion. The ingested food is first broken down in the mouth when it is chewed. Simultaneously it get mixed with the saliva. This process is called mastication or mechanical digestion. It prepares the food for chemical digestion, that is, the digestion by action of enzyme. The teeth help in chewing down the food. There are 4 kinds of teeth.
These are incisors, canines, premolars and molars, incisors are the cutting teeth. These help in biting and cutting the food. Canines are the tearing teeth that helps to tear and hold the food. Premolars and molars are the crushing and grinding teeth which helps in grinding the food. When we chew the food it is mixed with saliva, secreted by salivary glands softens the food. Saliva contains an enzyme called salivary amylase also called ptyalin, acts on starch to convert it in to maltose.
Question 15.
Fill in the blanks.
(i) The wave-like motion of the muscles that pushes the food along the alimentary canal is called …………….
Answer:
The wave-like motion of the muscles that pushes the food along the alimentary canal is called peristalsis.
(ii) The kind, number and arrangement of teeth in an animal is called ………..
Answer:
The kind, number and arrangement of teeth in an animal is called dentition.
(iii) ………….. is fat digesting enzyme.
Answer:
Lipase is fat digesting enzyme.
(iv) Excess of glucose is converted into glycogen and stored in …………. and also converted into fat and ……….. stored in
Answer:
Excess of glucose is converted into glycogen and stored in liver and also converted into fat and stored in adipose tissue.
(v) Enzymes are also called as …………. as they speed up chemical reactions without undergoing a change
themselves in organisms.
Answer:
Enzymes are also called as bio-catalysts as they speed up chemical reactions without undergoing a change themselves in organisms.
(vi) ………….. is the hardest and most minerlised substance in our body
Answer:
Enamel is the hardest and most minerlised substance in our body
(vii) The ………….. is the common passage for food and air from the mouth and nose to the throat.
Answer:
The pharynx is the common passage for food and air from the mouth and nose to the throat.
(viii) The gastric juice in stomach is rich in ………….
Answer:
The gastric juice in stomach is rich in hydrochloric acid.
(ix) …………. is the largest gland inside our body.
Answer:
Liver is the largest gland inside our body.
(x) Excess of amino acids are excreted in the form of …………. from human body.
Answer:
Excess of amino acids are excreted in the form of urea from human body.
Question 16.
Fill in the blanks.
1. Grinding of food is brought about by ………….. and ………….
Answer:
Grinding of food is brought about by premolars and molars.
2. Steapsin is also called ………….
Answer:
Steapsin is also called lipase.
3. Saliva contains ………….. which changes starch to
Answer:
Saliva contains salivary amylase which changes starch to maltose.
4. Peristalsis is caused by ………….
Answer:
Peristalsis is caused by wave-like motion of muscles in food pipe.
5. Pepsin acts on …………. to change them into and ………….
Answer:
Pepsin acts on proteins to change them into proteoses and peptones.
6. ………….. and ……….. help in digestion but food does not pass through them.
Answer:
Liver and Pancreas help in digestion but food does not pass through them.
7. Bile is secreted by ………….
Answer:
Bile is secreted by Liver.
8. Pancreatic juice has …………. and ………… enzymes.
Answer:
Pancreatic juice has trypsin and lipase enzymes.
9. Lipase acts one …………… to convert them into ……… and ………….
Answer:
Lipase acts on fats to convert them into fatty acids and glycerol.
10. Removal of undigested food is called
Answer:”
Removal of undigested food is called egestion.
ICSE Class 7 Biology Important Questions