Class 6 - Biology - Digestive System - Exercise And Solutions

EXERCISE

Multiple Choice questions:

1. Tick (√) the appropriate answer.

(i) The teeth which help in tearing the food are the

(a)    Incisors                         (b)    Canines

(c)    Premolars                     (d)    Molars

(ii) Last molar tooth in human beings is called

(a)    Adult tooth                 (b)    Wisdom tooth

(c)    Child tooth                  (d)    Elder’s tooth

(iii) The hardest substance in your body is

(a)    Dentine                       (b)    Bone

(c)    Cement                       (d)    Enamel

(iv) Saliva converts starch into

(a)    Glucose                       (b)    Sucrose

(c)    Maltose                      (d)    Lactose

(v) Proteins of the milk are converted into curd by the enzyme

(a)    Trypsin                       (b)    Rennin

(c)    Pepsin                         (d)    Erepsin

(vi) Bile juice is produced by

(a)    Stomach                      (b)    Liver

(c)    Pancreas                      (d)    Gall bladder

Short Answer questions

1. Write True or False in the following statement

(i)Molar help in cutting and tearing food. (FALSE)

(ii) Carbohydrates are digested into glucose. (TRUE)

(iii) Proteins are digested into fatty acids. (FALSE)

2. Fill in the blanks

(i) The teeth called canines are a total in four in number on the sides of

incisors.

(ii) Pharynx is a common opening of food pipe and wind pipe.

(iii)Molars are meant for crushing the food.

(iv) Incisors are used for biting and cutting the food.

(v) The canines are used for tearing the food.

(vi) The premolars and molars are used for crushing and grinding the food.

(vii) In an adult human, there are a total of 32 teeth.

(viii) The human teeth appear in two sets, the first set is called

temporary teeth which consists of only 20 teeth.

3. Name the following:

(i) End product of starch after digestion,  Maltose

(ii) The organ where protein digestion begins, Stomach

(iii) The organ into which the pancreatic juice and the bile juice are

Poured, Small intestine

(iv) The enzyme which digest fat in ileum, Lipase

(v) The simplest form of carbohydrates, Glucose

(vi) The part of elementary canal where water from the undigested

food is absorbed, Large Intestine

(vii) The end product of protein digestion, Amino acids

4. Identify and name the four types of teeth shown below and state their

functions.

A. Incisor: These are used for biting and cutting the food.

B. Canines: These are used to tear the food.

C. Premolars: These help in crushing and grinding the food.

D. Molars: These help in finer crushing and grinding of ingested food.

5. State whether the following statements are True or False.

(i) Wisdom tooth appears at the age of 5-6 years when the child starts

going to school. (FALSE)

(ii) The temporary set of teeth includes incisors, canines and premolars

Only. (TRUE)

(iii) The ducts from the salivary glands open into the duodenum. (FALSE)

(iv) Saliva changes starch into maltose. (TRUE)

6. Fill in the blanks in the table (1-5) by selecting the suitable names of

substances from the list given below:

[ steapsin, peptones, fatty acids, proteoses, protein ]

Digestive enzymes                 Acts on                                 to from

(i) Pepsin                                 Proteins                 peptones and proteoses (ii) Steapsin                                fats                              fatty acids

 7. (i) Name the juice secreted by the liver – Bile

(ii) Name the organ where this juice is temporarily stored – Gallbladder

(iii) What is the main function of this juice?

The main function of bile is emulsification in which it breaks down

fats into tinny droplets.

8. Name three enzymes found in the pancreatic juice and mention their

functions.

The three enzymes found in the pancreatic juice are

(i) Amylase : This acts on the starch and convert it into maltose.

(ii) Trypsin: This converts proteins and peptones into peptides.

(iii) Lipase: This converts emulsified fats into fatty acids and glycerol.

9. Name the three regions of the large intestine.

The three regions of the large intestine are Caecum, colon and Rectum.

10. Give alongside the diagram of the human alimentary canal.

(i) Name the parts 1-11 indicated by guidelines.

 

1. Stomach                 2. Bile duct

3. Pancreas                 4. Large intestine

5. Small intestine        6. Rectum

7. Appendix                8. Pancreatic duct

9. Gall bladder    10. Liver  11. Anus

(ii) State the function of the juice secreted by part 1

The juice secreted by the stomach is also known as gastric juice, which

kill the germs which may have entered with the food. This also prevents

rotting of food during its long stay in stomach and it activates the

enzyme pepsin.

(iii) State the function of three enzymes found in the juice secreted by

part 3.

The juice secreted by part 3 is known as pancreatic juice. The three

enzymes found in the pancreatic juice are

a) Amylase : This acts on the starch and convert it into maltose.

b) Trypsin: This converts proteins and peptones into peptides.

c) Lipase: This converts emulsified fats into fatty acids and glycerol.

Long Answer questions

1. Define the term nutrition.

The process by which all organisms synthesize their food and convert it

into simpler substance, so that it can be absorbed and utilized by the

cells of the body is called nutrition. The whole process of nutrition is

conducted through five steps. Ingestion, digestion, absorption,

assimilation and egestion.

2. What is the role of liver and pancreas respectively in the digestion of

Food?

The liver produces a greenish yellow fluid called bile, which breaks

down fats into tiny droplets by emulsification. The pancreas secrets

pancreatic juice which contains enzymes like amylase, trypsin and

lipase which help in the digestion of carbohydrates, proteins and fats

respectively.

3. Name the digestive juice secreted by the stomach and give its

function.

The digestive juice secreted by the stomach is known as gastric juice. Its

functions are:

(i) It kills the germs which may have entered with the food.

(ii) This also prevents rotting of food during its long stay in stomach.

(iii) It activates the enzyme pepsin.

4. Answer the following questions.

(i) Name the type of teeth present in humans.

Based on their different shapes and function human teeth are of four

kinds as following.

a) Incisors: These are chisel shaped and used for biting and cutting

the food.

b) Canines: These are pointed teeth and used for tearing the food.

c) Premolars: These help is crushing and grinding the food.

d) Molars: These have broad uneven surface and used for finer crushing

and grinding of food.

(ii) How the small intestine best suited for the digestion and absorption

of food?

The last part of the small intestine called ileum contains glands which

produces intestinal juice. This juice contains enzymes. Due to the action

of these enzymes the food completely digested in the ileum. The inner

lining of the small intestine contains a large number of tinny finger like

projections called villi. These villi greatly increase the inner surface area

for absorption of digested food. The villi absorbs the amino acids and

glucose to pass them into the blood system. The fatty acid pass into

special tubes called lymph vessels. Vitamins and mineral salts are directly

absorbed through the walls of the intestine.

(iii) What do you mean by absorption of food?

The digested food in the form of glucose, amino acids, fatty acids,

glycerol, vitamins and minerals are passed into the blood system

through villi, lymph vessels and walls of the intestine. This is known as

absorption of food.

5. Define the following terms: Egestion, digestion, assimilation.

Egestion: The process of eliminating the undigested food through the

anus is called egestion.

Digestion: Digestion is the process by which the complex chemical

compounds present in the food are broken into simpler

substances that are readily absorbed and utilized by the

body.

Assimilation: It is the utilization of the digested food or nutrients by the

body cells.

6. Rewrite the following parts of the human alimentary canal in their

correct sequence. Stomach, Oesophagus, large intestine, Small

intestine.

Oesophagus, Stomach, Small intestine, Large intestine

7. What is the fate of excess glucose in our body?

Liver takes the excess glucose and stores it in the form of glycogen.

When we need energy later, like in between meals the liver will release

glucose back into the blood stream.

8. Define the term digestion.

Digestion is the process by which the complex chemical compounds

present in the food are broken into simpler substances that are readily

absorbed and utilized by the body.

9. State the four ways in which saliva is useful to us.

The four ways in which saliva is useful to us are:

a) It moistens and lubricates the mouth cavity and the tongue to make

speaking and swallowing easy.

b) It cleans the mouth and destroys the germs.

c) The saliva binds the food particles and makes it into a mass called as

bolus.

d) Saliva contains amylase which helps to break starch into simple

sugars.

10. Food are classified into three groups on the basis of the functions they

perform in our body. Name these three groups, and briefly state their

functions. Also give two sources of each.

The Three groups of food on the basis of their functions are

a) Energy giving food – These food give us energy to do work.

Carbohydrate and fats present in the food provide us energy.

The main source of these food are Rice, potato, oil and butter.

b) Body building food -- These food help in the growth and repair of

damaged cells and tissues. These food contain proteins. The main

source of these food is Pulses. Milk and egg etc.

c) Protective food – These food help our self-keeping healthy and

diseases free. These food contain minerals and vitamins. The main

source of these food are vegetables and fruits.  

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Extra Questions and Answers

A. Objective Questions

1. Fill in the blanks:

a) Salivary amylase acts on starchy food and change it into maltose.

b) The food we eat passes through the alimentary canal.

c) The alimentary canal starts from the mouth and ends at the anus.

d) The word cell is derived from the Latin word cella.

e) The food canal together with the glands forms the digestive system.

f) The temporary teeth consists of 20 teeth.

g) Two teeth on either side of the canines are premolars.

h) Molar teeth are broad in shape and have uneven flat surface.

i) Tongue manipulates the food while chewing.

J) Saliva is a fluid containing water, salts and slimy mucus.

k) Saliva contains an enzyme called amylase which converts starch into

maltose.

l) The Oesophagus is a long and narrow tube which runs from back of the

throat, down through the chest to open into the stomach.

m) The food moves through the oesophagus by peristalsis.

n) The gastric juice contains water, hydrochloric acid and an enzyme

Pepsin.

o) Pepsin converts proteins into a simpler compound called peptones.

p) In the stomach the food changes into a pulp like thick paste called

chyme.

q) The short upper ‘U’ shaped part of the small intestine is called

duodenum.

r) The pancreatic juice contains amylase, trypsin and lipase.

s) Intestinal juice contains erepsin, maltase, sucrase and lactase.

t) The three regions of large intestine are caecum, colon and rectum.

u) Chocolates and sweet promote the growth of bacteria in the teeth.

2. Give one word for the following.

a) The food which provides us with all the necessary substances –

Nutritious food.

b) The last molar on each side of each jaw is called – Wisdom tooth.

c) The saliva binds the food particles and makes in into a mass called –

Bolus.

d) The slow wave like movement seen in the walls of oesophagus due to

the contraction and relaxation of its muscles – Peristalsis.

e) The process in which bile juice breaks down fats to tinny droplets –

Emulsification.

f) Bile is stored in – Gull Bladder.

g) This converts starch into maltose – Amylase

h) This converts proteins and peptones into peptides – Trypsin

i) This converts emulsified fats into fatty acids and glycerol – Lipase.

j) The second part of the small intestine is called – Jejunum.

k) The tinny finger like projections in the small intestine – Villi

l) The fatty acids pass through a special tube called – Lymph vessels

m) This part of the small intestine serves functions both for the digestion and

absorption of the digested food. – Ileum

n) The top portion of the tooth – Crown

o) The white hard layer which surrounds the crown – Enamel

p) The hardest substance in the body – Enamel

q) The bone like hard substance just below the enamel – Dentine

r) Dentine has a hollow space filled with soft material called – Pulp

s) The lower part of the tooth fixed with the jaw – Root

t) The process of eliminating the undigested food through the anus –

Egestion

u) The last part of the large intestine about 15cm long is called – Rectum

v) The undigested waste stored in the rectum is called – Faeces

w) Sticky substance that forms on the tooth – Plaque

B. Short Questions And Answers.

1. Why is small intestine long and narrow?

The small intestine is long and narrow so that the food can be remained in

the small intestine for about 3 -5 hours for digestion and absorption.

2. Why is wall of stomach highly muscular?

Walls of the stomach is highly muscular so that it can churn the food

thoroughly along with the digestive juices and can change it into a pulp

like thick paste called chime.

3. Name the enzymes contained in the intestinal juice.

Intestinal juice contains enzymes like erepsin, maltase, sucrose and

lactase.

4. Name the enzymes contained in the pancreatic juice.

Pancreatic juice contains enzymes like amylase, trypsin and lipase.

5. Explain the function of gastric juice in digestion.

The functions of gastric juice in digestion are

i) It kills the germs and prevent the rotting of food during its long stay in the

stomach.

ii) It activates the enzyme pepsin, which converts proteins into simpler

compound called peptones.

6. Define the following:

a) Emulsification   b) Caries   c) Villi    d) Rectum             e) Duodenum

f) Jejunum  g) ileum

a) Emulsification: The bile juices breaks down fats into tiny droplets. This

process is called emulsification.

b) Caries: The acid produced by the bacteria slowly corrodes the teeth

and forms cavities, which are known as caries.

c) Villi: The inner lining of the small intestine contains a large number of

tiny finger like projections called villi. The surface of the villi absorbs the

amino acids and glucose to pass them into the blood system.

d) Rectum: The rectum is the last part of the large intestine and is about

15 cm long. It stores the undigested waste matter called faeces. It

opens to the outside at the anus.

e) Duodenum: This is the upper ‘U’ shaped part of the small intestine. It

receives a common duct that receives both bile juice from the liver

and the pancreatic juice from the pancreas.

f) Jejunum: The second part of the small intestine is called jejunum. No

digestion takes place here.

g) Ileum: Ileum is the last part of the small intestine. It is a long narrow

coiled tube. It produces the intestinal juice and serves function both

for the digestion and absorption of the digested food.

7. Define the term nutrient.

Nutrient can be defined as a constituent of food that helps one way

or the other in the body’s function.

8. Differentiate between Macronutrients and Micronutrients.

Macronutrients	Micronutrients
These required in larger quantities.	These are required in minute quantities.
Example: Nutrients like Carbohydrates, fats and proteins.	Example: Nutrients like Minerals and vitamins

9. What is the alimentary canal consists of?

The elementary canal consists of mouth, oesophagus, stomach, small

intestine, large intestine and rectum.

 10. What are the different digestive glands?

The different digestive glands are salivary glands, liver and pancreas.

C. Long Questions And Answers.

Answer the following:

1. Classify the nutrients according to their groups and define their

functions.

Nutrients are classified into five major groups:

Carbohydrates: These provide energy to our body.

Proteins: These helps in the growth of our body.

Fats: These provide energy to our body as well as help in insulating the

body.

Minerals: These are need for specific roles in the body.

Vitamins: These helps in normal functioning of various body processes.

2. How the tongue is helpful to us?

The tongue helps us in many ways.

i) It manipulates the food while chewing.

ii) It helps in tasting the food.

iii) It helps in mixing the saliva with the food.

iv) It helps in cleaning the tooth when food particles are stuck into it.

v) It helps in speaking.

3. Name the different enzymes contained in the pancreatic juice and

state their functions.

The pancreatic juice contains enzymes like amylase, trypsin and lipase.

Amylase: This acts on the starch and converts it into maltose.

Trypsin: It converts proteins and peptones into peptides.

Lipase: It converts emulsified fats into fatty acids and glycerol.

4. Show the equations of conversion of starch, proteins and peptones,

emulsified fats, peptides, maltose, sucrose and lactose to their

respective forms while reacting with different enzymes.

Starch →  Amylase  →  Maltose

Proteins + Peptones →  Trypsin →      Peptides

Emulsified fat  →    Lipase  →      Fatty acids and glycerol

Peptides  →  Erepsin  →    Amino acids

Maltose   →   Maltase  →    Glucose

Sucrose  →   Sucrase  →   Glucose and fructose

Lactose  →    Lactase  →    Glucose and galactose

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