Free Kingdom Prokaryotae MCQs with Answers

491. The unique macro-molecule in the bacterial cell wall is:

• A. Polysaccharides
• B. Proteins
• C. Peptidoglycan
• D. Cholesterol

Explanation: Bacterial cell walls are primarily composed of peptidoglycan, which is a unique macromolecule consisting of both sugars (polysaccharides) and amino acids. This gives bacterial cell walls their rigidity and shape.

492. In bacteria, the resistance against heat is provided by:

• A. Granules
• B. Cysts
• C. Spores
• D. Plasmids

Explanation: Spores are thick, dormant, and tough structures produced by some bacteria that provide resistance or protection against harsh or adverse conditions.They are formed by the bacteria to protect themselves from adverse environmental conditions such as heat, UV rays, nutrient deprivation, presence of toxic chemicals, etc.

493. The smallest known bacteria belong to the genus:

• A. Mycoplasma
• B. Streplococcus
• C. Escherichia
• D. Bacillus

Explanation: These bacteria lack a cell wall and are among the tiniest free-living organisms.

494. An example of a bacteria requiring low concentration of oxygen is?

• A. Spirochete
• B. Ecoli
• C. Pseudomonas
• D. Campylobacter

Explanation: Option A: Spirochetes are a diverse group of bacteria that exhibit a helical or spiral shape. While some spirochetes are microaerophilic, many others can tolerate a wide range of oxygen levels.Option B: Escherichia coli (E. coli) is a facultative anaerobic bacterium, meaning it can survive and grow in both the presence and absence of oxygen.Option C: Pseudomonas is a genus of bacteria known for their ability to adapt to a variety of environmental conditions, including aerobic and anaerobic environments. While some species within the genus Pseudomonas are adapted to low-oxygen conditions, many others are capable of aerobic respiration. Option D: Campylobacter is an example of a bacteria that requires a low concentration of oxygen. It is considered a microaerophilic bacterium, meaning it thrives in environments with reduced levels of oxygen. Campylobacter species are commonly found in the gastrointestinal tracts of animals, including birds and mammals, and can cause infections in humans.

495. The scientist who first reported about microbes was:

• A. Antonie Van Leeuwenhoek
• B. Robert Koch
• C. Louis Pasteur
• D. Twort

Explanation: Option A is the right answer. Leeuwenhoek first discovered microbes and called them animalcules.

496. The germ theory of diseases was formulated by _.

• A. Louis Pasteur
• B. Robert Koch
• C. Christain Gram
• D. None of above

Explanation: Germ Theory states that microorganisms known as pathogens or "germs" can lead to disease. Robert Koch determined guidelines to prove that a disease is caused by a specific organism.

497. A type of bacterial cell that completely surrounded by flagella is called :

• A. Diplococcus
• B. Peritrichous
• C. Monotrichous
• D. A tetrad

Explanation: Bacteria can be classified according to the number of flagella on their cell wall, and peritrichous is a type will many flagella all over the cell .

498. Which of the following statements about the systemic effect of bacterial cells are true?

• A. Gram-negative bacteria are more likely to cause systemic effects because they lack an outer membrane which means they can infect host cells more quickly.
• B. Gram-negative bacteria are more likely to cause systemic effects because they have an outer membrane which is supposed to protect them from antibiotics
• C. Both Options A and B are correct
• D. None of these options is correct

Explanation: d) None of these options is correct.This option is the most accurate. Both Option A and Option B have inaccuracies in their statements. Gram-negative bacteria do have an outer membrane, and their systemic effects are not solely due to the absence of this membrane or its protective function against antibiotics. The systemic effects of bacterial infections depend on various factors, including the pathogenicity of the bacteria, the host's immune response, and the release of bacterial toxins.

499. In cocci, three plane division results in formation of sarcina which is a -----------

• A. Cube of eight cocci
• B. Square of four cocci
• C. Irregular structure
• D. Triangular 6 cocci

Explanation: Option A is correct since Sarcina is a cube of 8 cocci.

500. Under the microscope, the bacteria appear a bluish-purple colour. Which class of bacteria are on the slide?

• A. Gram-positive
• B. Gram-negative
• C. Both A and B
• D. None of these

Explanation: Correct option: A (fact) (Gram positive bacteria retain bluish purple dye when being tested). If the bacteria appear bluish-purple under the microscope, it indicates that they have retained the crystal violet stain after the Gram staining procedure. Gram-positive bacteria have a thick peptidoglycan layer in their cell wall, which allows them to retain the crystal violet stain and appear purple. Gram-negative bacteria, on the other hand, have a thinner peptidoglycan layer and are counterstained with a red or pink color. Therefore, the bacteria on the slide are most likely Gram-positive.