C1.2 Cell respiration Flashcards
C1.2.1—ATP as the molecule that distributes energy within cells
Include the full name of ATP (adenosine triphosphate) and that it is a nucleotide. Students should
appreciate the properties of ATP that make it suitable for use as the energy currency within cells.
C1.2.2—Life processes within cells that ATP supplies with energy
Include active transport across membranes, synthesis of macromolecules (anabolism), movement of the
whole cell or cell components such as chromosomes.
C1.2.3—Energy transfers during interconversions between ATP and ADP
Students should know that energy is released by hydrolysis of ATP (adenosine triphosphate) to ADP
(adenosine diphosphate) and phosphate, but energy is required to synthesize ATP from ADP and
phosphate. Students are not required to know the quantity of energy in kilojoules, but students should
appreciate that it is sufficient for many tasks in the cell.
C1.2.4—Cell respiration as a system for producing ATP within the cell using energy released from carbon
compounds
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Students should appreciate that glucose and fatty acids are the principal substrates for cell respiration but
that a wide range of carbon/organic compounds can be used. Students should be able to distinguish
between the processes of cell respiration and gas exchang
C1.2.5—Differences between anaerobic and aerobic cell respiration in humans
Include which respiratory substrates can be used, whether oxygen is required, relative yields of ATP, types
of waste product and where the reactions occur in a cell. Students should be able to write simple word
equations for both types of respiration, with glucose as the substrate. Students should appreciate that
mitochondria are required for aerobic, but not anaerobic, respiration.
C1.2.6—Variables affecting the rate of cell respiration
Application of skills: Students should make measurements allowing for the determination of the rate of
cell respiration. Students should also be able to calculate the rate of cellular respiration from raw data that
they have generated experimentally or from secondary data.
C1.2.7—Role of NAD as a carrier of hydrogen and oxidation by removal of hydrogen during cell respiration
Students should understand that oxidation is a process of electron loss, so when hydrogen with an
electron is removed from a substrate (dehydrogenation) the substrate has been oxidized. They should
appreciate that redox reactions involve both oxidation and reduction, and that NAD is reduced when it
accepts hydrogen.
C1.2.8—Conversion of glucose to pyruvate by stepwise reactions in glycolysis with a net yield of ATP and
reduced NAD
Include phosphorylation, lysis, oxidation and ATP formation. Students are not required to know the names
of the intermediates, but students should know that each step in the pathway is catalysed by a different
enzyme.
C1.2.9—Conversion of pyruvate to lactate as a means of regenerating NAD in anaerobic cell respiration
Regeneration of NAD allows glycolysis to continue, with a net yield of two ATP molecules per molecule of
glucose.
C1.2.10—Anaerobic cell respiration in yeast and its use in brewing and baking
Students should understand that the pathways of anaerobic respiration are the same in humans and
yeasts apart from the regeneration of NAD using pyruvate and therefore the final products.
C1.2.11—Oxidation and decarboxylation of pyruvate as a link reaction in aerobic cell respiration
Students should understand that lipids and carbohydrates are metabolized to form acetyl groups (2C),
which are transferred by coenzyme A to the Krebs cycle.
C1.2.12—Oxidation and decarboxylation of acetyl groups in the Krebs cycle with a yield of ATP and
reduced NAD
Students are required to name only the intermediates citrate (6C) and oxaloacetate (4C). Students should
appreciate that citrate is produced by transfer of an acetyl group to oxaloacetate and that oxaloacetate is
regenerated by the reactions of the Krebs cycle, including four oxidations and two decarboxylations. They
should also appreciate that the oxidations are dehydrogenation reactions
C1.2.13—Transfer of energy by reduced NAD to the electron transport chain in the mitochondrion
Energy is transferred when a pair of electrons is passed to the first carrier in the chain, converting reduced
NAD back to NAD. Students should understand that reduced NAD comes from glycolysis, the link reaction
and the Krebs cycle.
C1.2.14—Generation of a proton gradient by flow of electrons along the electron transport chain
Students are not required to know the names of protein complexes.
C1.2.15—Chemiosmosis and the synthesis of ATP in the mitochondrion
Students should understand how ATP synthase couples release of energy from the proton gradient with
phosphorylation of ADP.
