Maharashtra Board Class 9 Science Chapter 8 Useful and Harmful Microbes Solutions

Std 9 Science Chapter 8 Useful And Harmful Microbes Question Answer Maharashtra Board

Class 9 Science Chapter 8 Useful And Harmful Microbes Question Answer Maharashtra Board

Question 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: budding
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
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: rhizobium
(i) Nitrogenous compounds are required to produce proteins.
(ii) Rhizobia produce nitrogenous compounds by fixing atmospheric nitrogen and make it available for their host plants like leguminous plants.
In simple words: This question tests understanding of key microbial processes and products: yeast reproduction by budding, fungal toxins (mycotoxins), and the role of rhizobium in nitrogen fixation for leguminous plants.

🎯 Exam Tip: When explaining biological processes, ensure to define key terms and describe the mechanism clearly, linking cause and effect for full marks.

Question 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:

🎯 Exam Tip: Memorize the key microbes associated with different food products and biological processes, as this is a common type of factual recall question.

Question 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.
In simple words: This question requires identifying the outlier in a group based on a scientific classification, such as the type of pathogen or the affected organism.

🎯 Exam Tip: For "odd one out" questions, always provide the specific reason for your choice, classifying the common characteristic of the remaining items.

Question 4. Give scientific reasons.
a. Foam accumulates on a the surface of 'dal' kept for a long time in summer.
Answer:
- Dal is rich in proteins.
- During summer, bacteria attack the dal and cause fermentation resulting in the production of carbon dioxide gas.
- Therefore, foam accumulates on the surface of the 'dal' kept for long time in summer.
b. Why are naphthalene balls kept with clothes to be put away.
Answer:
- Naphthalene balls are balls of chemical pesticide and deodorant.
- They help to kill or repel insects such as moths, cockroaches, mice etc.
- Therefore, naphthalene balls are kept with clothes to be put away to prevent clothes from getting damaged.
In simple words: These scientific reasons explain common observations based on microbial activity (fermentation causing foam) and chemical properties (naphthalene balls acting as repellents).

🎯 Exam Tip: When giving scientific reasons, always state the underlying principle or mechanism (e.g., fermentation, chemical repellents) and connect it directly to the observed phenomenon.

Question 5. Write down the modes of infection and the preventive measures against fungal diseases.
Answer:
- Mode of infection: Contact with infected person or his/her belongings like clothes.
- Preventive measure: Personal hygiene and avoid contact with infected person.
In simple words: Fungal diseases typically spread through direct contact, and prevention involves maintaining personal cleanliness and avoiding close interaction with infected individuals or their items.

🎯 Exam Tip: For disease-related questions, always clearly state both the mode of transmission and practical preventive measures.

Question 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)
In simple words: This exercise matches various microbes with their primary functions or associated conditions, such as Rhizobium for nitrogen fixation or Yeast for bakery products.

🎯 Exam Tip: In matching questions, carefully understand the relationship between items in both columns to ensure accurate pairing. Cross-referencing can help confirm answers.

Question 7. Answer the following questions.
a. Which vaccines are given to infants? Why?
Answer:
- Hepatitis A and B, DTP (Diphtheria, Tetanus, Pertussis.) Polio, MMR (Measles, Mumps, Rubella), Chicken pox, Influenza, Tetanus, BCG, Rotavirus, etc.
- Vaccines consist of dead or weakened microbes. When these are swallowed or injected, the body produces antibodies to fight them.
- These antibodies remain in the body and protect it from any future attack of the disease causing microbes.
- Therefore, vaccines are given to infants for preventing diseases.
b. How is a vaccine produced?
Answer:
- Vaccines are made using the disease causing bacteria or virus but in a form that will not harm the human beings.
- Vaccine is made from dead or weakened microbes or their toxins.
- Vaccine stimulates the immune system to produce antibodies which give life-long protection against the disease.
- There are specific vaccines for specific diseases.
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:
- Generally, antibiotics work against any harmful bacteria, whether it is attacking humans or animals.
- But some of them are better suited to humans while some are better for animals. This is due to the adverse effects they show in different species.
- Also, the dosages of antibiotics for humans and animals differ.
e. Why is it necessary to safely store the pathogens of a disease against which vaccines are to be produced?
Answer:
- Pathogens are microbes which can cause diseases in us.
- For the preparation of a vaccine, a particular pathogen is cultured and grown in a laboratory.
- If these pathogens are not safely stored, they many get modified due to environmental factors, resulting in decrease in the efficiency of the vaccine.
- Also, the live pathogens may escape and cause diseases in us.
In simple words: This section covers the basics of vaccination in infants, vaccine production, how antibiotics work, and the importance of safely handling pathogens for vaccine development.

🎯 Exam Tip: Understand the difference between vaccines and antibiotics, their mechanisms of action, and the critical importance of safe pathogen handling in medical research and production.

Question 8. Answer the following questions in brief.
a. What are 'broad-spectrum antibiotics'?
b. What is fermentation?
Answer:
a. - Some antibiotics are useful against a wide variety of bacteria they are called broad-spectrum antibiotics. Examples - Ampicillin, amoxicillin, tetracycline, etc.
- When the pathogen cannot be identified even though the symptoms of the disease are visible, broad-spectrum antibiotics are used.
b. - Yeast uses sugar for food.
- Yeast grows and multiplies rapidly due to the carbon compounds in the sugar solution.
- In the process of obtaining nutrition, yeast cells convert the carbohydrates in the food into alcohol and carbon dioxide.
- Also, the bacteria Lactobacilli convert lactose, the sugar in milk into lactic acid.
- This process is called fermentation.
c. Define 'Antibiotic'.
Answer:
- Carbon compounds obtained from some bacteria and fungi for destroying or preventing the growth of harmful micro-organisms are called antibiotics.
- Antibiotics, a discovery of the 20th century, have brought a revolution in the field of medicine.
- Antibiotics mainly act against bacteria. Some antibiotics can destroy protozoa.
- Whenever a pathogenic micro-organism is definitely known, then narrow-spectrum antibiotics are used. Examples: Penicillin, gentamycin, erythromycin, etc.
In simple words: This section defines broad-spectrum antibiotics, explains the process of fermentation using yeast and lactobacilli, and provides a clear definition of what antibiotics are.

🎯 Exam Tip: Be precise with definitions (e.g., broad-spectrum vs. narrow-spectrum antibiotics) and understand the biochemical processes like fermentation, including key reactants and products.

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.
- They are the smallest organisms on earth.
- They are composed of prokaryotic or eukaryotic cells.
- They can be seen only with the help of a microscope.
- They are found in any kind of environment ranging from coolest polar regions to hottest of deserts. Also found in soil, water and air.
- Some of them are useful, whereas some of them are harmful micro-organisms.
In simple words: Microbes are microscopic organisms invisible to the naked eye, characterized by their small size, cellular structure (prokaryotic or eukaryotic), ubiquitous presence, and diverse roles as useful or harmful organisms.

🎯 Exam Tip: When asked about characteristics, list multiple distinct features for a comprehensive answer. Ensure to mention both prokaryotic and eukaryotic nature.

Question 2. How do you observe microbes?
Answer:
Microbes are observed using a microscope.
In simple words: Microbes are observed using a microscope because they are too small to be seen with the naked eye.

🎯 Exam Tip: Simple factual questions like this require direct and accurate answers. "Microscope" is the key term here.

Answer the following.

Question 1. Why are wineries located near Nashik in Maharashtra?
Answer:
- Nashik in Maharashtra is the leading grape producer in the country as it has the soil suitable for the production of grapes.
- Glucose and fructose, the sugars present in grape juice are fermented with the help of yeast to produce wines. Therefore, wineries are located near Nashik in Maharashtra.
In simple words: Wineries are in Nashik due to its abundant grape production, which provides the necessary sugars (glucose and fructose) for yeast fermentation into wine.

🎯 Exam Tip: Connect geographical location to agricultural resources and subsequent industrial processes. Explain the biological reason (fermentation) for the industry.

Question 2. Find out the uses of fungi to plants and animals?
Answer:
- Fungi decompose the bodies of dead animals and convert them into simple carbon compounds. These substances easily mix with air, water and soil from where they are again absorbed by plants and enter the food chain.
- Some fungi living in symbiotic association with plants help to absorb water and inorganic compounds like nitrate and phosphate.
- Fungi are also used to derive antibiotics like penicillin which are useful to animals.
- Ants grow fungi in their anthill and obtain food from it.
- Some species of wasps and insects lay their eggs in the fungal bodies growing on trees, thus ensuring a food supply for their larvae.
In simple words: Fungi are vital decomposers, form symbiotic relationships with plants for nutrient absorption, are sources of antibiotics for animals, and serve as food sources or hosts for insects.

🎯 Exam Tip: Categorize the uses (decomposition, symbiosis, medicine, food source) to provide a structured and comprehensive answer for the roles of fungi.

Question 3. What is the structure of lichen, a condiment? Where else is it used?
Answer:
- Lichen is a symbiotic association between a fungus and an algae (Cyanobacterium).
- Lichens are sensitive to environmental disturbances and are used in assessing air pollution in an area.
- Lichens are also used in making dyes, perfumes and in traditional medicines.
- A few lichen species are eaten by insects or animals such as reindeer.
In simple words: Lichens are a symbiotic partnership between a fungus and an algae, used as bio-indicators for air pollution, in dyes, perfumes, traditional medicine, and as a food source for some animals.

🎯 Exam Tip: Remember the symbiotic nature of lichens and their diverse applications beyond just a condiment, especially their role as environmental indicators.

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:
- Milk contains sugar called lactose which is broken down with help of Lactobacilli.
- Lactobacilli converts lactose into Lactic Acid. This process is called fermentation. As a result, the pH of milk decreases causing coagulation of milk proteins.
- Thus, milk proteins are separated from other constituents of milk and milk changes to yoghurt.
In simple words: Yoghurt is made by fermenting milk's lactose sugar into lactic acid using Lactobacilli bacteria, which lowers the pH, causing milk proteins to coagulate and thicken.

🎯 Exam Tip: When describing food production processes, identify the key microbe involved, the substrate it acts upon, the main product formed, and the observable changes in the food item.

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:
- A black powder or white disc floating on the pickle or murabba are fungi.
- Different fungal species depend on host (pickle and murabba) for their growth and reproduction.
- During this process, fungi secretes mycotoxins which are poisonous chemicals; which ultimately spoil the food. Consuming such food can cause food poisoning.
- Therefore, such food items are not good to eat.
In simple words: The black powder or white discs are fungi that grow on pickles or murabba, producing poisonous mycotoxins that spoil the food and make it unsafe for consumption.

🎯 Exam Tip: Highlight the danger of microbial growth on food, specifically mentioning the toxic compounds (mycotoxins) produced by fungi that render food unsafe.

Question 3. How many different industries depend upon the Lactobacilli bacteria?
Answer:
Industries like milk products, cider, cocoa, pickles, pharmaceuticals depend on Lactobacilli bacteria.
In simple words: Lactobacilli are crucial for several industries, including dairy products (like yogurt), beverage production (cider), cocoa processing, pickling, and even pharmaceuticals.

🎯 Exam Tip: Provide a diverse list of industries to demonstrate a broad understanding of the applications of Lactobacilli. Specific examples are highly valued.

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.
In simple words: In areas with ample milk, cottage industries can produce various dairy products like ghee, cheese, paneer, curd, and shrikhand, and also chocolate.

🎯 Exam Tip: When discussing industries, list specific products that can be manufactured. This shows detailed knowledge of how raw materials are utilized.

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.
In simple words: During the rainy season, leather and jute items often show whitish-green cotton-like growth or black/white discs, indicating fungal infection due to high moisture.

🎯 Exam Tip: Link environmental conditions (rainy season, moisture) directly to observed changes (fungal growth) on materials like leather and jute.

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.
In simple words: Once infected by fungus, these articles deteriorate quickly and lose their durability, rendering them unusable for an extended period.

🎯 Exam Tip: Emphasize the consequence of microbial damage – reduced lifespan and deterioration of the material.

Question 7. Why do these articles not get spoilt during the summer or winter?
Answer:
- Spores of fungi can germinate when there is sufficient moisture.
- During summer or winter the weather is hot and dry and so fungus cannot grow in such weather.
- Also microbes cannot survive extreme hot or cold temperatures of summer or winter. Therefore, these articles do not get spoilt during summer or winter.
In simple words: Fungal growth requires moisture, which is scarce in the hot and dry summer or cold winter, preventing spoilage of articles during these seasons.

🎯 Exam Tip: Explain the environmental factors (temperature, moisture) that inhibit microbial growth, contrasting them with conditions favorable for spoilage.

Question 8. Why do doctors advise you to take yoghurt or buttermilk if you have indigestion or abdominal discomfort?
Answer:
- The Lactobacilli present in yoghurt or buttermilk help to restore the natural microbial flora in the intestine, thus helping in digestion and absorption of nutrients.
- Also buttermilk helps to cool down the stomach and works as a laxative to ease the congestion during abdominal discomfort.
In simple words: Yoghurt and buttermilk contain beneficial Lactobacilli that restore gut flora, aiding digestion and nutrient absorption, while buttermilk also provides a cooling effect and acts as a mild laxative.

🎯 Exam Tip: Focus on the probiotic benefits of Lactobacilli, their role in gut health, and any additional symptomatic relief provided by the food item.

Question 9. Sometimes, yoghurt becomes bitter and froths up. Why does this happen?
Answer:
- Sometimes yoghurt becomes bitter due to excess fermentation by bacteria.
- Excess amount of lactic acid is produced making the curd bitter.
In simple words: Yoghurt turns bitter and froths due to excessive bacterial fermentation, leading to an overproduction of lactic acid which alters its taste.

🎯 Exam Tip: Link changes in taste and texture to over-fermentation and the accumulation of specific metabolic products like lactic acid.

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.
In simple words: Various fermented milk products like yoghurt, buttermilk, ghee, cheese, shrikhand, and sour cream can be made at home from milk cream.

🎯 Exam Tip: List several common examples of fermented milk products to demonstrate familiarity with home-based dairy processing.

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:
- Ethanol is a smokeless and high quality fuel. So it helps to reduce pollution when mixed with petrol or diesel.
- As petrol or diesel is a fossil fuel less consumption of it will lead to resourceful use of it and making the country self-efficient by moving towards sustainable fuel like ethanol.
In simple words: Ethanol is blended with fossil fuels to reduce air pollution due to its smokeless combustion and to promote sustainable fuel use and national energy self-sufficiency.

🎯 Exam Tip: When discussing policy-related science questions, address both environmental (pollution reduction) and economic/strategic (resource conservation, self-sufficiency) reasons.

Question 12. Chapattis made from wheat only swell up but bread becomes spongy, soft and easy to digest. Why is it so?
Answer:
- The chapatti dough has water, which on heating converts into steam and tries to escape.
- While doing so, it lifts up the upper layer of the chapatti. Therefore, the chapatti swells up.
- Bread is made by adding yeast to the flour.
- In the process of obtaining nutrition, the yeast cells convert the carbohydrates into alcohol and carbon dioxide.
- When this dough is baked, the carbon dioxide escapes out making the bread spongy, soft and easy to digest.
In simple words: Chapattis swell due to steam expanding within the dough, while bread becomes spongy and soft because yeast ferments carbohydrates, producing carbon dioxide that creates air pockets when baked.

🎯 Exam Tip: Clearly differentiate the leavening agents and mechanisms: steam for chapattis and carbon dioxide from yeast fermentation for bread, explaining how each contributes to the final texture.

Question 13. Salt is applied on the inner surface of pickle jars and the pickle is covered with oil. Why is this done?
Answer:
- Salt acts as a preservative. It prevents the growth of bacteria by forcing the microbes to lose water by osmosis. Hence, salt is applied on the inner surface of pickle jars.
- Pickle is covered with oil as oil acts as preservative. It seals off the air from the item that is being pickled and provides an environment in which microbes cannot grow.
In simple words: Salt preserves pickles by dehydrating microbes via osmosis, preventing their growth, while oil forms a barrier against air, creating an anaerobic environment that further inhibits microbial spoilage.

🎯 Exam Tip: Explain the mechanisms of preservation for both salt (osmosis) and oil (anaerobic environment, air seal) and how these actions inhibit microbial growth.

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 of the preservatives mixed with ready-to-eat foods to prevent them from spoiling.
In simple words: Ready-to-eat foods are preserved using common ingredients like salt and sugar, along with chemical preservatives such as sodium benzoate, citric acid, and sodium meta-bi-sulfite.

🎯 Exam Tip: List a variety of common preservatives, including both natural (salt, sugar) and chemical ones, to show comprehensive knowledge.

Question 15. Which plant and animal diseases are caused by micro-organisms and what are the measures to be taken against them?
Answer:
Plant diseases:
- Citrus canker is a bacterial disease that affects trees of citrus fruits.
- Rust of wheat is a fungal disease that affects wheat crops.
- Yellow vein mosaic is a viral disease which affects vegetables like bhindi (okra).
Preventive Measures:
- Seeds which are healthy and disease-free should be selected for sowing.
- Infected plants should be removed.
- Plants should be sprayed with fungicides and germicides to prevent diseases.
Animal diseases:
- Anthrax is a disease that affects cattle. It is caused by a bacterium.
- Foot and mouth is a dangerous disease in cattle caused by a virus.
- Rabies is a viral disease that affects animals.
Preventive Measures:
- The place where animals are kept should be washed with germicides.
- Animals should be dewormed regularly.
- The animals should be treated with necessary antibiotics for infectious diseases.
- They should be regularly vaccinated.
- Take the animals to a veterinary hospital for proper treatment and vaccination.
In simple words: Microorganisms cause various plant diseases (like citrus canker, wheat rust, yellow vein mosaic) and animal diseases (anthrax, foot and mouth, rabies), which are prevented through measures such as selecting healthy seeds, removing infected plants, spraying fungicides, maintaining animal hygiene, deworming, vaccinating, and providing veterinary care.

🎯 Exam Tip: For diseases, provide specific examples for both plants and animals, and ensure that the preventive measures listed are relevant to the type of disease and host.

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?
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र खमीर कोशिकाओं (Yeast cells) की सूक्ष्म संरचना को दर्शाता है, जिसमें कोशिका भित्ति (Cell wall), केंद्रक (Nucleus) और कोशिका द्रव्य (Cytoplasm) जैसे मुख्य भाग दिखाई दे रहे हैं। इसमें एक नवोदित कली (Bud) भी दर्शाई गई है, जो खमीर में अलैंगिक प्रजनन की प्रक्रिया को स्पष्ट करती है, जहाँ एक नई कोशिका मूल कोशिका से निकलती है।
Answer:
- After 10 minutes, the balloon is filled with a gas and gets inflated.
- Lime water turns milky thus proving that the gas accumulated is carbon dioxide.
In simple words: When yeast, sugar, and lukewarm water are mixed, fermentation produces carbon dioxide gas, which inflates a balloon and turns limewater milky, confirming the presence of CO2.

🎯 Exam Tip: When describing an experiment, clearly state the setup, observations, and conclusions, especially for indicators like limewater turning milky, which confirms CO2 presence.

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
In simple words: The bacteria responsible for fermenting milk and found in dairy products like buttermilk are called Lactobacilli.

🎯 Exam Tip: For MCQs, directly recall the correct term or concept. Here, associating "rod-shaped bacteria," "milk," and "buttermilk" immediately points to 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
In simple words: The characteristic sour taste of yoghurt comes from lactic acid, a product of bacterial fermentation of lactose in milk.

🎯 Exam Tip: Understand the chemical byproduct responsible for distinct tastes in fermented foods. Lactic acid is the key agent in dairy fermentation.

Question 3. Bacteria found in the root nodules of leguminous plants are - .
(a) clostridium
(b) streptococcus
(c) Lactobacilli
(d) Rhizobium
Answer: (d) Rhizobium
In simple words: Rhizobium bacteria live symbiotically in the root nodules of leguminous plants, where they fix atmospheric nitrogen.

🎯 Exam Tip: Connect specific bacteria with their known ecological roles or habitats, such as Rhizobium with nitrogen fixation in leguminous plants.

Question 4. A mutually beneficial relationship is called - .
(a) symbiosis
(b) parasitism
(c) autotropism
(d) none of these
Answer: (a) symbiosis
In simple words: Symbiosis is a biological interaction where two different organisms live in close association, both benefiting from the relationship.

🎯 Exam Tip: Know fundamental biological terms and their precise definitions. "Mutually beneficial relationship" is the direct definition of 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
In simple words: Antibiotics are substances derived from microorganisms that can kill or inhibit the growth of other harmful microorganisms.

🎯 Exam Tip: Remember the definition of antibiotics and their origin from bacteria and fungi for scoring well.

Question 6. Fungi release ......................................... into the food, making the food poisonous.
(a) cyanotoxins
(b) dinotoxins
(c) mycotoxins
(d) cytotoxins
Answer: (c) mycotoxins
In simple words: Fungi produce poisonous chemicals called mycotoxins, which can contaminate food and make it unsafe to eat.

🎯 Exam Tip: Knowing the specific term 'mycotoxins' for fungal toxins is key for this type of question.

Question 7. ......................................... produce bottle-shaped endospores in adverse conditions.
(a) Lactobacilli
(b) Clostridium
(c) Yeast
(d) Rhizobium
Answer: (b) Clostridium
In simple words: Clostridium bacteria form tough, bottle-shaped endospores that allow them to survive harsh environments.

🎯 Exam Tip: Understanding the unique characteristic of endospore formation by Clostridium is important here.

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
In simple words: Ida Bengston made significant contributions to understanding and treating gas gangrene by identifying its toxin and antitoxin.

🎯 Exam Tip: Remembering key scientists and their specific contributions to microbiology, like Ida Bengston's work, can be crucial for historical context questions.

Question 9. ......................................... is a smokeless and high quality fuel.
(a) Methanol
(b) Ethanol
(c) Petrol
(d) Diesel
Answer: (b) Ethanol
In simple words: Ethanol is known for its clean combustion, making it a high-quality, smokeless fuel.

🎯 Exam Tip: Focus on the properties of different fuels, especially those considered environmentally friendly or high quality, for related questions.

Question 10. Antibiotics mainly act against ......................................... .
(a) bacteria
(b) viruses
(c) algae
(d) fungi
Answer: (a) Bacteria
In simple words: Most antibiotics are specifically designed to target and kill bacteria, not viruses or other microorganisms.

🎯 Exam Tip: Clearly distinguish between antibiotics (for bacteria) and antivirals (for viruses) to avoid common misconceptions.

Question 11. ......................................... is a broad-spectrum antibiotic.
(a) Gentamycin
(b) Penicillin
(c) Amoxicillin
(d) Erythromycin
Answer: (c) Amoxicillin
In simple words: Amoxicillin is effective against a wide range of bacterial types, making it a broad-spectrum antibiotic.

🎯 Exam Tip: Learn to differentiate between broad-spectrum (effective against many bacteria) and narrow-spectrum antibiotics (effective against specific bacteria).

Question 12. ......................................... is a narrow-spectrum antibiotic.
(a) Ampicillin
(b) Amoxicillin
(c) Tetracyclin
(d) Penicillin
Answer: (d) Penicillin
In simple words: Penicillin is a narrow-spectrum antibiotic, meaning it targets a more limited group of bacteria compared to broad-spectrum options.

🎯 Exam Tip: Knowing examples of both broad-spectrum and narrow-spectrum antibiotics helps in identifying their applications and limitations.

Question 13. Antibiotic penicillin was discovered by ......................................... .
(a) Louis Pasteur
(b) Alexander Fleming
(c) Ida Bengston
(d) Van Ermengem
Answer: (b) Alexander Fleming
In simple words: Alexander Fleming famously discovered penicillin, a revolutionary antibiotic, by observing mold's effect on bacteria.

🎯 Exam Tip: This is a fundamental historical fact in microbiology; remember the scientist and their discovery.

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
In simple words: Van Ermengem's research identified Clostridium botulinum as the bacterium causing botulism, a severe form of food poisoning.

🎯 Exam Tip: Associate specific microbes with the diseases they cause and the scientists who made these connections.

Question 15. AIDS is caused by ......................................... .
(a) virus
(b) bacteria
(c) protozoa
(d) fungi
Answer: (a) Virus
In simple words: AIDS is caused by the Human Immunodeficiency Virus (HIV), which attacks the immune system.

🎯 Exam Tip: Understand the classifications of microorganisms and which category causes specific diseases (e.g., viruses for AIDS, bacteria for pneumonia).

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
In simple words: Dengue fever is transmitted to humans through the bite of infected Aedes mosquitoes.

🎯 Exam Tip: For vector-borne diseases like Dengue, identify the specific vector (mosquito) and mode of transmission.

Question 17. Pneumonia is caused by ......................................... .
(a) virus
(b) bacteria
(c) fungi
(d) protozoa
Answer: (b) bacteria
In simple words: While viruses and fungi can also cause pneumonia, bacterial infections are a very common cause.

🎯 Exam Tip: Be aware that some diseases can be caused by multiple types of pathogens, but often one type is the most common or specifically targeted in a question.

Question 18. ......................................... can be prevented by vaccination.
(a) Malaria
(b) AIDS
(c) Leprosy
(d) Chicken pox
Answer: (d) Chicken pox
In simple words: Chickenpox, caused by the varicella-zoster virus, can be effectively prevented through vaccination.

🎯 Exam Tip: Recognize common vaccine-preventable diseases as part of general health knowledge.

Question 19. Malaria is caused by ......................................... .
(a) protozoa
(b) bacteria
(c) fungi
(d) virus
Answer: (a) protozoa
In simple words: Malaria is caused by Plasmodium protozoa, which are transmitted by Anopheles mosquitoes.

🎯 Exam Tip: It's important to know that malaria is caused by a protozoan parasite, not a virus or bacteria.

Question 20. Bird flu (H7N9) and swine flu (H1N1) are caused by ......................................... .
(a) bacteria
(b) protozoa
(c) fungi
(d) virus
Answer: (d) virus
In simple words: Bird flu and swine flu are both types of influenza caused by specific strains of the influenza virus.

🎯 Exam Tip: Understand that many types of "flu" are viral infections, often named after their animal origin or specific viral strain.

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
In simple words: Lactobacilli ferment lactose in milk, producing lactic acid, which gives yogurt its sour taste and causes milk to curdle.

🎯 Exam Tip: Remember the specific product of lactose fermentation by Lactobacilli (lactic acid) as it's fundamental to dairy processes.

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
In simple words: The low pH created by lactic acid in fermented milk products inhibits the growth of many harmful microorganisms.

🎯 Exam Tip: Understand the role of pH in microbial growth and preservation of food products.

Question 23. Lactobacilli kill the harmful bacteria like ......................................... present in the alimentary canal.
(a) Rhizobium
(b) Saccharomyces
(c) Clostridium
(d) Alcanivorax
Answer: (c) Clostridium
In simple words: Lactobacilli, often considered beneficial bacteria, can help suppress harmful bacteria like Clostridium in the gut.

🎯 Exam Tip: Knowing specific examples of how beneficial microbes outcompete harmful ones, especially in the gut, is important for understanding probiotics.

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
In simple words: Yeast undergoes alcoholic fermentation, converting sugars (carbohydrates) into alcohol and carbon dioxide.

🎯 Exam Tip: Recall the end products of yeast fermentation, especially for applications in brewing and baking.

Question 25. Molasses is fermented with the help of yeast called ......................................... .
(a) Yarrowia lipolytica
(b) Alcanivorax
(c) Rhizobia
(d) Saccharomyces
Answer: (d) Saccharomyces
In simple words: Saccharomyces cerevisiae, commonly known as baker's yeast, is widely used to ferment molasses for alcohol production.

🎯 Exam Tip: Recognize Saccharomyces as the primary yeast used in industrial fermentation processes.

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
In simple words: Yarrowia lipolytica is a specific yeast used in bioremediation to absorb toxins, such as those found in palm oil production waste.

🎯 Exam Tip: Be aware of the specialized uses of microorganisms in industrial and environmental applications, beyond common examples.

Question 27. The bacteria which spoil cooked food are ......................................... .
(a) Saccharomyces
(b) Lactobacilli
(c) Clostridium
(d) Rhizobium
Answer: (c) Clostridium
In simple words: Clostridium species are known for spoiling cooked food, especially in anaerobic conditions, due to their ability to produce toxins.

🎯 Exam Tip: Understand which bacterial genera are commonly associated with food spoilage and foodborne illnesses.

Question 28. ......................................... can grow and reproduce only in living cells.
(a) Bacteria
(b) Viruses
(c) Fungi
(d) Protozoa
Answer: (b) Viruses
In simple words: Viruses are obligate intracellular parasites, meaning they must infect living host cells to replicate and survive.

🎯 Exam Tip: A key characteristic of viruses is their obligate intracellular parasitic nature, which distinguishes them from other microbes.

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.
In simple words: Leprosy is caused by bacteria, while AIDS, Hepatitis, and Dengue are all viral diseases.

🎯 Exam Tip: Group diseases by their causative pathogen (virus, bacteria, protozoa, fungi) for effective classification.

Question 2. Cholera, Leprosy, Pneumonia, Influenza.
Answer: Influenza. It is caused by a virus, whereas the rest are caused by bacteria.
In simple words: Influenza is a viral infection, whereas Cholera, Leprosy, and Pneumonia are typically caused by bacteria.

🎯 Exam Tip: Differentiating between viral and bacterial infections is a fundamental concept in microbiology and disease understanding.

Question 3. Ampicillin, Amoxycillin, Penicillin, Tetracycline.
Answer: Penicillin. It is a narrow-spectrum antibiotic, whereas others are broad-spectrum antibiotics.
In simple words: Penicillin targets a specific range of bacteria, making it a narrow-spectrum antibiotic, unlike Ampicillin, Amoxycillin, and Tetracycline which are broad-spectrum.

🎯 Exam Tip: Understanding the spectrum of activity (narrow vs. broad) is crucial for classifying antibiotics.

Question 4. Tetracycline, Penicillin, Gentamycin, Erythromycin.
Answer: Tetracycline. It is a broad-spectrum antibiotic, whereas others are narrow-spectrum antibiotics.
In simple words: Tetracycline is effective against a wide range of bacteria, categorizing it as broad-spectrum, while Penicillin, Gentamycin, and Erythromycin are generally narrow-spectrum.

🎯 Exam Tip: Memorize examples of both broad-spectrum and narrow-spectrum antibiotics to identify the odd one out based on their activity range.

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.
In simple words: This analogy tests knowledge of disease causes, microbial processes, and their applications or effects.

🎯 Exam Tip: For analogies, identify the relationship between the first pair and apply the same relationship to the second pair.

Match The Columns:

Question 1.

🎯 Exam Tip: Carefully review each disease and recall its primary pathogen type to match correctly.

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

Question 1. Lactobacilli are aerobic bacteria.
Answer: (1) False. Lactobacilli are anaerobic bacteria.
In simple words: Lactobacilli are typically anaerobic, meaning they do not require oxygen to grow and thrive.

🎯 Exam Tip: Understand the oxygen requirements of different bacteria (aerobic, anaerobic, facultative anaerobic).

Question 2. Lactobacilli converts lactose sugar into alcohol.
Answer: (2) False. The Lactobacilli converts lactose sugar into lactic acid.
In simple words: Lactobacilli convert lactose into lactic acid, a process called lactic acid fermentation, not alcohol.

🎯 Exam Tip: Differentiate between lactic acid fermentation (by Lactobacilli) and alcoholic fermentation (by yeast).

Question 3. Yoghurt has a specific sour taste due to acetic acid.
Answer: (3) False. Yogurt has a specific sour taste due to lactic acid.
In simple words: The sour taste of yogurt comes from the lactic acid produced by Lactobacilli during fermentation.

🎯 Exam Tip: Identify the specific acid responsible for the taste of fermented dairy products.

Question 4. The bacteria Clostridium are present in the root . nodules of leguminous plants.
Answer: (4) False. The bacteria Rhizobium are present in the root nodules of leguminous plants.
In simple words: Rhizobium, not Clostridium, forms a symbiotic relationship with leguminous plants, residing in their root nodules for nitrogen fixation.

🎯 Exam Tip: Know the specific bacteria associated with root nodules of leguminous plants and their function.

Question 5. Yeast cell is a prokaryotic cell.
Answer: (5) False. Yeast cell is a eukaryotic cell.
In simple words: Yeast cells are eukaryotic, possessing a membrane-bound nucleus and other organelles, unlike prokaryotic cells.

🎯 Exam Tip: Clearly distinguish between prokaryotic (bacteria) and eukaryotic (fungi, protozoa, animal, plant) cell types.

Question 6. The use of Rhizobium has helped to reduce the use of chemical fertilizers.
Answer: (6) True.
In simple words: Rhizobium's ability to fix atmospheric nitrogen provides natural nitrates to plants, reducing the need for synthetic chemical fertilizers.

🎯 Exam Tip: Understand the environmental and economic benefits of biological nitrogen fixation by microbes like Rhizobium.

Question 7. Ethanol is a smokeless and high quality fuel.
Answer: (7) True.
In simple words: Ethanol burns cleanly, producing less smoke and pollutants compared to traditional fossil fuels, hence its quality as a fuel.

🎯 Exam Tip: Be familiar with the properties that define a "high-quality" or "clean" fuel, such as low smoke production.

Question 8. A yeast, Yarrowia lipolytic is used to absorb the toxins released during the production of palm oil.
Answer: (8) False. A yeast, Yarrowia lipolytica is used to absorb the toxins released during the production of palm oil.
In simple words: The correct spelling is 'Yarrowia lipolytica', a specific yeast used for bioremediation, including absorbing toxins from palm oil production.

🎯 Exam Tip: Pay attention to the precise scientific names of microorganisms as minor spelling differences can denote different species or be considered incorrect.

Question 9. Gentamycin is a narrow-spectrum antibiotic.
Answer: (9) True.
In simple words: Gentamycin primarily targets specific types of bacteria, categorizing it as a narrow-spectrum antibiotic.

🎯 Exam Tip: Reiterate the concept of narrow-spectrum antibiotics and be able to provide examples.

Question 10. Antibiotics mainly act against bacteria.
Answer: (10) True.
In simple words: The primary function of antibiotics is to inhibit the growth of or kill bacteria, not other microbes like viruses.

🎯 Exam Tip: Reinforce the understanding that antibiotics are not effective against viral infections.

Question 11. Oil spills in oceans are cleared with the help of Alcanivorax bacteria.
Answer: (11) False. Oil spills in oceans are cleared with the help of Alcanivorax bacteria.
In simple words: Alcanivorax bacteria are known for their ability to break down hydrocarbons, making them useful in bioremediation of oil spills.

🎯 Exam Tip: Recognize specific microbial roles in bioremediation and environmental cleanup efforts.

Question 12. Tetracycline is a narrow-spectrum antibiotic.
Answer: (12) False. Tetracycline is a broad-spectrum antibiotic.
In simple words: Tetracycline is a broad-spectrum antibiotic, effective against a wide range of bacterial infections.

🎯 Exam Tip: Revisit and compare antibiotics based on their spectrum of activity to avoid confusion.

Question 13. Amoxicillin is a broad-spectrum antibiotic.
Answer: (13) True.
In simple words: Amoxicillin is indeed a broad-spectrum antibiotic, effective against a wide variety of bacterial pathogens.

🎯 Exam Tip: Keep examples of common broad-spectrum antibiotics in mind for identification questions.

Question 14. Penicillin is a group of antibiotics obtained from a fungus Saccharomyces.
Answer: (14) False. Penicillin is a group of antibiotics obtained from a fungus Penicillium.
In simple words: Penicillin is derived from the fungus Penicillium, not Saccharomyces.

🎯 Exam Tip: Correctly associate antibiotics with their specific microbial sources (e.g., Penicillin from Penicillium, not Saccharomyces).

Question 15. Antibiotic Penicillin was discovered by Alexander Fleming.
Answer: (15) True.
In simple words: Alexander Fleming's accidental discovery of penicillin from Penicillium mold marked a major breakthrough in medicine.

🎯 Exam Tip: This is a fundamental historical fact; know the discoverer of penicillin.

Question 16. The bacteria Clostridium cause food-poisoning.
Answer: (16) False. The bacteria Clostridium cause food poisoning.
In simple words: Clostridium species are indeed well-known causes of food poisoning, especially C. botulinum and C. perfringens.

🎯 Exam Tip: Understand the common foodborne pathogens and the types of illnesses they cause.

Question 17. Clostridium bacteria grow in aerobic conditions.
Answer: (17) False. Clostridium bacteria grow in anaerobic conditions.
In simple words: Clostridium species are strict anaerobes, meaning they cannot grow in the presence of oxygen.

🎯 Exam Tip: Remember that Clostridium bacteria are obligate anaerobes, which is why they are often found in canned foods or deep wounds.

Question 18. AIDS is caused by a virus.
Answer: (18) True.
In simple words: AIDS is caused by HIV, a retrovirus that attacks the immune system.

🎯 Exam Tip: Reconfirm that AIDS is a viral disease caused by HIV.

Question 19. Influenza is caused by a bacteria.
Answer: (19) False. Influenza is caused by a virus.
In simple words: Influenza, or the flu, is a respiratory illness caused by the influenza virus.

🎯 Exam Tip: Distinguish between influenza (viral) and bacterial infections with similar symptoms.

Question 20. Antibiotics useful to one person cannot be suggested to others also.
Answer: (20) False. Antibiotics useful to one person cannot be suggested to others as different diseases require different antibiotics.
In simple words: Antibiotics are specific to the type of infection and individual health, so a prescription for one person is not suitable for another.

🎯 Exam Tip: Emphasize the importance of personalized medical advice and avoiding self-medication with antibiotics due to resistance and specific needs.

Question 21. Dengue is caused by a bacteria.
Answer: (21) False. Dengue is caused by a virus.
In simple words: Dengue fever is caused by the dengue virus, transmitted by mosquitoes.

🎯 Exam Tip: Correctly identify Dengue as a viral disease.

Question 22. Dandruff and ringworm are caused by fungi.
Answer: (22) True.
In simple words: Both dandruff and ringworm are common skin conditions caused by fungal infections.

🎯 Exam Tip: Recognize common fungal skin infections and their characteristic symptoms.

Question 23. Pneumonia is spread through droplets spread in air by infected person.
Answer: (23) True.
In simple words: Pneumonia pathogens can be transmitted through respiratory droplets released by an infected person when coughing or sneezing.

🎯 Exam Tip: Understand common modes of transmission for respiratory infections, such as droplet spread.

Question 24. Chicken pox spread due to contaminated food and water.
Answer: (24) False. Chicken pox spread due to contact with infected person.
In simple words: Chickenpox primarily spreads through direct contact with an infected person or airborne transmission, not through contaminated food or water.

🎯 Exam Tip: Differentiate between airborne/contact transmission and food/waterborne transmission for various diseases.

Question 25. Ida Bengston was honoured with the Typhoid Medal' in 1947.
Answer: (25) False. Ida Bengston was honoured with the 'Typhus Medal' in 1947.
In simple words: Ida Bengston received the Typhus Medal, not Typhoid, for her significant contributions to microbiology.

🎯 Exam Tip: Pay close attention to specific details like names of awards and their associated diseases in historical questions.

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.
In simple words: Lactobacilli ferment milk sugar (lactose) into lactic acid, which causes milk proteins to coagulate and thicken, forming yogurt.

🎯 Exam Tip: Explain the biochemical process (fermentation) and its effect on milk proteins and pH when describing yogurt production.

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.
In simple words: Rhizobium bacteria in legume root nodules convert atmospheric nitrogen into usable forms for plants, acting as a natural fertilizer and lessening the need for chemical alternatives.

🎯 Exam Tip: Highlight the role of Rhizobium in nitrogen fixation and its environmental and agricultural benefits.

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.
In simple words: Amoxicillin is effective against a broad range of bacterial infections and is often used when the exact type of pathogen is not yet identified.

🎯 Exam Tip: Emphasize the utility of broad-spectrum antibiotics in cases where immediate treatment is needed before pathogen identification.

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.
In simple words: Molasses, a carbohydrate-rich byproduct of sugar production, is fermented by Saccharomyces yeast to produce ethanol.

🎯 Exam Tip: Describe the raw material (molasses), the microbe (Saccharomyces), and the main product (ethanol) in industrial fermentation.

Question 5. Clostridium bacteria produce bottle-shaped endospores.
Answer: These endospores help them to survive in adverse conditions.
In simple words: Clostridium bacteria form durable, bottle-shaped endospores as a survival mechanism against harsh environmental stress.

🎯 Exam Tip: Focus on the adaptive advantage of endospore formation for bacterial survival in unfavorable conditions.

Give Scientific Reasons:

Question 1. Lactobacilli are used for making yoghurt from milk.
Answer:
• Lactobacilli convert lactose, the sugar in the milk, into lactic acid. This process is called fermentation.
• As a result, the pH of milk decreases causing coagulation of milk proteins.
• Thus, milk proteins are separated from other constituents of milk and milk changes into yoghurt.
• Yoghurt has a specific sour taste due to lactic acid. The low pH destroys harmful microbes present in the milk. Therefore, Lactobacilli are used for making yoghurt from milk.
In simple words: Lactobacilli are used because they ferment lactose into lactic acid, which lowers milk pH, coagulates proteins to form yogurt, imparts a sour taste, and inhibits harmful microbes.

🎯 Exam Tip: Ensure to explain the step-by-step biochemical changes and their outcomes when detailing processes like yogurt production.

Question 2. Antibiotics should be taken only when prescribed by a doctor.
Answer:
• Antibiotics are a group of medicines used to kill disease-causing bacteria and certain protozoa.
• The doctor selects and prescribes the antibiotic best suited for our disease.
• If taken in extra dose, they can kill the useful bacteria present in our body.
• If the course of antibiotics is not completed, the bacteria develop resistance to that antibiotic making it ineffective.
• Therefore, antibiotics should be taken only when prescribed by a doctor.
In simple words: Antibiotics must be prescribed by a doctor to ensure the correct type and dosage are used, prevent harm to beneficial bacteria, and avoid antibiotic resistance from incomplete courses.

🎯 Exam Tip: Emphasize the risks of misuse of antibiotics, including resistance and destruction of beneficial microflora.

Question 3. Nowadays, seeds are coated with Rhizobial solution or powder before sowing.
Answer:
• When seeds coated with Rhizobial solution or powder are sown, Rhizobia enter the plantlets.
• This is called Rhizobial inoculation.
• Rhizobia can produce nitrogenous compounds from atmospheric nitrogen.
• This experiment has helped in the supply of nitrogen to cereal and other crops, besides leguminous crops.
• Therefore, nowadays seeds are coated with Rhizobial solution or powder before sowing.
In simple words: Seeds are coated with Rhizobium to inoculate them with nitrogen-fixing bacteria, which enhances nitrogen availability for the plants and reduces the need for synthetic fertilizers.

🎯 Exam Tip: Focus on the benefit of Rhizobial inoculation for improved nitrogen supply and reduced reliance on chemical fertilizers.

Question 4. Antibiotics are not effective against common cold or influenza.
Answer:
• Antibiotics are a group of medicines used to control inflections caused by bacteria.
• Common cold or influenza is caused by a virus.
• Antibiotics are not effective against viruses.
• Therefore, antibiotics are not effective against common cold or influenza.
In simple words: Antibiotics target bacteria, but common cold and influenza are caused by viruses, making antibiotics ineffective against them.

🎯 Exam Tip: Reiterate the specificity of antibiotics to bacteria and their lack of efficacy against viral infections.

Question 5. Cotton fabrics, gunny bags, leather items and wooden items do not last long.
Answer:
• Microscopic spores of fungi are present in the air.
• If there is sufficient moisture, spores germinate on cotton fabric, gunny bags, leather, wooden items etc.
• The fungal hyphae (fibres of the fungus) penetrate deep into the material to obtain nutrition and to reproduce.
• This causes the materials to wear and become weak.
• As a result, cotton fabric, gunny bags, leather and wooden items do not last long.
In simple words: Fungal spores in the air germinate on moist organic materials like cotton, jute, leather, and wood, and their growth (hyphae) degrades these materials, causing them to weaken and not last long.

🎯 Exam Tip: Explain the conditions for fungal growth (moisture), their mechanism of degradation (hyphae penetration), and the resulting impact on materials.

Question 6. Food on which fungi has grown cannot be eaten.
Answer:
• Various species of fungi grow on food items like pickles, murabba, jam, sauce, chutney etc.
• They use the nutrients in these food items for growth and reproduction.
• During this activity, fungi release mycotoxins, certain poisonous chemicals, into the food and thus food becomes poisonous.
• Hence, the food on which fungi have grown cannot be eaten.
In simple words: Food with fungal growth should not be eaten because fungi release poisonous mycotoxins as they consume nutrients, making the food harmful and toxic.

🎯 Exam Tip: Connect fungal growth on food directly to the production of mycotoxins, explaining why such food becomes unsafe.

Write Short Notes:

Question 1. Rhizobial inoculation.
Answer:
• Nowadays, seeds are coated with rhizobial solution or powder before sowing.
• After sowing, Rhizobia enter the plantlets.
• This is called Rhizobial inoculation.
• This experiment has helped in the supply of nitrogen to cereal and other crops, besides leguminous crops.
In simple words: Rhizobial inoculation involves coating seeds with Rhizobium bacteria before sowing, enabling the bacteria to enter plantlets and fix atmospheric nitrogen, thereby supplying nitrogen to crops and reducing the need for chemical fertilizers.

🎯 Exam Tip: Define Rhizobial inoculation and explain its purpose, process, and agricultural benefits in simple terms.

Question 2. Bio-remediation.
Answer:
• Bio-remediation is a technique that involves the use of organisms to break down environmental pollutants.
• Generally, fungi like yeast and bacteria are used for bio-remediation.
• A yeast, Yarrowia lipolytica is used to absorb the toxins released during the production of palm oil and the heavy metals and minerals released in some other industrial processes.
• Saccharomyces cerevisiae is used for absorption of a pollutant, arsenic.
• Oil spills in oceans are cleaned with the help of Alcanivorax bacteria.
In simple words: Bioremediation is the use of living organisms, primarily microbes like bacteria and fungi, to break down or absorb environmental pollutants and clean up contaminated sites.

🎯 Exam Tip: Provide a clear definition of bioremediation and give examples of specific microbes and their applications (e.g., Alcanivorax for oil spills, Yarrowia lipolytica for palm oil toxins).

Question 4. Clostridium.
Answer:
• Clostridium are the bacteria that spoil food.
• Out of about 100 different species of this bacterium, some are free living in the soil whereas some live in the alimentary canals of humans and other animals.
• These bacteria are rod-shaped and produce bottle-shaped endospores in adverse conditions.
• One special characteristic of these bacteria is that they cannot withstand the normal oxygen level of the air because they grow in anaerobic conditions.
In simple words: Clostridium is a genus of anaerobic, rod-shaped bacteria known for spoiling food, living in soil or animal guts, and forming resilient, bottle-shaped endospores to survive harsh conditions.

🎯 Exam Tip: Highlight key characteristics of Clostridium: its role in food spoilage, anaerobic nature, rod shape, and ability to form endospores.

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:
• Causative Pathogen: Virus.
• Mode of infection: Through blood and semen of infected person and milk of mother suffering from AIDS.
• Preventive measure: Safe sexual contact, avoid resuse of needles and injections.
In simple words: AIDS is caused by a virus transmitted through infected blood, semen, or mother's milk; prevention involves safe sexual practices and avoiding reuse of needles.

🎯 Exam Tip: For each disease, clearly identify the pathogen type, specific transmission routes, and actionable preventive measures.

Question 2. Write down the modes of infection and preventive measures against Bird Flu (H7N9) and Swine Flu (H1N1).
Answer:
- Mode of infection: Contact with infected birds and animals.
- Preventive measure: Personal hygiene, properly cooked meat.
In simple words: Bird Flu (H7N9) and Swine Flu (H1N1) are spread through contact with infected animals. Preventing them involves personal hygiene and consuming well-cooked meat.

🎯 Exam Tip: Focus on linking specific diseases to their modes of transmission and appropriate preventive actions for full marks.

Question 3. Write down the modes of infection and preventive measures against Malaria and dengue.
Answer:
- Mode of infection: Mosquito bite, unclean surroundings.
- Preventive measure: Cleanliness of surroundings, preventing stagnation of water, controlling mosquitoes.
In simple words: Malaria and dengue are spread by mosquito bites, which are common in unclean areas with stagnant water. Prevention involves maintaining clean surroundings and controlling mosquito populations.

🎯 Exam Tip: Remember to specify both the direct mode (mosquito bite) and contributing environmental factors (unclean surroundings) for complete answers.

Question 4. Write down the modes of infection and preventive measures against Pneumonia.
Answer:
- Mode of infection: Droplets spread in air by infected person.
- Preventive measure: Vaccination, avoiding contact with infected person.
In simple words: Pneumonia spreads through airborne droplets from an infected person. Prevention relies on vaccination and avoiding close contact with sick individuals.

🎯 Exam Tip: For respiratory diseases, always mention droplet transmission and personal hygiene/vaccination as key preventive measures.

Question 5. Write down the modes of infection and preventive measures for leprosy.
Answer:
- Mode of infection: Long term contact with infected person.
- Preventive measure: Avoiding contact with infected persons and their belongings.
In simple words: Leprosy is transmitted through prolonged contact with an infected person. Prevention involves avoiding sustained close contact with infected individuals and their personal items.

🎯 Exam Tip: Emphasize "long term contact" as the mode of transmission for leprosy, distinguishing it from more casual contact diseases.

Question 5. What are the modes of infection and preventive measures for Hepatitis?
Answer:
- Mode of infection: Contaminated water and food.
- Preventive measure: Use clean and filtered water, proper storage of food.
In simple words: Hepatitis spreads through contaminated food and water. To prevent it, ensure you consume clean, filtered water and store food properly.

🎯 Exam Tip: For water-borne diseases like Hepatitis, always highlight food and water safety, including filtration and proper storage.

Question 6. What are the modes of infection and preventive measures for Influenza.
Answer:
- Mode of infection: Contact with infected person.
- Preventive measure: Personal hygiene and avoiding contact with infected person.
In simple words: Influenza is spread through direct contact with an infected person. Maintaining good personal hygiene and avoiding close contact with sick individuals are key preventive measures.

🎯 Exam Tip: For common viral infections like influenza, mentioning contact transmission and general hygiene practices is crucial.

Answer The Following Questions:

Question 1. How is bread made?
Answer:
- Bread is made using flour, yeast, salt and water. The yeast uses sugar as food.
- In the process of obtaining nutrition, yeast cells convert the carbohydrates into alcohol and carbon dioxide. This process is called fermentation.
- The bubbles of carbon dioxide given off cause the dough to rise.
- This dough can be used to make bread.
- When this dough is baked, more bubbles of carbon dioxide reformed due to heat. As the gas escapes, the bread rises and becomes soft and fluffy.
In simple words: Bread is made by mixing flour, yeast, salt, and water. Yeast ferments the carbohydrates, producing carbon dioxide gas which makes the dough rise. When baked, the gas escapes, leaving the bread soft and spongy.

🎯 Exam Tip: Explain the role of yeast and fermentation in producing carbon dioxide, which is essential for the leavening process of bread.

Question 2. What is the advantage of Rhizobium to farmers?
Answer:
- The use of Rhizobium has helped to reduce the use of chemical fertilizers and thereby their adverse effects.
- It has also helped to reduce expenses on fertilizers and thus benefited the farmers.
In simple words: Rhizobium bacteria help farmers by fixing atmospheric nitrogen, reducing the need for expensive and potentially harmful chemical fertilizers, thus lowering cultivation costs.

🎯 Exam Tip: Highlight the economic and environmental benefits (reduced chemical fertilizer use) when discussing the advantages of Rhizobium.

Question 3. How can we observe Lactobacilli in buttermilk?
Answer:
- Smear a drop of fresh buttermilk on a glass slide.
- Stain it with methylene blue and put a coverslip over it.
- Observe the smear under the 10X objective of a compound microscope and then with the more powerful 60X objective.
- The blue rod-shaped organisms moving about are Lactobacilli.
In simple words: To observe Lactobacilli, smear stained buttermilk on a slide, cover it, and view under a microscope; the blue, rod-shaped moving organisms are Lactobacilli.

🎯 Exam Tip: Clearly list the steps for microscopic observation, including staining and using different objective lenses, to demonstrate practical knowledge.

Question 4. What is symbiosis? Give example.
Answer:
- Symbiosis is a mutually beneficial relationship.
- Example: Rhizobium living in root nodules of leguminous plants supply nitrates, nitrites and amino acids to that plant and in exchange get energy in the form of carbohydrates.
In simple words: Symbiosis is a close and long-term interaction between two different biological organisms where both benefit. A classic example is Rhizobium bacteria in legume root nodules, where bacteria provide nitrogen compounds to the plant, and the plant provides carbohydrates to the bacteria.

🎯 Exam Tip: Define symbiosis clearly as a "mutually beneficial" relationship and provide a specific, well-known biological example like Rhizobium-legume association.

Complete The Following Table:

Question 1. The spread and prevention of disease
Answer:

🎯 Exam Tip: Organize information clearly in tables for easy comparison and recall; ensure accuracy for each disease's pathogen, mode of infection, and prevention.

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

🎯 Exam Tip: When listing specific bacteria and diseases, ensure precise spelling and correct pairings to avoid losing marks.

Answer In Detail:

Question 1. How is alcohol produced?
Answer:
- Alcohol is often produced along with sugar in sugar factories.
- Molasses is produced from sugarcane juice. It is rich in carbohydrates.
- Molasses is fermented with the help of the yeast Saccharomyces.
- In this process, ethanol \( \left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right) \) alcohol is produced as a primary product and ester and other alcohols are produced as secondary products.
- Besides molasses, maize, barley and other grains are also used for industrial production of alcohol.
- Glucose and fructose, the sugars present in grape juice are also fermented with the help of yeast to produce alcohol which is used to make wines.
In simple words: Alcohol is produced primarily through the fermentation of carbohydrate-rich substances like molasses (from sugarcane), maize, barley, or grape juice using yeast, specifically Saccharomyces, which converts sugars into ethanol.

🎯 Exam Tip: Clearly explain the fermentation process, identifying the raw materials (e.g., molasses, grape juice) and the microorganism (yeast, Saccharomyces) involved in alcohol production.

Question 2. Give the uses of Lactobacilli.
Answer:
Uses of Lactobacilli:
- Various milk products like yoghurt, buttermilk, ghee, cheese, shrikhand, etc. can be obtained by fermentation of milk.
- Lactobacilli fermentation is useful for large scale production of cider, cocoa, pickles of vegetables etc.
In simple words: Lactobacilli are crucial for fermenting milk into products like yoghurt, buttermilk, and cheese, and are also used in large-scale production of items such as cider, cocoa, and pickled vegetables.

🎯 Exam Tip: Provide a broad range of examples for both milk-based and other food products to illustrate the versatility of Lactobacilli in fermentation.

Question 3. What is Penicillin? What is it used for?
Answer:
- Penicillin is a group of antibiotics obtained from a fungus, penicillium.
- It is used for controlling the infections caused by bacteria like Staphylococc, Clostridia, Streptococci, etc.
- Medicines containing Penicillin are useful to treat certain bacterial infections of the ear, nose, throat and skin as well as diseases like Pneumonia and scarlet fever.
In simple words: Penicillin is an antibiotic derived from the Penicillium fungus, used to treat various bacterial infections like those caused by Staphylococci, Clostridia, and Streptococci, including conditions such as pneumonia and scarlet fever.

🎯 Exam Tip: Mention both the origin (Penicillium fungus) and the broad spectrum of bacterial infections it targets, along with specific examples of diseases it treats.

Question 4. How was the antibiotic penicillin discovered?
Answer:
1. Alexander Fleming, a professor of microbiology at St. Mary's Hospital had cultured varieties of bacteria and fungi in petri dishes in his laboratory.
2. On 3rd September 1928, while observing Staphylococci cultures, he made an interesting observation in one petri dish.
3. In that petri dish, fungal colonies had grown but the area around those colonies was clean and clear, i.e. the bacteria had actually been destroyed.
4. After further studies, he confirmed that the fungus growing there was Penicillium and its secretion had destroyed the bacterial colonies.
5. Thus, the first antibiotic - penicillin had been discovered accidentlly and this formed the basis to find cures for incurable diseases.
In simple words: Penicillin was accidentally discovered by Alexander Fleming in 1928 when he noticed that Penicillium fungus growing in a petri dish inhibited the growth of surrounding bacterial colonies, leading to the identification of penicillin as the first antibiotic.

🎯 Exam Tip: Narrate the discovery as a chronological sequence of events, highlighting Fleming's key observation and the subsequent identification of Penicillium's antimicrobial properties.

Question 5. What are the precautions to be followed while taking antibiotics?
Answer:
- Antibiotics should be taken only when prescribed by a doctor.
- Don't purchase any antibiotic from medical stores without a prescription from a doctor.
- Don't consume antibiotics on your own to treat common diseases like a throat infection, common cold or influenza.
- Even if you feel well before completing of the prescribed course of the antibiotics, you must continue and complete it.
- Don't suggest to others the antibiotics which were useful to you.
In simple words: When taking antibiotics, always follow a doctor's prescription, never self-medicate, complete the entire course even if symptoms improve, and avoid recommending your antibiotics to others to prevent resistance and adverse effects.

🎯 Exam Tip: Focus on the importance of medical supervision, completing the full course, and avoiding self-medication to prevent antibiotic resistance and ensure efficacy.

Question 6. How can we observe Rhizobium bacteria in the roots of leguminous plant?
Answer:
- Take a plantlet of fenugreek, groundnut or any other bean and sterilize it with a 3 to 5% solution of hydrogen peroxide.
- Afterwards, keep it in a 70% solution of ethyl alcohol for 4 to 5 minutes.
- Clean the roots with sterile water and take thin sections of the root nodules.
- Select a good section and place it an a solution of saffranin for 2 to 3 minutes.
- Place the stained section on a glass slide, cover it with a coverslip and observe it under the compound microscope. The pinkish rod-shaped organisms are the Rhizobium bacteria.
In simple words: To observe Rhizobium, sterilize a leguminous plantlet's roots, prepare thin sections of nodules, stain them with saffranin, and then examine the pinkish rod-shaped bacteria under a compound microscope.

🎯 Exam Tip: Describe the steps of preparing a root nodule sample for microscopic observation, including sterilization, sectioning, staining, and viewing, to show practical knowledge.