BIOC0001 - METABOLISM EXAM QUESTIONS AND
ANSWERS WITH COMPLETE SOLUTIONS VERIFIED
LATEST UPDATE
Define metabolism.
The sum of all the chemical processes necessary to make possible the characteristics
of living cells/organisms.
What do each of the following use for energy, C and e-:
photoautotrophs
chemoautotrophs
photoheterotrophs
chemoheterotrophs?
Give examples of these/
Photoautotrophs - light for energy, inorganic sources for C (CO2) and e- (H2O, H2S).
Chemoautotrophs - inorganic compounds for energy and e- (H2, FeCO3, NH3) +
inorganic sources for C (CO2).
Photoheterotrophs - light for energy, organic sources for C and e- (Isopropanol, lactate)
,Chemoheterotrophs - organic compounds + sources (glucose, fats)
Why do organisms need a source of electrons?
For reducing power.
Organisms can be categorised according to their type of metabolism. What are:
higher plants
sulphur bacteria
higher animals
most microbes
non-sulphur purple bacteria
photosynthetic bacteria
blue-green algae?
Photoautotrophs
Chemoautotrophs
Chemoheterotrophs
Chemoheterotrophs
Photoheterotrophs
Photoautotrophs
Photoautotrophs
What are the differences between full oxidation (catabolism) and biosynthesis
(anabolism)?
Catabolism - Complex --> simple, mainly oxidative reactions, process releases energy
and occurs spontaneously (-ve ΔG).
, Anabolism - simple --> complex, mainly reductive reactions, process requires energy
and does not occur spontaneously (+ve ΔG).
Endergonic reactions (anabolism) have a positive change in Gibbs free energy.
How do these reactions occur in a cell?
Enzymes/ enzyme pathways can link pairs of reactions together; as long as the
exergonic reaction releases more energy than required for the endergonic reaction, the
net change in Gibbs free energy will be negative so is feasible.
In metabolic pathways, catabolic reactions break down fuels in small simple
compounds and release energy, which is stored; this is used to build up complex
organic molecules. In what form does this stored energy take?
High energy bonds (ATP), reduced coenzymes (NADH), concentration gradients (e.g.
H+).
Which is a better store of energy and why: NAD or FAD?
NAD - it is harder to reduce
Why may FAD may be used instead of NAD+?
If there is a weak reducing agent, it may not be able to reduce NAD+ but can instead
reduce FAD.
NAD is soluble, whereas FAD is protein bound.
FAD is not found in solution, it is always ________-bound. It is commonly used in
________ pathways as an ________ agent.
ANSWERS WITH COMPLETE SOLUTIONS VERIFIED
LATEST UPDATE
Define metabolism.
The sum of all the chemical processes necessary to make possible the characteristics
of living cells/organisms.
What do each of the following use for energy, C and e-:
photoautotrophs
chemoautotrophs
photoheterotrophs
chemoheterotrophs?
Give examples of these/
Photoautotrophs - light for energy, inorganic sources for C (CO2) and e- (H2O, H2S).
Chemoautotrophs - inorganic compounds for energy and e- (H2, FeCO3, NH3) +
inorganic sources for C (CO2).
Photoheterotrophs - light for energy, organic sources for C and e- (Isopropanol, lactate)
,Chemoheterotrophs - organic compounds + sources (glucose, fats)
Why do organisms need a source of electrons?
For reducing power.
Organisms can be categorised according to their type of metabolism. What are:
higher plants
sulphur bacteria
higher animals
most microbes
non-sulphur purple bacteria
photosynthetic bacteria
blue-green algae?
Photoautotrophs
Chemoautotrophs
Chemoheterotrophs
Chemoheterotrophs
Photoheterotrophs
Photoautotrophs
Photoautotrophs
What are the differences between full oxidation (catabolism) and biosynthesis
(anabolism)?
Catabolism - Complex --> simple, mainly oxidative reactions, process releases energy
and occurs spontaneously (-ve ΔG).
, Anabolism - simple --> complex, mainly reductive reactions, process requires energy
and does not occur spontaneously (+ve ΔG).
Endergonic reactions (anabolism) have a positive change in Gibbs free energy.
How do these reactions occur in a cell?
Enzymes/ enzyme pathways can link pairs of reactions together; as long as the
exergonic reaction releases more energy than required for the endergonic reaction, the
net change in Gibbs free energy will be negative so is feasible.
In metabolic pathways, catabolic reactions break down fuels in small simple
compounds and release energy, which is stored; this is used to build up complex
organic molecules. In what form does this stored energy take?
High energy bonds (ATP), reduced coenzymes (NADH), concentration gradients (e.g.
H+).
Which is a better store of energy and why: NAD or FAD?
NAD - it is harder to reduce
Why may FAD may be used instead of NAD+?
If there is a weak reducing agent, it may not be able to reduce NAD+ but can instead
reduce FAD.
NAD is soluble, whereas FAD is protein bound.
FAD is not found in solution, it is always ________-bound. It is commonly used in
________ pathways as an ________ agent.
