Digestive System

Solutions for Biology, Class 9, ICSE

Assertion Reason Type

6 questions

Question 2(i)

Assertion (A): The last molar on each side of both the jaws is called the wisdom tooth as it is responsible for the intelligence of a person.

Reason (R): The wisdom teeth are so called because they appear at an age of about 17-20 years when the human body is reaching maturity.

  1. A is True and R is False.
  2. A is false and R is True.
  3. Both A and R are True.
  4. Both A and R are False.
Assertion Reason Type

Answer:

A is false and R is True.

Reason — The wisdom tooth is not related to intelligence or mental ability. It is simply the last tooth to erupt in the dental arch. Wisdom teeth usually erupt between the ages of 17 and 25, a period sometimes referred to as the "age of wisdom."

Question 2(ii)

Assertion (A): Dentine forms the bulk of the tooth.

Reason (R): Dentine is a bone-like structure which covers and fixes the root of a tooth in position.

  1. A is True and R is False.
  2. A is false and R is True.
  3. Both A and R are True.
  4. Both A and R are False.
Assertion Reason Type

Answer:

A is True and R is False.

Reason — Dentine is the main structural component of a tooth. It lies beneath the enamel and forms the bulk (major portion) of both the crown and the root of the tooth. While dentine is a bone-like tissue, it does not fix the root of the tooth. The structure that covers and anchors the root in position is called cementum, not dentine.

Question 2(iii)

Assertion (A): Both ptyalin and amylopsin are the same with respect to their enzymatic activity.

Reason (R): Both of these enzymes convert starch into maltose.

  1. A is True and R is False.
  2. A is false and R is True.
  3. Both A and R are True.
  4. Both A and R are False.
Assertion Reason Type

Answer:

Both A and R are True.

Reason — Ptyalin is secreted by salivary glands. Amylopsin is secreted by the pancreas into the small intestine. Despite being secreted from different glands, both enzymes perform the same function: they break down starch into maltose. Both enzymes catalyze the hydrolysis of starch (a polysaccharide) into maltose (a disaccharide).

Question 2(iv)

Assertion (A): Pylorus is the structure which prevents the entry of food from the stomach to the oesophagus.

Reason (R): Pylorus has a ring of muscles to keep the opening of the stomach closed like a valve. It is located at the front end of the stomach.

  1. A is True and R is False.
  2. A is false and R is True.
  3. Both A and R are True.
  4. Both A and R are False.
Assertion Reason Type

Answer:

Both A and R are False.

Reason — The pylorus is located at the lower end of the stomach. It controls the passage of food from the stomach to the small intestine (duodenum). It is true that the pylorus has a ring of muscles that acts like a valve but it is located at the lower/back end of the stomach, not the front.

Question 2(v)

Assertion (A): Bile juice is produced in the kidneys and is stored in the liver.

Reason (R): Bile juice is poured in duodenum through the common bile duct. It converts the acidic pH of the food to alkaline and enables the pancreatic enzymes to act.

  1. A is True and R is False.
  2. A is false and R is True.
  3. Both A and R are True.
  4. Both A and R are False.
Assertion Reason Type

Answer:

A is false and R is True.

Reason — Bile juice is produced in the liver, not the kidneys. It is stored in the gallbladder, not the liver. Bile is released into the duodenum via the common bile duct. It neutralizes the acidic chyme from the stomach, making it alkaline. This alkaline environment is necessary for the action of pancreatic enzymes like trypsin and lipase.

Question 2(vi)

Assertion (A): The length of the small intestine is shorter than the large intestine.

Reason (R): Small intestine is highly coiled and folded in the abdomen.

  1. A is True and R is False.
  2. A is false and R is True.
  3. Both A and R are True.
  4. Both A and R are False.
Assertion Reason Type

Answer:

A is false and R is True.

Reason — The small intestine is actually much longer than the large intestine. The small intestine is highly coiled to fit within the limited space of the abdomen. This coiling increases the surface area for absorption.

Long Answer Type

5 questions

Question 1

What are the main characteristics of an enzyme?

Long Answer Type

Answer:

Main characteristics of enzymes are-

  1. It is a protein and is, therefore, destroyed by heating.
  2. It acts only on one kind of substance called the substrate i.e. it is specific.
  3. It always forms the same end-product(s) from the substrate.
  4. It only affects the rate of a chemical reaction and always speeds up the reaction.
  5. Like a catalyst, it can be used again and again.
  6. It acts best only at a particular pH,i.e. at a particular degree of acidity or alkalinity.
  7. It acts best within a narrow temperature range, usually between 35°and 40°C which is also called the optimum temperature.

Question 2

Why is the small intestine the most important organ of the digestive system?

Long Answer Type

Answer:

The small intestine serves two important functions of digestion and absorption. In the duodenum, it receives two digestive juices:

  1. The bile
  2. The pancreatic juice

Both the juices virtually complete the process of digestion of proteins, starch, carbohydrates etc. Once the food is broken down, the small intestine is responsible to absorb simple particles such as amino acids, glucose etc.

Question 3

How is the liver an important organ in our body?

Long Answer Type

Answer:

The liver is the largest gland of the body and it performs the following functions:

  1. Controls amino acid levels
  2. Produces foetal red blood cells
  3. Produces heparin and fibrinogen
  4. Checks blood volume
  5. Destructs dead red blood cells
  6. Detoxifies
  7. Produces bile
  8. Generates heat
  9. Controls blood sugar levels
  10. Storage of minerals and vitamins
  11. Excretes metallic and toxic substances

Question 4

List the enzymes and their action on food in the stomach and intestine.

Long Answer Type

Answer:

The table below shows the different regions, enzymes and the action of the enzymes on the food -

Part of the bodyName of the enzymeAction on food
StomachPepsinConverts proteins into polypeptides
Small intestine - DuodenumTrypsinActs on proteins peptones and proteases to produce peptides and amino acids.
 AmylopectinActs on starch to produce maltose
 SteapsinActs on emulsified fats to produce fatty acids and glycerol
Small intestine - IleumerepsinIt acts on proteins and peptides to produce amino acids
 MaltaseActs on maltose to produce glucose
 SucraseActs on sucrose to produce glucose and fructose
 LactaseActs on lactose to produce glucose and galactose
 LipaseActs on fats to produce fatty acids and glycerol

Question 5

You have been supplied with a sample of food. How will you perform tests for the presence of starch and proteins in it?

Long Answer Type

Answer:

The following tests can be carried out:

Test for starch:

Aim — To detect the presence of starch in the sample

Procedure and Inference —

  1. Add some starch powder to a test tube containing water, shake well. Boil well to make a solution.
  2. Add some drops of iodine solutions when the solution cools down.
  3. Iodine solution can be prepared by dissolving 1g iodine with 1g potassium iodide in 100ml of distilled water, dilute this solution before using.
  4. The solution in the test tube would turn blur-black indicating the presence of starch.

Test for proteins:

Aim — To detect the presence of proteins in the given sample

Procedure and Inference—

  1. In a test tube add a few pieces of the sample (hard-boiled egg)
  2. Add a few drops of dilute nitric acid so as to seal the food
  3. Gently heat the test tube, rinsing off the acid with water, to this add ammonium hydroxide
  4. Observe the changes – from the initial white, color changes to yellow
  5. After adding ammonium hydroxide – the color changes from yellow to orange.

Multiple Choice Type

12 questions

Question 1(i)

Pylorous is an opening from

  1. oesophagus into stomach
  2. mouth cavity into oesophagus
  3. stomach into intestine
  4. intestine into rectum
Multiple Choice Type

Answer:

stomach into intestine

Reason — The opening of the stomach into intestine is called pylorus. It has a ring of muscles (sphincter).

Question 1(ii)

Gastric juice contains

  1. HCl and pepsin
  2. pepsin and trypsin
  3. trypsin and HCl
  4. amylopsin and pepsin
Multiple Choice Type

Answer:

HCl and pepsin

Reason — Gastric juice is acidic and contains HCl and pepsin.

Question 1(iii)

The water from the digested food is mainly absorbed by

  1. stomach
  2. duodenum
  3. colon
  4. rectum
Multiple Choice Type

Answer:

colon

Reason — Colon absorbs most of the water and left-over nutrients.

Question 1(iv)

Which one of the following pairs of types of teeth perform one common function as stated against it?

  1. Incisors, canines — Holding
  2. Canines, premolars — Tearing
  3. Premolars, molars — Grinding
  4. Molars, incisors — Tearing
Multiple Choice Type

Answer:

Premolars, molars — Grinding

Reason — Premolars and molars carry out grinding of food.

Question 1(v)

The hardest substance in the human body is :

  1. Bone
  2. Enamel
  3. Cement
  4. Dentine
Multiple Choice Type

Answer:

Enamel

Reason — Enamel, which forms outer most covering of teeth is hardest substance of the human body.

Question 1(vi)

Which of the following teeth is bicuspid ?

  1. Molars
  2. Incisors
  3. Premolars
  4. Canines
Multiple Choice Type

Answer:

Premolars

Reason — Premolar has two hill-like projections or cusps on its surface.

Question 1(vii)

The temperature range within which enzymes can act best is :

  1. 20° to 30°C
  2. 35° to 40°C
  3. 40° to 45°C
  4. 35° to 50°C
Multiple Choice Type

Answer:

35° to 40°C

Reason — 35° to 40°C is the optimum temperature range when enzymes act best.

Question 1(viii)

Heterodont dentition is found in :

  1. Humans
  2. Snake
  3. Frog
  4. Lizards
Multiple Choice Type

Answer:

Humans

Reason — Mammals have teeth of different shapes.

Question 1(ix)

Which of the following enzymes is not found in pancreatic juice ?

  1. Sucrase
  2. Trypsinogen
  3. Amylopsin
  4. Steapsin
Multiple Choice Type

Answer:

Sucrase

Reason — Sucrase is present in intestinal juice.

Question 1(x)

The process of conversion of excess glucose into glycogen is termed as :

  1. Glycolysis
  2. Glycogenesis
  3. Glycogenolysis
  4. Defaecation
Multiple Choice Type

Answer:

Glycogenesis

Reason — The excess glucose present in our body is converted into glycogen by liver.

Question 1(xi)

Name the salivary gland P, Q and R based on their location given below:

Salivary glandLocation
PBeneath the ears
QBelow the tongue
RBeneath the lower jaw
  1. P — Parotid, Q — Submandibular, R — Sublingual
  2. P — Sublingual, Q — Parotid, R — Submandibular
  3. P — Submandibular, Q — Sublingual, R — Parotid
  4. P — Submandibular, Q — Parotid, R — Sublingual
Multiple Choice Type

Answer:

P — Parotid, Q — Sublingual, R — Submandibular

Reason — The saliva is secreted by three pairs of salivary glands :

  • parotid glands located just in front of and beneath each ear,
  • submandibular glands lying close to the inner side of the lower jaw on each side,
  • sublingual glands below the tongue.

Question 1(xii)

A biology teacher asked her students to give two examples of enzymes which act on different forms of carbohydrates.

Nishtha said: Amylopsin and invertase.

Ankur said: Steapsin and Maltase.

Prakriti said: Ptyalin and Amylopsin.

Aakash said: Maltase and Erepsin.

Who were correct?

  1. Ankur and Aakash
  2. Nishtha and Prakriti
  3. Nishtha and Ankur
  4. Nishtha and Aakash
Multiple Choice Type

Answer:

Nishtha and Prakriti

Reason

StudentEnzymes NamedSubstrate TypeResult
NishthaAmylopsin acts on starch
Invertase acts on sucrose
Both are carbohydratesCorrect
AnkurSteapsin acts on fats
Maltase acts on Maltose (carbohydrate)
One enzyme does not act on carbohydrateIncorrect
PrakritiPtyalin (salivary amylase) acts on starch
Amylopsin acts on starch
Both are carbohydratesCorrect
AakashMaltase acts on Maltose (carbohydrate)
Erepsin acts on Proteins
One enzyme does not act on carbohydrateIncorrect

Therefore, only Nishtha and Prakriti supplied two enzymes that each act on some form of carbohydrate.

Progress Check 1

3 questions

Question 1

Given below is a jumbled sequence of the different parts of the human alimentary canal. Rewrite them in correct sequence.

Stomach, Oesophagus, Large intestine, Small intestine, Pharynx.

Progress Check 1

Answer:

Pharynx → Oesophagus → Stomach → Small intestine → Large intestine

Question 2

Give the technical names for the following types of teeth in humans (on each side, in each jaw)

  1. The three last grinders.
  2. The pointed tooth for holding and tearing.
  3. The broad sharp cutting teeth.
  4. The two temporary (deciduous) grinding teeth.
Progress Check 1

Answer:

  1. Molars
  2. Canine
  3. Incisors
  4. Premolar

Question 3

Name the following parts of a tooth :

  1. Part exposed above the gum.
  2. The hard substance making the covering of the tooth.
  3. The soft connective tissue contained in the central space of the tooth.
  4. Bone-like structure fixing the root in position.
  5. Slight constriction between the root and the crown.
Progress Check 1

Answer:

  1. Crown
  2. Enamel
  3. Pulp
  4. Cementum
  5. Neck

Progress Check 2

2 questions

Question 1

Mention if the following statements are true or false:

  1. Saliva moistens and lubricates food.
  2. Saliva contains a protein-digesting enzyme.
  3. Saliva tends to destroy germs in the mouth.
  4. Peristalsis occurs through all regions of the gut.
  5. The food in stomach stays for about 10 hours.
  6. Gastric juice is alkaline.
  7. Gastric juice contains pepsinogen.
Progress Check 2

Answer:

  1. True
  2. False
    Corrected Statement — Saliva contains a starch-digesting enzyme.
  3. True
  4. True
  5. True
  6. False
    Corrected Statement — Gastric juice is acidic.
  7. False
    Corrected Statement — Gastric juice contains pepsin and renin.

Question 2

Name the three salivary glands.

Progress Check 2

Answer:

  1. Parotid glands
  2. Sub-mandibular glands
  3. Sublingual glands

Progress Check 3

4 questions

Question 1

Mention if the following statements are true (T) or false (F)

  1. Intestinal villi have a lymph vessel called lacteal.
  2. Intestine is narrow for fast movement of food.
  3. Large intestine secretes no enzymes.
  4. Bile neutralizes the acid content of the food received from the stomach.
  5. Pancreatic juice has enzymes to digest all the major components of food.
  6. The anus is surrounded by circular muscles.
Progress Check 3

Answer:

  1. True
  2. False
    Corrected Statement — Intestine is narrow for slow movement of food.
  3. True
  4. True
  5. True
  6. True

Question 2

Name the following :

  1. The three subdivisions of the small intestine.
  2. The three subdivisions of the large intestine.
Progress Check 3

Answer:

  1. Duodenum, Jejunum, Ileum
  2. Caecum, Colon, Rectum

Question 3

Name the enzyme which digests :

  1. Starch in the mouth
  2. Fats in the ileum
  3. Protein in duodenum
  4. Sucrose in the ileum
Progress Check 3

Answer:

  1. Salivary amylase or Ptyalin
  2. Intestinal lipase
  3. Trypsin
  4. Sucrase/invertase

Question 4

What are the end-products of digestion of :

  1. Proteins
  2. Fats
  3. Starch
  4. Sucrose
Progress Check 3

Answer:

  1. Amino acid
  2. Fatty acid and Glycerol
  3. Maltose
  4. Glucose and Fructose

Progress Check 4

1 question

Question 1

Fill in the blanks.

  1. Liver stores glucose as ............... .
  2. Liver produces ............... only in embryo.
  3. Urea is produced in ............... by the deamination of extra............... .
  4. For testing the action of saliva on starch, the material has to be kept at a temperature of about ............... °C.
Progress Check 4

Answer:

  1. Liver stores glucose as glycogen .
  2. Liver produces RBC only in embryo.
  3. Urea is produced in liver by the deamination of extra amino acid .
  4. For testing the action of saliva on starch, the material has to be kept at a temperature of about 38°C.

Progress Check 5

1 question

Question 1

Mention the constituent of food if the end result of the test shows :

  1. White to yellow and yellow to orange colour.
  2. Turning blue-black after adding iodine solution.
  3. Blue green to deep red with appearance of precipitate.
  4. Ash that does not burn after continued heating.
Progress Check 5

Answer:

  1. Protein
  2. Starch
  3. Glucose
  4. Minerals

Short Answer Type

8 questions

Question 1

Define the following terms:

(a) Digestion

(b) Enzymes

(c) Peristalsis

(d) Dentition

(e) Defaecation

(f) Assimilation

Short Answer Type

Answer:

(a) Digestion — Digestion is any change which makes the food soluble and of such chemical nature that it can be absorbed readily through living membranes.

(b) Enzymes — An enzyme is a protein that acts on a specific substance to form a specific end product. It best acts at a particular temperature and pH.

(c) Peristalsis — It is defined as the rhythmic contraction and relaxation of the muscles of the alimentary canal which pushes the food along the gut.

(d) Dentition — The arrangement of teeth in a particular species is called dentition.

(e) Defaecation — The expulsion of undigested remains of food from the alimentary canal is called defaecation.

(f) Assimilation — It is the conversion of the absorbed digested food into body material.

Question 2

What are the end-products of the digestion of: starch, proteins and fats respectively?

Short Answer Type

Answer:

The end products are as follows:

Starch — Maltose
Proteins — Small peptides and amino acids
Fats — Glycerol and fatty acids

Question 3

Write the exact locations of the following :

(a) Liver

(b) Sub-mandibular gland

(c) Pylorus

(d) Pancreas

(e) Caecum

Short Answer Type

Answer:

(a) located in upper right side of abdomen just below the diaphragm.

(b) close to the inner side of the lower jaw on each side.

(c) between stomach and small intestine.

(d) located behind the stomach.

(e) at junction of large and small intestine.

Question 4

Write the important roles of the following :

(a) Rectum

(b) Gastric juice

(c) Epiglottis

(d) Small intestine

(e) Tongue

Short Answer Type

Answer:

(a) Rectum temporarily stores undigested food and wastes, to be defaecated through the anus.

(b) Gastric juice plays two key roles (i) it kills any germs which may have entered along with the food (ii) it activates pepsinogen to act on proteins.

(c) Epiglottis closes the opening of wind pipe.

(d) Most of the digestion and absorption of nutrition occur in small intestine.

(e) Tongue helps in mixing of food in buccal cavity and pushes it through pharynx.

Question 5

Give reasons/explain :

(a) Only animals require a digestive system and not plants.

(b) There are no enzymes to digest vitamins.

(c) Thorough chewing of food in mouth is helpful in digestion.

(d) Bile juice does not contain any enzyme but is still important in digestion.

(e) The inner layer of small intestine has a large number of finger-like projections called villi.

Short Answer Type

Answer:

(a) Animals are heterotrophs. They obtain their nutrients by consuming organic matter, such as other organisms or plant material. Hence, they need a digestive system to break down complex molecules, such as proteins, carbohydrates, and lipids, into smaller, absorbable forms. In contrast, plants are autotrophs, capable of synthesizing their own food through photosynthesis. Hence, they don't require a digestive system.

(b) Vitamins do not need digestion. They are absorbed directly through the intestine wall.

(c) Chewing of food breaks the food into small particles which helps in easy digestion.

(d) Bile contains a lot of sodium bicarbonate which neutralises the acid content of the food received from the stomach and makes it alkaline so that pancreatic and intestinal enzymes can act on it.

(e) The villi enormously increase the inner surface area of the intestines which facilitates the absorption of digested food.

Question 6

What is roughage? Give two examples.

Short Answer Type

Answer:

Roughage is the undigestible portion of the diet. It is a dietary fibre that majorly contains cellulose. Examples – Green leafy vegetables, fruits, beans, nuts.

Question 7

Mention two ways in which the ileum of a mammal is adapted for the absorption of digested food.

Short Answer Type

Answer:

The two ways in which the ileum of mammals is adapted for the absorption of digested food are:

  1. Very long to provide much more surface area for absorption.
  2. Ileum has numerous villi which further causes the surface area to increase thereby increasing the quantity of absorption of digested food.

Question 8

The stomach secretes gastric juice, which contains hydrochloric acid. What is its function?

Short Answer Type

Answer:

Hydrochloric acid performs the following functions in the stomach-

  1. It kills any germs which may have entered along with the food.
  2. It activates pepsin to act on proteins. Pepsin digests proteins into peptides.

Structured Application Skill Type

8 questions

Question 1

Draw a labelled diagram to show the internal structure of a mammalian tooth with two roots.

Structured Application Skill Type

Answer:

Below labelled diagram shows the internal structure of a mammalian tooth with two roots :

Draw a labelled diagram to show the internal structure of a mammalian tooth with two roots. Digestive System, Concise Biology ICSE Class 9.

Question 2

Complete the following table by filling in the blanks 1 to 8.

OrganEnzymeFood acted uponFinal product
1Pepsin23
Mouth45Disaccharide
67Maltose8
Structured Application Skill Type

Answer:

1 – Stomach

2 – Proteins

3 – Polypeptides

4 – Amylase

5 – Starch

6 – Ileum

7 – Maltase

8 – Glucose

Question 3

Study the diagram given below and then answer the questions that follow:

Name the parts labeled 1, 2, 3, 4, 5 and 6. Identify the tooth and give a reason to support your answer. Digestive System, Concise Biology ICSE Class 9.

(a) Name the parts labeled 1, 2, 3, 4, 5 and 6.

(b) Identify the tooth and give a reason to support your answer.

(c) Describe the structure of the part labeled '3'.

(d) Give the total number of the type of tooth mentioned in '1' above, in the mouth of an adult and state its function.

Structured Application Skill Type

Answer:

(a) The parts are-

  • 1 → Enamel
  • 2 → Dentine
  • 3 → Pulp
  • 4 → Gum
  • 5 → Crown
  • 6 → Cement

(b) The type of teeth shown in the given figure has only one root. Hence it is a canine or incisor that is used to bite or pierce.

(c) The part labelled '3'(Pulp) is a soft connective tissue present in the pulp cavity of the tooth. It consists of blood capillaries, lymph vessels and nerve fibres. From the crown of the tooth, the pulp opens through the pulp cavity at the base of the root.

(d) The type of teeth mentioned in the figure and its function are as follows:

Type of teethNumber of teethFunction
Incisors8Used to cut and bite
Canines4Used to tear and hold food
Premolars8Used to grind and crush food
Molars12Used to grind and crush food

Question 4

Study the following dental formula and then answer the questions that follow:

i34c00pm01m11i\dfrac{3}{4} \enspace c\dfrac{0}{0} \enspace pm\dfrac{0}{1} \enspace m\dfrac{1}{1}

(a) What is the total number of teeth in the (i) upper jaw and (ii) lower jaw?

(b) State the total number of teeth present in the dentition.

(c) Give the dental formula of an adult human being.

Structured Application Skill Type

Answer:

(a) The total number of teeth in the upper jaw are 8 and lower jaw are 12.

(b) The total number of teeth present in the given dentition are 20 teeth.

(c) The dental formula of an adult is as follows:

Human adult: 2,1,2,32,1,2,3=32\dfrac{2, 1, 2, 3}{2, 1, 2, 3} = 32 (permanent teeth with 4 wisdom teeth added)

Question 5

The figures (A, B, C and D) shown below represent different kinds of teeth in humans. Study the figures and answer the following questions:

Identify and name the four types of teeth shown below and state their functions. Digestive System, Concise Biology Solutions ICSE Class 9.

(a) What kind of teeth do A, B, C and D represent ?

(b) Write one structural feature/shape of each.

(c) Mention the number of teeth of each kind in one jaw with their specific position.

(d) Name two minerals present in teeth.

(e) What do you mean by 'Wisdom tooth'?

Structured Application Skill Type

Answer:

(a)

  • A → Incisor
  • B → Canine
  • C → Premolar
  • D → Molar

(b)

  • A → Broad and sharp
  • B → Conical and sharply pointed
  • C → Two hill-like projections(bicuspid)
  • D → Large grinding surface

(c)

  • A → Four, centre of each jaw
  • B → Two, one on each side of incisor
  • C → Four, two on side of each canine
  • D → Six, three on each side

(d) Calcium and phosphorous.

(e) Last molar on each side of jaw is called wisdom teeth.

Question 6

Draw a neat diagram of the "Microscopic Structure of an intestinal villus" and label the parts given below :

  1. Epithelium
  2. Capillaries
  3. Lacteals

Answer the following questions :

(a) What is the advantage of having a large number of villi on the inner surface of small intestine ?

(b) Write the important role of lacteals.

(c) Name the juice secreted from the glandular cells of small intestine.

(d) Name the specific secretions of:

  1. Salivary gland
  2. Stomach
  3. Liver
  4. Pancreas
Structured Application Skill Type

Answer:

Below is the labelled diagram of the "Microscopic Structure of an intestinal villus":

Draw a neat diagram of the Microscopic Structure of an intestinal villus and label the parts. Digestive System, Concise Biology Solutions ICSE Class 9.

(a) A large number of villi enormously increase the inner surface area of the small intestine which facilitates the absorption of digested food.

(b) The fatty acids and glycerol are absorbed into the lacteals to enter the lymphatic system which forms a network all over the body to ultimately empty its contents into the blood stream.

(c) Intestinal juice

(d)

  1. Salivary gland - Saliva (amylase)
  2. Stomach - Gastric juice
  3. Liver - Bile
  4. Pancreas - Pancreatic juice

Question 7

Vedika observed the following structure in a biology chart showing the digestive system.

Vedika observed the following structure in a biology chart showing the digestive system. Concise Biology Solutions ICSE Class 9.

(a) Name the structure which stores bile juice.

(b) Mention the gland which secretes bile juice.

(c) What are the three enzymes found in the pancreatic juice which can act over proteins, carbohydrates and emulisifed fats ?

Structured Application Skill Type

Answer:

(a) Gall bladder

(b) Liver

(c) Trypsin – Acts on proteins, Amylopsin (Pancreatic amylase) – Acts on carbohydrates (starch), Steapsin (Pancreatic lipase) – Acts on emulsified fats

Question 8

Write the correct word for the items (i) to (viii).

(i) A predator:

GRIET\boxed{\text{GRIET}} \quad ...............

(ii) Deficiency of Folic acid (B9) produces:

MIAAAEN\boxed{\text{MIAAAEN}} \quad ...............

(iii) A digestive enzyme:

ENPISP\boxed{\text{ENPISP}} \quad ...............

(iv) A part of tooth:

TEEDINN\boxed{\text{TEEDINN}} \quad ...............

(v) Fatty acids are absorbed into:

TACLELAS\boxed{\text{TACLELAS}} \quad ...............

(vi) Maltase acts on:

LESOMAT\boxed{\text{LESOMAT}} \quad ...............

(vii) Excess amino acids are broken down in:

RIVEL\boxed{\text{RIVEL}} \quad ...............

(viii) An enzyme which digest starch:

YEALMAS\boxed{\text{YEALMAS}} \quad ...............

Structured Application Skill Type

Answer:

(i) A predator:

GRIET\boxed{\text{GRIET}} \quad TIGER

(ii) Deficiency of Folic acid (B9) produces:

MIAAAEN\boxed{\text{MIAAAEN}} \quad ANAEMIA

(iii) A digestive enzyme:

ENPISP\boxed{\text{ENPISP}} \quad PEPSIN

(iv) A part of tooth:

TEEDINN\boxed{\text{TEEDINN}} \quad DENTINE

(v) Fatty acids are absorbed into:

TACLELAS\boxed{\text{TACLELAS}} \quad LACTEALS

(vi) Maltase acts on:

LESOMAT\boxed{\text{LESOMAT}} \quad MALTOSE

(vii) Excess amino acids are broken down in:

RIVEL\boxed{\text{RIVEL}} \quad LIVER

(viii) An enzyme which digest starch:

YEALMAS\boxed{\text{YEALMAS}} \quad AMYLASE

Very Short Answer Type

7 questions

Question 1

What is the dental formula of a normal human adult?

Very Short Answer Type

Answer:

Human adult: 2,1,2,32,1,2,3=32\dfrac{2, 1, 2, 3}{2, 1, 2, 3} = 32 (permanent teeth with 4 wisdom teeth added)

Question 2

Mention two reflexes which occur when a person chews and swallows food.

Very Short Answer Type

Answer:

The two reflexes which occur when a person chews and swallows food are-

  1. Reflex when a person chews — Secretion of saliva.
  2. Reflex when a person swallows — The tongue presses upward and back against the roof (palate) of the mouth and this forces the bolus (the ball of chewed food ) into the throat or the pharynx.

Question 3

Given below is the "Internal structure of a tooth". Match the structures marked (a) to (e) with their characteristics or functions given in the table.
Example: (e) - 5: The soft connective tissue.

Given below is the Internal structure of a tooth. Match the structures marked (a) to (e) with their characteristics or functions given in the table. Concise Biology ICSE Class 9.
Very Short Answer Type

Answer:

Internal structure of a toothCharacteristics / Functions
(a) Enamel2. Hardest substance in the body
(b) Dentine4. Forms the bulk of the tooth
(c) Cementum1. Covers and fixes the root in position
(d) Root6. The embedded part of the tooth
(e) Pulp5. The soft connective tissue
(f) Crown3. The exposed part of the tooth

Question 4

Match the terms given in column A with those of column B.

Column AColumn B
PtyalinProteins and peptides
RenninEmulsified fat
ErepsinProtein
SteapsinStarch
PepsinCasein
Very Short Answer Type

Answer:

Column AColumn B
PtyalinStarch
RenninCasein
ErepsinProteins and peptides
SteapsinEmulsified fat
PepsinProtein

Question 5

Consider the following two statements A & B and select the statements from (i) – (iv) that hold true.

A. Small intestine is shorter than large intestine.

B. Small intestine is wider than large intestine.

Options:

(i) Both the statements are correct.

(ii) Both the statements are wrong.

(iii) Statement A is correct, B is wrong.

(iv) Statement B is correct, A is wrong.

Very Short Answer Type

Answer:

The statement that holds true is:

(ii) Both the statements are wrong.

Reason — Small intestine is longer than the large intestine. It is about 7 meters longer while large intestine is about 1.5 meters long. Large intestine is wider than the small intestine.

Question 6

Name these:

  1. Two main divisions of the digestive system
  2. Three digestive glands
  3. Three pairs of salivary glands
  4. Three parts small intestine
  5. Three parts of large intestine
Very Short Answer Type

Answer:

  1. Alimentary canal and digestive glands.
  2. Salivary gland, liver and pancreas.
  3. Parotid glands, sub-mandibular glands and sublingual glands.
  4. Duodenum, Jejunum, Ileum.
  5. Caecum, Colon, Rectum.

Question 7

Choose the odd one out and write the category of the remaining terms :

  1. Pepsin, Trypsin, Steapsin, Erepsin
  2. Lactase, Peptidase, Invertase, Maltase
  3. Glucose, Fructose, Galactose, Starch
  4. Ileum, Colon, Duodenum, Jejunum
  5. Palate, Crown, Root, Neck
Very Short Answer Type

Answer:

  1. Steapsin is odd one out. Remaining terms (Pepsin, Trypsin and Erepsin) are protein digesting enzymes.
  2. Peptidase is odd one out. Lactase, Invertase and Maltase are sugar digesting enzymes.
  3. Starch is odd one out. Glucose, Fructose and Galactose are simple sugar.
  4. Colon is odd one out. Ileum, Duodenum and Jejunum are parts of small intestine.
  5. Palate is odd one out. Crown, Root and Neck are parts of teeth.