Digestive reactions where large molecules are broken down into smaller ones are referred as
Answer: B
Correct answer: catabolism
Breaking large molecules into smaller ones, with the release of energy, is catabolism. Digestion is the obvious example. Anabolism and biosynthesis are the opposite process, and metabolism is the sum of the two.
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The Entner-Doudoroff pathway differs from glycolysis chiefly in that it yields ________.
Answer: B
Correct answer: only 1 net ATP per glucose
The Entner-Doudoroff pathway produces a net 1 ATP, along with 1 NADH and 1 NADPH, per glucose. Despite the lower yield it is the main route in Pseudomonas and several other Gram-negative genera, and its distinctive intermediate KDPG is used to identify it.
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As the electron flow through the chains, much of their free energy is conserved in the form of ATP. This process is called
Answer: A
Correct answer: oxidative phosphorylation
As electrons pass down the transport chain, the carriers pump protons across the membrane, and the proton-motive force so created drives ATP synthase. Capturing energy this way - electron flow to proton gradient to ATP - is oxidative phosphorylation, and it accounts for the great majority of the ATP from aerobic respiration.
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Which of the following statements is correct?
Answer: A
Correct answer: Phosphate repression can not be eliminated by optimization of nutrient medium, deregulated medium must be used as production strains
Phosphate represses the enzymes of many secondary metabolic pathways, and the repression cannot simply be lifted by adjusting the medium - phosphate is also needed for growth, so there is no concentration that both feeds the culture and releases the pathway. Industry therefore uses phosphate-deregulated mutants, strains selected to be insensitive to the repression.
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Fermentation of a glucose molecule has the potential to produce a net number of _____ATPs.
Answer: B
Correct answer: 2
Fermentation yields a net 2 ATP per glucose: glycolysis makes 4 by substrate-level phosphorylation and spends 2 in the preparatory phase. Nothing further is gained, because the fermentation steps that follow exist only to reoxidise NADH so that glycolysis can continue.
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The bacteriochlorophylls used by the anoxygenic bacteria have absorbance maxima located in the_____portion(s) of the spectrum.
Answer: D
Correct answer: infrared
Bacteriochlorophylls absorb in the near infrared, at wavelengths beyond about 700 nm and up to 1000 nm or more. That is what lets anoxygenic bacteria live beneath a layer of algae or cyanobacteria: they use the long wavelengths the organisms above them cannot.
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Most of the energy in aerobic respiration of glucose is captured by
Answer: B
Correct answer: electron transport of electrons from NADH
Substrate-level phosphorylation contributes only 4 ATP per glucose. The great bulk comes from reoxidising the NADH and FADH2 through the electron transport chain, whose proton gradient drives ATP synthase - some 34 of the roughly 38 ATP.
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A nucleotide contains which of the following?
Answer: D
Correct answer: all of these
A nucleotide has three parts: a five-carbon sugar (deoxyribose in DNA, ribose in RNA), a nitrogenous base, and one or more phosphate groups. Sugar plus base alone is a nucleoside; adding the phosphate makes it a nucleotide.
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The time required for a cell to undergo binary fission is called the:
Answer: C
Correct answer: generation time
The generation time (doubling time) is the interval in which one cell becomes two, or a population doubles. It varies enormously - about 20 minutes for E. coli in rich medium, some 20 hours for Mycobacterium tuberculosis - and it is what sets the slope of the exponential phase of the growth curve.
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Bacteriochlorophyll differs from chlorophyll in what way?
Answer: D
Correct answer: Both (b) and (c)
Bacteriochlorophyll and chlorophyll differ in their side groups and, as a direct consequence, in their absorption spectra - bacteriochlorophyll absorbs in the near infrared where chlorophyll cannot. What they share is the chelated metal: both hold magnesium at the centre of the ring, so the first statement is false.
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