The protein of which the hook and filament of a flagellum are composed is
Answer: B
Correct answer: flagellin
The filament and hook are built from flagellin, a globular protein that self-assembles into a hollow helical tube. Subunits travel up the hollow core and add themselves at the tip, so the flagellum grows from its far end.
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Surface area/volume ratio of bacteria is exceedingly low compared to the same ratio for larger organisms of similar shape.
Answer: B
Correct answer: False
The opposite is true: because surface area falls with the square of the linear dimension and volume with the cube, a very small cell has an exceedingly high surface-to-volume ratio. That is the central advantage of being small - a large membrane area serving a small cytoplasm allows rapid uptake of nutrients and rapid growth.
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The crosswalls constrict which of the following parts and then grow inwards to form septum?
Answer: D
Correct answer: plasmalemma
Septum formation begins with a ring of new wall material growing inwards from the existing wall. As it advances it constricts the plasmalemma, drawing the membrane in with it until the cross-wall is complete - usually leaving a central pore.
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Bacteria having no flagella are unable to
Answer: A
Correct answer: move
Flagella are the organelles of motility, so a bacterium without them cannot swim. It can still reproduce, grow on agar, and adhere - adhesion being the work of fimbriae. (Some non-flagellated bacteria do move by gliding or twitching, but not by swimming.)
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The common word for bacteria which are helically curved rods is
Answer: D
Correct answer: spirilla
Spirilla are rigid helically curved rods, moved by polar flagella. Spirochaetes are the flexible helical forms, driven by internal axial filaments; cocci are spherical and bacilli straight rods.
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Peptidoglycan is also known as
Answer: B
Correct answer: murein mucopeptide
Peptidoglycan is also called murein (from murus, a wall) or murein mucopeptide. NAM and NAG are its two sugars, and diaminopimelic acid one of the amino acids of its peptide side chains - components rather than alternative names for the polymer.
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What is the approximate size of the bacterial cell?
Answer: D
Correct answer: 0.5 to 1.0 micrometer in diameter
A typical bacterium is about 0.5-1.0 μm across and a few micrometres long - small enough to need a light microscope at its limit, or an electron microscope for detail. The small size gives a very high surface-to-volume ratio, which is what allows such rapid exchange with the environment and such fast growth.
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Polyisoprenoid branched-chain lipids are present in which of the following?
Answer: A
Correct answer: Archaebacteria
Archaea have membranes quite unlike anyone else’s: branched polyisoprenoid chains linked to glycerol by ether bonds rather than the straight fatty acids and ester bonds of bacteria and eukaryotes. Ether bonds and branched chains are far more stable, which is part of how the extreme thermophiles and acidophiles among them survive.
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Chemically the capsule may be
Answer: C
Correct answer: either (a) or (b)
Most capsules are polysaccharide, but some are polypeptide - Bacillus anthracis has a capsule of poly-D-glutamic acid, whose D-amino acids resist degradation. Either kind resists phagocytosis, which is what makes capsulated strains the virulent ones.
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