Free Kingdom Prokaryotae MCQs with Answers

451. Sulphur bacteria belongs to which group of bacteria called

• A. Beta-proteobacteria
• B. Alpha-proteobacteria
• C. Gamma-proteobacteria
• D. Delta-proteobacteria

Explanation: The correct answer is Gamma-proteobacteria. This group includes sulfur bacteria that oxidize hydrogen sulfide (H2S) to obtain energy, engaging in sulfur cycling. Beta-proteobacteria are involved in nitrogen recycling, Alpha-proteobacteria are known for their symbiotic relationships with eukaryotic hosts, and Delta-proteobacteria form complex structures and are not primarily involved in sulfur oxidation.

452. Cell wall is only absent in:

• A. Archaeobacteria
• B. Eubacteria
• C. Mycoplasma
• D. Cyanobacteria

Explanation: Mycoplasmas are unique among prokaryotes due to their lack of a cell wall, which gives them flexibility and resistance to certain antibiotics. In contrast, Archaeobacteria have cell walls composed of unique substances, Eubacteria have peptidoglycan-based cell walls, and Cyanobacteria also have peptidoglycan in their cell walls, which supports their structure and function. Understanding these differences highlights the distinct characteristics of Mycoplasma within the prokaryotic kingdom.

453. Diameter of E. coli is_ to_ micrometer:

• A. 0.5-1.5
• B. 2.0-4.0
• C. 1.1-1.5
• D. 2.0-6.0

Explanation: The correct diameter range for E. coli is 1.1-1.5 micrometers, as E. coli cells are typically around this size. Option C is correct because it accurately captures this range based on the usual size of these bacterial cells. Option A, although close, slightly underestimates the upper end of the range. Options B and D overestimate the size, suggesting dimensions that are not typical for E. coli, which are generally smaller and more consistent with Option C.

454. Single cell of rod shaped bacteria is called as:

• A. Bacilli
• B. Staphylobacillus
• C. Bacillus
• D. Diplobacilli

Explanation: The correct answer is Bacillus. A single rod-shaped bacterium is known as a bacillus. The term 'bacilli' is the plural form, referring to multiple rod-shaped bacteria. 'Diplobacilli' describes two rod-shaped bacteria attached together, and 'Staphylobacillus' is not a recognized term in microbiology.

455. Nitrifying bacteria are the examples of:

• A. Heterotrophic bacteria
• B. Chemosynthetic bacteria
• C. Saprophytic bacteria
• D. Parasitic bacteria

Explanation: Nitrifying bacteria are the examples of chemosynthetic bacteria. Nitrifying bacteria are a group of bacteria that plays a crucial role in the nitrogen cycle by converting ammonia into nitrites, and further into nitrates. These bacteria obtain energy for their metabolic processes through chemosynthesis, which involves the oxidation of inorganic compounds.

456. The cell wall of bacteria is made up of:

• A. Chitin
• B. Cellulose
• C. Peptidoglycan
• D. Pectin

Explanation: A cell wall is defined as a rigid external layer that is specifically designed to provide structural support and rigidity.Diagram:

457. Robert Koch postulated the ''Germ theory of disease''. Which one of these statements is not correct about this theory?

• A. A specific organism can always be found associated with a disease
• B. The organism cannot be isolated and grown in a pure culture in the laboratory
• C. The pure culture will produce the disease when innoculated into a suscepticle animal
• D. It is possible to recover the organisms in pure culture from an experimentally infected animal

Explanation: The germ theory of disease states that some diseases are caused by microorganisms. Robert Koch formulated four postulates, which are the main pillars of the germ theory of disease. These are used to find out whether the organism found in disease lesions is the causal agent of the disease or not.1. A specific organism can always be found in association with a given disease.2. The organism can be isolated and grown in pure culture in the laboratory.3. The pure culture will produce the disease when inoculated into susceptible animals.4. It is possible to recover the organism in pure culture from an experimentally infected animal

458. The bacteria which range in size from 0.75-1.25 micrometers in diameter are:

• A. E.Coli
• B. Staphylococci and Streptococci
• C. Spirochetes
• D. Epulophiscuim fishelsoni

Explanation: Staphylococci and Streptococci are 0.75 - 1.25n in diameter. The average size of staphylococci and streptococci can vary slightly depending on the specific species and growth conditions, but generally, they fall within the range of 0.5 to 1.0 micrometers (μm) in diameter.

459. Many bacteria are motile due to the presence of:

• A. Flagella
• B. Pilli
• C. Cilia
• D. Microtubules

Explanation: Flagella are long, whip-like structures that many microorganisms, including bacteria and some single-celled eukaryotes, use for locomotion. These thread-like appendages are primarily involved in the movement of these organisms through their environment. Flagella can vary in number, structure, and arrangement depending on the species. The primary function of flagella is to enable motility. By rotating or waving in a coordinated manner, they propel the organism through liquid environments, such as water or bodily fluids.

460. Cell wall structure of a cell of unknown origin was studied and was found to contain polysaccharide chain linked with short chains of amino acid. What do you think it can be?

• A. Bacteria
• B. Fungi Cell
• C. Algae
• D. Cortex cells

Explanation: The description of a cell wall containing polysaccharide chains linked with short chains of amino acids is characteristic of bacterial cell walls. Bacterial cell walls are primarily composed of peptidoglycan, which is a complex molecule consisting of alternating sugars and short amino acid chains. The peptidoglycan provides structural integrity to bacterial cells and is a defining feature of bacterial cell walls.