Calling all budding microbiologists and cell biology enthusiasts! Are you ready to tackle prokaryote practice problems and sharpen your insights? Dive into our free Prokaryote Practice Problems Quiz to test your grasp of cell components and master prokaryotic cell structure quizzes. This quick unicellular organism test also helps you reinforce prokaryote vs eukaryote practice with bite-sized challenges. When you need a fast review, check out our prokaryotic versus eukaryotic cells worksheet or try interactive labeling a prokaryotic cell drills. Ready to level up? Take the quiz now and conquer those microbiology quiz questions!
Which of the following structures is unique to prokaryotic cells?
Nucleus
Nucleoid region
Mitochondria
Endoplasmic reticulum
Prokaryotic cells lack a membrane-bound nucleus and instead organize their DNA within a nucleoid region. This region is not enclosed by a membrane, distinguishing it from the eukaryotic nucleus. Other structures like mitochondria and endoplasmic reticulum are absent in prokaryotes. More on the nucleoid.
The cell wall of most bacteria is primarily composed of:
Cellulose
Chitin
Peptidoglycan
Lignin
Bacterial cell walls are mainly made of peptidoglycan, a mesh-like polymer of sugars and amino acids that provides structural strength. Cellulose and chitin are found in plants and fungi respectively. Lignin is a complex polymer in plant vascular tissues. Learn more about peptidoglycan.
In prokaryotes, DNA is located in:
Nucleus
Nucleolus
Nucleoid
Mitochondria
Prokaryotic DNA resides in the nucleoid, an irregularly shaped region within the cytoplasm. They do not have a true nucleus bounded by a membrane. The nucleolus is an eukaryotic substructure where ribosomal RNA is made. Details on the nucleoid.
Which organelle is absent in prokaryotic cells?
Ribosome
Golgi apparatus
Cell membrane
Cytoplasm
Prokaryotes do not have membrane-bound organelles such as the Golgi apparatus. They do contain ribosomes, a plasma membrane, and cytoplasm. The Golgi is only found in eukaryotic cells where it processes and packages proteins. More on the Golgi apparatus.
Prokaryotic ribosomes are of which size?
80S
70S
60S
50S
Bacterial ribosomes are 70S, composed of a 50S large subunit and a 30S small subunit. Eukaryotic ribosomes are 80S. The 'S' stands for Svedberg units, reflecting sedimentation rates during ultracentrifugation. More on bacterial ribosomes.
Which structure aids in bacterial movement?
Flagella
Pili
Capsule
Fimbriae
Flagella are long, whip-like appendages that propel bacteria through liquid environments. Pili and fimbriae are shorter and primarily involved in attachment or conjugation. Capsules protect against desiccation and phagocytosis. Learn about bacterial flagella.
The semi-rigid layer outside the plasma membrane in many bacteria is called:
Cytoskeleton
Cell wall
Lipopolysaccharide
Golgi body
The bacterial cell wall is a semi-rigid structure surrounding the plasma membrane that maintains cell shape and prevents osmotic lysis. Lipopolysaccharide is part of the outer membrane in Gram-negative bacteria. Cytoskeleton and Golgi bodies are eukaryotic components. More on bacterial cell walls.
Plasmids in bacteria are:
Small circular DNA molecules
Large linear chromosomes
Proteins
Lipids
Plasmids are small, usually circular, double-stranded DNA molecules that replicate independently of the bacterial chromosome. They often carry genes beneficial under certain conditions, such as antibiotic resistance. They are not proteins or lipids. Read more on plasmids.
Gram-negative bacteria have an outer membrane containing:
Teichoic acid
Lipopolysaccharide (LPS)
Peptidoglycan
Mycolic acid
The outer membrane of Gram-negative bacteria contains lipopolysaccharide (LPS), which contributes to endotoxin activity. Teichoic acids are found in Gram-positive bacteria. Peptidoglycan is in the periplasmic space but not uniquely in the outer membrane. More on LPS.
The function of bacterial pili includes:
Protein synthesis
Attachment to surfaces
Photosynthesis
DNA replication
Pili are hair-like projections that help bacteria adhere to surfaces and host tissues. They are not involved in protein synthesis or DNA replication directly. Some specialized pili (sex pili) are involved in DNA transfer. Details on pili.
Which of the following is not part of the bacterial cell envelope?
Mitochondria
Periplasmic space
Cell membrane
Capsule
The bacterial cell envelope consists of structures outside the cytoplasm: cell membrane, cell wall (which may include periplasmic space), and capsule. Mitochondria are intracellular organelles found only in eukaryotes. More on the bacterial cell envelope.
Which structure protects bacteria from phagocytosis and desiccation?
Pili
Capsule
Flagella
Ribosomes
The bacterial capsule is a polysaccharide layer that shields cells from host immune defenses and prevents drying out. Pili and flagella serve different functions, such as attachment and motility. Ribosomes are involved in protein synthesis. Learn about capsules.
The bacterial cytoskeleton is composed of proteins functionally similar to:
Actin and tubulin
Collagen
Keratin
Cellulose
Bacteria have cytoskeletal proteins like MreB and FtsZ that are functionally analogous to eukaryotic actin and tubulin, respectively. These proteins help maintain cell shape and are involved in cell division. Collagen, keratin, and cellulose are structural molecules in other organisms. More on the bacterial cytoskeleton.
Endospores are formed by some bacteria during:
Favorable conditions
Unfavorable conditions
Cell division
Protein synthesis
Endospores are highly resistant structures produced by bacteria such as Bacillus and Clostridium when they face harsh conditions. This allows them to survive extremes of heat, desiccation, and chemicals. They are not part of normal cell division or active metabolism. Read about endospore formation.
Which bacterial appendage is primarily involved in conjugation?
Sex pilus
Flagellum
Fimbriae
Capsule
The sex pilus is a specialized structure that forms a bridge between bacterial cells to transfer plasmid DNA during conjugation. Fimbriae and capsules do not facilitate genetic exchange. Flagella are used for motility. More on the sex pilus.
The peptidoglycan layer of Gram-positive bacteria is characterized by:
Thin layer and outer membrane
Thick layer and teichoic acids
Presence of LPS
Presence of mycolic acids
Gram-positive bacteria have a thick peptidoglycan layer that often contains teichoic acids, which provide structural stability and antigenic properties. Gram-negatives have a thin layer plus an outer LPS membrane. Mycolic acids are characteristic of mycobacteria. About Gram-positive cell walls.
Which of the following enzymes degrades peptidoglycan by hydrolyzing bonds in the cell wall?
DNA polymerase
Lysozyme
Lipase
Amylase
Lysozyme cleaves the ?-1,4-glycosidic bonds between N-acetylmuramic acid and N-acetylglucosamine in peptidoglycan. It is found in many secretions like tears and saliva. DNA polymerase, lipase, and amylase have different substrate specificities. Learn about lysozyme.
Bacterial chemotaxis refers to movement in response to:
Light
Temperature
Chemical gradients
pH changes
Chemotaxis is the directed movement of bacteria toward attractants or away from repellents based on chemical gradients. Phototaxis is a response to light, thermotaxis to temperature, and pH taxis to acidity. More on bacterial chemotaxis.
Which protein is essential for bacterial cell division by forming a contractile ring?
FtsZ
Actin
Tubulin
Myosin
FtsZ polymerizes at the future division site to form a Z-ring that constricts the cell during cytokinesis. It is homologous to tubulin in eukaryotes. Actin and myosin are eukaryotic cytoskeletal proteins not used in bacterial division. About FtsZ.
The process by which bacteria take up naked DNA from the environment is called:
Transduction
Transformation
Conjugation
Replication
Transformation involves uptake of free DNA fragments from the environment into a bacterial cell, which may then recombine with its genome. Transduction is DNA transfer by bacteriophages, and conjugation is direct cell-to-cell transfer. More on transformation.
In Gram-negative bacteria, the periplasmic space is located between:
Inner and outer membranes
Cell wall and capsule
Cytoplasm and membrane
Nucleoid and cell membrane
The periplasmic space in Gram-negative bacteria lies between the inner (cytoplasmic) membrane and the outer membrane, containing a thin peptidoglycan layer and various enzymes. Other options do not describe its correct location. Details on the periplasmic space.
Which prokaryote uses gas vesicles to maintain buoyancy?
Escherichia coli
Cyanobacteria
Staphylococcus aureus
Bacillus subtilis
Cyanobacteria produce gas vesicles—protein-bound structures—to regulate buoyancy and position in the water column for optimal light exposure. E. coli, S. aureus, and B. subtilis do not form gas vesicles. Learn about gas vesicles.
In bacteria, the function of the SpoIIIE protein during sporulation is to:
Degrade peptidoglycan
Pump DNA into forespores
Synthesize spore coat
Initiate germination
SpoIIIE is a DNA translocase that transports the remaining portion of the chromosome into the forespore compartment during sporulation in Bacillus species. It does not degrade peptidoglycan or synthesize the spore coat. More on SpoIIIE.
The lipid A portion of lipopolysaccharide (LPS) is recognized by which component of the mammalian immune system?
Toll-like receptor 4
Complement C3
MHC II
T-cell receptor
Lipid A, the endotoxic moiety of LPS, is specifically detected by Toll-like receptor 4 (TLR4) on immune cells, triggering inflammatory responses. Complement C3 and adaptive receptors like MHC II or T-cell receptors are not direct LPS sensors. Learn about TLR4.
Bacterial microcompartments (e.g., carboxysomes) are made of:
Lipid bilayer
Protein shell
Peptidoglycan
Polysaccharide matrix
Microcompartments like carboxysomes are enclosed by a protein shell composed of hexameric and pentameric proteins, not a lipid membrane. They compartmentalize metabolic enzymes. Peptidoglycan and polysaccharides are not structural components of these compartments. More on carboxysomes.
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Study Outcomes
Identify Prokaryotic Cell Components -
Recognize and name the key structures of prokaryotic cells, such as the cell wall, plasma membrane, ribosomes, and nucleoid region.
Differentiate Prokaryote vs Eukaryote -
Distinguish between prokaryotic and eukaryotic cells by comparing their complexity, organelles, and genetic organization.
Analyze Prokaryotic Cell Functions -
Explain the roles of major prokaryotic structures in processes like protein synthesis, nutrient uptake, and reproduction.
Apply Knowledge to Quiz Questions -
Use your understanding of cell structure and function to accurately answer prokaryote practice problems and reinforce key concepts.
Evaluate Unicellular Organism Traits -
Assess the characteristics that define unicellular organisms and understand how these traits influence microbial life.
Interpret Microbiology Quiz Results -
Review your answers to identify areas of strength and improvement, guiding further study on prokaryotic cells.
Cheat Sheet
Cell Envelope Complexity -
The prokaryotic cell envelope comprises a plasma membrane, a cell wall made of peptidoglycan, and sometimes an outer capsule. Gram-positive bacteria have a thick peptidoglycan layer that retains crystal violet dye, while Gram-negative bacteria feature a thin peptidoglycan sheet plus an LPS-rich outer membrane. A handy mnemonic is "Purple Plus, Pink Thin" to recall Gram stain results.
Nucleoid Region & Plasmids -
Genetic material in prokaryotes resides in a nucleoid region containing a single circular chromosome and often extrachromosomal plasmids. Plasmids can carry genes for antibiotic resistance or metabolic pathways, enabling rapid adaptation under selective pressure. Remember: "One Ring to Rule Them All" to picture the lone chromosome in the cytoplasm.
70S Ribosomes & Protein Synthesis -
Prokaryotic ribosomes are 70S particles composed of 30S and 50S subunits, distinct from the 80S ribosomes found in eukaryotes. The formula "3 + 5 = 7" may help you recall their Svedberg unit sizes. These ribosomes facilitate protein synthesis and are targeted by many antibiotics, such as tetracyclines and aminoglycosides.
Appendages: Flagella & Pili -
Cellular appendages include flagella for motility and pili for attachment or DNA transfer. A flagellum's basal body, hook, and filament work like a rotary motor to propel the cell, while type IV pili enable twitching motility and conjugation. Think "Flagella Flourish, Pili Pair" to connect structure with function.
Binary Fission & Gene Exchange -
Prokaryotes reproduce asexually via binary fission, where one cell splits into two genetically identical daughters, often in as little as 20 minutes under ideal conditions. Horizontal gene transfer - through conjugation, transformation, and transduction (the "CTT" trio) - boosts genetic diversity and can spread beneficial traits across populations. This rapid division and exchange power microbial evolution on a global scale.
