Digestive System Long Answer Biology Class-9 ICSE Selina Publishers

Digestive System Long Answer Biology Class-9 ICSE Selina Publishers Solutions Chapter-11. Step By Step ICSE Selina Concise Solutions of Chapter-11 Digestive System with Exercise-11 including MCQs, Very Short Answer Type, Short Answer Type, Long Answer Type and Structured/Application Questions Solved Visit official Website CISCE for detail information about ICSE Board Class-9.

Digestive System Exe-11 Long Answer Biology Class-9 ICSE Concise Selina Publishers

Board ICSE
Publications Selina Publication
Subject Biology
Class 9th
Chapter-11 Digestive System
Book Name Concise
Topics Solution of D. Long Answer Type
Academic Session 2023-2024

D. Long Answer Type 

Digestive System Class-9 Biology Concise Solutions  

Page 121

Question 1.

What are the main characteristics of an enzyme ?

Answer:

Enzymes are biological  catalysts. They speed up reaction although they are not changed in the  reaction . Enzymes are proteins , and therefore are folded chains of amino acids with a specific shape.

Main characteristics of an enzyme:

  • It is a protein and is, therefore, destroyed by heating.
  • It acts only on one kind of substance called the substrate i.e. it is specific.
  • It always forms the same end-product(s) from the substrate.
  • It only affects the rate of a chemical reaction and always speeds up the reaction.

Question 2.

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

Answer:

The small intestine is the most important organ of the digestive system as it serves both, for digestion and absorption. It receives two digestive juices; the bile and the pancreatic juice in the duodenum. These two juices virtually complete the digestion of starch, proteins, carbohydrates, etc. After the breakdown of food, the small intestine absorbs simple substances such as glucose, amino acids, etc.

Question 3.

How is the liver an important organ in our body?

Answer:

Liver is an important organ in our body as it serves the following functions:

  • Production of bile
  • Control of blood sugar levels
  • Control of amino acid levels
  • Synthesis of foetal red blood cells
  • Produce fibrinogen and heparin
  • Regulate blood volume
  • Destroy dead red blood cells
  • Store vitamin and minerals
  • Excrete toxic and metallic poisons
  • Produce heat
  • Detoxification

Question 4.

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

Answer:

REGION ENZYME ACTION

ON

FOOD

Stomach Pepsin Acts on proteins

and

converts

it into polypeptides

Small intestine
Duodenum Amylopectin Acts on

starch

and

converts

it into

maltose

Trypsin Acts on remaining proteins, proteoses

and

peptones

to produce peptides

and

amino

acids

Ileum Erepsin Acts on proteins

and polypeptides and

converts

them into small

peptides

and

amino

acids

Sucrase Acts on sucrose

and

converts

it into

glucose

and

fructose

Lactase Acts on lactose

and

converts

it into

glucose

and

galactose

 

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?

Answer:

Test for starch:
  • Take the food item to be tested. Put it into a test-tube containing water and boil to make a solution.
  • Cool the solution and add 2-3 drops of dilute iodine solution to it.
  • Blue-black colour of the solution indicates the presence of starch in the food item.
Test for proteins:
  • Take the food item to be tested in a test tube.
  • Add few drops of dilute nitric acid to it.
  • Heat the test-tube gently.
  • Rinse off the acid with water and add few drops of ammonium hydroxide to it.
  • Colour change from colourless to yellow and then from yellow to orange red indicates the presence of protein in the food item.

—  : End of Digestive System D. Long Answer Class-9 ICSE Biology Solutions :–

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