Biology OCR A - Respiration
Why do living organisms need to respire? - Answer - Respiration is the process that
occurs in living cells and releases energy stored in organic molecules.
- This energy is immediately used to synthesise molecules of ATP from ADP and
inorganic phosphate.
- ATP in cells can be hydrolysed to release energy in order to drive biological processes
Why do living organism need energy? - Answer When energy is released from organic
molecules, via respiration, it can be used to make ATP to drive biological processes
such as:
- Active transport
- Endocytosis
- Exocytosis, including secretion of large molecules from cells
- Synthesis of large molecules such as proteins, e.g. collagen, enzymes and antibodies
- DNA replication
- Cell division
- Movement - such as the movement of bacterial flagella, of eukaryotic cilia and
undulipodia, and motor proteins that walk along cytoskeleton threads in cells, moving
organelles
- Activation of chemicals - glucose is phosphorylated at the beginning of respiration so
that it becomes more reactive and able to be broken down to release more energy
what is metabolism? - Answer All the chemical reactions that take place within living
cells are known collectively as metabolism
What is the difference between catabolic and anabolic reactions? - Answer Anabolic
reactions are metabolic reactions where large molecules are synthesised from smaller
molecules while catabolic reactions are metabolic reactions involving the hydrolysis of
large molecules to smaller ones.
Why would it be wrong to say that respiration creates energy? - Answer - Respiration
releases energy from respiratory substrates such as glucose, but it does not create or
make energy as energy cannot be created.
- However, some of the released energy can be used to make ATP.
, Biology OCR A - Respiration
What is the role of ATP? - Answer ATP is the standard intermediary between energy-
releasing and energy-consuming metabolic reactions in both eukaryotic and prokaryotic
cells.
Structure of an ATP molecule - Answer ribose 5-carbon sugar, adenine nitrogenous
base, 3 phosphate (phosphoryl) groups
Is ATP stable or unstable? Why? - Answer - ATP is relatively stable (it does not break
down to ADP and P i) when in solution in cells, but is readily hydrolysed by enzyme
catalysis.
- However, whilst in solution, it can easily be moved from place to place within a cell.
Why is ATP referred to as the universal energy currency? - Answer ATP is referred to
as the universal energy currency, as it occurs in all living cells and is a source of energy
that can be used by cells in small amounts.
Why is heat released from the hydrolysis of ATP not seen as wasteful? - Answer Heat
helps keep living organisms 'warm' and enables their enzyme-catalysed reactions to
proceed at or near their optimum rate
What is glycolysis? - Answer It is the first stage of respiration; a 10-stage metabolic
pathway that converts glucose to pyruvate.
- Glycolysis is a biochemical pathway that occurs in the cytoplasm of all living
organisms that respire, including many prokaryotes.
How many reactions does the glycolysis pathway involve? - Answer The pathway
involves a sequence of 10 reactions, each catalysed by a different enzyme, some with
the help of the coenzyme, NAD.
What are the three main stages of glycolysis? - Answer 1. Phosphorylation of glucose to
hexose bisphosphate.
2. Splitting each hexose bisphosphate molecule into two triose phosphate molecules.
3. Oxidation of triose phosphate to pyruvate.
Phosphorylation - Stage of glycolysis - Answer 1. One molecule of ATP is hydrolysed
and the released phosphoryl group is added to glucose to make hexose
monophosphate.
2. Another molecule of ATP is hydrolysed and the phosphoryl group added to the
hexose phosphate to form a molecule of hexose bisphosphate. This sugar has one
phosphate group at carbon atom number one and another at carbon atom number six.
Why do living organisms need to respire? - Answer - Respiration is the process that
occurs in living cells and releases energy stored in organic molecules.
- This energy is immediately used to synthesise molecules of ATP from ADP and
inorganic phosphate.
- ATP in cells can be hydrolysed to release energy in order to drive biological processes
Why do living organism need energy? - Answer When energy is released from organic
molecules, via respiration, it can be used to make ATP to drive biological processes
such as:
- Active transport
- Endocytosis
- Exocytosis, including secretion of large molecules from cells
- Synthesis of large molecules such as proteins, e.g. collagen, enzymes and antibodies
- DNA replication
- Cell division
- Movement - such as the movement of bacterial flagella, of eukaryotic cilia and
undulipodia, and motor proteins that walk along cytoskeleton threads in cells, moving
organelles
- Activation of chemicals - glucose is phosphorylated at the beginning of respiration so
that it becomes more reactive and able to be broken down to release more energy
what is metabolism? - Answer All the chemical reactions that take place within living
cells are known collectively as metabolism
What is the difference between catabolic and anabolic reactions? - Answer Anabolic
reactions are metabolic reactions where large molecules are synthesised from smaller
molecules while catabolic reactions are metabolic reactions involving the hydrolysis of
large molecules to smaller ones.
Why would it be wrong to say that respiration creates energy? - Answer - Respiration
releases energy from respiratory substrates such as glucose, but it does not create or
make energy as energy cannot be created.
- However, some of the released energy can be used to make ATP.
, Biology OCR A - Respiration
What is the role of ATP? - Answer ATP is the standard intermediary between energy-
releasing and energy-consuming metabolic reactions in both eukaryotic and prokaryotic
cells.
Structure of an ATP molecule - Answer ribose 5-carbon sugar, adenine nitrogenous
base, 3 phosphate (phosphoryl) groups
Is ATP stable or unstable? Why? - Answer - ATP is relatively stable (it does not break
down to ADP and P i) when in solution in cells, but is readily hydrolysed by enzyme
catalysis.
- However, whilst in solution, it can easily be moved from place to place within a cell.
Why is ATP referred to as the universal energy currency? - Answer ATP is referred to
as the universal energy currency, as it occurs in all living cells and is a source of energy
that can be used by cells in small amounts.
Why is heat released from the hydrolysis of ATP not seen as wasteful? - Answer Heat
helps keep living organisms 'warm' and enables their enzyme-catalysed reactions to
proceed at or near their optimum rate
What is glycolysis? - Answer It is the first stage of respiration; a 10-stage metabolic
pathway that converts glucose to pyruvate.
- Glycolysis is a biochemical pathway that occurs in the cytoplasm of all living
organisms that respire, including many prokaryotes.
How many reactions does the glycolysis pathway involve? - Answer The pathway
involves a sequence of 10 reactions, each catalysed by a different enzyme, some with
the help of the coenzyme, NAD.
What are the three main stages of glycolysis? - Answer 1. Phosphorylation of glucose to
hexose bisphosphate.
2. Splitting each hexose bisphosphate molecule into two triose phosphate molecules.
3. Oxidation of triose phosphate to pyruvate.
Phosphorylation - Stage of glycolysis - Answer 1. One molecule of ATP is hydrolysed
and the released phosphoryl group is added to glucose to make hexose
monophosphate.
2. Another molecule of ATP is hydrolysed and the phosphoryl group added to the
hexose phosphate to form a molecule of hexose bisphosphate. This sugar has one
phosphate group at carbon atom number one and another at carbon atom number six.
