AP Biology : Understanding Bacteria
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Example Question #31 : Understanding Bacteria
Gram-negative bacteria are __________ than Gram-positive bacteria to most antibiotics because __________.
less resistant . . . they lack the peptidoglycan layer that retains the Gram stain and would protect their plasma membrane from the antibiotic
less resistant . . . they lack the lipopolysaccharide layer that retains the Gram stain and would protect their plasma membrane from the antibiotics
more resistant . . . they have an outer membrane made of peptidoglycan that blocks the lipopolysaccharide cell wall from the Gram stain and protects it from antibiotics
more resistant . . . they have an outer membrane made of lipopolysaccharide that blocks the peptidoglycan cell wall from the Gram stain and protects it from antibiotics
more resistant . . . they have an outer membrane made of lipopolysaccharide that blocks the cellulose cell wall from the Gram stain and protects it from antibiotics
more resistant . . . they have an outer membrane made of lipopolysaccharide that blocks the peptidoglycan cell wall from the Gram stain and protects it from antibiotics
In Gram staining, the dye is retained by the peptidoglycan cell wall, which in Gram-positive bacteria, is very thick and is the outermost layer of the bacterial cell. This peptidoglycan cell wall is also what is targeted by most antibiotics. In Gram-negative bacteria, there is a layer of peptidoglycan but it is very thin and is protected from both the Gram stain and most antibiotics by an outer membrane made of lipopolysaccharides. One of the incorrect answers mentions a cell wall made of cellulose, but that is what makes up the cell walls of plants, not bacteria.
Example Question #31 : Understanding Bacteria
Which of the following is the term used to describe reproduction in bacteria?
Binary fission
Transformation
Translation
Transduction
Conjugation
Binary fission
Binary fission is the process by which bacteria use to reproduce. Transduction and conjugation and transformation are all processes by which bacteria exchange genetic material (usually in the form of plasmids). Reproduction occurs rapidly though binary fission.
Example Question #32 : Understanding Bacteria
Which of the following items is not found in prokaryotic cells?
Vesicles
Mitochondria
Ribosomes
Cell wall
Microtubules
Mitochondria
The correct answer is mitochondria. This organelle is found in eukaryotic cells, which means that prokaryotic cells generate ATP through other means. All other items listed are found in prokaryotic cells.
Example Question #33 : Understanding Bacteria
Penicillin is an antibiotic that works by blocking the formation of peptidoglycan. This antibiotic disrupts bacterial cell growth by inhibiting the production of which of these?
Bacterial proteins
Bacterial nucleic acids
Bacterial cell walls
Bacterial flagella
Bacterial plasma membranes
Bacterial cell walls
Bacteria contain a cell wall made of peptidoglycan. This peptidoglycan is what is used when looking at the "Gram stain" of a bacteria. By inhibiting the formation of peptidoglycan, penicillin works by blocking the production of bacterial cell walls. Bacteria cannot survive without their cell walls.
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