Questions & Answers
ICSE - Grade - 9
Subject: Biology
Chapter - 09 - Economic Importance of Bacteria and Fungi
Types of Questions
MCQ
- Which group of organisms are considered prokaryotic?
a) Algae
b) Fungi
c) Bacteria
d) Protozoa
Answer: c) Bacteria - Which of the following is used in the production of antibiotics?
a) Yeast
b) Penicillium
c) Mushroom
d) Nostoc
Answer: b) Penicillium - Which vaccine is prepared by using weakened or killed bacteria?
a) Toxoid
b) Serum
c) Vaccine
d) Antibiotic
Answer: c) Vaccine - Which of the following destroys bacterial toxins inside the body?
a) Antitoxin
b) Vaccine
c) Serum
d) Antibiotic
Answer: a) Antitoxin - Which type of bacteria convert atmospheric nitrogen into compounds usable by plants?
a) Denitrifying bacteria
b) Nitrifying bacteria
c) Nitrogen-fixing bacteria
d) Saprophytic bacteria
Answer: c) Nitrogen-fixing bacteria - Rhizobium is an example of:
a) Nitrifying bacteria
b) Nitrogen-fixing bacteria
c) Denitrifying bacteria
d) Pathogenic bacteria
Answer: b) Nitrogen-fixing bacteria - Which bacteria convert ammonia into nitrates?
a) Denitrifying bacteria
b) Saprophytes
c) Nitrifying bacteria
d) Nitrogen-fixing bacteria
Answer: c) Nitrifying bacteria - Which bacteria convert nitrates into free nitrogen?
a) Nitrogen-fixing
b) Nitrifying
c) Denitrifying
d) Saprophytic
Answer: c) Denitrifying - Which of the following bacteria is involved in the production of curd?
a) Rhizobium
b) Lactobacillus
c) Salmonella
d) Clostridium
Answer: b) Lactobacillus - Which process spoils food by bacteria?
a) Photosynthesis
b) Putrefaction
c) Fermentation
d) Nitrogen fixation
Answer: b) Putrefaction - Which of the following is a preventive measure against bacterial food spoilage?
a) Freezing
b) Sun drying
c) Salting
d) All of these
Answer: d) All of these - Which of the following is a bacterial disease in plants?
a) Citrus canker
b) Smut
c) Rust
d) Wilt of cotton
Answer: a) Citrus canker - Which of the following is a bacterial disease in animals?
a) Foot and mouth disease
b) Tuberculosis
c) Ringworm
d) Rust
Answer: b) Tuberculosis - The bacterium used in leather tanning is:
a) Lactobacillus
b) Rhizobium
c) Clostridium
d) Streptococcus
Answer: c) Clostridium - Antibiotics are obtained from:
a) Bacteria and fungi
b) Algae only
c) Viruses only
d) Protozoa
Answer: a) Bacteria and fungi - Which of the following is the first discovered antibiotic?
a) Streptomycin
b) Penicillin
c) Tetracycline
d) Chloramphenicol
Answer: b) Penicillin - Serums provide:
a) Natural immunity
b) Active immunity
c) Passive immunity
d) Artificial immunity
Answer: c) Passive immunity - Vaccines provide:
a) Passive immunity
b) Natural immunity
c) Active immunity
d) Temporary immunity
Answer: c) Active immunity - Toxoids are:
a) Weakened pathogens
b) Modified toxins
c) Antibodies
d) Antibiotics
Answer: b) Modified toxins - Which of the following gives flavour to tea during fermentation?
a) Bacteria
b) Viruses
c) Algae
d) Protozoa
Answer: a) Bacteria - Which microorganism is used in brewing industry?
a) Penicillium
b) Rhizopus
c) Saccharomyces
d) Clostridium
Answer: c) Saccharomyces - Which process is carried out by yeast in wine production?
a) Photosynthesis
b) Putrefaction
c) Alcoholic fermentation
d) Nitrification
Answer: c) Alcoholic fermentation - In bread-making, yeast produces:
a) Oxygen and alcohol
b) Carbon dioxide and alcohol
c) Ammonia and nitrogen
d) Acids
Answer: b) Carbon dioxide and alcohol - Which of the following fungi is edible?
a) Penicillium
b) Agaricus
c) Rhizopus
d) Aspergillus
Answer: b) Agaricus - Which of the following increases the softness and porosity of bread?
a) Alcohol
b) Carbon dioxide
c) Oxygen
d) Enzymes
Answer: b) Carbon dioxide - Cheese is produced by:
a) Algae
b) Bacteria
c) Yeast
d) Virus
Answer: b) Bacteria - Which fungus is used in the production of penicillin?
a) Penicillium notatum
b) Saccharomyces cerevisiae
c) Rhizopus stolonifer
d) Aspergillus niger
Answer: a) Penicillium notatum - Mushroom is rich in:
a) Carbohydrates only
b) Proteins and vitamins
c) Fats only
d) Starch
Answer: b) Proteins and vitamins - The nutritive value of mushrooms is closest to:
a) Meat
b) Fruits
c) Cereals
d) Leafy vegetables
Answer: a) Meat - Which fungus is used in the production of citric acid?
a) Aspergillus niger
b) Saccharomyces
c) Rhizopus
d) Mucor
Answer: a) Aspergillus niger - Spoilage of bread is caused by:
a) Yeast
b) Penicillium
c) Rhizopus
d) Both b and c
Answer: d) Both b and c - Which bacterial process reduces soil fertility?
a) Nitrogen fixation
b) Nitrification
c) Denitrification
d) None of these
Answer: c) Denitrification - Antibiotic “Streptomycin” is obtained from:
a) Fungi
b) Bacteria
c) Virus
d) Protozoa
Answer: b) Bacteria - Which disease is caused by Mycobacterium tuberculosis?
a) Anthrax
b) Typhoid
c) Tuberculosis
d) Plague
Answer: c) Tuberculosis - Which fungus is commonly called baker’s yeast?
a) Saccharomyces cerevisiae
b) Aspergillus niger
c) Rhizopus stolonifer
d) Penicillium
Answer: a) Saccharomyces cerevisiae - Which of the following is a harmful role of bacteria?
a) Nitrification
b) Nitrogen fixation
c) Food spoilage
d) Leather tanning
Answer: c) Food spoilage - Antibiotics act against:
a) Viruses only
b) Bacteria only
c) Both bacteria and viruses
d) Protozoa
Answer: b) Bacteria only - Clostridium tetani causes:
a) Tuberculosis
b) Typhoid
c) Tetanus
d) Anthrax
Answer: c) Tetanus - Yeast reproduces mainly by:
a) Binary fission
b) Budding
c) Fragmentation
d) Spore formation
Answer: b) Budding - Which of the following is not a fungal product?
a) Wine
b) Bread
c) Cheese
d) Serum
Answer: d) Serum - Which of the following is not an antibiotic?
a) Penicillin
b) Streptomycin
c) Tetracycline
d) Vaccine
Answer: d) Vaccine - Which fungus is used in the ripening of cheese?
a) Penicillium
b) Rhizopus
c) Aspergillus
d) Yeast
Answer: a) Penicillium - Which bacterium is used in sewage treatment?
a) Rhizobium
b) Nitrosomonas
c) Pseudomonas
d) Clostridium
Answer: c) Pseudomonas - Who discovered Penicillin?
a) Robert Koch
b) Louis Pasteur
c) Alexander Fleming
d) Edward Jenner
Answer: c) Alexander Fleming - Which fungus is commonly called black bread mould?
a) Penicillium
b) Rhizopus
c) Aspergillus
d) Yeast
Answer: b) Rhizopus - A toxoid is used to immunize against:
a) Viral diseases
b) Bacterial toxins
c) Fungal infection
d) Food poisoning
Answer: b) Bacterial toxins - Which of the following methods preserves milk?
a) Pasteurisation
b) Fermentation
c) Putrefaction
d) Distillation
Answer: a) Pasteurisation - Which is a fungal disease in humans?
a) Ringworm
b) Typhoid
c) Tetanus
d) Cholera
Answer: a) Ringworm - Which fungus is edible and cultivated commercially?
a) Agaricus
b) Penicillium
c) Aspergillus
d) Rhizopus
Answer: a) Agaricus - Which of the following is both useful and harmful?
a) Yeast
b) Bacteria
c) Fungi
d) All of these
Answer: d) All of these
Fill in the Blanks
- Bacteria are ______ organisms without a true nucleus.
Answer: prokaryotic - The bacterium Rhizobium is found in the root nodules of ______ plants.
Answer: leguminous - Bacteria like Rhizobium help in ______ fixation.
Answer: nitrogen - Conversion of ammonia into nitrites and nitrates is called ______.
Answer: nitrification - Conversion of nitrates into free nitrogen is called ______.
Answer: denitrification - ______ bacteria reduce soil fertility by releasing nitrogen gas.
Answer: Denitrifying - Lactobacillus bacteria convert milk sugar into ______ during curd formation.
Answer: lactic acid - The bacterium Clostridium is used in ______ tanning.
Answer: leather - Food spoilage by bacteria is mainly due to the process of ______.
Answer: putrefaction - Preservation of food by heating and cooling milk is called ______.
Answer: pasteurisation - Citrus canker is a ______ disease in plants.
Answer: bacterial - Tuberculosis is a ______ disease in humans.
Answer: bacterial - Antibiotics are obtained from both ______ and ______.
Answer: bacteria, fungi - The first discovered antibiotic was ______.
Answer: Penicillin - Penicillin was discovered by ______.
Answer: Alexander Fleming - Streptomycin is obtained from ______ bacteria.
Answer: Streptomyces - ______ provide active immunity to the body.
Answer: Vaccines - ______ provide passive immunity to the body.
Answer: Serums - ______ neutralise toxins produced by bacteria.
Answer: Antitoxins - ______ are modified toxins used for vaccination.
Answer: Toxoids - The flavour of tea is enhanced by the action of ______.
Answer: bacteria - Yeast belongs to the group of organisms called ______.
Answer: fungi - Yeast respires anaerobically to produce ______ and ______.
Answer: alcohol, carbon dioxide - In bread making, the ______ gas released by yeast makes the dough soft and porous.
Answer: carbon dioxide - The fungus used in brewing and baking is ______.
Answer: Saccharomyces cerevisiae - The fungus Penicillium notatum is used in producing the antibiotic ______.
Answer: Penicillin - Mushrooms such as ______ are edible and cultivated commercially.
Answer: Agaricus - Mushrooms are rich in ______ and vitamins.
Answer: proteins - The nutritive value of mushrooms is closest to that of ______.
Answer: meat - Citric acid is produced with the help of the fungus ______.
Answer: Aspergillus niger - Cheese is prepared with the help of ______.
Answer: bacteria - Some varieties of cheese are ripened with ______ fungi.
Answer: Penicillium - The fungus commonly called “black bread mould” is ______.
Answer: Rhizopus - Ringworm in humans is caused by ______ infection.
Answer: fungal - ______ is a preventive measure against bacterial food spoilage by reducing water content.
Answer: Sun drying - ______ is a preventive measure against bacterial food spoilage by low temperature.
Answer: Freezing - The vaccine for smallpox was discovered by ______.
Answer: Edward Jenner - ______ is a bacterial disease in cattle.
Answer: Anthrax - In alcoholic fermentation, sugar is converted into ______ and alcohol.
Answer: carbon dioxide - Pseudomonas bacteria are used in ______ treatment.
Answer: sewage - ______ is a fungal product used in making bread and alcoholic drinks.
Answer: Yeast - The bacteria that cause tetanus are called ______.
Answer: Clostridium tetani - A serum contains ready-made ______ to fight diseases.
Answer: antibodies - The antibiotic “tetracycline” is produced by ______.
Answer: Streptomyces - ______ discovered the process of pasteurisation.
Answer: Louis Pasteur - ______ are unicellular fungi used in industries.
Answer: Yeasts - The fungus used in commercial production of enzymes and organic acids is ______.
Answer: Aspergillus - The bacterial disease of rice caused by Xanthomonas oryzae is ______.
Answer: bacterial blight - The edible mushroom is ______, while poisonous mushrooms include ______.
Answer: Agaricus, Amanita - Antibiotics are effective against ______ but not against ______.
Answer: bacteria, viruses
Name the Following
- Name the bacteria that fix atmospheric nitrogen in root nodules of legumes.
Answer: Rhizobium - Name the bacteria that convert ammonia into nitrites.
Answer: Nitrosomonas - Name the bacteria that convert nitrites into nitrates.
Answer: Nitrobacter - Name the bacteria that convert nitrates into free nitrogen.
Answer: Pseudomonas denitrificans - Name the bacteria used in the production of curd.
Answer: Lactobacillus - Name the bacterium used in leather tanning.
Answer: Clostridium - Name one bacterial disease of plants.
Answer: Citrus canker - Name one bacterial disease of animals.
Answer: Anthrax - Name one bacterial disease of humans.
Answer: Tuberculosis - Name the bacterium that causes tetanus.
Answer: Clostridium tetani - Name the bacterium that causes typhoid.
Answer: Salmonella typhi - Name the first discovered antibiotic.
Answer: Penicillin - Name the fungus used in the production of Penicillin.
Answer: Penicillium notatum - Name the scientist who discovered Penicillin.
Answer: Alexander Fleming - Name one antibiotic obtained from bacteria.
Answer: Streptomycin - Name the scientist who discovered pasteurisation.
Answer: Louis Pasteur - Name the scientist who discovered the smallpox vaccine.
Answer: Edward Jenner - Name the type of immunity given by vaccines.
Answer: Active immunity - Name the type of immunity given by serums.
Answer: Passive immunity - Name the substances that neutralise toxins of bacteria.
Answer: Antitoxins - Name the modified toxins used for vaccination.
Answer: Toxoids - Name the process by which milk is preserved by heating and cooling.
Answer: Pasteurisation - Name the process by which bacteria spoil food.
Answer: Putrefaction - Name one preventive method to stop bacterial spoilage of food.
Answer: Freezing (or Salting / Sun drying) - Name the bacterium used in sewage treatment.
Answer: Pseudomonas - Name the fungus used in brewing and baking industries.
Answer: Saccharomyces cerevisiae - Name the common name of Saccharomyces cerevisiae.
Answer: Baker’s yeast - Name the gas produced by yeast during bread-making.
Answer: Carbon dioxide - Name the alcoholic beverage prepared with yeast fermentation.
Answer: Wine - Name one fungus used in cheese ripening.
Answer: Penicillium - Name the edible mushroom commonly cultivated.
Answer: Agaricus - Name one poisonous mushroom.
Answer: Amanita - Name one fungus that causes spoilage of bread.
Answer: Rhizopus - Name the common name of Rhizopus.
Answer: Black bread mould - Name one fungus used in the production of citric acid.
Answer: Aspergillus niger - Name one fungal disease in humans.
Answer: Ringworm - Name the organism used in the production of alcohol.
Answer: Yeast - Name the organism used in the production of vinegar.
Answer: Acetobacter - Name the bacteria that give flavour to tea.
Answer: Bacteria (specific fermenting bacteria) - Name the bacterium used in the production of antibiotics.
Answer: Streptomyces - Name the antibiotic obtained from Streptomyces.
Answer: Streptomycin - Name the first vaccine discovered in history.
Answer: Smallpox vaccine - Name the edible part of a mushroom.
Answer: Fruiting body - Name the fungus that reproduces mainly by budding.
Answer: Yeast - Name the type of sugar fermented by yeast.
Answer: Glucose - Name one fungus that produces organic acids commercially.
Answer: Aspergillus - Name the bacteria that provide fertility to soil.
Answer: Nitrogen-fixing bacteria - Name the bacteria that reduce soil fertility.
Answer: Denitrifying bacteria - Name the industry where Clostridium is used.
Answer: Leather tanning industry - Name the industry where Saccharomyces is used.
Answer: Brewing and baking industry
Answer in One Word
- The bacteria that fix atmospheric nitrogen in legumes.
Answer: Rhizobium - The process of conversion of ammonia into nitrites and nitrates.
Answer: Nitrification - The bacteria that convert nitrates into free nitrogen.
Answer: Denitrifying bacteria - The bacterium that converts milk to curd.
Answer: Lactobacillus - The bacterium used in leather tanning.
Answer: Clostridium - The disease of plants caused by bacteria.
Answer: Citrus canker - The bacterial disease of cattle.
Answer: Anthrax - The bacterial disease of humans caused by Mycobacterium tuberculosis.
Answer: Tuberculosis - The bacterium causing typhoid.
Answer: Salmonella typhi - The bacterium causing tetanus.
Answer: Clostridium tetani - The first discovered antibiotic.
Answer: Penicillin - The fungus used to produce penicillin.
Answer: Penicillium - The scientist who discovered penicillin.
Answer: Alexander Fleming - An antibiotic obtained from Streptomyces.
Answer: Streptomycin - The scientist who discovered pasteurisation.
Answer: Louis Pasteur - The scientist who discovered the smallpox vaccine.
Answer: Edward Jenner - The immunity developed by vaccines.
Answer: Active - The immunity developed by serums.
Answer: Passive - The substances that neutralise toxins of bacteria.
Answer: Antitoxins - Modified toxins used as vaccines.
Answer: Toxoids - The process of heating milk to destroy bacteria.
Answer: Pasteurisation - The process by which bacteria spoil food.
Answer: Putrefaction - A method of food preservation by drying.
Answer: Dehydration - A bacterium used in sewage treatment.
Answer: Pseudomonas - The unicellular fungus used in baking.
Answer: Yeast - The common name of Saccharomyces cerevisiae.
Answer: Baker’s yeast - The gas responsible for the porous texture of bread.
Answer: Carbon dioxide - The beverage obtained by fermentation of sugar by yeast.
Answer: Wine - The fungus used in cheese ripening.
Answer: Penicillium - An edible mushroom.
Answer: Agaricus - A poisonous mushroom.
Answer: Amanita - The fungus commonly called black bread mould.
Answer: Rhizopus - A fungal disease in humans.
Answer: Ringworm - The acid produced by Aspergillus niger.
Answer: Citric - The bacterium that adds fertility to the soil.
Answer: Nitrogen-fixing - The bacteria that lower soil fertility.
Answer: Denitrifying - A bacterial disease transmitted through contaminated water.
Answer: Cholera - A fungal product used in baking and brewing.
Answer: Yeast - The antibiotic obtained from Penicillium notatum.
Answer: Penicillin - The edible part of a mushroom.
Answer: Fruiting body - The process by which yeast reproduces.
Answer: Budding - The sugar fermented by yeast.
Answer: Glucose - The fungus used in commercial enzyme production.
Answer: Aspergillus - The bacterium that causes bacterial blight of rice.
Answer: Xanthomonas oryzae - The antibiotic discovered by Selman Waksman.
Answer: Streptomycin - The disease prevented by BCG vaccine.
Answer: Tuberculosis - The product formed when yeast ferments sugar anaerobically.
Answer: Alcohol - The microorganism that gives flavour to tea.
Answer: Bacteria - The organism that converts alcohol into vinegar.
Answer: Acetobacter - The fungus cultivated as food and rich in proteins.
Answer: Mushroom
ICSE - Grade 9 - Physics
All Chapters
- Chapter 1 Measurement and Experimentation
- Chapter 2 Motion in one dimension
- Chapter 3 Laws of Motion
- Chapter 4 Pressure in fluids and Atmospheric pressure
- Chapter 5 Upthrust in Fluids, Archimedes’ Principle and Floatation
- Chapter 6 Heat and energy
- Chapter 7 Reflection of light
- Chapter 8 Propagation of Sound waves
- Chapter 9 Current Electricity
- Chapter 10 Magnetism
ICSE - Grade 9 - Chemistry
All Chapters
- Chapter 1 The Language of Chemistry
- Chapter 2 Chemical Changes and Reactions
- Chapter 3 Water
- Chapter 4 Atomic Structure and Chemical Bonding
- Chapter 5 The periodic table
- Chapter 6 Study of the first Element Hydrogen
- Chapter 7 Study of Gas laws
- Chapter 8 Atmospheric Pollution
ICSE - Grade 9 - Mathematics
All Chapters
- Chapter 1 Rational and Irrational Numbers
- Chapter 2 Compound Interest [Without Using Formula]
- Chapter 3 Compound Interest [Using Formula]
- Chapter 4 Expansions
- Chapter 5 Factorisation
- Chapter 6 Simultaneous Equations
- Chapter 7 Indices
- Chapter 8 Logarithms
- Chapter 9 Triangles
- Chapter 10 Isosceles Triangles
- Chapter 11 Inequalities
- Chapter 12 Midpoint and Its Converse
- Chapter 13 Pythagoras Theorem
- Chapter 14 Rectilinear Figures
- Chapter 15 Construction of Polygons
- Chapter 16 Area Theorems
- Chapter 17 Circle
- Chapter 18 Statistics
- Chapter 19 Mean and Median
- Chapter 20 Area and Perimeter of Plane Figures
- Chapter 21 Solids
- Chapter 22 Trigonometrical Ratios
- Chapter 23 Trigonometrical Ratios of Standard Angles
- Chapter 24 Solutions of Right Triangles
- Chapter 25 Complementary Angles
- Chapter 26 Coordinate Geometry
- Chapter 27 Graphical Solution
- Chapter 28 Distance Formula
ICSE - Grade 9 - Biology
All Chapters
- Chapter 1 Introducing Biology
- Chapter 2 Cell: The Unit Of Life
- Chapter 3 Tissues: Plant And Animal Tissue
- Chapter 4 The Flower
- Chapter 5 Pollination and Fertilization
- Chapter 6 Seeds: Structure and Germination
- Chapter 7 Respiration in Plants
- Chapter 8 Five Kingdom Classification
- Chapter 9 Economic Importance of Bacteria and Fungi
- Chapter 10 Nutrition
- Chapter 11 Digestive system
- Chapter 12 Skeleton: Movement and Locomotion
- Chapter 13 Skin: The Jack of all trades
- Chapter 14 The Respiratory System
- Chapter 15 Hygiene: [A key to Healthy Life]
- Chapter 16 Diseases: Cause and Control
- Chapter 17 Aids to Health
- Chapter 18 Health Organizations
- Chapter 19 Waste Generation and Management
ICSE - Grade 9 - History
All Chapters
- Chapter 1 – The Harappan Civilisation
- Chapter 2 – The Vedic Period
- Chapter 3 – Jainism and Buddhism
- Chapter 4 – The Mauryan Empire
- History — Chapter 5
The Sangam Age - Chapter 6 – The Age of the Guptas
- Chapter 7 – Medieval India — (A) The Cholas
- Chapter 8 – Medieval India — (B) The Delhi Sultanate
- Chapter 9 – Medieval India — (C) The Mughal Empire
- Chapter 10 – Medieval India — (D) Composite Culture
- Chapter 11 – The Modern Age in Europe — (A) Renaissance
- Chapter 12 – The Modern Age in Europe — (B) Reformation
- Chapter 13 – The Modern Age in Europe — (C) Industrial Revolution
ICSE - Grade 9 - Civics
All Chapters
- Chapter 1: Our Constitution
- Chapter 2: Salient Features of the Constitution — I
- Chapter 3: Salient Features of the
- Constitution — II
- Chapter 4: Elections
- Chapter 5: Local Self-Government — Rural
- Chapter 6: Local Self-Government — Urban
ICSE - Grade 9 - Geography
All Chapters
- Ch 1 – Earth as a Planet
Ch 2 – Geographic Grid: Latitudes and Longitudes
Ch 3 – Rotation and Revolution
Ch 4 – Earth’s Structure
Ch 5 – Landforms of the Earth
Ch 6 – Rocks
Ch 7 – Volcanoes
Ch 8 – Earthquakes
Ch 9 – Weathering
Ch 10 – Denudation
Ch 11 – Hydrosphere
Ch 12 – Composition and Structure of the Atmosphere
Ch 13 – Insolation
Ch 14 – Atmospheric Pressure and Winds
Ch 15 – Humidity
Ch 16 – Pollution
Ch 17 – Sources of Pollution
Ch 18 – Effects of Pollution
Ch 19 – Preventive Measures
Ch 20 – Natural Regions of the World
Find the Odd Man Out
- Rhizobium, Nitrosomonas, Nitrobacter, Salmonella
Answer: Salmonella
Explanation: Salmonella is a pathogenic bacterium, others are useful in nitrogen cycle. - Lactobacillus, Clostridium, Penicillium, Rhizobium
Answer: Penicillium
Explanation: Penicillium is a fungus, others are bacteria. - Typhoid, Cholera, Tuberculosis, Ringworm
Answer: Ringworm
Explanation: Ringworm is a fungal disease, others are bacterial diseases. - Citrus canker, Anthrax, Rust of wheat, Tuberculosis
Answer: Rust of wheat
Explanation: Rust of wheat is a fungal disease, others are bacterial diseases. - Penicillin, Streptomycin, Vaccine, Tetracycline
Answer: Vaccine
Explanation: Vaccine gives immunity, others are antibiotics. - Antitoxin, Toxoid, Serum, Penicillin
Answer: Penicillin
Explanation: Penicillin is an antibiotic, others are related to immunity. - Nitrification, Denitrification, Putrefaction, Photosynthesis
Answer: Photosynthesis
Explanation: Photosynthesis is carried out by plants, others are bacterial processes. - Freezing, Salting, Sun drying, Fermentation
Answer: Fermentation
Explanation: Fermentation spoils food, others preserve it. - Penicillium, Aspergillus, Rhizopus, Lactobacillus
Answer: Lactobacillus
Explanation: Lactobacillus is a bacterium, others are fungi. - Alexander Fleming, Edward Jenner, Louis Pasteur, Gregor Mendel
Answer: Gregor Mendel
Explanation: Mendel is the father of genetics, others worked on microbes/vaccines. - Curd, Cheese, Vinegar, Tuberculosis
Answer: Tuberculosis
Explanation: Tuberculosis is a disease, others are microbial products. - Bread, Wine, Beer, Anthrax
Answer: Anthrax
Explanation: Anthrax is a bacterial disease, others are products of fermentation. - Agaricus, Amanita, Penicillium, Lactobacillus
Answer: Lactobacillus
Explanation: Lactobacillus is a bacterium, others are fungi. - Carbon dioxide, Alcohol, Oxygen, Lactic acid
Answer: Oxygen
Explanation: Yeast does not produce oxygen during fermentation, others are products. - Nitrosomonas, Nitrobacter, Rhizobium, Plasmodium
Answer: Plasmodium
Explanation: Plasmodium is a protozoan parasite, others are bacteria. - Cheese, Bread, Wine, Cholera
Answer: Cholera
Explanation: Cholera is a disease, others are useful products of microbes. - Clostridium tetani, Salmonella typhi, Mycobacterium tuberculosis, Aspergillus niger
Answer: Aspergillus niger
Explanation: Aspergillus is a fungus, others are bacteria. - Vaccine, Serum, Antitoxin, Nitrification
Answer: Nitrification
Explanation: Nitrification is a soil bacterial process, others are immunity-related. - Typhoid, Tetanus, Tuberculosis, Smallpox
Answer: Smallpox
Explanation: Smallpox is viral, others are bacterial diseases. - Citric acid, Acetic acid, Lactic acid, Penicillin
Answer: Penicillin
Explanation: Penicillin is an antibiotic, others are microbial acids. - Freezing, Boiling, Salting, Smoking
Answer: Boiling
Explanation: Boiling is a temporary method, others preserve food for longer periods. - Agaricus, Yeast, Amanita, Anthrax
Answer: Anthrax
Explanation: Anthrax is a bacterial disease, others are fungi. - Streptomycin, Tetracycline, Chloramphenicol, Vaccine
Answer: Vaccine
Explanation: Vaccine is not an antibiotic, others are antibiotics. - Wine, Beer, Bread, Ringworm
Answer: Ringworm
Explanation: Ringworm is a fungal disease, others are products of yeast. - Rhizopus, Penicillium, Aspergillus, Salmonella
Answer: Salmonella
Explanation: Salmonella is a bacterium, others are fungi. - Putrefaction, Fermentation, Pasteurisation, Curdling
Answer: Pasteurisation
Explanation: Pasteurisation preserves food, others are microbial processes. - Anthrax, Citrus canker, Tuberculosis, Malaria
Answer: Malaria
Explanation: Malaria is protozoan, others are bacterial diseases. - Agaricus, Amanita, Lactobacillus, Penicillium
Answer: Lactobacillus
Explanation: Lactobacillus is a bacterium, others are fungi. - Edward Jenner, Alexander Fleming, Louis Pasteur, Charles Darwin
Answer: Charles Darwin
Explanation: Darwin worked on evolution, others on microbes and vaccines. - Penicillin, Cheese, Wine, Anthrax
Answer: Anthrax
Explanation: Anthrax is a disease, others are useful microbial products. - Ringworm, Rust, Smut, Tuberculosis
Answer: Tuberculosis
Explanation: Tuberculosis is bacterial, others are fungal diseases. - Pasteurisation, Freezing, Sun drying, Fermentation
Answer: Fermentation
Explanation: Fermentation spoils food, others preserve food. - Rhizobium, Nitrosomonas, Nitrobacter, Aspergillus
Answer: Aspergillus
Explanation: Aspergillus is a fungus, others are bacteria in nitrogen cycle. - Acetobacter, Penicillium, Aspergillus, Rhizopus
Answer: Acetobacter
Explanation: Acetobacter is a bacterium, others are fungi. - Anthrax, Tuberculosis, Tetanus, Ringworm
Answer: Ringworm
Explanation: Ringworm is fungal, others are bacterial diseases. - Wine, Bread, Beer, Tuberculosis
Answer: Tuberculosis
Explanation: Tuberculosis is a disease, others are useful products of yeast. - Nitrification, Denitrification, Nitrogen fixation, Photosynthesis
Answer: Photosynthesis
Explanation: Photosynthesis is not a bacterial nitrogen process. - Edward Jenner, Alexander Fleming, Louis Pasteur, Robert Frost
Answer: Robert Frost
Explanation: Robert Frost was a poet, others are microbiologists/scientists. - Lactobacillus, Clostridium, Rhizobium, Rust
Answer: Rust
Explanation: Rust is a fungal disease, others are bacteria. - Tetanus, Tuberculosis, Cholera, Ringworm
Answer: Ringworm
Explanation: Ringworm is fungal, others are bacterial diseases. - Streptomycin, Vaccine, Serum, Antitoxin
Answer: Streptomycin
Explanation: Streptomycin is an antibiotic, others give immunity. - Freezing, Salting, Pickling, Putrefaction
Answer: Putrefaction
Explanation: Putrefaction spoils food, others preserve food. - Nitrosomonas, Nitrobacter, Rhizobium, Amoeba
Answer: Amoeba
Explanation: Amoeba is a protozoan, others are bacteria. - Cheese, Bread, Wine, Rust
Answer: Rust
Explanation: Rust is a fungal disease, others are useful microbial products. - Amanita, Agaricus, Penicillium, Yeast
Answer: Penicillium
Explanation: Penicillium is mould, others are edible fungi (or yeast). - Anthrax, Cholera, Tuberculosis, AIDS
Answer: AIDS
Explanation: AIDS is viral, others are bacterial diseases. - Carbon dioxide, Alcohol, Oxygen, Antibiotic
Answer: Antibiotic
Explanation: Antibiotic is not a fermentation product of yeast. - Clostridium, Salmonella, Lactobacillus, Aspergillus
Answer: Aspergillus
Explanation: Aspergillus is a fungus, others are bacteria. - Louis Pasteur, Alexander Fleming, Edward Jenner, Isaac Newton
Answer: Isaac Newton
Explanation: Newton was a physicist, others worked in microbiology. - Bread, Wine, Beer, Tuberculosis
Answer: Tuberculosis
Explanation: Tuberculosis is a disease, others are useful microbial products.
Match the Pair
Set 1
Column A
- Rhizobium
- Nitrosomonas
- Nitrobacter
- Pseudomonas
- Denitrifying bacteria
Column B
a. Converts ammonia into nitrites
b. Reduces soil fertility
c. Converts nitrites into nitrates
d. Nitrogen fixation in legumes
e. Used in sewage treatment
Correct Answers:
1 – d
2 – a
3 – c
4 – e
5 – b
Set 2
Column A
- Lactobacillus
- Clostridium
- Acetobacter
- Xanthomonas citri
- Bacillus anthracis
Column B
a. Causes citrus canker
b. Converts alcohol into vinegar
c. Leather tanning
d. Causes anthrax
e. Converts milk sugar into lactic acid
Correct Answers:
1 – e
2 – c
3 – b
4 – a
5 – d
Set 3
Column A
- Mycobacterium tuberculosis
- Salmonella typhi
- Vibrio cholerae
- Clostridium tetani
- Edward Jenner
Column B
a. Causes typhoid
b. Causes tuberculosis
c. Causes cholera
d. Developed smallpox vaccine
e. Causes tetanus
Correct Answers:
1 – b
2 – a
3 – c
4 – e
5 – d
Set 4
Column A
- Louis Pasteur
- Alexander Fleming
- Selman Waksman
- Pasteurisation
- Penicillium notatum
Column B
a. Discovery of penicillin
b. Process of heating and cooling milk
c. Discovered streptomycin
d. Produced antibiotic penicillin
e. Father of Microbiology
Correct Answers:
1 – e
2 – a
3 – c
4 – b
5 – d
Set 5
Column A
- Vaccine
- Serum
- Antitoxin
- Toxoid
- BCG
Column B
a. Contains weakened or dead microbes
b. Used to prevent tuberculosis
c. Contains ready-made antibodies
d. Neutralises bacterial toxins
e. Modified toxin used for vaccination
Correct Answers:
1 – a
2 – c
3 – d
4 – e
5 – b
Set 6
Column A
- Sun-drying
- Freezing
- Smoking
- Salting
- Dehydration
Column B
a. Low temperature slows bacterial growth
b. Removes moisture
c. Preserves meat and fish
d. Uses sunlight to prevent spoilage
e. Preserves food by removing water completely
Correct Answers:
1 – d
2 – a
3 – c
4 – b
5 – e
Set 7
Column A
- Yeast
- Saccharomyces cerevisiae
- Carbon dioxide
- Alcohol fermentation
- Budding
Column B
a. Common baker’s yeast
b. Gas that makes dough rise
c. Reproduction in yeast
d. Converts sugar into alcohol
e. Used in baking and brewing
Correct Answers:
1 – e
2 – a
3 – b
4 – d
5 – c
Set 8
Column A
- Wine
- Beer
- Cheese
- Penicillium
- Mushroom
Column B
a. Made by fermenting grapes
b. Ripening involves fungi
c. Edible fungus
d. Fermented cereal grains
e. Fungus used in antibiotics
Correct Answers:
1 – a
2 – d
3 – b
4 – e
5 – c
Set 9
Column A
- Agaricus
- Amanita
- Ringworm
- Aspergillus niger
- Rhizopus
Column B
a. Poisonous mushroom
b. Causes skin disease in humans
c. Used for citric acid production
d. Common edible mushroom
e. Black bread mould
Correct Answers:
1 – d
2 – a
3 – b
4 – c
5 – e
Set 10
Column A
- Nitrogen cycle
- Nitrification
- Denitrification
- Nitrogen fixation
- Putrefaction
Column B
a. Conversion of ammonia to nitrites/nitrates
b. Conversion of nitrates into nitrogen gas
c. Process of nitrogen circulation in nature
d. Spoilage of proteins by bacteria
e. Conversion of atmospheric nitrogen into compounds
Correct Answers:
1 – c
2 – a
3 – b
4 – e
5 – d
Short Answer Questions
- Which antibiotic was discovered by Alexander Fleming?
Answer: Alexander Fleming discovered the antibiotic penicillin from the fungus Penicillium notatum. - What are vaccines?
Answer: Vaccines are preparations of weakened or killed germs that stimulate the body to develop immunity against a disease. - What is the role of serums in medicine?
Answer: Serums provide ready-made antibodies that give immediate passive immunity to the patient. - What are toxoids?
Answer: Toxoids are chemically treated bacterial toxins that lose their harmful effect but still stimulate immunity. - What is the role of nitrogen-fixing bacteria?
Answer: Nitrogen-fixing bacteria convert free nitrogen of the atmosphere into nitrogen compounds usable by plants. - Give one example of a symbiotic nitrogen-fixing bacterium.
Answer: Rhizobium lives in root nodules of legumes and fixes nitrogen for the plant. - What is the function of nitrifying bacteria?
Answer: Nitrifying bacteria convert ammonia into nitrites and nitrates which can be absorbed by plants. - What is the role of denitrifying bacteria?
Answer: Denitrifying bacteria break down nitrates into free nitrogen, reducing soil fertility. - How are bacteria used in leather tanning?
Answer: Certain bacteria decompose organic matter and help in softening and tanning of hides to make leather. - How do bacteria help in tea production?
Answer: Bacteria help in fermentation during curing of tea leaves which improves flavour and aroma. - Name a bacterium used in vinegar production and its role.
Answer: Acetobacter aceti converts alcohol into acetic acid which is used in vinegar production. - How does Lactobacillus help in milk products?
Answer: Lactobacillus converts lactose in milk into lactic acid leading to curdling of milk. - What is anthrax and which organism causes it?
Answer: Anthrax is a fatal disease of cattle caused by the bacterium Bacillus anthracis. - What is citrus canker?
Answer: Citrus canker is a bacterial disease of citrus plants caused by Xanthomonas citri. - What is ring rot of potato?
Answer: Ring rot of potato is a bacterial disease caused by Corynebacterium sepedonicum. - How is tuberculosis transmitted to humans from animals?
Answer: Tuberculosis can spread to humans through infected milk from diseased cattle. - What is brucellosis?
Answer: Brucellosis is a bacterial disease of sheep and goats that causes abortion and fever. - How does pasteurisation prevent bacterial spoilage of milk?
Answer: Pasteurisation kills harmful bacteria in milk by heating it without affecting taste or nutrition. - How does yeast help in bread making?
Answer: Yeast ferments sugar to produce carbon dioxide which makes bread soft and spongy. - What makes bread rise during baking?
Answer: The carbon dioxide released by yeast during fermentation causes bread to rise. - Which fungus produces penicillin and how is it used?
Answer: Penicillium notatum produces penicillin which is used as an antibiotic to kill harmful bacteria. - What is streptomycin and its source?
Answer: Streptomycin is an antibiotic produced by the bacterium Streptomyces griseus. - How does Penicillium help in cheese production?
Answer: Penicillium species grow in cheese and give it special flavour and texture. - How is wine produced?
Answer: Wine is produced by fermenting sugars in grapes with yeast to form alcohol. - Which edible fungus is cultivated on a large scale and why?
Answer: Mushrooms like Agaricus are cultivated as they are highly nutritious and rich in protein. - What is the nutritive value of mushrooms?
Answer: Mushrooms are rich in proteins, vitamins, and minerals but low in fats. - How is soy sauce prepared?
Answer: Soy sauce is prepared by fermenting soybeans with the fungus Aspergillus oryzae. - Which fungus causes spoilage of bread?
Answer: Bread is spoiled by Rhizopus which grows as black mould. - What is ringworm and what causes it?
Answer: Ringworm is a fungal disease of human skin caused by Trichophyton. - How do bacteria help in buttermilk preparation?
Answer: Lactic acid bacteria ferment milk sugars and convert milk into buttermilk. - What is BCG vaccine used for?
Answer: The BCG vaccine is used to prevent tuberculosis. - What is DPT vaccine used for?
Answer: The DPT vaccine protects against diphtheria, pertussis, and tetanus. - What are antitoxins?
Answer: Antitoxins are ready-made antibodies produced against toxins to provide immediate passive immunity. - How is tetanus toxoid prepared?
Answer: Tetanus toxoid is prepared by chemically treating tetanus toxin to make it harmless. - What is the role of Aspergillus niger in industry?
Answer: Aspergillus niger is used in the large-scale production of citric acid. - Why is Aspergillus flavus harmful?
Answer: Aspergillus flavus produces aflatoxins which are poisonous to humans and animals. - How does Clostridium botulinum cause food poisoning?
Answer: Clostridium botulinum grows in improperly canned food and produces a deadly toxin. - What is lockjaw and what causes it?
Answer: Lockjaw is another name for tetanus caused by Clostridium tetani. - How do fungi affect wheat crops?
Answer: Fungi cause rust disease in wheat which reduces crop yield. - What is the common name of Agaricus bisporus?
Answer: The common name of Agaricus bisporus is button mushroom. - How is alcohol made from molasses?
Answer: Yeast ferments sugars present in molasses to produce alcohol. - How does pickling prevent bacterial spoilage?
Answer: Pickling uses salt or vinegar which creates conditions unsuitable for bacterial growth. - How does Lactobacillus convert milk to curd?
Answer: Lactobacillus ferments lactose in milk to form lactic acid, which coagulates proteins and sets curd. - How is Roquefort cheese ripened?
Answer: Roquefort cheese is ripened by the fungus Penicillium roqueforti. - How is Swiss cheese produced?
Answer: Swiss cheese is produced using Propionibacterium shermanii which releases CO₂ and forms characteristic holes. - Why is yeast used in the baking industry?
Answer: Yeast produces carbon dioxide during fermentation which makes dough rise in baking. - Which fungus is cultivated as food?
Answer: Edible mushrooms like Agaricus campestris are cultivated for food. - What is citrus canker and its cause?
Answer: Citrus canker is a bacterial disease of citrus plants caused by Xanthomonas citri. - Which antibiotic is obtained from Cephalosporium?
Answer: The fungus Cephalosporium produces the antibiotic cephalosporin. - What is the importance of yeast in brewing?
Answer: Yeast ferments sugars in fruit juices or grains to produce alcohol in brewing industries.
Puzzles
Q.1. I live in the root nodules of legumes and fix nitrogen. Who am I?
Ans. Rhizobium
Q.2. I convert ammonia into nitrites. Name me.
Ans. Nitrosomonas
Q.3. I convert nitrites into nitrates. Who am I?
Ans. Nitrobacter
Q.4. I reduce soil nitrates back into nitrogen gas. Who am I?
Ans. Denitrifying bacteria (Pseudomonas)
Q.5. I am the first antibiotic discovered, produced by a fungus. Who am I?
Ans. Penicillin
Q.6. I am a weakened toxin used in vaccines. Who am I?
Ans. Toxoid
Q.7. I provide immediate immunity as I contain ready-made antibodies. Who am I?
Ans. Serum
Q.8. I neutralize bacterial toxins inside the body. Who am I?
Ans. Antitoxin
Q.9. I turn milk into curd by producing lactic acid. Who am I?
Ans. Lactobacillus
Q.10. I am used to make bread spongy. Who am I?
Ans. Yeast (Saccharomyces cerevisiae)
Q.11. I give flavour to tea leaves after fermentation. Who am I?
Ans. Bacteria and fungi during tea fermentation
Q.12. I soften animal hides in leather tanning. Who am I?
Ans. Bacteria
Q.13. I cause citrus canker in oranges and lemons. Who am I?
Ans. Xanthomonas citri
Q.14. I cause ring disease in potatoes. Who am I?
Ans. Clavibacter
Q.15. I am a fungal food rich in protein, often called vegetarian’s meat. Who am I?
Ans. Mushroom (Agaricus)
Q.16. I am a fermented drink made from grapes. Who am I?
Ans. Wine
Q.17. I am the bacterium that causes anthrax in cattle. Who am I?
Ans. Bacillus anthracis
Q.18. I am a bacterial disease that reduces milk yield in cattle. Who am I?
Ans. Tuberculosis (Mycobacterium bovis)
Q.19. I am a fungus that produces aflatoxins in stored grains. Who am I?
Ans. Aspergillus flavus
Q.20. I am a fungal antibiotic other than penicillin. Who am I?
Ans. Cephalosporin
Q.21. I am added to dough to make it rise. Who am I?
Ans. Yeast
Q.22. I am the chemical process yeast uses to make alcohol. What am I?
Ans. Fermentation
Q.23. I am the gas produced by yeast in bread-making. Who am I?
Ans. Carbon dioxide
Q.24. I am used to preserve jams by reducing water content. Who am I?
Ans. Sugar
Q.25. I am used in pickles to prevent bacterial growth. Who am I?
Ans. Salt
Q.26. I am the process of heating milk to kill bacteria. Who am I?
Ans. Pasteurization
Q.27. I am a bacterial vaccine used to protect against TB. Who am I?
Ans. BCG vaccine
Q.28. I am a toxoid vaccine used against diphtheria. Who am I?
Ans. DPT vaccine
Q.29. I am the fungus that ripens Roquefort cheese. Who am I?
Ans. Penicillium roqueforti
Q.30. I am the product formed when milk proteins coagulate. Who am I?
Ans. Curd
Q.31. I am responsible for souring of milk. Who am I?
Ans. Lactic acid bacteria
Q.32. I am used as a preservative in vinegar. Who am I?
Ans. Acetic acid (produced by Acetobacter)
Q.33. I am a fungal infection of bread. Who am I?
Ans. Bread mould (Rhizopus)
Q.34. I am a fungus used in brewing industry. Who am I?
Ans. Yeast
Q.35. I am a fungus used in the production of penicillin. Who am I?
Ans. Penicillium notatum
Q.36. I am a food rich in proteins, vitamins, and minerals but low in calories. Who am I?
Ans. Mushroom
Q.37. I am the organism responsible for foul smell in meat and fish spoilage. Who am I?
Ans. Bacteria
Q.38. I am the bacterial process that adds nitrogen to soil. Who am I?
Ans. Nitrogen fixation
Q.39. I am the bacterial process that removes nitrogen from soil. Who am I?
Ans. Denitrification
Q.40. I am the bacterium that lives freely in soil and fixes nitrogen. Who am I?
Ans. Azotobacter
Q.41. I am the bacterium used in preparation of vinegar. Who am I?
Ans. Acetobacter aceti
Q.42. I am the fungal structure used for mushroom cultivation. Who am I?
Ans. Mycelium
Q.43. I am a fungus eaten as food and also used in soups. Who am I?
Ans. Mushroom
Q.44. I am the bacterium that helps fermenting coffee and cocoa. Who am I?
Ans. Lactic acid bacteria
Q.45. I am the method of preserving food by freezing. Who am I?
Ans. Refrigeration
Q.46. I am the immediate immune response given by injecting antibodies. Who am I?
Ans. Passive immunity (serum therapy)
Q.47. I am a harmful bacterium that can spoil canned food. Who am I?
Ans. Clostridium botulinum
Q.48. I am the useful role of yeast in baking, brewing, and wine-making. Who am I?
Ans. Fermentation
Q.49. I am the nutritive value of mushrooms that makes them valuable. What am I?
Ans. Rich source of proteins, vitamins, and minerals
Q.50. I am the group of organisms including bacteria and fungi that have great economic importance. Who am I?
Ans. Microorganisms
Difference Between:
Q.1. Difference between useful and harmful bacteria
Ans.
- Useful bacteria: Rhizobium, Lactobacillus – used in nitrogen fixation, curd preparation, antibiotics, and food industry.
- Harmful bacteria: Xanthomonas, Clostridium – cause plant and human diseases and spoil food.
Q.2. Difference between antibiotics and antitoxins
Ans.
- Antibiotics: Substances produced by microorganisms (fungi/bacteria) that kill or inhibit bacteria; used to treat infections (e.g., Penicillin).
- Antitoxins: Antibodies produced against bacterial toxins; neutralize toxins but do not kill bacteria directly.
Q.3. Difference between vaccine and toxoid
Ans.
- Vaccine: Contains weakened or killed microorganisms to stimulate immunity.
- Toxoid: Inactivated bacterial toxin that produces immunity without causing disease (e.g., tetanus toxoid).
Q.4. Difference between nitrogen-fixing and nitrifying bacteria
Ans.
- Nitrogen-fixing bacteria: Convert atmospheric nitrogen into ammonia/nitrates usable by plants (Rhizobium, Azotobacter).
- Nitrifying bacteria: Convert ammonia into nitrites and then nitrates (Nitrosomonas, Nitrobacter).
Q.5. Difference between nitrifying and denitrifying bacteria
Ans.
- Nitrifying bacteria: Increase soil fertility by producing nitrates from ammonia.
- Denitrifying bacteria: Reduce soil fertility by converting nitrates back into atmospheric nitrogen (Pseudomonas).
Q.6. Difference between yeast and bacteria
Ans.
- Yeast: Eukaryotic fungus, used in baking, brewing, and wine-making; facultative anaerobe.
- Bacteria: Prokaryotic organism, used in medicine, agriculture, and industry; can be aerobic or anaerobic.
Q.7. Difference between curd and cheese
Ans.
- Curd: Formed by bacterial fermentation of milk (Lactobacillus), semi-solid, mildly sour.
- Cheese: Prepared by bacterial or fungal fermentation of milk; solid, aged, has characteristic flavour (Penicillium).
Q.8. Difference between useful fungi and harmful fungi
Ans.
- Useful fungi: Produce antibiotics, alcohol, bread, cheese; used in mushroom cultivation.
- Harmful fungi: Cause food spoilage, plant diseases, and produce toxins (e.g., Aspergillus).
Q.9. Difference between alcoholic fermentation and lactic acid fermentation
Ans.
- Alcoholic fermentation: Yeast converts sugars into ethanol + CO₂; used in wine and beer.
- Lactic acid fermentation: Lactobacillus converts sugars into lactic acid; used in curd and yoghurt.
Q.10. Difference between serums and vaccines
Ans.
- Serums: Contain ready-made antibodies; provide immediate passive immunity.
- Vaccines: Contain weakened/killed microorganisms; induce active immunity over time.
Q.11. Difference between spoilage of food by bacteria and fungi
Ans.
- Bacteria: Produce foul odour, gas, and slime (e.g., milk spoilage).
- Fungi: Form moulds or mycelium on food surfaces (e.g., bread mould, grains).
Q.12. Difference between wine and beer production
Ans.
- Wine: Fermented from fruit juice (grapes) by yeast, primarily alcoholic content.
- Beer: Fermented from cereals (barley/wheat) by yeast, contains alcohol + foam due to CO₂.
Q.13. Difference between edible mushrooms and poisonous fungi
Ans.
- Edible mushrooms: Non-toxic, nutritious, used as food (Agaricus).
- Poisonous fungi: Toxic, can cause illness or death (Amanita species).
Q.14. Difference between active immunity and passive immunity
Ans.
- Active immunity: Produced when body generates antibodies after vaccination or infection; long-lasting.
- Passive immunity: Received from external source (serum/antitoxin); immediate but short-lived.
Q.15. Difference between pasteurization and refrigeration
Ans.
- Pasteurization: Heating milk to kill harmful bacteria; kills only pathogens, not all microbes.
- Refrigeration: Lowers temperature to slow bacterial growth; does not kill bacteria.
Q.16. Difference between soil bacteria and pathogenic bacteria
Ans.
- Soil bacteria: Useful, enrich soil fertility (Rhizobium, Azotobacter).
- Pathogenic bacteria: Harmful, cause diseases in plants and animals (Clavibacter, Bacillus anthracis).
Q.17. Difference between active and dormant bacterial forms
Ans.
- Active form: Bacteria are metabolically active, multiply rapidly.
- Dormant form: Bacteria form spores under harsh conditions, remain inactive until conditions improve.
Q.18. Difference between sericulture and mushroom cultivation
Ans.
- Sericulture: Rearing silkworms for silk production; insects involved.
- Mushroom cultivation: Growing edible fungi for food; fungus involved.
Q.19. Difference between bacterial and fungal antibiotics
Ans.
- Bacterial antibiotics: Produced by bacteria (e.g., Streptomycin by Streptomyces).
- Fungal antibiotics: Produced by fungi (e.g., Penicillin by Penicillium).
Q.20. Difference between active and passive role of microbes in industry
Ans.
- Active role: Microbes participate directly in fermentation (yeast in bread, wine).
- Passive role: Microbial enzymes used in leather tanning or flavour development without growth.
Assertion and Reason
Assertion: Rhizobium is useful to farmers.
Reason: It causes root nodules in leguminous plants and fixes atmospheric nitrogen.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Nitrosomonas helps in nitrification.
Reason: It converts ammonia into nitrites.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Nitrobacter is harmful to agriculture.
Reason: It converts nitrites into nitrates.
Answer: Assertion is false, Reason is true.
Assertion: Lactobacillus is used in making curd.
Reason: It converts lactose sugar of milk into lactic acid.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Yeast is used in bakeries.
Reason: Yeast produces carbon dioxide which makes the dough rise.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Yeast respires aerobically during alcohol production.
Reason: In absence of oxygen, yeast produces alcohol and carbon dioxide.
Answer: Assertion is false, Reason is true.
Assertion: Aspergillus niger is used in citric acid production.
Reason: It is a pathogenic bacterium.
Answer: Assertion is true, Reason is false.
Assertion: Vinegar is produced by Acetobacter.
Reason: Acetobacter converts alcohol into acetic acid.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Penicillin is an antibiotic obtained from Penicillium notatum.
Reason: It kills or inhibits the growth of harmful bacteria.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Antibiotics are used to treat viral diseases.
Reason: Antibiotics kill bacteria but not viruses.
Answer: Assertion is false, Reason is true.
Assertion: Edward Jenner is called the “Father of Immunology”.
Reason: He discovered the smallpox vaccine.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Louis Pasteur disproved spontaneous generation.
Reason: He proved that microorganisms come only from pre-existing microorganisms.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Pasteurisation prevents milk spoilage.
Reason: In pasteurisation, milk is heated to 62°C for 30 minutes or 72°C for 15 seconds and then cooled rapidly.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Smoking and salting preserve fish and meat.
Reason: They make the environment unsuitable for bacterial growth.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Freezing preserves food.
Reason: Low temperature stops bacterial growth completely.
Answer: Assertion is true, Reason is false.
Assertion: Sun-drying prevents food spoilage.
Reason: It removes moisture which bacteria and fungi need to grow.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Cholera is a viral disease.
Reason: It is caused by Vibrio cholerae, a bacterium.
Answer: Assertion is false, Reason is true.
Assertion: Tuberculosis is caused by Mycobacterium tuberculosis.
Reason: It affects the lungs in humans.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Typhoid is spread by contaminated water and food.
Reason: It is caused by Salmonella typhi.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Citrus canker is a fungal disease.
Reason: It is caused by Xanthomonas citri, a bacterium.
Answer: Assertion is false, Reason is true.
Assertion: Tetanus is caused by Clostridium tetani.
Reason: The bacterium enters through wounds.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Anthrax affects humans and cattle.
Reason: It is caused by Bacillus anthracis.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Ringworm is caused by bacteria.
Reason: It is actually caused by a fungus.
Answer: Assertion is false, Reason is true.
Assertion: Rust of wheat is caused by a virus.
Reason: It is a fungal disease.
Answer: Assertion is false, Reason is true.
Assertion: Polio can be prevented by vaccination.
Reason: Vaccines stimulate the body to produce immunity.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Vaccines provide active immunity.
Reason: They stimulate the body to produce antibodies.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Serum provides active immunity.
Reason: Serum contains ready-made antibodies.
Answer: Assertion is false, Reason is true.
Assertion: Antitoxins neutralise toxins produced by bacteria.
Reason: They are antibodies produced against bacterial toxins.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Toxoids are inactivated toxins.
Reason: They are used for vaccination.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Putrefaction is useful for food preservation.
Reason: It spoils food by bacterial action.
Answer: Assertion is false, Reason is true.
Assertion: Fermentation is used in alcohol production.
Reason: Yeast converts sugars into alcohol and carbon dioxide.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Yeast is used in making antibiotics.
Reason: Yeast produces alcohol, not antibiotics.
Answer: Assertion is false, Reason is true.
Assertion: Cheese making involves bacteria.
Reason: Lactic acid bacteria convert lactose into lactic acid and help curd formation.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Yeast is used in beer and wine making.
Reason: Yeast ferments sugar in grains and fruits.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Rust, Smut and Ringworm are bacterial diseases.
Reason: They are fungal diseases.
Answer: Assertion is false, Reason is true.
Assertion: Antibiotics are produced only by fungi.
Reason: Some antibiotics are produced by bacteria too.
Answer: Assertion is false, Reason is true.
Assertion: Fleming discovered Penicillin.
Reason: He observed Penicillium fungus inhibiting bacterial growth.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Jenner developed vaccination for rabies.
Reason: Pasteur developed rabies vaccine, not Jenner.
Answer: Assertion is false, Reason is true.
Assertion: Nitrogen fixation improves soil fertility.
Reason: Nitrogen-fixing bacteria convert atmospheric nitrogen into usable compounds.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Denitrifying bacteria are useful for agriculture.
Reason: They reduce soil fertility by converting nitrates to nitrogen gas.
Answer: Assertion is false, Reason is true.
Assertion: Antibiotics are chemical substances secreted by microorganisms.
Reason: They can destroy or inhibit the growth of other microorganisms.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Alcoholic fermentation is an aerobic process.
Reason: It occurs in absence of oxygen.
Answer: Assertion is false, Reason is true.
Assertion: Lactic acid bacteria spoil milk.
Reason: They curdle milk and are useful in curd preparation.
Answer: Assertion is true, Reason is true, but Reason does not explain Assertion.
Assertion: Smoking kills bacteria in food.
Reason: Smoke creates a dry, antimicrobial environment around the food.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Freezing kills bacteria permanently.
Reason: Freezing only slows down their growth but does not kill them.
Answer: Assertion is false, Reason is true.
Assertion: Diseases like Tuberculosis and Typhoid are communicable.
Reason: They spread from one person to another.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Vaccination provides quick relief in infections.
Reason: Vaccines act immediately.
Answer: Both Assertion and Reason are false.
Assertion: Antibiotics can be misused.
Reason: Overuse makes bacteria resistant to them.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: Some fungi are edible.
Reason: Mushrooms like Agaricus are eaten as food.
Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.
Assertion: All bacteria are harmful to humans.
Reason: Some bacteria are useful in food, medicine, and agriculture.
Answer: Assertion is false, Reason is true.
True or False
- Rhizobium helps in nitrogen fixation in leguminous plants.
Answer: True - Nitrifying bacteria reduce soil fertility.
Answer: False (They improve fertility by converting ammonia into nitrites/nitrates) - Denitrifying bacteria are useful for agriculture.
Answer: False (They reduce soil fertility) - Nitrosomonas converts ammonia into nitrites.
Answer: True - Lactobacillus converts milk sugar into lactic acid.
Answer: True - Clostridium is used in leather tanning.
Answer: True - Acetobacter converts alcohol into vinegar.
Answer: True - Citrus canker is a fungal disease.
Answer: False (It is caused by a bacterium) - Tuberculosis is caused by Mycobacterium tuberculosis.
Answer: True - Typhoid is caused by a virus.
Answer: False (It is caused by a bacterium) - Tetanus is caused by Clostridium tetani.
Answer: True - Anthrax is a disease caused by Bacillus anthracis.
Answer: True - Alexander Fleming discovered streptomycin.
Answer: False (He discovered penicillin) - Selman Waksman discovered streptomycin.
Answer: True - Edward Jenner discovered the vaccine for rabies.
Answer: False (He developed smallpox vaccine) - Louis Pasteur developed the rabies vaccine.
Answer: True - Vaccines provide passive immunity.
Answer: False (They provide active immunity) - Serums provide passive immunity.
Answer: True - Antitoxins are antibodies that neutralise toxins.
Answer: True - Toxoids are modified toxins used as vaccines.
Answer: True - Pasteurisation involves heating milk at high temperature and cooling rapidly.
Answer: True - Putrefaction is useful for food preservation.
Answer: False (It spoils food) - Freezing kills bacteria permanently.
Answer: False (It slows growth but does not kill them) - Drying removes moisture and prevents bacterial growth.
Answer: True - Salting helps preserve fish and meat.
Answer: True - Smoking is used to preserve meat.
Answer: True - Yeast is a multicellular fungus.
Answer: False (It is unicellular) - Yeast reproduces by budding.
Answer: True - Saccharomyces cerevisiae is called brewer’s yeast.
Answer: True - Yeast respires anaerobically during alcohol fermentation.
Answer: True - Carbon dioxide makes bread spongy and soft.
Answer: True - Wine is produced by fermenting grapes with yeast.
Answer: True - Beer is produced from fruits like grapes.
Answer: False (Beer is made from cereals) - Cheese ripening involves bacteria and fungi.
Answer: True - Penicillium is used in the ripening of some cheeses.
Answer: True - Penicillin is an antibiotic obtained from bacteria.
Answer: False (It is obtained from fungus) - Streptomycin is obtained from Streptomyces.
Answer: True - Agaricus is an edible mushroom.
Answer: True - Amanita is a common edible mushroom.
Answer: False (It is poisonous) - Ringworm is caused by bacteria.
Answer: False (It is caused by fungi) - Rust of wheat is a fungal disease.
Answer: True - Aspergillus niger is used to produce citric acid.
Answer: True - Rhizopus is commonly known as black bread mould.
Answer: True - Yeast is used in the production of antibiotics.
Answer: False (It is used in baking and alcohol production) - Nitrogen cycle maintains soil fertility.
Answer: True - Denitrification converts nitrates into nitrogen gas.
Answer: True - Vaccines provide immediate relief from infections.
Answer: False (They take time to develop immunity) - Overuse of antibiotics can make bacteria resistant.
Answer: True - Mushrooms are rich in proteins and vitamins.
Answer: True - All fungi are harmful to humans.
Answer: False (Many fungi are useful)
Long Answer Questions
- Explain the role of bacteria in medicine.
Answer: Bacteria play an important role in medicine as they are used in the preparation of antibiotics, vaccines, sera, antitoxins, and toxoids. Antibiotics like streptomycin are obtained from bacteria such as Streptomyces. Vaccines made from killed or weakened bacteria help the body build immunity. Sera contain ready-made antibodies for immediate protection. Antitoxins neutralise bacterial toxins, and toxoids are chemically modified toxins that provide long-term immunity. - What are antibiotics? Give examples.
Answer: Antibiotics are chemical substances produced by certain microbes which can kill or inhibit the growth of harmful bacteria without damaging human tissues. They are widely used to treat bacterial infections. Examples include penicillin from the fungus Penicillium notatum, streptomycin from Streptomyces griseus, and tetracycline from Streptomyces aureofaciens. - Explain what vaccines are and how they work.
Answer: Vaccines are preparations of killed or weakened germs which, when introduced into the body, stimulate the immune system to produce antibodies against specific diseases. They provide active immunity, meaning the body learns to fight the disease itself. For example, BCG vaccine is used against tuberculosis and DPT vaccine protects against diphtheria, pertussis, and tetanus. - Differentiate between serum and vaccine.
Answer: A serum is a preparation containing ready-made antibodies that provides immediate passive immunity, useful in emergencies like snake bite or tetanus exposure. A vaccine, on the other hand, contains weakened or killed germs which stimulate the body to develop its own antibodies, thus providing long-lasting active immunity. - What are toxoids? Give examples.
Answer: Toxoids are bacterial toxins that have been chemically treated so that they lose their harmful effect but still retain the ability to stimulate antibody formation. They are used in vaccines to protect against diseases caused by bacterial toxins. Examples include diphtheria toxoid and tetanus toxoid. - Explain the role of nitrogen-fixing bacteria in agriculture.
Answer: Nitrogen-fixing bacteria convert free nitrogen gas from the atmosphere into nitrogen compounds like nitrates and ammonia which plants can use. Some like Rhizobium live symbiotically in root nodules of leguminous plants, while free-living forms like Azotobacter and Clostridium fix nitrogen directly in the soil. This natural process enriches soil fertility and reduces the need for artificial fertilizers. - Describe nitrifying bacteria and their importance.
Answer: Nitrifying bacteria are soil bacteria that convert ammonia into nitrites and then nitrates, which are easily absorbed by plants. Nitrosomonas converts ammonia into nitrites, while Nitrobacter converts nitrites into nitrates. This process, known as nitrification, is an essential part of the nitrogen cycle that maintains soil fertility. - What is the role of denitrifying bacteria in nature?
Answer: Denitrifying bacteria like Pseudomonas convert nitrates in the soil back into free atmospheric nitrogen. While this reduces soil fertility by removing nitrates, it plays an important role in maintaining the balance of nitrogen in the atmosphere. - How do bacteria help in leather tanning?
Answer: In the leather industry, bacteria are used to decompose unwanted proteins, hair, and flesh from animal hides. Bacterial action softens and cleans the hides, making them suitable for tanning. The tanned leather then becomes durable, flexible, and useful for making goods like shoes, belts, and bags. - Explain the role of bacteria in the tea industry.
Answer: Certain bacteria help in the fermentation process of curing tea leaves, which enhances flavour and aroma. Bacterial enzymes modify the chemical composition of tea leaves, reducing bitterness and improving the overall quality of the beverage. - How do bacteria cause food spoilage?
Answer: Bacteria decompose proteins, fats, and carbohydrates present in food, producing unpleasant odour, taste, and toxins. For example, Clostridium botulinum in canned food produces dangerous toxins causing botulism. Spoiled food can lead to serious illnesses if consumed. - Describe three methods of food preservation against bacteria.
Answer:
- Refrigeration: Slows down bacterial growth by keeping food at low temperature.
- Pasteurisation: Destroys harmful bacteria by heating milk and cooling it rapidly.
- Pickling/Salting: Uses vinegar or salt to create an environment where bacteria cannot grow.
- Name some bacterial diseases in animals and their effects.
Answer: Cattle suffer from anthrax caused by Bacillus anthracis, which is often fatal. Sheep and goats suffer from brucellosis causing abortion and weakness. Tuberculosis affects cattle and may be transmitted to humans through infected milk. These diseases reduce livestock health and productivity. - What are bacterial diseases in plants? Give examples.
Answer: Bacterial diseases in plants damage crops, leading to poor yield and economic loss. Citrus canker in citrus fruits is caused by Xanthomonas citri. Potato suffers from ring rot caused by Corynebacterium sepedonicum. Such diseases destroy food crops and cause great agricultural losses. - Describe the economic importance of fungi in medicine.
Answer: Fungi produce important antibiotics like penicillin from Penicillium notatum, which kills harmful bacteria. Streptomycin from Streptomyces also fights bacterial infections. These fungal antibiotics have revolutionised medicine by curing deadly diseases like pneumonia, tuberculosis, and syphilis. - Explain the role of yeast in the baking industry.
Answer: Yeast ferments sugar in dough, releasing carbon dioxide gas which gets trapped in the dough, making it rise. During baking, the gas escapes, leaving the bread soft, spongy, and porous. Thus, yeast is essential in bread and cake making. - How is wine produced using fungi?
Answer: Wine is produced by fermenting sugars present in grape juice with yeast (Saccharomyces cerevisiae). Yeast enzymes convert sugars into alcohol and carbon dioxide. The alcohol remains in the liquid, making it an alcoholic beverage. - Describe the role of fungi in cheese production.
Answer: In cheese-making, fungi such as Penicillium roqueforti grow inside the cheese and produce enzymes that give it unique flavours and textures. Some cheeses like Roquefort and Camembert owe their distinct taste to fungal fermentation. - What is mushroom cultivation and its importance?
Answer: Mushrooms are edible fungi like Agaricus bisporus that are cultivated under controlled conditions. They are rich in proteins, vitamins, and minerals, making them highly nutritious. Mushroom cultivation is also an important industry providing food and employment. - What is the nutritive value of mushrooms?
Answer: Mushrooms are high in protein, contain essential amino acids, vitamins like B-complex and vitamin D, and minerals like potassium and phosphorus. They are low in fat and calories, making them a healthy food option.
- Explain the process of leather tanning by bacteria.
Leather tanning is the process of treating animal hides to make them durable and resistant to decay. Certain bacteria play an important role in tanning by decomposing the organic matter, softening the hides, and removing hair from them. Bacterial enzymes help in the breakdown of proteins and fats present in the skin, making it pliable and suitable for tanning. This biological method is considered eco-friendly compared to chemical methods.
- How do bacteria contribute to the flavour of tea?
During the fermentation of tea leaves, bacteria and fungi act on the chemical constituents of the leaves, particularly polyphenols. The microbial activity brings about biochemical changes that develop the characteristic aroma and flavour of tea. Without the bacterial role in fermentation, tea would lack its distinct taste and quality.
- Explain the spoilage of food caused by bacteria.
Food spoilage occurs when bacteria multiply in food, breaking down proteins, carbohydrates, and fats. This results in bad smell, sour taste, discoloration, and sometimes production of harmful toxins. For example, milk turns sour due to bacterial action, while meat and fish produce foul odours. Spoiled food becomes unsafe for consumption as it may cause food poisoning.
- What are the preventive measures to avoid food spoilage by bacteria?
Preventive measures include refrigeration and freezing to slow down bacterial growth, pasteurization to kill harmful bacteria in milk, canning and bottling to prevent contamination, salting and sugaring to reduce water content in food, and using preservatives such as vinegar. Proper hygiene and airtight storage are also important for reducing bacterial spoilage.
- Discuss the harmful effects of bacteria on plants.
Bacteria cause several plant diseases leading to reduced yield and economic loss. Examples include citrus canker in lemon and orange caused by Xanthomonas citri, and ring disease of potatoes caused by Clavibacter. These diseases damage leaves, fruits, and stems, resulting in poor quality and quantity of produce. Such bacterial infections can spread rapidly, affecting entire crops.
- Describe two bacterial diseases of animals.
(i) Anthrax – caused by Bacillus anthracis, affects cattle, sheep, and goats; symptoms include fever, swelling, and difficulty in breathing.
(ii) Tuberculosis – caused by Mycobacterium bovis in cattle; leads to weakness, weight loss, and reduced milk production. These diseases spread to humans in some cases, making them zoonotic.
- State the economic importance of yeast in alcohol production.
Yeast, especially Saccharomyces cerevisiae, plays a vital role in alcohol production. It ferments sugars into alcohol and carbon dioxide. This property is used in making beer, wine, whisky, and other alcoholic beverages. The process of fermentation by yeast is cheap and efficient, making it one of the most economically important microorganisms.
- How is yeast used in baking industry?
In baking, yeast ferments the sugar present in dough to release carbon dioxide, which gets trapped in the gluten network of flour, causing the dough to rise and become spongy. This gives bread and cakes their soft texture. Yeast also adds flavour to baked goods through fermentation products.
- Explain the role of fungi in the production of antibiotics.
Certain fungi produce substances called antibiotics that inhibit the growth of harmful bacteria. For example, Penicillium notatum produces penicillin, the first widely used antibiotic. These antibiotics revolutionized medicine by treating previously fatal bacterial infections. Other fungi like Cephalosporium also produce useful antibiotics.
- What is the nutritive value of mushrooms?
Mushrooms are rich in proteins, vitamins (especially B-complex and vitamin D), and minerals such as potassium, iron, and phosphorus. They are low in fat and calories, making them suitable for healthy diets. Mushrooms also contain dietary fibres that aid digestion. Because of this high nutritive value, mushrooms are often considered a vegetarian alternative to meat.
- Describe the role of yeast in cheese production.
In cheese making, microorganisms including fungi and bacteria play a crucial role. Yeast, along with lactic acid bacteria, helps in fermentation and curdling of milk. It aids in breaking down lactose into lactic acid, which helps coagulate milk proteins. Certain types of cheese, like Roquefort and Camembert, also use fungi to develop characteristic flavour, aroma, and texture. Without the action of yeast and fungi, cheese would lack its unique properties.
- Explain mushroom cultivation as an industry.
Mushroom cultivation is an important agro-based industry. It requires controlled conditions of temperature, humidity, and ventilation. Mushrooms are grown on substrates like straw, compost, or wood. They are harvested after fruiting bodies develop. Mushroom farming is profitable as it requires little space, grows quickly, and provides a nutritious food source. It also offers employment opportunities in rural areas.
- How do nitrifying bacteria help in agriculture?
Nitrifying bacteria such as Nitrosomonas and Nitrobacter convert ammonia into nitrites and then into nitrates. These nitrates are absorbed by plants for protein synthesis and growth. This natural process enriches soil fertility and reduces the need for chemical fertilizers. Thus, nitrifying bacteria are crucial for maintaining the nitrogen cycle in agriculture.
- Distinguish between nitrogen-fixing bacteria and denitrifying bacteria.
Nitrogen-fixing bacteria, like Rhizobium and Azotobacter, convert atmospheric nitrogen into ammonia and nitrates, enriching soil fertility and helping plants. On the other hand, denitrifying bacteria such as Pseudomonas convert nitrates back into atmospheric nitrogen, reducing soil fertility. Thus, nitrogen-fixers are beneficial to agriculture while denitrifiers are harmful.
- Explain the process of vaccine preparation using bacteria.
Vaccines are prepared using killed or weakened forms of disease-causing bacteria. Sometimes, their toxins are inactivated to form toxoids, which are used to stimulate immunity. When introduced into the body, vaccines help produce antibodies without causing the disease itself. For example, the BCG vaccine uses a weakened form of Mycobacterium bovis to protect against tuberculosis.
- How do serums and antitoxins work in protecting humans?
Serums are prepared from the blood of animals or humans who have developed immunity to a disease. They contain ready-made antibodies that provide immediate protection when injected into a patient. Antitoxins are antibodies produced to neutralize specific bacterial toxins, such as tetanus antitoxin. They are used in emergency cases where quick action is required.
- What are toxoids? How are they useful?
Toxoids are bacterial toxins that have been chemically inactivated but still retain their ability to stimulate the immune system. For example, diphtheria and tetanus vaccines are prepared using toxoids. They are safe for use and provide long-lasting immunity by encouraging the body to produce specific antibodies without causing disease.
- Explain the role of fungi in wine production.
In wine production, yeast (Saccharomyces cerevisiae) ferments sugars present in grape juice into alcohol and carbon dioxide. This process is anaerobic and releases energy for yeast survival while producing ethanol. The type and strain of yeast, along with fermentation conditions, influence the taste, flavour, and alcohol content of wine. This method has been practiced since ancient times.
- How is yeast used in bread making?
Yeast ferments the sugar present in flour dough, releasing carbon dioxide and alcohol. The carbon dioxide gets trapped in the dough, causing it to expand and rise. The alcohol evaporates during baking, leaving the bread soft, porous, and spongy. Yeast fermentation also gives bread a pleasant flavour and aroma.
- Give a detailed account of antibiotics produced from fungi.
The discovery of antibiotics from fungi was revolutionary in medicine. Penicillium notatum produces penicillin, the first antibiotic used to kill bacteria by destroying their cell walls. Other fungi like Cephalosporium produce cephalosporins. These antibiotics are used to treat bacterial infections such as pneumonia, syphilis, and tonsillitis. Fungal antibiotics saved millions of lives and marked the beginning of the antibiotic era.
- Explain the harmful role of fungi in food spoilage.
Fungi like Aspergillus and Rhizopus spoil food by growing on bread, fruits, and vegetables. They break down nutrients and secrete toxins, making food unfit for consumption. For example, aflatoxins produced by Aspergillus flavus contaminate grains and groundnuts, causing health hazards. Fungal spoilage not only wastes food but also poses risks to human health.
- What are the differences between useful and harmful fungi?
Useful fungi include yeast for baking and brewing, Penicillium for antibiotic production, and edible mushrooms for nutrition. Harmful fungi cause diseases in plants like rusts and smuts, spoil food, and produce toxins. Thus, while useful fungi have industrial and medicinal value, harmful fungi reduce agricultural yield and cause economic losses.
- Explain the role of fungi in mushroom cultivation.
Mushroom cultivation is based on growing the fruiting bodies of fungi under controlled conditions. The fungal mycelium grows in substrates like straw or compost. With proper temperature and humidity, mushrooms develop within weeks. This industry is important because mushrooms are highly nutritious and commercially valuable.
- How does fermentation by yeast differ in alcohol and bread production?
In alcohol production, yeast ferments sugars under anaerobic conditions to produce ethanol, which is preserved and consumed. In bread making, fermentation also produces alcohol, but it evaporates during baking, leaving behind carbon dioxide that makes bread spongy. Thus, alcohol is the main product in wine, while carbon dioxide is the important product in bread.
- Describe the role of bacteria in nitrogen fixation.
Nitrogen-fixing bacteria like Rhizobium live in root nodules of leguminous plants and convert atmospheric nitrogen into ammonia. Free-living bacteria like Azotobacter also fix nitrogen in the soil. This ammonia is later converted into nitrates, which plants use for protein synthesis. Nitrogen fixation enriches soil fertility and reduces dependence on chemical fertilizers.
- How do denitrifying bacteria harm soil fertility?
Denitrifying bacteria like Pseudomonas convert nitrates in the soil back into nitrogen gas, releasing it into the atmosphere. This reduces the amount of nitrates available to plants, lowering soil fertility and agricultural productivity. Hence, denitrification is considered harmful for farming.
- Explain the importance of bacteria in dairy industry.
Bacteria play a key role in the dairy industry by converting milk into products like curd, cheese, butter, and yoghurt. Lactobacillus converts lactose into lactic acid, which helps in curdling milk and giving flavour to curd. In cheese production, bacteria contribute to fermentation, texture, and aroma. Thus, bacterial action is indispensable in dairy product manufacturing.
- What is the importance of edible mushrooms in human diet?
Edible mushrooms are rich in proteins, vitamins, and minerals but low in fats and calories, making them an ideal food. They also contain dietary fibres and antioxidants that promote good health. Mushrooms are used as a meat substitute for vegetarians and are highly valued in culinary practices worldwide.
- Describe the economic importance of fungi in baking industry.
Fungi, especially yeast, are widely used in baking. Yeast ferments sugars in dough to release carbon dioxide, which makes bread soft and fluffy. It also produces flavouring compounds that improve taste. The baking industry depends heavily on yeast fermentation, which provides both economic and nutritional benefits.
- Write a detailed account of bacterial diseases in plants with examples.
Bacteria cause several plant diseases that reduce crop yield and quality. For example, citrus canker caused by Xanthomonas citri produces lesions on leaves and fruits of lemon and orange, lowering their market value. Ring disease of potatoes caused by Clavibacter blocks xylem vessels, leading to wilting and crop loss. These diseases spread quickly through water, soil, and insects, making them difficult to control. Preventive measures include crop rotation, resistant varieties, and proper sanitation.
Give Reasons
Q.1. Give reason: Bacteria are called microscopic organisms.
Ans. Bacteria are called microscopic organisms because they are extremely small and can only be seen under a microscope.
Q.2. Give reason: Some bacteria are called nitrogen-fixing bacteria.
Ans. They are called nitrogen-fixing bacteria because they convert atmospheric nitrogen into ammonia and nitrates which plants can absorb.
Q.3. Give reason: Nitrifying bacteria are useful in agriculture.
Ans. Nitrifying bacteria are useful because they convert ammonia into nitrates, which enrich soil fertility and are essential for plant growth.
Q.4. Give reason: Denitrifying bacteria are considered harmful.
Ans. They are harmful because they convert soil nitrates back into atmospheric nitrogen, reducing soil fertility.
Q.5. Give reason: Rhizobium bacteria are found in leguminous plants.
Ans. They live in root nodules of legumes where they fix nitrogen, benefiting the plant with nitrogen compounds.
Q.6. Give reason: Bacteria are used in vaccine preparation.
Ans. Weakened or killed bacteria or their toxins are used to prepare vaccines that help develop immunity.
Q.7. Give reason: Toxoids are preferred in some vaccines.
Ans. Toxoids are preferred because they are inactive toxins that safely stimulate the body to produce antibodies.
Q.8. Give reason: Antitoxins are used in emergency cases.
Ans. They provide immediate neutralization of bacterial toxins when rapid action is needed, as in tetanus infection.
Q.9. Give reason: Serums provide immediate immunity.
Ans. Serums contain ready-made antibodies that directly fight pathogens without waiting for the body to produce them.
Q.10. Give reason: Bacteria are important in the dairy industry.
Ans. They help convert milk into curd, butter, cheese, and yoghurt through fermentation.
Q.11. Give reason: Curd tastes sour.
Ans. It tastes sour because Lactobacillus bacteria ferment lactose into lactic acid, giving sourness.
Q.12. Give reason: Antibiotics are called life-saving drugs.
Ans. They kill or inhibit disease-causing bacteria, saving humans from fatal infections.
Q.13. Give reason: Penicillin is regarded as a miracle drug.
Ans. Penicillin, produced from Penicillium fungus, was the first antibiotic that successfully treated many bacterial diseases.
Q.14. Give reason: Yeast is widely used in baking industry.
Ans. Yeast ferments sugar to release carbon dioxide, making dough soft, spongy, and well-risen.
Q.15. Give reason: Yeast is important in alcohol production.
Ans. Yeast ferments sugars in fruits and grains to produce ethanol used in wine, beer, and whisky.
Q.16. Give reason: Yeast is called facultative anaerobe.
Ans. Yeast can survive both in the presence of oxygen (respiration) and in its absence (fermentation).
Q.17. Give reason: Tea has characteristic flavour after fermentation.
Ans. Microbial fermentation of tea leaves alters their chemical constituents, developing flavour and aroma.
Q.18. Give reason: Leather tanning sometimes uses bacteria.
Ans. Bacterial enzymes break down unwanted proteins and fats in animal hides, making leather soft and pliable.
Q.19. Give reason: Spoiled food emits foul odour.
Ans. Bacteria break down proteins and fats in food, releasing foul-smelling gases.
Q.20. Give reason: Spoiled food should not be eaten.
Ans. It contains harmful bacteria and toxins that can cause food poisoning.
Q.21. Give reason: Refrigeration slows down food spoilage.
Ans. Low temperature reduces bacterial activity and multiplication, delaying spoilage.
Q.22. Give reason: Milk is pasteurized.
Ans. Pasteurization kills harmful bacteria while preserving useful nutrients in milk.
Q.23. Give reason: Salting helps preserve food.
Ans. Salt draws out water from food and bacterial cells, inhibiting bacterial growth.
Q.24. Give reason: Sugar is used in preservation of jams.
Ans. High sugar concentration reduces water availability, preventing bacterial growth.
Q.25. Give reason: Bacteria cause diseases in plants.
Ans. Some bacteria invade plant tissues, producing toxins and blocking transport systems, leading to disease.
Q.26. Give reason: Citrus canker reduces fruit yield.
Ans. The bacterial infection damages leaves and fruits, lowering both quality and quantity.
Q.27. Give reason: Anthrax is dangerous to cattle.
Ans. It causes fever, swelling, and sudden death in cattle due to Bacillus anthracis.
Q.28. Give reason: Tuberculosis reduces milk production in cattle.
Ans. Infected cattle become weak, lose weight, and produce less milk.
Q.29. Give reason: Some fungi are called edible fungi.
Ans. Mushrooms like Agaricus are edible because they are non-toxic and highly nutritious.
Q.30. Give reason: Mushrooms are considered protein-rich food.
Ans. They contain high-quality proteins and essential amino acids.
Q.31. Give reason: Mushrooms are low-calorie food.
Ans. They contain very little fat and carbohydrates, making them suitable for weight control.
Q.32. Give reason: Mushrooms are considered a vegetarian substitute for meat.
Ans. They are rich in proteins, vitamins, and minerals, similar to meat in nutritive value.
Q.33. Give reason: Bread becomes spongy when yeast is added.
Ans. Yeast fermentation produces carbon dioxide that makes the dough porous and spongy.
Q.34. Give reason: Alcoholic beverages have different flavours.
Ans. Different strains of yeast and varying fermentation conditions create unique flavours.
Q.35. Give reason: Fungi are used in cheese making.
Ans. Fungi help ripen cheese and impart special flavour and texture.
Q.36. Give reason: Food grains sometimes become poisonous.
Ans. Fungi like Aspergillus produce aflatoxins in stored grains, making them poisonous.
Q.37. Give reason: Antibiotics do not work against viral diseases.
Ans. Antibiotics act only on bacterial cell structures, not on viruses which lack such structures.
Q.38. Give reason: Tetanus requires immediate injection of antitoxin.
Ans. The bacterial toxin of tetanus spreads rapidly, and only antitoxin can neutralize it quickly.
Q.39. Give reason: Soil fertility is maintained by microbes.
Ans. Nitrogen-fixing and nitrifying bacteria enrich soil by adding usable nitrogen compounds.
Q.40. Give reason: Fungi can spoil stored fruits.
Ans. Fungi grow on moist fruits, feeding on sugars and releasing toxins.
Q.41. Give reason: Lactobacillus is useful in human diet.
Ans. It converts milk into curd, improving digestion and nutritional value.
Q.42. Give reason: Some bacteria are used in medicine.
Ans. They help in preparing antibiotics, vaccines, serums, and toxoids for human health.
Q.43. Give reason: Some fungi are industrially important.
Ans. They are used in brewing, baking, wine-making, and antibiotic production.
Q.44. Give reason: Wine is considered a fermented beverage.
Ans. It is produced by fermentation of grape juice sugars into alcohol by yeast.
Q.45. Give reason: Bacterial toxins are dangerous.
Ans. They damage host tissues and cause severe symptoms of bacterial diseases.
Q.46. Give reason: Not all fungi are harmful.
Ans. While some fungi cause spoilage and disease, many provide food, medicine, and industrial products.
Q.47. Give reason: Proper hygiene prevents bacterial diseases.
Ans. Hygiene reduces bacterial entry and spread, lowering risk of infection.
Q.48. Give reason: Antibiotics should not be overused.
Ans. Overuse leads to antibiotic resistance, making bacteria stronger and difficult to treat.
Q.49. Give reason: Food preservation is essential.
Ans. It prevents bacterial and fungal growth, reducing food spoilage and wastage.
Q.50. Give reason: Mushrooms are commercially cultivated.
Ans. They are nutritious, grow quickly, require little space, and provide good income.
Arrange the Words
Case Studies
Case Study 1:
A farmer noticed that his leguminous crops were growing very well without extra fertilizers. On examining the roots, he found small nodules.
Q. What bacteria might be present in the nodules and what is their role?
Ans. Rhizobium bacteria are present; they fix atmospheric nitrogen into ammonia, enriching soil fertility.
Case Study 2:
A child was injected with a serum after being bitten by a dog suspected of rabies.
Q. Why was serum given immediately instead of waiting for a vaccine?
Ans. Serum contains ready-made antibodies providing immediate protection, whereas vaccines take time to induce immunity.
Case Study 3:
A batch of bread in a bakery was soft, spongy, and had a pleasant aroma.
Q. Which microorganism was responsible for this and how?
Ans. Yeast (Saccharomyces cerevisiae) fermented sugars, releasing carbon dioxide (makes dough rise) and alcohol (evaporates, giving aroma).
Case Study 4:
A cheese factory used Penicillium roqueforti to ripen cheese.
Q. Why is this fungus important in cheese making?
Ans. It imparts characteristic flavour, aroma, and texture to the cheese.
Case Study 5:
A student observed some milk turning sour in the refrigerator.
Q. Which bacteria caused this and what is the chemical change?
Ans. Lactobacillus bacteria converted lactose into lactic acid, souring the milk.
Case Study 6:
A farmer noticed yellow lesions on orange trees reducing the yield of fruits.
Q. Identify the probable bacterial disease and its cause.
Ans. Citrus canker caused by Xanthomonas citri.
Case Study 7:
A laboratory produced penicillin to treat bacterial infections.
Q. Which fungus produces penicillin and what is its economic importance?
Ans. Penicillium notatum; it saves lives by treating bacterial infections, a major medical breakthrough.
Case Study 8:
A stored grain stock developed mould and was found to be toxic.
Q. Which fungus could be responsible and why is it harmful?
Ans. Aspergillus flavus; it produces aflatoxins which are poisonous and can cause liver damage.
Case Study 9:
Wine was prepared from grape juice using microorganisms.
Q. Which microorganism is used and what process occurs?
Ans. Yeast ferments sugars anaerobically into ethanol (alcohol) and carbon dioxide.
Case Study 10:
A soil sample contained Nitrosomonas and Nitrobacter.
Q. Explain their role in agriculture.
Ans. Nitrosomonas converts ammonia into nitrites; Nitrobacter converts nitrites into nitrates, enriching soil fertility.
Case Study 11:
A child was vaccinated with BCG at birth.
Q. Why was this vaccine given and which disease does it prevent?
Ans. BCG contains weakened Mycobacterium bovis and protects against tuberculosis.
Case Study 12:
A farmer noticed wilting of potato plants due to bacterial infection.
Q. Name the bacterium and how it affects the plant.
Ans. Clavibacter; it blocks xylem vessels causing wilting and reducing crop yield.
Case Study 13:
A jam manufacturer adds high sugar to preserve fruit jam.
Q. Explain how sugar prevents spoilage.
Ans. High sugar reduces water availability, preventing bacterial and fungal growth.
Case Study 14:
A person injected with tetanus antitoxin immediately after injury.
Q. Why was antitoxin preferred over vaccine in this case?
Ans. Antitoxin provides immediate neutralization of bacterial toxin, whereas a vaccine takes time to induce immunity.
Case Study 15:
A tea factory observed that fermented tea had improved flavour.
Q. What role do microorganisms play in tea processing?
Ans. Bacteria and fungi ferment tea leaves, altering chemical composition to develop flavour and aroma.
Case Study 16:
A bakery uses yeast to make bread rise but the dough remained flat.
Q. Suggest a reason for this failure.
Ans. Yeast may be inactive due to incorrect temperature, expired yeast, or insufficient sugar to ferment.
Case Study 17:
A farmer observes that crops need nitrogen fertilizer, but legumes grow well naturally.
Q. Explain why legumes do not need extra nitrogen.
Ans. Legumes have Rhizobium in root nodules that fix atmospheric nitrogen for plant use.
Case Study 18:
Mushrooms are grown commercially under controlled conditions.
Q. Why is controlled environment important for mushroom cultivation?
Ans. Temperature, humidity, and substrate must be controlled for optimum growth and yield of mushrooms.
Case Study 19:
A bakery prepares alcoholic beverages using yeast.
Q. What is the process and what is the end product?
Ans. Yeast ferments sugars anaerobically into ethanol; end product is alcohol (wine, beer, etc.).
Case Study 20:
Stored vegetables develop foul smell after a few days.
Q. Explain the cause and how it can be prevented.
Ans. Bacteria and fungi decompose vegetables, producing foul-smelling gases; prevention includes refrigeration, salting, or canning.
Numericals
Find out free resources that you need.
ICSE
Grade 8
Grade 9
CBSE
Grade 8
Grade 9
Subjects we teach
“Arise, awake, and learn by approaching the excellent teachers”
Shiksha Marg 108 gives you all free resources to ensure you get the best results. Get ready for you ICSE and CBSE exams!.
