Free Kingdom Prokaryotae MCQs with Answers

311. Bacteria can also detect and move in response to chemical signals. This type of behavior is called:

• A. Chemotropism
• B. Chemotaxis
• C. Locomotion
• D. Repulsion

Explanation: Chemotaxis is the biological process by which cells, typically microorganisms such as bacteria, move in response to chemical gradients in their environment. It is a crucial mechanism for the navigation of cells toward attractants (positive chemotaxis) or away from repellents (negative chemotaxis).

312. Thick, rigid spiral bacterium:

• A. Spirochaete
• B. Pseudomonas
• C. Spirillum
• D. Rhizobium

Explanation: Spirillum is a type of bacterium characterized by its spiral or helical shape. Spirilla are often elongated and have a rigid structure. Spirilla can be further classified based on their mobility and the presence of flagella. Some spirilla are motile and have flagella, which allow them to move through liquid environments. Others are non-motile and do not possess flagella.

313. A bacillus bacterium with a single flagellum at one end is described as:

• A. Monotrichous
• B. Lophotrichous
• C. Amphitrichous
• D. Peritrichous

Explanation: "Monotrichous" is a term used to describe the arrangement of flagella on a bacterial cell. In a monotrichous arrangement, a bacterium has a single flagellum, a whip-like appendage used for motility, emerging from one end of the cell.

314. These are hollow, non-helical, filamentous appendages:

• A. Flagella
• B. Pilli
• C. Trichomes
• D. Plasmids

Explanation: These are hollow, nonhelical, filamentous appendages. Pili are smaller than flagella and are not involved in motility. True pili are only present in gram-negative bacteria. They are made up of a special protein called pilin. They are primarily involved in a mating process between cells called the conjugation process. Some pili function as a means of attachment of bacteria to various surfaces.

315. Following are the various names for nucleoid, EXCEPT:

• A. Nuclear body
• B. Chromatin body
• C. Nuclear region
• D. Nucleus

Explanation: The nucleus is a membrane-bound organelle found in eukaryotic cells. It is often referred to as the "control center" of the cell since it houses the cell's DNA and controls gene expression. The nucleus contains chromatin, nucleoli, and other structures involved in cellular processes. However, the term "nucleus" is not used to describe the DNA-containing region in prokaryotic cells. Instead, prokaryotes have a nucleoid, which is a distinct structure without a membrane that contains the genetic material. In summary, the correct option is D) Nucleus, because the nucleoid is a term specifically used in prokaryotic cells, while the other options refer to various structures or regions within the nucleus of eukaryotic cells.

316. Some_ occasionally reach the length of 500 micrometer:

• A. Spirochetes
• B. Diplococci
• C. Streptococci
• D. Cocci

Explanation: Spirochetes are a group of bacteria that are characterized by their spiral shape. They are typically long and slender, and some species can indeed reach a length of 500 micrometers or even longer. Spirochetes are known for their unique way of moving by rotating their entire body, which allows them to navigate through various environments, including tissues and body fluids. Some well-known examples of spirochetes include Treponema pallidum, the bacteria that causes syphilis.

317. The structure used for sexual contact between bacteria is/are:

• A. Flagella
• B. Plasmid
• C. Mesosome
• D. Pili

Explanation: Pili (singular: pilus) are hair-like appendages on the surface of bacteria. They are involved in various functions, including attachment to surfaces and bacterial motility. However, some bacteria also possess a specific type of pilus called a sex pilus or F pilus. Sex pilus is involved in a process called bacterial conjugation, which is a form of sexual contact between bacteria. During conjugation, a donor bacterium transfers a plasmid (often containing antibiotic resistance genes) to a recipient bacterium through the sex pilus. Therefore, the correct option for the structure used for sexual contact between bacteria is D) Pili.

318. Certain electromagnetic radiations below_ nm are effective in killing of microorganisms:

• A. 100
• B. 200
• C. 300
• D. 400

Explanation: This is a fact that you will need to remember that Certain electromagnetic radiations below 300 nm are effective in killing of microorganisms.The effective range for germicidal UV radiation is typically below 300 nanometers (nm). This range, specifically in the 100 to 280 nm region, is the most effective for disinfection and is often referred to as the germicidal or UVC range.

319. Which of the following is not found in all bacteria?

• A. Cell membrane
• B. Nucleoid
• C. Ribosomes
• D. Capsule

Explanation: The capsule is a slimy, protective layer that surrounds some bacterial cells. It is composed of polysaccharides or similar materials and helps bacteria evade the host immune system and resist environmental stresses. However, not all bacteria possess capsules; it is a feature found in certain bacterial species but not in all. The capsule of a bacterium is a specific and well-defined structure. The capsule is a protective layer that surrounds the bacterial cell, located outside the cell wall (if present). It is composed of a gel-like substance, primarily consisting of polysaccharides or occasionally polypeptides.

320. Students were asked to give a guess about a unicellular organism with darkly stained nucleus. Which of the following can be straight away excluded from the list:

• A. Paramecium
• B. Amoeba
• C. Plasmodium
• D. Lactobacillus

Explanation: Lactobacillus is a genus of bacteria, and bacteria do not have nuclei in the same way that eukaryotic cells (such as protists) do. Bacterial genetic material is contained within a region called the nucleoid, which is not membrane-bound and does not exhibit the same dark staining characteristics as eukaryotic nuclei. Since Lactobacillus is a bacterium and not a unicellular organism with a darkly stained nucleus, it can be excluded from the list.