Samacheer Kalvi 9th Science Solutions Chapter 22 Pdf

Tamilnadu Board Samacheer Kalvi 9th Science Solutions Chapter 22: Tamilnadu State Board Solution Class 10 Science Chapter 22 – World of Microbes.

Samacheer Kalvi 9th Science Solutions Chapter 22: Overview

Board	Samacheer Kalvi
Class	9
Subject	Science
Chapter	22
Chapter Name	World of Microbes

Samacheer Kalvi 9th Science Solutions Chapter 22 World of Microbes

Choose the correct answer.

1.) Which of the following is transmitted through air?

a.) Tuberculosis

b.) Meningitis

c.) Typhoid

d.) Cholera

Ans:a. Tuberculosis

Explanation: Because, it is transmitted through the droplet infection from sputum of infected person.

2.) One of the means of indirect transmission of a disease is

a.) sneezing

b.) coughing

c.) vectors

d.) droplet infection

Ans:c. vectors

Explanation: Because, vector is an agent that acts as an intermediate carrier of the pathogen.

3.) Diphtheria affects the

a.) lungs

b.) throat

c.) blood

d.) liver

Ans:b. throat

Explanation: Because, diphtheria affects the upper respiratory tract that is nose, throat.

4.) The primary organ infected during tuberculosis is

a.) bone marrow

b.) intestine

c.) spleen

d.) lungs

Ans:d. lungs

Explanation: Because, tuberculosis directly affects the lungs as it is transmitted through the droplet infection from sputum of infected person.

5.)Microbes that generally enter the body through nose are likely to affect

a.) gut

b.) lungs

c.) liver

d.) lymph nodes

Ans:b. lungs

Explanation: Because, nose, throat and lungs are upper respiratory organs connected internally to each other.

6.) The organ affected by jaundice is

a.) liver

b.) lungs

c.) kidney

d.) brain

Ans:a. liver

Explanation: Because, jaundice directly affects the liver.

7.) Poliomyelitis virus enters the body through

a.) skin

b.) mouth and nose

c.) ears

d.) eye

Ans: b. mouth and nose

Fill in the blanks.

1) __________ break down organic matter and animal waste into ammonia.

Ans: Nitrification break down organic matter and animal waste into ammonia

2) Typhoid fever is caused by __________.

Ans: Typhoid fever is caused by Salmonella typhi.

3) H1N1 virus causes __________.

Ans:H1N1 virus causesSwine Flu.

4) __________ is a vector of viral disease dengue.

Ans:Aedes aegypti mosquito is a vector of viral disease dengue.

5) __________ Vaccine gives considerable protection against tuberculosis.

Ans:BCG vaccine gives considerable protection against tuberculosis

6) Cholera is caused by __________ and malaria is caused by __________.

Ans: Cholera is caused by Vibrio cholera and malaria is caused by Plasmodium.

III. Expand the following.

Ans:

i) ORS: Oral Rehydration Solution

ii) HIV : Human Immunodeficiency Virus

iii) DPT: Diphtheria, Pertussis and Tetanus

iv) WHO: World Health Organization

v) BCG: Bacillus Calmette Guerin

Pick out the odd one.

Ans:

i) AIDS, Retrovirus, Lymphocytes, BCG,

BCG, because BCG is the vaccine which protects against tuberculosis.

ii) Bacterial disease, Rabies, Cholera, Common cold and Influenza.

Rabies, because it is virus which is spread through the saliva of infected person.

State whether true or false. If false, correct the statement.

1.) Rhizobium, associated with root nodules of leguminous plants fixes atmospheric nitrogen

Ans: True

Because, it is symbiotic microbe which converts atmospheric nitrogen to available form of nitrogen.

2.) Non- infectious diseases remain confined to the person who develops the disease and do not spread to others.

Ans: True

Because, it cannot spread or infect to the other persons.

3.) The process of vaccination was developed by Jenner.

Ans: True

4.) Hepatitis B is more dangerous than Hepatitis A.

Ans: True

Because, it is transferred from infected mother to their babies or by sexual contact. It is also transmitted by contact with infected persons secretion such as saliva, sweat, tears, breast milk and blood.

Match the following.

Ans:

1.) Swine flu: Influenza virus H1N1

2.) Genital warts: Human Papilloma virus

3.) AIDS: Human Immunodeficiency Virus

4.) Tuberculosis: Mycobacterium

VII. Define the following.

Ans:

1.) Pathogen :

Pathogen is the biological agent that causes disease to its host.

For example: bacteria, viruses etc.

2.) Vaccines :

This are prepared by killing or making the microbes inactive. This inactive microbes are unable to cause disease but stimulate the body to produce antibodies against the antigen in the microbes.

3.) Bacteriophages:

The viruses which infect bacterial cells are called as bacteriophage.

For example: T4 bacteriophage.

4.) Prions:

Prions are viral particles which contains only proteins. They do not contain nucleic acid.

They are infectious and smaller than viruses. They are found in neurons and are rod shaped.

VIII.Answer very briefly.

1.) Distinguish between Virion and Viroid.

Ans:

Virion:

Virion is the simple virus particle which grow and multiply only on living cells.
They can live in plants, animals, human beings and even bacteria.

Viroid:

It is a free pathogenic RNA of virus.
They occurs in plant cells and also produces diseases in plants.

2.) Name the vector of the malarial parasite. Mention the species of malarial parasite which cause malignant and fatal malaria.

Ans:

Malaria is the one of the major health problem of developing countries.

It is caused by Protozoan parasite Plasmodium.

Malaria caused by Plasmodium falciparum is malignant and fatal.

Malaria spreads through the bite of an insect vector, the female Anopheles mosquito which feeds on human blood and usually lasts less than 10 days.

3.) What is triple antigen? Mention the disease which can be prevented by using the antigen.

Ans:

DPT which is also called as triple vaccine because it is a combined vaccine for protection against Diphtheria, Pertussis i.e. whooping cough and Tetanus.

4.) Name the chronic diseases associated with respiratory system.

Ans:

The chronic diseases associated with the respiratory tract are as follows:

Tuberculosis caused by Mycobacterium tuberculosis affects the lungs.

Diphtheria caused by Corynebacterium dipetherae affects the upper respiratory tract that is nose and throat.

Whooping cough caused by Bordetalla pertussis affects the respiratory tract.

5.) Name the organism causing diarrhoeal disease and give one precaution against it.

Ans:

Chlorella is the acute diarrhoeal disease which is caused by Vibrio cholerae.

It is transmitted through contaminated food, water oral route and through houseflies.

It affects the intestinal tract.

It is prevented by taking hygienic sanitary condition, intake of oral rehydration solution (ORS).

6.) Name two common mosquitoes and the diseases they transmit.

Ans:

The diseases caused by common mosquito are as given below:

Malaria caused by Plasmodium falciparum is malignant and fatal.

It spreads through the bite of an insect vector, the female Anopheles mosquito which feeds on human blood and usually lasts less than 10 days.

Chikunguniya is caused by virus and it is transmitted in humans by the bite of infected Aedes aegypti mosquito during day time.

Dengue which is known as break bone fever is caused by virus and it is transmitted by Aedes aegypti mosquito.

Answer briefly.

1.) Give an account of classification of bacteria based on the shape.

Ans:

Bacteria are microscopic, single celled prokaryotic organisms without nucleus and cell organelles. Most of the bacterial species exist as a single celled forms while some appears as a filaments of loosely joined cells. Their size varies from less than 1-10 um in length and 0.2-1 um in width. They may be motile or non-motile.

On the basis of their shapes bacteria are classified as follows.

1.) Spherical shaped bacteria

Spherical shaped bacteria are called as cocci or coccus for a single cell.

2.) Rod shaped bacteria

Rod shaped bacteria are called as bacilli or bacillus for a single cell.

3.) Spiral shaped bacteria

Spiral shaped bacteria are called as spirilla or spirillum for a single cell.

2) Describe the role of microbes in agriculture and industries.

Ans:

Microbes in agriculture:

Microbes play most important role in agriculture as bio control agents and bio fertilizers.

They plays very important role in the cycling of elements like carbon, nitrogen, oxygen, sulphur and phosphorus which are called as biological scavengers.

1) Microbes as bio fertilizers:

Microorganisms which enrich the soil with nutrients are called as bio fertilizers.

Bacteria, cyanobacteria and fungi are the main sources of bio fertilizers.

Also nitrogen is one of the main source of plant materials.

Atmospheric nitrogen can be converted into available form of nitrogen by microbes either by in free living conditions or by having symbiotic relationship with the plants like Azotobacter, Nitrosomonas Nostoc, symbiotic microbes like Rhizobium, Frankia etc.

2) Microbes as biological agents

Microorganisms used for controlling harmful or pathogenic organisms and pests of plants are called as biocontrol agents. Bacillus thuringienesis is a species of bacteria that produces a protein called as cry protein. This protein is toxic to the insect larva and kills them.

Microbes in industries:

Microorganisms play most important role in the production of wide variety of valuable products for the welfare of human beings.

1.) Production of fermented beverages:

Beverages like wine are produced by fermentation of grape fruits by Saccharomyces cerevisiae.

2.) Curing of coffee beans, tea leaves and tobacco leaves:

Beans of coffee and cocoa, leaves of tea and tobacco are fermented by the bacteria Bacillus megaterium which gives the special aroma or odor.

1) Production of curds:

Lactobacillus sp. converts milk to curds.

2) Production of organic acids, enzymes and vitamins:

Oxalic acid, acetic acid and citric acid are produced by fungus Aspergillus niger. Enzymes like lipase, invertase, proteases and glucose oxidase are derived from microbes. Yeasts are rich sources of vitamin B complex.

3) Explain the various types of viruses with examples.

Ans:

Viruses are non-cellular, self-replicating parasites. They are made up of a protein that covers the central nucleic acid molecule either RNA or DNA. A simple virus particle is often called as virion which grow and multiply only in living cells.

Viruses are classified as follows.

1.) Plant viruses:

Viruses that infects plants are called as plant viruses.
For example: Tobacco mosaic virus, cauliflower mosaic virus, potato virus etc.

2.) Animal viruses:

Viruses that infects animals are called as animal viruses.
For example: Adenovirus, Retroviruses, Influenza virus, polio virus etc.

3.) Bacteriophages:

Viruses that infects bacterial cells are called as bacteriophages.
For example: T4 bacteriophage.

4) Suggest the immunization schedule for a new born baby till 12 months of age. Why it is necessary to follow the schedule?

Ans:

The world health organization in the year 1970 has given the schedule of immunization for children. According to this schedule all the children should have to give the all doses properly at proper age. Due to which they get immunized and will be protected from diseases in future already.

The immunization schedule for children is as follows

Age	Vaccine	Dosage
New born	BCG	1^st dose
15 days	Oral Polio	1^st dose
6^th week	DPT and Polio	1^st dose
10^th week	DPT and Polio	1^st dose
14^th week	DPT and Polio	1^st dose
9-12 months	Measles	1^st dose

Assertion and reason type questions. Mark the correct statement as.

a) If both A and R are true and R is correct explanation of A.

b) If both A and R are true but R is not the correct explanation of A.

c) If A is true but R is false.

d) If both A and R are false.

1.) Assertion: Chicken pox is a disease indicated by scars and marks in the body.

Reason: Chicken pox causes rashes on face and further spreads throughout the body.

Ans: a) if both A and R are true and R is correct explanation of A

2.)Assertion: Dengue can be treated by intake of antibiotics.

Reason: Antibiotics blocks the multiplication of viruses.

Ans: d) If both A and R are false

Higher Order Thinking Skills.

1) Suggest precautionary measures you can take in your school to reduce the incidence of infectious disease.

Ans:

Precautionary measures that can be take in our school to reduce the incidence of infectious disease are as follows.

We all keep classrooms, benches clean every day.
While in lunch time, we wash our hands properly with hand wash.
The ill persons or students are advised to take rest at home.
At weekend we all do cleanliness in school campus and announcement regarding it are made.
For privacy, clean toilets and ladies washrooms are also used by students.
The taps of water at drinking water tank are washed and cleaned daily.
One staff member is allotted to check all this requirements and sanitation facilities in our school.
Sanitary machines are also available for cleaning purpose.

2) Tejas suffered from typhoid while, Sachin suffered from tuberculosis. Which disease could have caused more damage and why?

Ans:

Typhoid is the enteric fever caused by Salmonella typhi. It is transmitted through contaminated food and water with faeces of infected person and through houseflies.
It directly affects the small intestine and the symptoms are high fever, weakness, abdominal pain, headache, loss of appetite, rashes on chest and upper abdomen.
Typhoid is treated if the patient reaches the doctor in proper time. The typhoid vaccine are also given to the patient which prevent from further typhoid in future. We have to take improvements of basic sanitation and treatment with antibiotic drugs.

Tuberculosis is caused by Mycobacterium tuberculosis and it is transmitted through the droplet infection from sputum of infected person. It directly affects the lungs. The symptoms found are persistent cough, chest pain, loss of weight and appetite.
But, after attacking to lungs it affects the bones also. And after certain treatment also, the organism remains dominant in the body. If after treatment again the immunity of patients become less then it will be affected again by tuberculosis.

Hence, tuberculosis is more dangerous than typhoid.