Free Kingdom Prokaryotae MCQs with Answers

421. The given diagram shows the process of conjugation in bacteria.The option that correctly identifies the labelled structure X, cells Y and Z is

• A. A
• B. B
• C. C
• D. D

Explanation: Structure X is pilus. Bacteria possessing the F plasmid are designated as F+. So Y is F+.Bacteria lacking the F plasmid are designated as F-. So Z is F-.. This makes option B correct. All other options are incorrect.

422. Which of the following features is related to thermophilic bacteria?

• A. Bacteria that thrive in high-temperature environments like hot springs
• B. Cyanobacteria play an important role in nitrogen fixation
• C. The bacterial species Salmonella typhi causes typhoid in humans
• D. Bacteria in the large intestine of humans synthesize vitamins

Explanation: The correct answer is Option A:Bacteria that thrive in high-temperature environments like hot springsThermophilic bacteria are known for their ability to survive and function at high temperatures, often found in environments such as hot springs and hydrothermal vents. The other options describe features of different types of bacteria or their roles in ecosystems, but do not specifically relate to thermophilic bacteria.

423. Based on the modes of nutrition, bacteria that serve the role of decomposers in the environment are categorised as

• A. Photoautotrophs
• B. Chemoautotrophs
• C. Photoheterotrophs
• D. Chemoheterotrophs

Explanation: Decomposers play a crucial role in ecosystems by breaking down dead organic material and recycling nutrients. These organisms are classified as chemoheterotrophs because they obtain their energy and carbon from organic compounds, which they decompose. In contrast, photoautotrophs and chemoautotrophs derive their carbon from carbon dioxide and not from decomposing organic matter. Photoheterotrophs use light for energy but, like chemoautotrophs, are not primarily decomposers.

424. One of the hypotheses about origin of life is that life began deep in the oceans, in underwaterhot springs. The occurrence of which of the following organisms supports the givenhypothesis?

• A. Sycon
• B. Green algae
• C. Zooflagellates
• D. Archaebacteria

Explanation: Archaebacteria are a group of microorganisms that are well-known for their ability to thrive in extreme environments, such as those found in deep ocean hydrothermal vents. This supports the hypothesis that life could have originated in such harsh conditions. In contrast, the other organisms listed-Sycon, green algae, and zooflagellates-do not specifically exhibit adaptations for surviving in these extreme environments. Green algae, for instance, require sunlight for photosynthesis and are not typically found in the dark depths of the ocean. Sycon and zooflagellates also lack the specialized adaptations necessary for life in hydrothermal vent conditions.

425. The arrangement of flagella in bacterial cells shown in the diagram is:

• A. Monotrichous
• B. lopotrichous
• C. peritrichous
• D. monopolar bitrichous

Explanation: The lophotrichous bacteria have several flagella located at the same place on their surface. When a tuft of flagella arises from one side of bacteria it is lophotrichous arrangement.

426. In bacterial cells the absorption of DNA from medium to cell results in

• A. Transformation
• B. Transduction
• C. Conjugation
• D. Translation

Explanation: The process of absorption of DNA into the cell from its immediate environment is called transformation.As a result cell is transformed into new type of cell.

427. The bacterium, with a tuft of flagella present at each of the two poles, is called:

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

Explanation: Amphitrichous refers to a type of bacterial flagellation where a single flagellum is present at both ends of the cell. This arrangement allows for movement in both directions, giving the bacteria greater mobility and versatility in navigating their environment.

428. Example of bacteria requiring low concentration of oxygen is?

• A. Spirochete
• B. Seudomonas
• C. E.coli
• D. Campylobacter

Explanation: Campylobacter is a genus of bacteria that are mostly microaerophilic, i.e. they require a very low concentration of oxygen to survive. At higher concentrations, these can not survive.

429. Unlike eukaryotes, prokaryotes have no membrane-bound organelles. How, then, are prokaryotes able to generate energy?

• A. Prokaryotes generate sodium gradients across their nuclear membranes
• B. Prokaryotes do not generate energy
• C. Prokaryotes produce energy via photosynthesis
• D. Prokaryotes generate proton gradients across their plasma membranes

Explanation: Although prokaryotes lack mitochondria and other membrane-bound organelles, they are able to generate a proton gradient across their cell membranes, and thus produce ATP by chemiosmosis.

430. Which of the following bacteria are thick rigid and spiral?

• A. Coccus
• B. Vibrio
• C. Spirillum
• D. Bacillus

Explanation: Option C is correct as bacteria classified as "spirillum" are spiral in shape.