Important Questions Test: Microorganisms Friend And Foe - 2 - UPSC MCQ

Penicillium ascomycetous fungi are of major importance in the natural environment as well as food and drug production. Some members of the genus produce penicillin, a molecule that is used as an antibiotic, which kills or stops the growth of certain kinds of bacteria.

Malaria is caused by protozoa.
Protozoa are single-celled organisms that can infect humans and cause various diseases. In the case of malaria, the specific protozoan parasite responsible for the disease is called Plasmodium.
Here is a detailed explanation of why malaria is caused by protozoa:
1. Malaria:
Malaria is a life-threatening disease that affects millions of people worldwide. It is transmitted through the bite of infected female Anopheles mosquitoes.
2. Protozoa:
Protozoa are microscopic organisms that belong to the kingdom Protista. They are eukaryotic, meaning they have a true nucleus and other cellular organelles. Protozoa can be found in various environments, including soil, water, and the bodies of plants and animals.
3. Plasmodium:
The protozoan parasite Plasmodium is the causative agent of malaria. There are several species of Plasmodium that can infect humans, including Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, and Plasmodium ovale.
4. Life cycle:
The life cycle of Plasmodium involves two hosts: mosquitoes and humans. When an infected mosquito bites a human, it injects the sporozoites (infective form of the parasite) into the bloodstream. The sporozoites then travel to the liver, where they multiply and develop into merozoites.
5. Infection:
The merozoites are released into the bloodstream and invade red blood cells. Inside the red blood cells, they multiply and cause the cells to burst, releasing more merozoites. This cycle of invasion, multiplication, and bursting of red blood cells leads to the characteristic symptoms of malaria, such as fever, chills, headache, and fatigue.
6. Transmission:
When a mosquito bites an infected person, it ingests the gametocytes (sexual forms of the parasite) present in the bloodstream. Inside the mosquito, the gametocytes undergo sexual reproduction, resulting in the formation of sporozoites. These sporozoites migrate to the mosquito's salivary glands, ready to infect another human when the mosquito feeds again.
7. Prevention and treatment:
Preventing malaria involves measures such as using insecticide-treated bed nets, indoor residual spraying, and taking antimalarial drugs. Treatment of malaria usually involves the use of antimalarial medications to kill the parasite and alleviate symptoms.
In conclusion, malaria is caused by the protozoan parasite Plasmodium, which is transmitted to humans through the bite of infected mosquitoes. Understanding the biology and life cycle of Plasmodium is crucial for effective prevention and treatment of malaria.

Mushroom, the conspicuous umbrella-shaped fruiting body (sporophore) of certain fungi, typically of the order Agaricales in the phylum Basidiomycota but also of some other groups.

Rhizobium bacteria
Key Points:
- Rhizobium bacteria are a type of soil bacteria that form a symbiotic relationship with leguminous plants.
- They play a crucial role in nitrogen fixation, which is the process of converting atmospheric nitrogen into a form that plants can use.
- The bacteria enter the roots of leguminous plants and form nodules, which are specialized structures where nitrogen fixation occurs.
- Inside the nodules, the bacteria convert atmospheric nitrogen into ammonia, which is then utilized by the plants for their growth and development.
- This symbiotic relationship benefits both the bacteria and the plants, as the bacteria receive nutrients from the plants while providing them with a vital nutrient.
- In addition to nitrogen fixation, Rhizobium bacteria also contribute to soil fertility by improving soil structure and nutrient availability.
- They can enhance plant growth and productivity by facilitating the uptake of other essential nutrients, such as phosphorus and potassium.
- Rhizobium bacteria are not known to cause any diseases in humans or animals.
- However, it is important to note that there are other bacteria that can cause diseases in plants, but Rhizobium bacteria are not among them.
Conclusion:
- Rhizobium bacteria are beneficial soil bacteria that play a crucial role in nitrogen fixation and plant growth.
- They form a symbiotic relationship with leguminous plants, contributing to their nitrogen requirements and overall productivity.
- Rhizobium bacteria do not cause diseases and are instead important contributors to soil fertility and agricultural sustainability.

Answer:
Definition of Cocci:
- Cocci are a type of bacteria that are characterized by their round or spherical shape.
- They can occur in various arrangements, including singularly, in pairs (diplococci), in chains (streptococci), or in clusters (staphylococci).
Shape of Cocci:
- Cocci are round-shaped bacteria.
- Their shape is similar to that of a sphere or a ball.
Options:
- A:

Rod-shaped

- This option is incorrect because rods are elongated, cylindrical in shape, not round-shaped like cocci.
- B:

Round-shaped

- This option is correct. Cocci are round-shaped bacteria.
- C:

Spiral

- This option is incorrect. Spiral bacteria have a corkscrew-like shape.
- D:

Comma

- This option is incorrect. Comma-shaped bacteria are curved or bent, not round-shaped like cocci.
Conclusion:
- Cocci are bacteria that have a round or spherical shape.
- Therefore, the correct answer is Option B: Round-shaped.

Amoeba, also spelled as Ameba, is a genus that belongs to protozoa, which are unicellular eukaryotes (organisms with membrane-bound cell organelles). The name Amoeba is derived from the Greek word amoibe, which means change. There are many species, of which the most extensively studied is Amoeba proteus. Majority of the species are very minute and are not visible to the naked eye. In spite of its small size, the genomic content is several times more than the human genome. The species A. dubia consists of about 370 billion base pairs; whereas, human genome has about 3 billion base pairs.

Microorganisms are
- Microorganisms are living organisms that are too small to be seen with the naked eye.
- They are found in various environments such as soil, water, air, and even inside our bodies.
- There are different types of microorganisms, including bacteria, fungi, viruses, protozoa, and algae.
- Microorganisms can be both unicellular and multicellular, depending on the type.
- Some microorganisms, such as bacteria and protozoa, are unicellular, meaning they are made up of a single cell.
- Other microorganisms, such as fungi and algae, can be multicellular, meaning they are made up of multiple cells.
- Multicellular microorganisms are more complex in structure and function compared to unicellular microorganisms.
- Microorganisms play vital roles in various ecosystems as decomposers, producers, and even as pathogens causing diseases.
- They are involved in nutrient cycling, decomposition of organic matter, and the production of essential substances like antibiotics and enzymes.
- Understanding microorganisms is important in fields like medicine, agriculture, and environmental science.

The correct answer is A as Spirogyra is
 A kind of  algae

Scientist who discovered fermentation:
The correct answer is Louis Pasteur.
Explanation:
Fermentation is a metabolic process in which microorganisms, such as yeast or bacteria, convert sugars into alcohol or acids. Louis Pasteur, a French chemist and microbiologist, made significant contributions to the understanding of fermentation. Here is a detailed explanation of his work:
1. Spontaneous Generation: Pasteur conducted experiments to debunk the theory of spontaneous generation, which proposed that living organisms could arise from non-living matter. He showed that fermentation was caused by the growth of microorganisms present in the air, rather than a spontaneous generation of life.
2. Germ Theory of Disease: Pasteur's investigations into fermentation led to the development of the germ theory of disease. He demonstrated that microorganisms were responsible for the spoilage of food and the spread of diseases. This laid the foundation for modern microbiology and the understanding of how fermentation occurs.
3. Pasteurization: Pasteur developed the process of pasteurization, which involves heating liquids to a specific temperature to kill harmful bacteria and extend their shelf life. This technique is widely used in the preservation of food and beverages, including milk, wine, and beer.
4. Vaccination: Pasteur's work on fermentation also led to advancements in vaccination. He developed vaccines for diseases such as anthrax and rabies by attenuating or weakening the disease-causing microorganisms. This was a groundbreaking achievement in the field of immunology.
In conclusion, Louis Pasteur is credited with discovering fermentation and making significant contributions to the understanding of microbiology, disease prevention, and food preservation.

The air in our atmosphere is composed of molecules of different gases. The most common gases nitrogen  (78%), oxygen (about 21%), argon (almost 1%) and carbon dioxide (0.03%). Other molecules are present in  the atmosphere as well, but in very small quantities. Composition of air is measured in percent by volume,  at sea level at 15C and 101325 Pa.

B is the correct option.Microbes are minute, unicellular organisms that are invisible to the naked eye. They are also known as microorganisms or microscopic organisms as they could only be seen under a microscope or magnifying glass.

The correct option is A.
Viruses are ultramicroscopic organisms that are visible only through electron microscopes. Therefore, they need to infect a host cell.  The virus gets inside the host cells and makes hundred and thousands of copies of itself by using the host machinery.

Sir  Alexander Fleming, is credited with the discovery of Penicillin in 1928.
So, the given statement is false.

Rhizobium is a bacteria which can fix the atmospheric nitrogen.
Explanation:
Rhizobium is a genus of bacteria that forms a symbiotic relationship with leguminous plants, such as peas, beans, and clover. This symbiotic relationship is known as nitrogen fixation, where the bacteria convert atmospheric nitrogen into a form that is usable by plants. Here's a detailed explanation:
1. Rhizobium bacteria:
- Rhizobium is a type of bacteria that resides in the root nodules of leguminous plants.
- It forms a mutualistic relationship with these plants, benefiting both the bacteria and the plant.
2. Atmospheric nitrogen:
- Atmospheric nitrogen is abundant in the air, but plants cannot directly use it in this form.
- Nitrogen is an essential nutrient for plant growth and development, and it is often a limiting factor in plant productivity.
3. Nitrogen fixation:
- Rhizobium bacteria have the unique ability to fix atmospheric nitrogen.
- They possess an enzyme called nitrogenase, which converts atmospheric nitrogen (N2) into ammonia (NH3), a form of nitrogen that plants can use.
4. Symbiotic relationship:
- Leguminous plants provide Rhizobium bacteria with a suitable environment and nutrients in the form of carbohydrates.
- In return, the bacteria supply the plants with fixed nitrogen, enhancing their growth and fertility.
5. Importance:
- The nitrogen fixed by Rhizobium bacteria is crucial for the growth and development of leguminous plants.
- It reduces the dependence on synthetic nitrogen fertilizers, which can be costly and environmentally harmful.
- Nitrogen fixation by Rhizobium bacteria also contributes to the overall nitrogen cycle in the ecosystem.
In conclusion, Rhizobium bacteria have the ability to fix atmospheric nitrogen, making them essential for the nitrogen nutrition of leguminous plants. This symbiotic relationship between the bacteria and the plants plays a vital role in agriculture and ecosystem functioning.

Explanation:
Fungi and Mushrooms:
- Fungi are a group of organisms that belong to the kingdom Fungi.
- Mushrooms are a type of fungi.
- Fungi are distinct from plants, animals, and bacteria.
Characteristics of Fungi:
- Fungi do not have chlorophyll, so they cannot perform photosynthesis.
- Fungi obtain nutrients by decomposing organic matter or by forming symbiotic relationships with other organisms.
- Fungi reproduce through the production of spores.
Mushrooms as Fungi:
- Mushrooms are the fruiting bodies of certain types of fungi.
- The main body of the fungus, known as the mycelium, is usually hidden beneath the surface.
- The mycelium absorbs nutrients from the environment and can be extensive, spreading over a large area.
Why Mushroom is a Fungi:
- Mushrooms share all the characteristics of fungi mentioned above.
- They do not have chlorophyll and obtain nutrients from organic matter.
- They reproduce through the production of spores.
- Mushrooms are the visible reproductive structures of certain fungi.
Conclusion:
- Based on the characteristics and classification of fungi, it is correct to say that mushrooms are a type of fungi.
- Therefore, the statement "Mushroom is a fungi" is true.

The correct answer is A as A pathogen may also be referred to as an infectious agent, or simply a germ. The term pathogen came into use in the 1880s. Typically, the term is used to describe an infectious microorganism or agent, such as a virus, bacterium

The correct answer is A as it is caused by  a bacteria called bacillus anthrasis

Explanation:
The statement "Oxygen and nitrogen make up 78% of air" is False. Here's why:
- Air is a mixture of various gases, including oxygen, nitrogen, carbon dioxide, and trace amounts of other gases.
- The two most abundant gases in the Earth's atmosphere are nitrogen (N2) and oxygen (O2).
- Nitrogen makes up about 78% of the air, while oxygen makes up about 21%.
- The remaining 1% is composed of trace gases, such as carbon dioxide (CO2), argon (Ar), and other gases.
- It is important to note that the exact composition of the atmosphere can vary slightly depending on location and other factors.
In summary, while nitrogen makes up approximately 78% of the air, oxygen only makes up about 21%. Therefore, the statement is false.

Louis Pasteur discovered the process of fermentation within the yeast cells in 1856.
So, the given statement is incorrect.
As, Edward Jenner developed smallpox vaccine in 1796.

Foot and mouth disease (FMD) is a severe, highly contagious viral disease of livestock that has a significant economic impact. The disease affects cattle, swine, sheep, goats and others.
So, as it is a viral disease ; the given statement is incorrect.