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 :–
Return to Return to Concise Selina ICSE Biology Class-9
Thanks
Please share with your friends