Free Kingdom Prokaryotae MCQs with Answers

241. Function of pilus in bacteria is to:

• A. Increase pathogenicity of bacteria
• B. Degrade host plasma membrane
• C. Degrade host enzymes
• D. Exchange of genetic material

Explanation: Pili (singular: pilus) arehair-like appendages found on the surface of some bacterial cells. One of the primary functions of pili is to facilitate the exchange of genetic material between bacterial cells, a process known as bacterial conjugation.Role of pili in bacterial conjugation- Pili act as a bridge between two bacterial cells, allowing for direct cell-to-cell contact.- The pilus of one bacterium attaches to a receptor on the surface of another bacterium.- The attached bacteria then form a conjugation bridge, allowing for the transfer of genetic material, such as plasmids.

242. The number of layers of cell wall in Gram-positive bacteria is:

• A. 1
• B. 2
• C. 3
• D. 4

Explanation: In Gram-positive bacteria, there is only one major layer in the cell wall, while Gram-negative bacteria have two major layers in the cell wall.

243. Bacterial cell have ability to maintain its shape through :

• A. Cell wall
• B. Capsule
• C. Cell wall & slime
• D. Slime

Explanation: The bacterial cell wall is a rigid structure that provides structural support and helps maintain the shape of the bacterial cell. It is responsible for giving bacteria their characteristic shapes, such as rod-shaped (bacilli), spherical (cocci), or spiral (spirilla), and it also plays a role in protecting the cell from osmotic pressure changes.The capsule (option B) and slime (option D) are not primarily responsible for maintaining the cell shape but may have other functions, such as protecting the cell or aiding in adhesion. Option C mentions both the cell wall and slime, but the cell wall is the primary component responsible for shape maintenance.

244. Which of the following is an example of spiral-shaped bacteria?

• A. Diplococcus pneumoniae
• B. Hyphomicrobium
• C. Escherichia coil
• D. Pseudomonas

Explanation: Hyphomicrobium is a genus of bacteria that exhibits a spiral or helical shape. It is known for its spiral or curved rod morphology. The other options, Diplococcus pneumoniae (Option A), Escherichia coli (Option C), and Pseudomonas (Option D), do not typically exhibit a spiral shape; they have different bacterial morphologies.

245. All the following are disinfectants to control bacterial growth except:

• A. Tincture of Iodine
• B. Potassium Permanganate
• C. Mercuric Chloride
• D. Hydrogen Peroxide

Explanation: **Tincture of iodine** (option A) is not typically used as a disinfectant to control bacterial growth. Tincture of iodine is more commonly used as an antiseptic for disinfecting skin or mucous membranes. It contains iodine dissolved in alcohol and is often used for wound care or as a preoperative skin disinfectant.The other options, **Mercuric Chloride** (Option C), **Potassium Permanganate** (Option B), and **Hydrogen Peroxide** (Option D), can be used as disinfectants to control bacterial growth in various settings. They are more commonly employed for this purpose.

246. Number of major layer/layers of cell wall in gram positive bacteria is/are:

• A. 1
• B. 2
• C. 3
• D. 4

Explanation: In Gram-positive bacteria, there is only one major layer in the cell wall while hgram negative bacteria has two major layers.

247. The capsule of a bacterial cell is a sticky gelatinous structure made up of protein and:

• A. Lipids
• B. Carbohydrates
• C. Nucleotide
• D. Alcohol

Explanation: Option B is correct.The capsule of a bacterial cell is a sticky gelatinous structure made up of carbohydrates. The capsule is a layer of polysaccharide material that surrounds the cell wall of some bacteria. It is composed of repeating units of sugar molecules. The capsule is a dynamic structure that can be produced or shed by the bacteria in response to environmental conditions. The capsule has a number of functions, including: Protecting the bacteria from dehydration Helping the bacteria to adhere to surfaces Evasion of the host immune system Some bacteria, such as Streptococcus pneumoniae, have a thick capsule that is essential for their virulence. The capsule protects the bacteria from phagocytosis, a process by which white blood cells engulf and destroy bacteria. The other options are not components of the bacterial capsule: Lipids are a type of organic molecule that is made up of fatty acids and glycerol. They are found in the cell membrane and other cellular structures. Nucleotides are the building blocks of DNA and RNA. Nucleotides are joined together by phosphodiester bonds to form DNA and RNA molecules. The order of the nucleotides in DNA and RNA determines the genetic code. Alcohols are a type of organic molecule that contains a hydroxyl group (OH). They are found in a variety of foods and beverages.

248. Saprophytic bacteria are:

• A. Autotrophs
• B. Decomposers
• C. Parasites
• D. Photosynthetic

Explanation: Option B is correct.Saprophytic bacteria are decomposers. Decomposers are organisms that break down dead organic matter. Saprophytic bacteria play an important role in the environment by breaking down dead plants and animals, which releases nutrients back into the soil and air. Examples of saprophytic bacteria include: Bacillus subtilis, Clostridium tetani ,Escherichia coliAutotrophs are organisms that can make their own food from sunlight and carbon dioxide. Decomposers are not autotrophs because they cannot make their own food. Parasites are organisms that live on or inside another organism and get their nutrients from that organism. Saprophytic bacteria are not parasites because they do not live on or inside another organism. Photosynthetic organisms are organisms that use sunlight to convert carbon dioxide into oxygen and carbohydrates. Saprophytic bacteria are not photosynthetic because they do not use sunlight to make their own food.

249. Salmonella typhi causing typhoid and Clostridium tetani causing tetanus are which type of bacteria?

• A. Bacilli
• B. Spirilla
• C. Cocci
• D. Comma

Explanation: Option A is correct.Salmonella typhi and Clostridium tetani are both bacilli. Bacilli are rod-shaped bacteria. They are one of the three main shapes of bacteria, along with cocci (spherical bacteria) and spirilla (spiral bacteria). Bacilli are found in a wide variety of environments, including soil, water, and the human body. Some bacilli are beneficial, such as those that produce lactic acid in yogurt and cheese. Other bacilli are pathogens, which means that they can cause disease. Salmonella typhi and Clostridium tetani are both examples of pathogenic bacilli. Salmonella typhi causes typhoid, a serious disease that can be fatal if it is not treated. Typhoid is transmitted through contaminated food and water. It causes fever, headache, and diarrhea. Clostridium tetani causes tetanus, a disease that affects the nervous system. Tetanus is caused by a toxin that is produced by the bacteria. The toxin causes muscle spasms, which can be severe and life-threatening. Tetanus is transmitted through contact with contaminated soil or other objects. Both Salmonella typhi and Clostridium tetani can be prevented by vaccination. The typhoid vaccine is recommended for people who are traveling to areas where typhoid is common. The tetanus vaccine is recommended for everyone as part of the routine childhood immunization schedule.Spirilla:Spiral bacteria.Example; Campylobacter (food poisoning), Leptospira (leptospirosis), Treponema pallidum (syphilis) Cocci: Spherical bacteria.Examples; Streptococcus (strep throat), Staphylococcus (staph infection), Neisseria (meningitis, gonorrhea) Comma-shaped bacteria are a type of spirilla. Comma-shaped bacteria include: Vibrio cholerae (cholera), Vibrio parahaemolyticus (food poisoning), and Helicobacter pylori (stomach ulcers).

250. Select a method which cause the oxidation of constituent of a bacterial cell wall

• A. Dry Heat
• B. Moist Heat
• C. Filtration
• D. Ultraviolet Radiation

Explanation: This is the correct answer. Dry heat is a method of sterilization that involves exposing microorganisms, including bacteria, to high temperatures in a dry environment. This process causes the oxidation of the constituents of the bacterial cell wall, leading to cell death.Therefore, dry heat is the method that primarily causes the oxidation of the constituents of a bacterial cell wall.