Free Biodiversity and Variety of Life MCQs with Answers

2831. 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.

2832. 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.

2833. Rod-shaped bacteria are known as_:

• A. Bacilli
• B. Cocci
• C. Vibrio
• D. Sarcina

Explanation: Rod-shaped bacteria are known as bacilli. They are one of the two main shapes of bacteria, the other being cocci (spherical bacteria). Bacilli are typically about 1-2 micrometers long and 0.5-1 micrometers wide. They can be found in a variety of environments, including soil, water, and the human body. Rod-shaped bacteria, also known as bacilli (singular: bacillus), are a common bacterial morphological form characterized by their elongated, cylindrical shape. These bacteria are typically longer than they are wide and may vary in length, from short rods to long filamentous forms. Rod-shaped bacteria can be found in a wide range of bacterial species and play various ecological and biological roles.

2834. If lipopolysaccharides did not appear in the wall of bacteria on staining, then it will be known as_:

• A. Gram-positive
• B. Gram positive & Gram negative
• C. Gram-negative
• D. Capsule

Explanation: If lipopolysaccharides (LPS) did not appear in the wall of bacteria on staining, it would be known as Gram-positive bacteria. The Gram staining technique is a widely used method to differentiate bacteria into two broad groups: Gram-positive and Gram-negative. The staining process involves the application of crystal violet, iodine, alcohol, and safranin to bacterial cells. Gram-positive bacteria retain the crystal violet stain due to their thick peptidoglycan layer in the cell wall, which traps the dye. They appear purple under a microscope. Gram-positive bacteria generally lack or have low amounts of LPS in their cell walls.

2835. CV-1 complex is formed during Gram staining in:

• A. Mycoplasmas
• B. Gram negative bacteria
• C. Gram positive bacteria
• D. Archaeobaeteria

Explanation: CV-1 complex is formed during Gram staining in Gram-positive bacteria. The Gram stain is a method of differentiating between two main types of bacteria: gram-positive and gram-negative. The Gram stain is based on the different chemical compositions of the cell walls of these two types of bacteria. During the Gram stain, the bacteria are first treated with crystal violet, which stains all bacteria purple. Then, they are treated with iodine, which forms a complex with the crystal violet. This complex is called the CV-1 complex. Gram-positive bacteria retain the CV-1 complex because their thick cell walls prevent the decolorizer from penetrating the cell.

2836. Which of the following is not correct for bacterial flagellum?

• A. It arises from basal body
• B. It is involved in chemotaxis
• C. It is proteinaceous in nature
• D. It is responsible for conjugation

Explanation: The bacterial flagellum is not responsible for conjugation. Conjugation is a type of horizontal gene transfer in which DNA is transferred from one bacterium to another. The DNA is transferred through a pilus, which is a long, thin protein structure that is produced by one of the bacteria. The pilus attaches to the other bacterium, and the DNA is then transferred through the pilus. Pili is responsible for conjugation process.

2837. The entire cell wall of bacteria is often regarded as a single huge molecule or molecular complex called_:

• A. Capsule
• B. Secondary wall
• C. Slime capsule
• D. Saculus

Explanation: The sacculus is the rigid layer that forms the outermost part of the cell wall in bacteria. It is made up of peptidoglycan, a polymer of sugars and amino acids. The sacculus is responsible for providing the cell with its shape and strength. It also helps to protect the cell from the environment and from attack by the host immune system. Hence the entire cell wall of bacteria is often regarded as a single huge molecule or molecular complex called sacculus.

2838. Which of the following contains peptidoglycan cell wall?

• A. Penecillium
• B. Bacterium
• C. Adiantum
• D. Polytrichum

Explanation: Bacteria contain a peptidoglycan cell wall. Peptidoglycan is a specific structural component of bacterial cell walls, and it is not found in fungi or other organisms. In contrast, fungi have a different type of cell wall primarily composed of chitin, which is distinct from the peptidoglycan cell walls of bacteria. So, the correct answer is "Bacteria."

2839. A bacterium with tuft of flagella at both poles is called?

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

Explanation: Amphitrichous is a condition when a tuft of flagella at each of two poles is present.

2840. What is true for pili and flagella like structures of bacteria:

• A. Both are same in size
• B. Both are involved in locomotion
• C. Both are composed of proteins
• D. All of above

Explanation: Both pili and flagella are composed of proteins, but they are made up of different proteins. Pili are made up of pilins, which are small, elongated proteins. Flagella are made up of flagellin, which is a larger, more complex protein.