Free Biodiversity and Variety of Life MCQs with Answers

2361. Methicillin-resistant Staphylococcus aureus is an antibiotic-resistant "superbug" that can cause deadly infections in humans. What would these Gram-positive bacteria look like under a microscope?

• A. Purple spheres
• B. Clear rods
• C. Pink rods
• D. Purple spirals

Explanation: Methicillin-resistant Staphylococcus aureus (MRSA) is a type of Gram-positive bacterium that is resistant to multiple antibiotics, including methicillin and other β-lactam antibiotics. When viewed under a microscope after Gram staining, MRSA appears as Gram-positive cocci(purple spheres).

2362. The filamentous appendages called pili are present only on:

• A. Gram-positive bacteria
• B. Gram-negative bacteria
• C. Chemosynthetic bacteria
• D. None of above

Explanation: Pili, are more commonly found in Gram-negative bacteria. While some Gram-positive bacteria may have surface appendages or structures that serve similar functions, true pili are a characteristic feature of many Gram-negative bacteria.

2363. Pili are hollow appendages in bacteria that are used for:

• A. Motility
• B. Conjugation
• C. Chemical detection
• D. None of above

Explanation: Based on the explanations provided, the correct answer to the question is option B) Conjugation. Pili in bacteria are used for bacterial conjugation, which involves the transfer of genetic material between bacterial cells.

2364. Cell wall is only absent in which of the following group of bacteria?

• A. Staphylococci
• B. Pseudomonas
• C. Diplococcus pneumonia
• D. Mycoplasmas

Explanation: Based on the explanations provided, the correct answer to the question is option D) Mycoplasmas. Mycoplasmas are the only group of bacteria that lack a cell wall.

2365. Which of the following structure is not present in all bacteria?

• A. Cell membrane
• B. Chromatin
• C. Ribosome
• D. Capsule

Explanation: Based on the explanations provided, the correct answer to the question is option D) Capsule. The capsule is not present in all bacteria, unlike the cell membrane, ribosome, and bacterial DNA (nucleoid region), which are universal features of bacterial cells.

2366. Which of the following is not a method of genetic recombination in bacterium?

• A. Conjugation
• B. Transformation
• C. Transduction
• D. Binary Fission

Explanation: Based on the explanations provided, the correct answer to the question is option D) Binary Fission. Binary fission is not a method of genetic recombination but rather a form of asexual reproduction used by bacteria to produce identical copies of themselves.

2367. Which of the following bacteria do not commonly have flagella?

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

Explanation: Based on the explanations provided, the correct answer to the question is option A) Cocci. Cocci bacteria do not commonly have flagella. While some bacilli (option B) and vibrio bacteria (option D) may have flagella, the presence of flagella in cocci is less common. Streptobacillus (option C) is a type of bacillus and may or may not have flagella, depending on the species.

2368. What allows bacteria to stain positively with gram stain?

• A. The bacteria is anaerobic
• B. The bacterial sample was pretreated with 3% ethanol
• C. The bacteria's periplasmic space
• D. The bacteria's thick peptidoglycan cell walls

Explanation: Based on the explanations provided, the correct answer to the question is option D) The bacteria's thick peptidoglycan cell walls. The presence of thick peptidoglycan in the cell wall allows bacteria to stain positively with the Gram stain, appearing purple.

2369. Flagella are basically composed of?

• A. Protein
• B. Enzyme
• C. Chemical
• D. None of above

Explanation: Flagella is composed of protein flagellin.

2370. Characteristic of prokaryotic cells?

• A. Absence of membrane bound cell organelles
• B. Absence of nucleus
• C. Presence of 70S ribosomes
• D. All of these

Explanation: Prokaryotes lack membrane-bound organelles such as mitochondria. They do not contain a nucleus as there is no membrane separating the nuclear contents from the cytoplasm so, the nucleus is absent in prokaryotes. Prokaryotes do contain ribosomes and they are smaller than those in eukaryotes. Prokaryotes contain 70s while eukaryotes contain 80s ribosomes. All of these are characteristics of prokaryotes.