Kingdom Monera MCQ Quiz in বাংলা - Objective Question with Answer for Kingdom Monera - বিনামূল্যে ডাউনলোড করুন [PDF]

The correct answer is: Endospore

Explanation: Dipicolinic acid is a chemical substance found in high concentrations in bacterial endospores. Endospores are a dormant, tough, and non-reproductive structure produced by certain bacteria (notably members of the genera Bacillus and Clostridium). These structures are highly resistant to extreme conditions such as heat, radiation, chemical disinfectants, and desiccation.

• Capsule: A polysaccharide layer outside the cell wall that protects bacteria from phagocytosis and desiccation.
• Flagella: Long, whip-like structures used for bacterial motility.
• Pili: Hair-like structures on the surface of bacteria that are involved in adhesion to surfaces and in the exchange of genetic material during conjugation.
• Endospores are the only bacterial components listed that contain dipicolinic acid.

Function of Dipicolinic Acid in Endospores:

• Dipicolinic acid, in combination with calcium ions, helps to dehydrate the spore core, which is crucial for the heat resistance and overall stability of the endospore.
• It also plays a role in stabilizing the DNA and proteins within the spore, preventing damage under adverse conditions.

The correct answer is: P-3, Q-2 , R-4, S-1 

Explanation:

• Coccus (plural: cocci) refers to spherical-shaped bacteria. e.g., Neisseria: Neisseria species are gram-negative cocci responsible for diseases such as gonorrhea (Neisseria gonorrhoeae) and meningitis (Neisseria meningitidis).
• Rod-shaped bacteria (also called bacilli) are elongated and cylindrical. e.g., Bacillus: Bacillus species are gram-positive rods known for producing spores and causing diseases such as anthrax (Bacillus anthracis).
• Comma-shaped bacteria are curved rods that resemble a comma (,). e.g., Vibrio: Vibrio species are gram-negative and often associated with waterborne diseases, including cholera (Vibrio cholerae).
• Spiral-shaped bacteria have a twisted or helical structure. e.g., Treponema: Treponema species are known for their spiral shape and include pathogens like Treponema pallidum, which causes syphilis.

Additional Information

• Identifying Bacterial Shapes: Recognizing these bacterial shapes aids in initial identification and diagnosis. For instance, detecting cocci in a gram stain can quickly narrow down the possible genera involved in an infection.
• Treatment Implications: Different bacterial shapes and their corresponding genera have varying susceptibilities to antibiotics, influencing treatment choices. For example, understanding that Vibrio causes cholera can lead to the prompt use of rehydration solutions and appropriate antibiotics.

The correct answer is: Recombination frequency is high, F factor transfer frequency is low
 

Explanation:

• Hfr strain: An Hfr (high frequency of recombination) strain is a type of E. coli where the F factor (a piece of DNA that allows for gene transfer) is integrated into the bacterial chromosome.
• F- strain: An F- strain is a type of E. coli that does not have the F factor.

When an Hfr strain conjugates (mates) with an F- strain:

• High recombination frequency: The Hfr strain begins to transfer its DNA starting from the middle of the F factor, which means parts of the bacterial chromosome are transferred to the F- strain. This allows for lots of recombination (mixing of genetic material) between the donor's DNA and the recipient's DNA.
• Low F factor transfer frequency: The entire bacterial chromosome is rarely transferred because the connection between the two cells often breaks before the process is completed. As a result, the F factor (located at the end of the transfer) usually does not get transferred, so the F- strain remains F-.

In summary, when an Hfr strain transfers genes to an F- strain, there is a high chance of genetic recombination but a low chance that the F factor itself will be transferred.

The correct answer is A-Bacilli, B-Spirilla, C-Vibrio, D-Cocci

Concept:

• Bacteria are microscopic single-celled organisms that come in various shapes and sizes. They can be classified based on their shape into several categories, including cocci (spherical), bacilli (rod-shaped), spirilla (spiral-shaped), and vibrios (comma-shaped).
• The shape of bacteria is an important characteristic that helps in the identification and classification of bacterial species.

Explanation:

• Bacilli: Rod-shaped bacteria are called bacilli. They appear as elongated, rod-like structures under the microscope. Examples of bacilli include Escherichia coli and Bacillus anthracis.
• Spirilla: These are spiral-shaped bacteria. They have a helical or corkscrew shape and are known for their unique spiral structure. An example of a spirillum is Spirillum minus.
• Cocci: These are spherical or round-shaped bacteria. They can exist as single cells, in pairs (diplococci), in chains (streptococci), or in clusters (staphylococci). Examples include Streptococcus pneumoniae and Staphylococcus aureus.
• Vibrios: These are comma-shaped bacteria. They have a curved rod shape that resembles a comma. An example of a vibrio is Vibrio cholerae, the bacterium that causes cholera.

Key Points

• Bacteria are the sole members of the Kingdom Monera and they are the most abundant microorganisms.
• These can live in extreme habitats such as hot springs, deserts, snow, and deep oceans, where very few other life forms can survive.
• Some of the bacteria are autotrophic, i.e. they can synthesize their own food from inorganic substances.
• They are either photosynthetic autotrophic or chemosynthetic autotrophic.
• Bacteria are heterotrophs also and they do not synthesize their own food but depend on other organisms or on dead organic matter for food.

Explanation:

• Photoautotrophic bacteria trap light energy and convert it into chemical energy and make their own food like plants. 
• Photoautotrophic bacteria may carry out either oxygenic photosynthesis or anoxygenic photosynthesis.
• Oxygenic Photosynthetic bacteria use H₂O as an electron donor and oxygen is produced in the reaction. e.g., cyanobacteria.
• The majority of photosynthetic bacteria are anoxygenic, as they lack the ability to use water as an electron donor.
• Instead of H₂O, anoxygenic bacteria use H₂S, H₂, or thiosulphate as reducing agents and hydrogen sources.
• The schematic presentation of anoxygenic photosynthesis -​

CO₂ + 2H₂S + light energy → [CH₂O] + 2S + H₂O

• Anoxygenic means they cannot split H₂O, so no oxygen is evolved.
• They possess a photosynthetic pigment known as bacteriochlorophyll.
• Examples of anoxygenic bacteria are green sulfur bacteria, purple sulfur bacteria, purple non-sulfur bacteria, phototrophic acidobacteria, heliobacteria, and FAPs (filamentous anoxygenic phototrophs).

Hence, the correct option is (1).

Key Points

• Bacteria are the sole members of the Kingdom Monera and they are the most abundant microorganisms.
• These can live in extreme habitats such as hot springs, deserts, snow, and deep oceans, where very few other life forms can survive.
• Some of the bacteria are autotrophic, i.e. they can synthesize their own food from inorganic substances.
• They are either photosynthetic autotrophic or chemosynthetic autotrophic.
• Bacteria are heterotrophs also and they do not synthesize their own food but depend on other organisms or on dead organic matter for food.

Explanation:

• Photoautotrophic bacteria trap light energy and convert it into chemical energy and make their own food like plants. 
• Photoautotrophic bacteria may carry out either oxygenic photosynthesis or anoxygenic photosynthesis.
• Oxygenic Photosynthetic bacteria use H₂O as an electron donor and oxygen is produced in the reaction. e.g., cyanobacteria.
• The majority of photosynthetic bacteria are anoxygenic, as they lack the ability to use water as an electron donor.
• Instead of H₂O, anoxygenic bacteria use H₂S, H₂, or thiosulphate as reducing agents and hydrogen sources.
• The schematic presentation of anoxygenic photosynthesis -​

CO₂ + 2H₂S + light energy → [CH₂O] + 2S + H₂O

• Anoxygenic means they cannot split H₂O, so no oxygen is evolved.
• They possess a photosynthetic pigment known as bacteriochlorophyll.
• Examples of anoxygenic bacteria are green sulfur bacteria, purple sulfur bacteria, purple non-sulfur bacteria, phototrophic acidobacteria, heliobacteria, and FAPs (filamentous anoxygenic phototrophs).

Hence, the correct option is (1).

Concept:

• Pili or pilus (singular) is an appendage present on the surface of bacteria that looks like hair.
• Pili is made up of the protein, pilin.
• Primarily this pilus helps in the attachment of bacterial cell to a specific surface.
• But some specific sex pili helps in transfer of genetic material (DNA, plasmid) and the process by which these pili transfer the genetic material is known as conjugation.
• In case of E.coli bacterium, the sex pili is controlled by the fertility factor.

Fig : Bacterial conjugation

Explanation:

Assertion : Pili are tubular structures present in bacteria which help in conjugation.

• This statement is true because sex pili helps in conjugation.

Reason : Formation of pili is controlled by F+ or fertility factor.

• This statement is also true but does not explain the assertion well because formation of sex pili is controlled by fertility factor but this does not explain the conjugation process.

So, the correct answer is option 2).