Free Biodiversity and Variety of Life MCQs with Answers

2241. DNA of bacteria is present in:

• A. Nucleoid
• B. Nucleus
• C. Mitochondria
• D. Mesosome

Explanation: The DNA of bacteria is present in the nucleoid. The nucleoid is a distinct region within the bacterial cell where the genetic material (chromosomal DNA) is located. Unlike eukaryotic cells, bacteria do not have a membrane-bound nucleus, so their genetic material is dispersed within the nucleoid region.

2242. Antibiotics act against:

• A. Bacterial diseases
• B. Allergies
• C. Viral Diseases
• D. Bacterial and Viral Diseases

Explanation: Antibiotics are medications that are used to treat bacterial infections. They work by killing or preventing the growth of bacteria. Antibiotics do not work against viruses, fungi, or parasites. Antibiotics are medications specifically designed to treat bacterial infections and diseases. They work by targeting and killing bacteria or inhibiting their growth. Antibiotics are not effective against viral infections, such as the common cold or flu, as viruses are different from bacteria in terms of their structure and replication mechanisms.

2243. It is responsible for drug resistance in bacteria:

• A. Slime
• B. Plasmid
• C. Capsule
• D. Pili

Explanation: Plasmids can be responsible for drug resistance in bacteria. Plasmids are small, circular pieces of DNA that can be found in bacteria. They are not essential for the survival of bacteria, but they can carry genes that confer resistance to antibiotics.

2244. Which one of the following is a specific structure of bacterial cell?

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

Explanation: The capsule is an outer wrapping or envelope found in certain bacterial cells but missing in others. The bacteria having it are called encapsulated and make smooth surfaced colonies. They are more virulent for the host and resistant against the host immune system. The bacteria which lack capsule are called non-encapsulated and make rough-surfaced colonies and are vulnerable to host immune system that is why they are genus less virulent.

2245. Bacteria vary in:

• A. Size
• B. Size as well as in shape
• C. Shape
• D. Cell type

Explanation: Bacteria vary in both size and shape. Size ranges from microscopic, such as 0.5 to 5 micrometers, and shape can be diverse, including spheres (cocci), rods (bacilli), and spirals (spirilla).

2246. Pick up the bacteria with exceptional shape:

• A. Square
• B. Vibrio
• C. Spirillum
• D. Spirochete

Explanation: Square-shaped bacteria are not commonly found in nature and are considered exceptional in bacterial morphology. Bacteria with a square shape are not commonly observed in nature. Most bacteria are characterized by shapes such as cocci (spherical), bacilli (rod-shaped), or spirilla (spiral-shaped). Square bacteria would be an exceptional and unusual morphology.

2247. Heat sensitive compounds like antibodies seras and hormones can be sterilized by means of:

• A. Radiations
• B. Chemicals
• C. Membrane filters
• D. Dry heat

Explanation: Compounds such as antibiotics, seras, hormones, etc are heat sensitive. Heat-sensitive compounds can be sterilized by membrane filters. The sterilization process is a process that involves physical agents used to control bacteria and other microorganisms. A membrane filter is a type of filter that is used to remove particles and microorganisms from a liquid or gas. It consists of a thin, porous membrane that is placed in a filter holder. The liquid or gas is passed through the membrane, which traps the particles and microorganisms and allows the clean fluid to pass through. Membrane filters are commonly used in microbiology to remove bacteria and other microorganisms from liquids such as water or culture media. They are also used in industrial applications to remove impurities from liquids or gases. The pore size of the membrane can be adjusted to allow for the removal of particles of different sizes.

2248. Which is not present in bacteria?

• A. Peptidoglycan
• B. rRNA
• C. Histones
• D. Teichoic acid

Explanation: In general, bacteria do not contain histones. Histones are a class of proteins that play a crucial role in the packaging and organization of DNA in eukaryotic cells, such as those found in plants, animals, and fungi. Histones help condense the long, linear DNA strands into a compact and organized structure known as chromatin, which is essential for regulating gene expression and DNA replication.

2249. The structure which contains the gene for drug resistance in bacteria are

• A. Nucleoids
• B. Mesosomes
• C. Chromatin Bodies
• D. Plasmids

Explanation: "The explanation for this question will be added soon!".

2250. In which of the following phases of bacterial growth, is the death rate more rapid than the multiplication rate?

• A. Stationary phase
• B. LAG phase
• C. Decline phase
• D. LOG phase

Explanation: The correct answer is the decline phase. During this phase, the conditions are no longer favorable for bacterial growth due to the depletion of nutrients and accumulation of waste products, resulting in a death rate that exceeds the growth rate. In contrast, the stationary phase is characterized by an equilibrium between growth and death rates. The lag phase involves adaptation to new conditions with minimal cell division, while the log phase is marked by rapid and exponential bacterial growth.