Free Biodiversity and Variety of Life MCQs with Answers

2811. Single cell of rod shaped bacteria is called as:

• A. Bacilli
• B. Strephylobaccilus
• C. Bacillus
• D. Diplobacilli

Explanation: A. Rod shaped bacteria (plural)B. Chain of bacilliD. Pair arrangement

2812. Which of the following organelles are present in all the bacteria?

• A. Mesosome
• B. Ribosomes
• C. Golgi bodies
• D. Mitochondria

Explanation: The correct answer is 'Ribosomes.' In bacteria, which are prokaryotic organisms, ribosomes are present and essential for protein synthesis. These are not membrane-bound and are found throughout the cytoplasm. Other options such as Golgi bodies, mitochondria, and chloroplasts are membrane-bound organelles found in eukaryotic cells, not in bacteria. Mesosomes were once thought to be a common organelle in bacteria, but they are now largely considered artifacts of cell preparation.

2813. Vibrio cholera is an example of _ type of bacteria.

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

Explanation: Bacteria are classified according to their shape, which is an essential characteristic for identification. The primary shapes are:Cocci: These are spherical bacteria, and examples include Streptococcus pneumoniae.Bacilli: These are rod-shaped bacteria, with Escherichia coli being a common example.Spirilla: These are spiral-shaped bacteria, such as Treponema pallidum.Vibrio: These are comma-shaped bacteria, and Vibrio cholerae is the organism responsible for cholera.Since the question specifically mentions Vibrio cholerae, the correct answer is Vibrio. The other options are incorrect because they refer to different bacterial shapes that do not apply to Vibrio cholerae.

2814. In a bacterial cell, plasma membrane with all things present within it is called:

• A. Cytoplasmic matrix
• B. Cytoplasm
• C. Protoplasm
• D. Cell Structure

Explanation: The correct answer is 'Protoplasm'. In the context of bacteria, the protoplasm is the term used to describe all the living contents within the plasma membrane, which includes both the cytoplasm and the genetic material. The 'Cytoplasmic matrix' refers only to the fluid part of the cytoplasm, excluding organelles and other inclusions. 'Cytoplasm' typically refers to the contents within the cell membrane excluding the nucleus, which is not wholly applicable to prokaryotes as they lack a defined nucleus. 'Cell Structure' is a non-specific term that does not precisely address the composition within the plasma membrane.

2815. Cell wall is only absent in the following group of bacteria:

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

Explanation: The correct option is D: Mycoplasmas. These bacteria are distinctive in lacking a cell wall, which makes them naturally resistant to antibiotics such as penicillin that target cell wall synthesis. Mycoplasmas rely on a specialized cell membrane containing sterols for stability and are often pathogenic in animals. In contrast, Staphylococci, Pseudomonas, and Diplococcus pneumoniae all possess cell walls made largely of peptidoglycan, which is essential for their structural integrity and vulnerability to certain antibiotics.

2816. Which of the following will not survive in the presence of oxygen?

• A. Aerotolerant anaerobe
• B. Facultative anaerobe
• C. Obligate aerobe
• D. Obligate anaerobe

Explanation: Obligate anaerobes are organisms that cannot survive in the presence of oxygen as they lack the necessary enzymes to process it, making them vulnerable to its toxic effects. They rely on anaerobic respiration or fermentation for energy. Other options like facultative anaerobes can survive in both conditions, while obligate aerobes and aerotolerant anaerobes can survive in the presence of oxygen, making them incorrect choices for this question.

2817. Which of the following is true regarding the bacteria?

• A. Bacteria contain plasma membranes that are made up of triglycerides
• B. Gram staining reveals that bacteria contain cell walls, but no cell membranes
• C. Bacteria do not contain a membrane-bound nucleus, but they contain an non membrane-bound region called the nucleoid
• D. All of these options are false

Explanation: Option A: All cells including bacteria contain cell membrane but it is not made up of triglycerides.Option B: Gram staining tells us about the nature of cell wall gram-positive and gram-negative bacteria. It does not tell about cell membranes.Option C: Bacteria do not contain membrane-bound organelles such as mitochondria or chloroplasts, as eukaryotes do. However, photosynthetic bacteria, such as cyanobacteria, may be filled with tightly packed folds of their outer.

2818. Which of the following is the most responsible factor for bacterial cell motility?

• A. Cilia
• B. Flagella
• C. Pili
• D. Pseudopodia

Explanation: The correct answer is Flagella. Flagella are the main organelles for motility in bacteria, allowing them to swim through liquid environments. They are complex structures made of protein subunits that rotate to propel the cell.

2819. Which of the following contains genes for drug and disease resistance in bacteria?

• A. Plasmid
• B. Nucleoid
• C. Mesosomes
• D. All of these

Explanation: Plasmids are small, circular, double-stranded DNA molecules that are separate from the bacterial chromosomal DNA, often harboring genes that confer resistance to antibiotics and other environmental stresses. These genes can be transferred between bacteria, enabling rapid spread of resistance. The nucleoid, while being essential for the cell's genetic information, does not typically harbor such accessory genes. Mesosomes, on the other hand, are not involved in genetic functions but are rather structural components hypothesized to play roles in processes like cell division and respiration.

2820. The filamentous appendages called pilli are present only on?

• A. Gram-positive bacteria
• B. Gram-negative bacteria
• C. Chemo-synthetic bacteria
• D. None of the above

Explanation: Pili are filamentous structures primarily found on gram-negative bacteria. These appendages are crucial for various functions such as adhesion to surfaces, facilitating bacterial conjugation (exchange of genetic material), and sometimes aiding in motility. The cell wall structure of gram-negative bacteria, characterized by a thinner peptidoglycan layer, supports the extension of pili. In contrast, gram-positive bacteria have a thicker peptidoglycan layer that typically prevents pili formation, although they may have other attachment mechanisms. Chemo-synthetic bacteria do not predominantly rely on pili as they are more concerned with chemical energy production processes.