A prokaryotic cell may possess each of the following cellular components EXCEPT
flagella.
a nucleus.
ribosomes.
a cell wall.
a cell membrane
The Correct Answer is B
A. Flagella: Flagella are whip-like appendages used for motility and are commonly found in prokaryotic cells such as bacteria. They are anchored in the cell membrane and cell wall and function to propel the cell toward nutrients or away from harmful stimuli. Their presence is consistent with prokaryotic structure and physiology.
B. Nucleus: Prokaryotic cells lack a membrane-bound nucleus. Instead, their genetic material exists as a single circular DNA molecule located in the nucleoid region of the cytoplasm. The absence of a nucleus is a defining feature that differentiates prokaryotes from eukaryotes.
C. Ribosomes: Prokaryotic cells contain ribosomes, typically 70S in size, which are responsible for protein synthesis. These ribosomes are dispersed throughout the cytoplasm and facilitate translation of messenger RNA into functional proteins.
D. Cell wall: Most prokaryotes possess a rigid cell wall that maintains cell shape, provides structural support, and protects against osmotic stress. In bacteria, the cell wall is primarily composed of peptidoglycan, which differs structurally from eukaryotic cell walls.
E. Cell membrane: The plasma membrane is a phospholipid bilayer that encloses the cytoplasm of prokaryotic cells. It regulates the movement of substances in and out of the cell and houses proteins essential for energy production, nutrient transport, and signal transduction.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is E
Explanation
A. riboflavin: Certain microorganisms, such as fungi and bacteria, are used industrially to synthesize riboflavin (vitamin B2). Microbial fermentation allows large-scale production of this essential vitamin for dietary supplements and food fortification. The use of microbes provides a cost-effective and scalable method compared to chemical synthesis.
B. acetone: Acetone can be produced through microbial fermentation, particularly using Clostridium species in the acetone-butanol-ethanol (ABE) fermentation process. This method was historically important for industrial solvent production before petrochemical methods became widespread. Microbial synthesis allows renewable production from carbohydrate sources.
C. insulin: Recombinant DNA technology uses genetically engineered bacteria or yeast to produce human insulin. Microbes are transformed with the insulin gene, allowing high-yield production of biologically active insulin for diabetes treatment. This method replaced extraction from animal pancreases, improving safety and scalability.
D. aspirin: Aspirin (acetylsalicylic acid) is chemically synthesized from salicylic acid and acetic anhydride. Microorganisms are not typically used in its industrial production, making this an exception among commonly microbially produced compounds.
E. riboflavin, acetone and insulin: Microorganisms are commercially exploited to synthesize riboflavin, acetone, and insulin through fermentation or recombinant DNA technology. These processes demonstrate the economic and therapeutic benefits of microbial biotechnology in vitamins, solvents, and pharmaceuticals.
Correct Answer is A
Explanation
A. Cocci, bacilli, coccobacilli, vibrios, spirilla, and spirochetes: These are all recognized bacterial shapes. Cocci are spherical, bacilli are rod-shaped, coccobacilli are short rods, vibrios are comma-shaped, spirilla are rigid spiral-shaped bacteria, and spirochetes are flexible, corkscrew-shaped bacteria. These morphological classifications are used in microbiology to identify and categorize bacterial species.
B. Cocci, diplocytes, flagella, fimbriae, and spores: While cocci are a bacterial shape, diplocytes refers to paired cocci, flagella and fimbriae are appendages, and spores are dormant survival structures. This list mixes shapes with structures, hence does not exclusively describe bacterial morphology.
C. Bacilli, nuclei, ribosomes, mitochondria, and cocci: Bacilli and cocci are bacterial shapes, but nuclei, ribosomes, and mitochondria are cellular organelles not used to define bacterial morphology. Bacteria are prokaryotes and lack membrane-bound organelles.
D. Spirilla, cilia, capsules, and peptidoglycan: Spirilla is a bacterial shape, but cilia are eukaryotic structures, capsules are extracellular protective layers, and peptidoglycan is a cell wall component. Only spirilla refers to bacterial morphology.
E. Spirochetes, lysosomes, peroxisomes, and cocci: Spirochetes and cocci are bacterial shapes, but lysosomes and peroxisomes are eukaryotic organelles. This list is not limited to recognized bacterial morphologies.
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