Balbharti Maharashtra State Board Class 9 Science Solutions Chapter 8 Useful and Harmful Microbes Notes, Textbook Exercise Important Questions and Answers.

Class 9 Science Chapter 8 Useful and Harmful Microbes Textbook Questions and Answers

1. Complete the statements using the proper option from those given below. Explain the statements. (mycotoxins, budding, rhizobium)

a. Yeast reproduces asexually by the …………………….. method.
Answer:
The yeast cells develop small round bodies on the parent cell. These are called buds. New daughter cells develop from these buds.

b. Toxins of fungal origin are called …………………….. .
Answer:
Mycotoxins are poisonous chemicals released into the food by fungi. This makes the food poisonous.

c. Leguminous plants can produce more proteins due to …………………….. .
Answer:

2. Write the names of microbes found in the following food materials.
yogurt, bread, root nodules of leguminous plants, idli, dosa, spoiled potato curry.
Answer:

3. Identify the odd word out and say why it is the odd one?

a. Pneumonia, diphtheria, chicken pox, cholera.
Answer:
Chickenpox. It is caused by a virus, whereas others are caused by bacteria.

b. Lactobacilli, rhizobia, yeast, clostridia.
Answer:
Yeast. It is a fungus, whereas the rest are bacteria.

c. Root rot, rust (tambura), rubella, mozaic.
Answer:
Rubella. It is a disease of humans, whereas the rest are diseases of plants.

4. Give scientific reasons.

a. Foam accumulates on a the surface of ‘dal’ kept for a long time in summer.
Answer:

b. Why are naphthalene balls kept with clothes to be put away.
Answer:

5. Write down the modes of infection and the preventive measures against fungal diseases.
Answer:

6. Match the pairs.

‘A’ group ‘B’ group
1. Rhizobium a. Food poisoning
2. Clostridium b. Nitrogen fixation
3. Penicillium c. Bakery products
4. Yeast d. Production of antibiotics
Answer:
(1 – b),
(2 – a),
(3 – d),
(4 – c)

7. Answer the following questions.

a. Which vaccines are given to infants? Why?
Answer:

b. How is a vaccine produced?
Answer:

c. How do antibiotics cure disease?
Answer:
Antibiotics cure diseases by destroying or preventing the growth of harmful micro-organisms.

d. Are the antibiotics given to humans and animals the same? Why?
Answer:

e. Why is it necessary to safely store the pathogens of a disease against which vaccines are to be produced?
Answer:

8. Answer the following questions in brief.

a. What are ‘broad-spectrum antibiotics’?
b. What is fermentation?
Answer:

c. Define ‘Antibiotic’.
Answer:

Class 9 Science Chapter 8 Useful and Harmful Microbes Intext Questions and Answers

Can you recall?

Question 1.
What is meant by microbes? What are their characteristics?
Answer:
Microbes are tiny microscopic organisms which cannot be seen with the unaided eye.

Characteristics of Microbes.

Question 2.
How do you observe microbes?
Answer:
Microbes are observed using a microscope.

Answer the following.

Question 1.
Why are wineries located near Nashik in Maharashtra?
Answer:

Question 2.
Find out the uses of fungi to plants and animals?
Answer:

Question 3.
What is the structure of lichen, a condiment? Where else is it used?
Answer:

Open-ended questions

Answer the following questions:

Class 9 Science Chapter 8 Useful And Harmful Microbes Exercise Question 1.
How is yoghurt made from milk? What exactly happens in this process?
Answer:

Useful And Harmful Microbes Class 9 Exercise Question 2.
Sometimes, you may notice a black powder or white discs floating on the pickle or murabba, when a jar is opened after a long time. What exactly is this? Why are such food items not good to eat?
Answer:

8 Useful And Harmful Microbes Class 9 Question 3.
How many different industries depend upon the Lactobacilli bacteria?
Answer:
Industries like milk products, cider, cocoa, pickles, pharmaceuticals depend on Lactobacilli bacteria.

Useful And Harmful Microbes Class 9 Question 4.
Which types of cottage industries and factories can be started in areas with abundant milk production?
Answer:
Cottage industries like the manufacture of milk products like ghee, cheese, paneer, curd, shrikhand, etc. and chocolate making can be started in areas with abundant milk production.

9th Class Science Chapter 8 Useful And Harmful Microbes Exercise Question 5.
Which changes do you notice in leather articles and gunny (jute) bags during the rainy season?
Answer:
In rainy season we can notice whitish-green cotton-like growth or black powder or white discs on leather articles and gunny (jute) bags during the rainy season as these articles are infected by fungus.

Class 9th Science Chapter 8 Useful And Harmful Microbes Exercise Question 6.
For how long afterwards can you use those articles?
Answer:
Those articles cannot be used for long as they wear out and do not last long.

Question 7.
Why do these articles not get spoilt during the summer or winter?
Answer:

Question 8.
Why do doctors advise you to take yoghurt or buttermilk if you have indigestion or abdominal discomfort?
Answer:

Question 9.
Sometimes, yoghurt becomes bitter and froths up. Why does this happen?
Answer:

Question 10.
Which different milk products are obtained at home by fermentation of the cream from the milk?
Answer:
Yoghurt, buttermilk, ghee, cheese, shrikhand, sour cream, etc.

Question 11.
Recently, it has been made compulsory in India and some other countries to mix 10% ethanol with fuels like petrol and diesel. What is the reason for this?
Answer:

Question 12.
Chapattis made from wheat only swell up but bread becomes spongy, soft and easy to digest. Why is it so?
Answer:

Question 13.
Salt is applied on the inner surface of pickle jars and the pickle is covered with oil. Why is this done?
Answer:

Question 14.
Which preservatives are mixed with ready to eat foods to prevent them from spoiling?
Answer:
Common salt, sugar, sodium benzoate, citric acid, sodium meta-bi-sulfite etc. are some 1 of the preservatives mixed with ready-to-eat foods to prevent them from spoiling.

Question 15.
Which plant and animal diseases are caused by micro-organisms and what are the 1 measures to be taken against them? Answer:
Plant diseases:

Preventive Measures:

Animal diseases:

Preventive Measures:

Answer the following questions:

Question 1.
Bring ‘active dry yeast’ from the market. Mix a spoonful of yeast, two spoonfuls sugar with a sufficient quantity of lukewarm water in a bottle. Fix a colourless, transparent balloon on the mouth of that bottle.

What changes do you observe after 10 minutes? Mix limewater with the gas accumulated in the balloon. Collect that limewater in a beaker and observe it. What do you notice?

Class 9 Science Chapter 8 Useful and Harmful Microbes Additional Important Questions and Answers

Select the correct option:

Question 1.
The rod-shaped bacteria found in milk or buttermilk are called ……………………. .
(a) Rhizobium
(b) Clostridium
(c) Lactobacilli
(d) Saccharomyces
Answer:
(c) Lactobacilli

Question 2.
Yoghurt has a specific sour taste due to ……………………. .
(a) lactic acid
(b) citric acid
(c) acetic acid
(d) alcohol
Answer:
(a) lactic acid

Question 3.
Bacteria found in the root nodules of leguminous plants are ……………………. .
(a) clostridium
(b) streptococcus
(c) Lactobacilli
(d) Rhizobium
Answer:
(d) Rhizobium

Question 4.
A mutually beneficial relationship is called ……………………. .
(a) symbiosis
(b) parasitism
(c) autotropism
(d) none of these
Answer:
(a) symbiosis

Question 5.
Carbon compounds obtained from bacteria and fungi for destroying or preventing the growth of harmful micro-organisms are called ……………………. .
(a) probiotics
(b) antibiotics
(c) antibodies
(d) antigens
Answer:
(b) antibiotics

Question 6.
Fungi release ……………………. into the food, making the food poisonous.
(a) cyanotoxins
(b) dinotoxins
(c) mycotoxins
(d) cytotoxins
Answer:
(c) mycotoxins

Question 7.
……………………. produce bottle-shaped endospores in adverse conditions.
(a) Lactobacilli
(b) Clostridium
(c) Yeast
(d) Rhizobium
Answer:
(b) Clostridium

Question 8.
……………………. conducted important research on the toxin responsible for gas gangrene and the antitoxin responsible for treating it.
(a) Ida Bengston
(b) Van Ermengem
(c) Louis Pasteur
(d) Alexander Fleming
Answer:
(a) Ida Bengston

Question 9.
……………………. is a smokeless and high quality fuel.
(a) Methanol
(b) Ethanol
(c) Petrol
(d) Diesel
Answer:
(b) Ethanol

Question 10.
Antibiotics mainly act against ……………………. .
(a) bacteria
(b) viruses
(c) algae
(d) fungi
Answer:
(a) Bacteria

Question 11.
……………………. is a broad-spectrum antibiotic.
(a) Gentamycin
(b) Penicillin
(c) Amoxicillin
(d) Erythromycin
Answer:
(c) Amoxicillin

Question 12.
……………………. is a narrow-spectrum antibiotic.
(a) Ampicillin
(b) Amoxicillin
(c) Tetracyclin
(d) Penicillin
Answer:
(d) Penicillin

Question 13.
Antibiotic penicillin was discovered by ……………………. .
(a) Louis Pasteur
(b) Alexander Fleming
(c) Ida Bengston
(d) Van Ermengem
Answer:
(b) Alexander Fleming

Question 14.
……………………. proved that the anaerobic bacterium Clostridium botulinum is responsible for food poisoning.
(a) Louis Pasteur
(b) Ida Bengston
(c) Alexander Fleming
(d) Van Ermengem
Answer:
(d) Van Ermengem

Question 15.
AIDS is caused by ……………………. .
(a) virus
(b) bacteria
(c) protozoa
(d) fungi
Answer:
(a) Virus

Question 16.
Dengue is caused by ……………………. .
(a) droplets spread in air
(b) contact with infected person
(c) mosquito bite
(d) contaminated water and food
Answer:
(c)mosquitobite

Question 17.
Pneumonia is caused by ……………………. .
(a) virus
(b) bacteria
(c) fungi
(d) protozoa
Answer:
(b) bacteria

Question 18.
……………………. can be prevented by vaccination.
(a) Malaria
(b) AIDS
(c) Leprosy
(d) Chicken pox
Answer:
(d) Chicken pox

Question 19.
Malaria is caused by ……………………. .
(a) protozoa
(b) bacteria
(c) fungi
(d) virus
Answer:
(a) protozoa

Question 20.
Bird flu (H₇N₉) and swine flu (H₁N₁) are caused by ……………………. .
(a) bacteria
(b) protozoa
(c) fungi
(d) virus
Answer:
(d) virus

Question 21.
The Lactobacilli convert lactose, the sugar in the milk, into ……………………. .
(a) lactic acid
(b) acetic acid
(c) alcohol
(d) citric acid
Answer:
(a) lactic acid

Question 22.
The ……………………. destroys harmful microbes present in the milk.
(a) high pH
(b) neutral pH
(c) low pH
(d) none of these
Answer:
(c) low pH

Question 23.
Lactobacilli kill the harmful bacteria like ……………………. present in the alimentary canal.
(a) Rhizobium
(b) Saccharomyces
(c) Clostridium
(d) Alcanivorax
Answer:
(c) Clostridium

Question 24.
During fermentation, yeast cells convert carbohydrates into ……………………. .
(a) glucose and fructose
(b) alcohol and carbon dioxide
(c) proteins and fats
(d) fatty acids and amino acids
Answer:
(b) alcohol and carbon dioxide

Question 25.
Molasses is fermented with the help of yeast called ……………………. .
(a) Yarrowia lipolytica
(b) Alcanivorax
(c) Rhizobia
(d) Saccharomyces
Answer:
(d) Saccharomyces

Question 26.
A yeast ……………………. is used to absorb the toxins released during the production of palm oil.
(a) Yarrowia lipolytica
(b) Alcanivorax
(c) Saccharomyces cerevisiae
(d) Penicillium
Answer:
(a) Yarrowia lipolytica

Question 27.
The bacteria which spoil cooked food are ……………………. .
(a) Saccharomyces
(b) Lactobacilli
(c) Clostridium
(d) Rhizobium
Answer:
(c) Clostridium

Question 28.
……………………. can grow and reproduce only in living cells.
(a) Bacteria
(b) Viruses
(c) Fungi
(d) Protozoa
Answer:
(b) Viruses

Find the odd man out:

Question 1.
AIDS, Hepatitis, Leprosy, Dengue.
Answer:
Leprosy. It is caused by bacteria, whereas the rest are caused by viruses.

Question 2.
Cholera, Leprosy, Pneumonia, Influenza.
Answer:
Influenza. It is caused by a virus, whereas the rest are caused by bacteria.

Question 3.
Ampicillin, Amoxycillin, Penicillin, Tetracycline.
Answer:
Penicillin. It is a narrow-spectrum antibiotic, whereas others are broad-spectrum antibiotics.

Question 4.
Tetracycline, Penicillin, Gentamycin, Erythromycin.
Answer:
Tetracycline. It is a broad-spectrum antibiotic, whereas others are narrow-spectrum antibiotics.

Complete the analogy:

Question 1.
(1) Dengue : Virus :: Malaria : …………………………. .
(2) Hepatitis : Virus :: Pneumonia : …………………………. .
(3) Cholera : Bacteria :: Swine flu : …………………………. .
(4) Swine flu : HJNJ : : Bird Flu : …………………………. .
(5) Measles : Virus :: Ringworm : …………………………. .
(6) Yoghurt: Lactobacilli : : Bread : …………………………. .
(7) Oil spills: Alcanivorax :: Absorption of arsenic : …………………………. .
(8) Rhizobium : Nitrogen fixation : : Clostridium : …………………………. .
Answer:
(1) Protozoa
(2) Bacteria
(3) Virus
(4) HyN9
(5) Fungi
(6) Yeast
(7) Saccharomyces cerevisiae
(8) Food poisoning.

Match the columns:

Question 1.

Answer:
(1 – d),
(2 – b),
(3 – a),
(4 – c)

State whether the following statements are true or false. Correct the false statements:

(1) Lactobacilli are aerobic bacteria.
(2) Lactobacilli converts lactose sugar into alcohol.
(3) Yoghurt has a specific sour taste due to acetic acid.
(4) The bacteria Clostridium are present in the root . nodules of leguminous plants.
(5) Yeast cell is a prokaryotic cell.
(6) The use of Rhizobium has helped to reduce the use of chemical fertilizers.
(7) Ethanol is a smokeless and high quality fuel.
(8) A yeast, Saccharomyces cerevisiae is used for absorbing toxins released during palm oil production.
(9) Gentamycin is a narrow-spectrum antibiotic.
(10) Antibiotics mainly act against bacteria.
(11) Oil spills in oceans are cleared with the help of Clostridium bacteria.
(12) Tetracycline is a narrow-spectrum antibiotic.
(13) Amoxicillin is a broad-spectrum antibiotic.
(14) Penicillin is a group of antibiotics obtained from a fungus Saccharomyces.
(15) Antibiotic Penicillin was discovered by Alexander Fleming.
(16) The bacteria Lactobacilli cause food-poisoning.
(17) Clostridium bacteria grow in aerobic conditions.
(18) AIDS is caused by a virus.
(19) Influenza is caused by a bacteria.
(20) Antibiotics useful to one person can be suggested to others also.
(21) Dengue is caused by a bacteria.
(22) Dandruff and ringworm are caused by fungi.
(23) Pneumonia is spread through droplets spread in air by infected person.
(24) Chicken pox spread due to contaminated food and water.
(25) Ida Bengston was honoured with the Typhoid Medal’ in 1947.
Answer:
(1) False. Lactobacilli are anaerobic bacteria.
(2) False. The Lactobacilli converts lactose sugar into lactic acid.
(3) False. Yogurt has a specific sour taste due to lactic acid.
(4) False. The bacteria Rhizobium are present in the root nodules of leguminous plants.
(5) False. Yeast cell is a eukaryotic cell.
(6) True.
(7) True.
(8) False. A yeast, Yarrowia lipolytic is used to absorb the toxins released during the production of palm oil.
(9) True.
(10) True.
(11) False. Oil spills in oceans are cleared with the help of Alcanivorax bacteria.
(12) False. Tetracycline is a broad-spectrum antibiotic.
(13) True.
(14) False. Penicillin is a group of antibiotics obtained from a fungus Penicillium.
(15) True.
(16) False. The bacteria Clostridium cause food? poisoning.
(17) False. Clostridium bacteria grow in anaerobic conditions.
(18) True.
(19) False. Influenza is caused by a virus.
(20) False. Antibiotics useful to one person cannot be suggested to others as different diseases require different antibiotics.
(21) False. Dengue is caused by a virus.
(22) True.
(23) True.
(24) False. Chicken pox spread due to contact with infected person.
(25) False. Ida Bengston was honoured with the ‘Typhus Medal’ in 1947.

Complete the statements using the proper option from those given below. Explain the statements: (mycotoxins, budding, Rhizobium, molasses, endospores, broad-spectrum, Lactobacilli)

Question 1.
Lactobacilli bacteria are used for making yoghurt.
Answer:
The lactobacilli convert lactose, the sugar in the milk, into lactic acid. As a result, the pH of milk decreases causing a coagulation of milk proteins. Milk changes into yogurt.

Question 2.
The use of Rhizobium has helped to reduce the use of chemical fertilizers.
Answer:
Rhizobium bacteria are found in the root nodules of leguminous plants. They help to convert atmospheric nitrogen into nitrogen compounds and provide it to the plants. This helps to reduce the use of chemical fertilizers and their adverse effects.

Question 3.
Amoxicillin is a broad-spectrum antibiotic.
Answer:
This antibiotic is useful against a wide variety of bacteria. It is used against pathogens which cannot be identified during symptoms of a disease.

Question 4.
Ethanol is produced by the fermentation of molasses.
Answer:
Molasses is produced from sugarcane juice. It is rich in carbohydrates. When it is fermented with the help of the yeast called Saccharomyces, ethanol (C2H5OH) is produced.

Question 5.
Clostridium bacteria produce bottle-shaped endospores.
Answer:
These endospores help them to survive in adverse conditions.

Give scientific reasons:

Question 1.
Lactobacilli are used for making yoghurt from milk.
Answer:

Question 2.
Antibiotics should be taken only when prescribed by a doctor.
Answer:

Question 3.
Nowadays, seeds are coated with Rhizobial solution or powder before sowing.
Answer:

Question 4.
Antibiotics are not effective against common cold or influenza.
Answer:

Question 5.
Cotton fabrics, gunny bags, leather items and wooden items do not last long.
Answer:

Question 6.
Food on which fungi has grown cannot be eaten.
Answer:

Write short notes:

Question 1.
Rhizobial inoculation.
Answer:

Question 2.
Bio-remediation.
Answer:

Question 4.
Clostridium.
Answer:

Write down the mode of infection and preventive measures for the following:

Question 1.
Write down the causative pathogen, mode of infection and preventive measures of AIDS.
Answer:

Question 2.
Write down the modes of infection and preventive measures against Bird Flu (H7N9) and Swine Flu (HjN.,).
Answer:

Question 3.
Write down the modes of infection and preventive measures against Malaria and dengue.
Answer:

Question 4.
Write down the modes of infection and preventive measures against Pneumonia.
Answer:

Question 5.
Write down the modes of infection and preventive measures for leprosy.
Answer:

Question 5.
What are the modes of infection and preventive measures for Hepatitis?
Answer:

Question 6.
What are the modes of infection and preventive measures for Influenza.
Answer:

Answer the following questions:

Question 1.
How is bread made?
Answer:

Question 2.
What is the advantage of Rhizobium to farmers?
Answer:

Question 3.
How can we observe Lactobacilli in buttermilk?
Answer:

Question 4.
What is symbiosis? Give example.
Answer:

Complete the following table:

Question 1.
The spread and prevention of disease
Answer:

Question 2.
Different species of Clostridium bacteria and the diseases caused by them.
Answer:

Answer in detail:

Question 1.
How is alcohol produced?
Answer:

Question 2.
Give the uses of Lactobacilli.
Answer:
Uses of Lactobacilli:

Question 3.
What is Penicillin? What is it used for?
Answer:

Question 4.
How was the antibiotic penicillin discovered?
Answer:

Question 5.
What are the precautions to be followed while taking antibiotics?
Answer:

Question 6.
How can we observe Rhizobium bacteria in the roots of leguminous plant?
Answer: