Economic Importance of Bacteria for ICSE Class 9 🌿🦠 with detailed explanations:

Multiple Choice Questions (MCQs) 🌟

Question 1
Answer: a) These are unicellular and prokaryotic 🦠
✅ Bacteria are classified as prokaryotic organisms because they lack a true nucleus and membrane-bound organelles, unlike plants which are eukaryotic.

Question 2
Answer: b) Streptomyces 💊
✅ The bacterium Streptomyces is known for producing antibiotics like streptomycin, which was discovered after penicillin and is effective in treating tuberculosis.

Question 3
Answer: c) Bacillus ➖
✅ Rod-shaped bacteria are called bacilli. They are one of the most common shapes found among bacterial species.

Question 4
Answer: c) Rhizobium 🌼
✅ Rhizobium bacteria are nitrogen-fixing bacteria that form symbiotic relationships with leguminous plants, converting atmospheric nitrogen into usable nitrates.

Question 5
Answer: Peptidoglycan
✅ The bacterial cell wall is mainly composed of peptidoglycan, which provides structural strength and protection.

Question 6
Answer: Plasmid
✅ Plasmids are small, circular DNA molecules that float freely in the cytoplasm of bacterial cells and can replicate independently.

Question 7
Answer: c) Binary fission ➗
✅ Bacteria commonly reproduce by binary fission, where one cell divides into two identical daughter cells.

Question 8
Answer: d) Because they lack a distinct nucleus enclosed by a nuclear membrane. 🚫🔬
✅ Bacteria are prokaryotic because they lack a membrane-bound nucleus.

Question 9
Answer: b) Typhoid 🤒
✅ The TAB vaccine is used to prevent Typhoid, a bacterial infection that affects the intestines.

Question 10
Answer: d) Vaccines 💉
✅ Vaccines are biological preparations containing weakened or killed microorganisms that stimulate the immune system to fight diseases.

Very Short Answer Type ✍️

Question 1

• (a) Flagellum 🏊♂️
• (b) Fermentation 🍵
• (c) Tanning 🐄
• (d) White rust 🌿
• (e) Selman Waksman 👨🔬

Question 2

• Penicillium ➡️ Antibiotic 💊
• Diplococci ➡️ Bacteria occurring in pairs 🦠🦠
• Streptococci ➡️ Bacteria occurring in chains 🔗

Question 3

• (a) Alexander Fleming 👨🔬
• (b) Rhizobium 🌱
• (c) Insulin ⚗️
• (d) Pseudomonas 🌿
• (e) Saprophytic and parasitic 🍽️

Question 4

• (a) Nitrosomonas 🔁
• (b) Nitrobacter ➕

Short Answer Type 📝

Question 1
✅ Bacteria in the air may exist as spores or as part of dust particles, often being inactive but becoming active when they settle on suitable surfaces.

Question 2
✅ Spore formation is a survival mechanism, not reproduction, as it allows bacteria to withstand harsh conditions but does not result in an increase in population.

Question 3
✅ Bacteria are simple organisms as they are unicellular, lack a true nucleus, and have simple cell structures without membrane-bound organelles.

Question 4

• Antibiotics: Substances produced by bacteria to inhibit or destroy other microorganisms. 💊
• Antitoxins: Substances that neutralize toxins produced by bacteria. 🛡️
• Serum: The fluid part of blood used for immunity. 💉
• Botulism: A severe form of food poisoning caused by Clostridium botulinum. ⚠️
• Pasteurization: The process of heating food to eliminate pathogenic microbes. 🔥

Question 5

• (a) Anthrax, Brucellosis 🐄
• (b) Blight in potatoes, Citrus canker 🌿
• (c) Cholera, Tuberculosis 👩⚕️
• (d) Nitrosomonas, Nitrobacter 🧪
• (e) Azotobacter, Clostridium 🌱

Question 6

• (a) TAB ➡️ Typhoid, Paratyphoid A and B vaccine 🔬
• (b) BCG ➡️ Bacillus Calmette–Guérin vaccine 💉
• (c) DNA ➡️ Deoxyribonucleic Acid 🧬
• (d) GMO ➡️ Genetically Modified Organism 🌽

Question 7

• (a) Sunlight helps kill harmful bacteria and reduces moisture, preventing bacterial growth. ☀️
• (b) Sealed food can still be unsafe if improperly processed, allowing bacteria like Clostridium botulinum to thrive. 🍲

Question 8

• Decay: Natural decomposition of organic matter by microorganisms. 🔄
• Putrefaction: Decomposition of proteins leading to foul smells. ☠️
• Pasteurization: Heating to destroy pathogens but not all microorganisms. 🔥
• Sterilization: Eliminating all forms of life, including spores. ⚗️

Question 9
✅ Yes, bacteria exist in aquariums, especially in gravel and filters, where they help decompose waste and maintain ecological balance. 🐠

Long Answer Type 📝

Long Answer Type Questions on the Economic Importance of Bacteria 🌿🦠

Question 1:

How do bacteria obtain their nourishment? 🍽️

Answer:
Bacteria obtain their nourishment through different modes of nutrition, broadly classified into autotrophic and heterotrophic types.

1. Autotrophic Bacteria: These bacteria can produce their own food using simple inorganic substances. They are further divided into:

1. Photoautotrophs: These bacteria, like Cyanobacteria, use sunlight for photosynthesis, converting carbon dioxide and water into glucose and oxygen.
2. Chemoautotrophs: These bacteria, such as Nitrosomonas and Nitrobacter, derive energy from chemical reactions involving inorganic substances like ammonia, nitrites, or sulfur compounds.
3. Heterotrophic Bacteria: These bacteria depend on organic matter for their nutrition. They are categorized as:

2. Saprophytic Bacteria: These feed on dead and decaying organic matter, playing an essential role in decomposition and recycling nutrients.
3. Parasitic Bacteria: These derive nourishment from living hosts, often causing diseases in plants, animals, and humans.
4. Symbiotic Bacteria: These live in mutual association with other organisms. For instance, Rhizobium bacteria live in the root nodules of leguminous plants and help in nitrogen fixation.

Thus, bacteria utilize diverse nutritional methods that contribute significantly to ecological balance and nutrient cycles.

Question 2:

Explain any two industrial applications of bacteria. 🏭

Answer:
Bacteria have numerous industrial applications, contributing to economic growth and sustainability. Two significant industries where bacteria are crucial include:

1. Pharmaceutical Industry:

1. Certain bacteria are used for the production of antibiotics. For example, Streptomyces is a bacterium that produces streptomycin, an antibiotic effective against tuberculosis. Penicillium fungi (though not bacteria) and bacterial species have revolutionized the treatment of bacterial infections.
2. Bacteria like Escherichia coli are genetically engineered to produce human insulin, which is vital for diabetic patients. They are also used in the production of vaccines and vitamins.
3. Food Industry:

2. Lactobacillus bacteria are widely used in dairy industries for the fermentation of milk to produce curd, cheese, yogurt, and butter. The lactic acid produced by these bacteria helps in the coagulation of milk proteins.
3. In the production of fermented foods like vinegar, pickles, and beverages, bacteria play a vital role.

Thus, bacteria significantly contribute to the pharmaceutical and food industries, ensuring health, nutrition, and economic development.

Question 3:

What are antibiotics? Name any two examples. 💊

Answer:
Antibiotics are chemical substances produced by microorganisms, such as bacteria and fungi, which can kill or inhibit the growth of other harmful microorganisms. They are used to treat various bacterial infections in humans, animals, and plants.

Antibiotics work by targeting the bacterial cell wall, protein synthesis, or metabolic pathways, thereby eliminating the infection. However, antibiotics are ineffective against viral infections.

Two examples of antibiotics include:

1. Penicillin: Discovered by Alexander Fleming in 1928, it is the first known antibiotic. It is effective against Gram-positive bacteria and is widely used to treat infections like pneumonia, meningitis, and throat infections.
2. Streptomycin: Discovered by Selman Waksman, it is used primarily to treat tuberculosis and other bacterial infections. It inhibits protein synthesis in bacterial cells, leading to their destruction.

Antibiotics have revolutionized modern medicine, saving countless lives and preventing the spread of infectious diseases. However, their misuse can lead to antibiotic resistance, a significant global health concern.

Question 4:

Explain the process by which leguminous plants transform atmospheric nitrogen into nitrates. 🌿

Answer:
Leguminous plants, such as peas, beans, and lentils, form a symbiotic relationship with nitrogen-fixing bacteria, particularly Rhizobium species. These bacteria reside in specialized structures called root nodules on the plant’s roots. The process several steps:

1. Formation of Nodules: The roots of leguminous plants release chemical signals that attract Rhizobium bacteria. The bacteria enter the root hairs and stimulate the formation of nodules where they reside.
2. Nitrogen Fixation: Inside the nodules, Rhizobium bacteria use the enzyme nitrogenase to convert inert atmospheric nitrogen (N₂) into ammonia (NH₃). This process requires energy, which is supplied by the plant in the form of carbohydrates.
3. Conversion to Nitrates: The ammonia produced is then converted into ammonium ions (NH₄⁺), which the plant absorbs and uses to synthesize proteins and other essential compounds. Some ammonium ions are further oxidized by nitrifying bacteria into nitrates (NO₃⁻), enriching the soil.
4. Benefits: The plant benefits by receiving a usable form of nitrogen, while the bacteria gain nutrients and shelter from the plant. This natural nitrogen fixation is vital for sustainable agriculture, promoting crop growth and maintaining soil health.

Question 5:

Describe how nitrates present in the soil are transformed back into atmospheric nitrogen. 🔄

Answer:
The process of converting soil nitrates back into atmospheric nitrogen is known as denitrification. This process is essential for maintaining the balance of nitrogen in the environment. Denitrifying bacteria, such as Pseudomonas and Clostridium, play a crucial role in this cycle.

1. Anaerobic Conditions: Denitrification occurs in anaerobic (oxygen-deprived) conditions, such as waterlogged soils, marshes, or deep soil layers.
2. Stepwise Reduction: The denitrifying bacteria convert nitrates (NO₃⁻) in the soil into nitrogen gas (N₂) through a series of chemical reactions. The process follows these steps:

2. Nitrates (NO₃⁻) → Nitrites (NO₂⁻)
3. Nitrites (NO₂⁻) → Nitric oxide (NO)
4. Nitric oxide (NO) → Nitrous oxide (N₂O)
5. Nitrous oxide (N₂O) → Nitrogen gas (N₂)
6. Release into the Atmosphere: The nitrogen gas is then released into the atmosphere, completing the nitrogen cycle.
7. Importance of Denitrification:

4. It prevents the accumulation of excess nitrates in the soil, which can cause soil degradation.
5. Helps maintain the nitrogen balance in the ecosystem.
6. Reduces the risk of nitrate pollution in water bodies, preventing eutrophication.

Thus, denitrification is a crucial natural process ensuring the recycling of nitrogen and promoting ecological balance.