Digestion ICSE class 9

(Q.1)  Name the glands associated with digestive system.

(Ans) The glands associated with digestive system are salivary glands, liver and pancreas.

(Q.2)  What is alimentary canal?

(Ans) Alimentary canal is a long muscular tube, which starts with the mouth and ends at the anus.

(Q.3)  How many teeth are normally present in adult human?

(Ans) Normally 32 teeth are present in adult human.

(Q.4)  Name the three regions of the large intestine.

(Ans) The three regions of the large intestine are:
i) Caecum
ii) Colon
iii) Rectum

(Q.5)  How many sets of teeth appear in mammals during its life?

(Ans) Mammalian teeth appear in two sets during its life.�
i) Temporary or deciduous teeth
ii) Permanent teeth.

(Q.10)  What is bile?

(Ans) It is the digestive juice secreted by the cells of liver, which is stored in gall bladder.

(Q.11)  Name the muscle regulating the exit of food from the stomach.

(Ans) Sphincter muscle.

(Q.12)  Define emulsification.

(Ans) It is the process of breaking down large fat droplets into fine emulsion by the bile juice.

(Q.32)  What is the pH of stomach acid?

(Ans) pH of HCl in stomach is between 1.0-2.0

(Q.34)  Name the three sub-regions of small intestine. Which of the region has finger like projections in its wall?

(Ans)

The three sub–regions of small intestine are:
i) Duodenum�
ii) Jejunum�
iii) Ileum�
Ileum has finger like projections in its wall, known as villi.

(Q.35)  Label the different types of teeth (A, B, C and D) in following diagram.

(Ans)

A) Incisors
B) Canine
C) Premolars
D)� Molars

(Q.36)  �Define the following terms: i) Digestion ii) Heterodont

(Ans) i) The process of conversion of complex food substances into simple forms is known as digestion.
ii) Teeth that are different in shape are called heterodont. For example mammalian teeth.

(Q.37)  Name the parts of tooth that�are�present in�vertical section.

Ans) In vertical section, a tooth shows following parts:
i) Enamel
ii) Dentine
iii) Cement
iv) Pulp�

(Q.38)  Give number of following teeth in human. i) Temporary teeth ii) Premolar iii) Molar iv) Incisor

(Ans)

Teeth	Number in human
Temporary teeth	20
Premolar	8 (2 in each half of jaw)
Molar	12 (3 in each half of jaw)
Incisor	8 (2 in each half of jaw)

(Q.39)  Name the structures of digestive system in which following are present: i) Villi ii) Pylorus� iii) Anus iv) Enamel

(Ans)
i) Small intestine
ii) Stomach
iii) Large intestine (rectum)
iv) Tooth

(Q.40)  Write the basic differences between autotrophic and heterotrophic nutrition.
(Ans) In autotrophic nutrition: Carbon dioxide and water are converted into carbohydrates by green plants in the presence of sunlight. In heterotrophic nutrition: Other organisms take up the ready-made complex food prepared by green plant. (Q.41)  Name and write the function of the enzyme present in human saliva.

(Ans) Salivary amylase. It breaks down starch into sugar.

(Q.42)  Why do herbivores need a longer intestine as compared to�the carnivores?

(Ans) Herbivores need longer intestine, as they need to digest the cellulose of grasses and other plants, whereas�carnivorous eat meat which is easier to digest. Thus they have shorter intestine

(Q.43)  Bile juice is released from which organ? Give two functions of bile juice.

(Ans) Bile�is released from liver. It helps�in emulsification of fats and it also activates lipases.

(Q.44)  Fill in the vacant column with reference to the digestive glands of man. Digestive gland Digestive juices Salivary gland � � Gastric juice Liver � � Pancreatic juice

(Ans)

Digestive gland	Digestive juices
Salivary gland	Saliva
Gastric glands	Gastric juice
Liver	Bile
Pancreas	Pancreatic juice

(Q.45)  Identify the following pictures and give one characteristic of each. (i)� (ii) (iii)

(Ans)

i) Liver: Largest digestive gland in the body.
ii) Molars: Last three teeth on each side in each jaw.
iii) Large intestine: Consists of three sub regions; caecum, colon and rectum.

(Q.46)  Differentiate between temporary and permanent teeth. �

(Ans)

Temporary Teeth	Permanent Teeth
20 in number	32 in number
Fall out as a result of their roots being dissolved	Lasts throughout life
Grows when the child is 7-8 months old.	Replace temporary teeth at 12 years of age

(Q.47)  Label the points (A, B, C, D, E and F) in the following diagram.

(Ans)

A) Buccal (mouth) cavity�
B) Oesophagus
C) Stomach
D) Duodenum
E) Jejunum�
F) Large intestine�

(Q.48)  Describe the structure of stomach.

(Ans)  Stomach is a j-shaped bag like structure, which is located in upper left portion of abdominal cavity, below the diaphragm. Stomach can hold 2-3 litres of food.�One side stomach is connected with oesophagus and on the other side to small intestine (duodenum).Opening of the stomach into the intestine is called Pylorus.

(Q.49)  How does the process of nutrition take place in amoeba? Explain with the help of labeled figures.

(Ans) Amoeba takes food using finger like extension of cell surface called pseudopodia. These pseudopodia fuse to form food vacuole. Food is digested in food vacuole and then diffuses into the cytoplasm. The undigested food moves�to the�surface as vacuole and is egested out.

                         

(Q.50)  Give suitable name to the following: i) Fleshy muscular organ that is attached to the floor of buccal cavity. ii) Last molar on each side of jaw that appears in later age. iii) Arrangement of teeth in each half of upper and lower jaw, represented by numbers. iv) Ring of muscles present at the front and lower end of stomach. v) Worm shaped tube, present in large intestine.

(Ans)
i) Tongue�ii) Wisdom tooth
iii) Dental formula
iv) Sphincter�
v) Vermiform appendix

(Q.51)  State true or false and rewrite the false statement correctly. i) Exposed part of tooth above the gum is called root. ii) Dental formula for adult human is 2120. iii) Oesophagus does not produce any digestive enzyme. iv) Rectum is a part of large intestine that is present at the junction of small and large intestine. v) Liver is the largest gland in the body.
(Ans) i) False, exposed part of tooth above the gum is called crown. ii) False, dental formula for adult human is 2123. iii) True iv) False, caecum is a part of large intestine that is present at the junction of small and large intestine. v) True � (Q.1)  Name the organ in which water is absorbed from undigested food.

(Ans) Absorption of water from the undigested food takes place in the large intestine.

(Q.2)  Name�the end products of digestion.

(Ans) Glucose, fatty acids, glycerol and amino acids are the end products of digestion.

(Q.3)  Name the pigments that give bile its characteristic yellowish green colour.

(Ans) Biliverdin and bilirubin are the pigments that give bile its characteristic yellowish green colour.

(Q.4)  Name�the organ that serves� for digestion as well as for the absorption of food?

(Ans) Small intestine serves both for digestion and absorption.

(Q.5)  What is deglutition?

(Ans) The egestion of faeces (undigested food) through the anal opening is called defaecation.

(Q.6)  What is defaecation ?

(Ans) The regions of alimentary canal that do not produce any digestive enzymes are:
i) Oesophagus
ii) Large intestine

(Q.7)  Name the regions of alimentary canal that does not produce any digestive enzymes.

(Ans) The regions of alimentary canal that do not produce any digestive enzymes are:
i) Oesophagus
ii) Large intestine

(Q.8)  Name the enzymes present in the pancreatic juice.

(Ans) The pancreatic juice contains three types of enzymes:
i) Amylopsin
ii) Trypsin�
iii) Steapsin

(Q.28)  Define the following: i) Peristalsis ii) Chyme

(Ans) i) Wave of contraction caused by the circular muscles of the alimentary canal for pushing the food forward in the canal is called peristalsis.
ii) Pulp like thick paste formed in stomach after the churning of ingested food is called chyme.

(Q.29)  Define bile and give its two main functions.

(Ans) Yellowish green watery fluid produced in the liver is called bile.

Two main functions of bile are:
i) Breaks large globules of fat into tiny droplets by reducing their surface tension.
 Fat       Emulsified fat
ii) Sodium bicarbonate present in bile neutralises the acid content of food and makes it alkaline.
 Acidic chime   Alkaline chyme

(Q.30)  Name one enzyme which digests: i) Protein in stomach ii) Fat in small intestine iii) Leftover starch into maltose iv) Milk protein in stomach

(Ans) i) Pepsin
ii) Steapsin
iii) Amylase
iv) Rennin

(Q.31)  What are the functions of large intestine ?

(Ans) The two major functions of large intestine are as follows:
(i) Absorption of some water, minerals and certain drugs.
(ii) Secretion of mucus which helps in adhering the waste (undigested) particles together and lubricating it for an easy passage.

(Q.32)  What is peristaltic movement? How are they helpful�in human digestion?

(Ans) The muscles of the food canal contract rhythmically. These movements are peristalsis and these movements push the food forward.

(Q.33)  What are the secretions received by different parts of the small intestine? Mention some of the nutrients or substrates on which they act.

(Ans)

Parts of small Intestine	Secretions	Substrate
Duodenum	Bile and pancreatic juice	Fat, starch and proteins
Ileum	Intestinal juice	Protein, fat and maltose

(Q.34)  How does assimilation of different nutrients occur in the digestive system?

(Ans) Food after getting digested is absorbed in the alimentary canal and gets assimilated in the following ways:
i) Sugar, amino acids and vitamins are carried to liver where they are converted to insoluble form and stored. For example, glucose is converted to glycogen.
ii) Nutrients, like amino acids, circulate in blood and serve as building blocks of protein.
iii) Excess amino acids are broken down and converted into urea for excretion.
iv) Fatty acids and glycerol are transported through the lymphatic system to different organs.
v) Excess fats are deposited under the skin.

(Q.35)  Give any six functions of the liver.

(Ans) Some of the functions of the liver are:
i) Produces bile
ii) Control of blood sugar level
iii) Produces fibrinogen and prothrombin
iv) Destroys dead red blood cells
v) Detoxification of substances, including drugs and alcohol
vi) Produces heparin

(Q.36)  What is the role of sphincter in the stomach?

(Ans) Sphincter is a ring of muscles present in the stomach that has the following role:
i) Prevents passing of food from the stomach until it is thoroughly
churned up
ii) Prevents regurgitation from the duodenum
iii) Prevents back flow of food into the oesophagus

(Q.37)  Write a brief note on liver .

(Ans) Liver-� Liver is the largest gland of the body. It weights about 1.2 to 1.5 kg in an adult human. It is situated in the abdominal cavity, just below the diaphragm and has two lobes. The structural and functional units of liver are hepatic lobules whihc contain hepatic cells. Each lobule is covered by a thin connective tissue sheath called the Glisson’s capsule. The bile secreted by the hepatic cells passes through the hepatic ducts and is stored and concentrated in a thin muscular sac called the gall bladder situated in the right lobe of the liver.

(Q.38)  Sketch a flow diagram for the various pathways for breakdown of glucose.

(Ans)

(Q.39)  Describe what happens to the eaten food�in stomach?

(Ans) The gastric glands present in the wall of stomach release HCl, pepsin, and mucus.

- HCl creates acidic medium in the stomach to facilitate the action of enzyme pepsin.

- HCl in the stomach is a primary body defence against microorganisms.

- Pepsin is protein-digesting enzyme.

- Mucus protects the lining of stomach from the acidic action of�HCl.

(Q.40)  Give suitable name to the following: i) Expulsion of the undigested remains of the food from the alimentary canal. ii) Ducts that form common bile duct. iii) Part of alimentary canal that secretes no enzyme and absorbs water in large quantity. iv) Secretion of stomach that converts inactive form of pepsin to active form. v) Process of taking food into the mouth.

(Ans)

i) Defecation
ii) Hepatic and cystic duct
iii) Large intestine
iv) Gastric juice
v) Ingestion

(Q.41)  State true or false and rewrite the false statement correctly. i) Saliva contains protein digesting enzyme. ii) Gastric juice is alkaline in nature. iii) Peristalsis occurs through all the regions of alimentary canal. iv) Liver stores excess glucose as glycerol and fatty acids. v) Pancreatic amylase digests left over starch.

(Ans)

i) False, saliva contains starch digesting enzyme.
ii) False, gastric juice is acidic in nature.
iii) True
iv) False, liver stores excess glucose as glycogen.
v) True