9700_y16_sy

Cambridge International AS and A Level Biology 9700 syllabus Syllabus content
A Level Syllabus content
12 Energy and respiration
Energy is a fundamental concept in biology. All living things require a source of cellular energy to drive
their various activities. ATP is the universal energy currency as its molecules are small, soluble and easily
hydrolysed to release energy for cellular activities. All organisms respire to release energy from energyrich
molecules such as glucose and fatty acids and transfer that energy to ATP. Respiration is a series
of enzyme-catalysed reactions that release energy in small ‘packets’. In eukaryotes, aerobic respiration
occurs in mitochondria.
Candidates will be expected to use the knowledge gained in this section to solve problems in familiar and
unfamiliar contexts.
Learning outcomes
Candidates should be able to:
12.1 Energy
ATP is the universal energy
currency as it provides the
immediate source of energy
for cellular processes.
a) outline the need for energy in living organisms, as illustrated
by anabolic reactions, such as DNA replication and protein
synthesis, active transport, movement and the maintenance of
body temperature
b) describe the features of ATP that make it suitable as the
universal energy currency
c) explain that ATP is synthesised in substrate-linked reactions in
glycolysis and in the Krebs cycle
d) outline the roles of the coenzymes NAD, FAD and
coenzyme A in respiration
e) explain that the synthesis of ATP is associated with the
electron transport chain on the membranes of mitochondria
and chloroplasts (see 12.2g)
f) explain the relative energy values of carbohydrate, lipid and
protein as respiratory substrates and explain why lipids are
particularly energy-rich
g) define the term respiratory quotient (RQ) and determine RQs
from equations for respiration
h) carry out investigations, using simple respirometers, to
determine the RQ of germinating seeds or small invertebrates
(e.g. blowfly larvae)
12.2 Respiration
Respiration is the process
whereby energy from
complex organic molecules is
transferred to ATP.
a) list the four stages in aerobic respiration (glycolysis, link
reaction, Krebs cycle and oxidative phosphorylation) and state
where each occurs in eukaryotic cells
b) outline glycolysis as phosphorylation of glucose and the
subsequent splitting of fructose 1,6-bisphosphate (6C) into two
triose phosphate molecules, which are then further oxidised to
pyruvate with a small yield of ATP and reduced NAD
c) explain that, when oxygen is available, pyruvate is converted
into acetyl (2C) coenzyme A in the link reaction
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