Respiration involves the breakdown of nutrients to release energy in cells. It requires oxygen and enzymes. Aerobic respiration uses oxygen to break down glucose, releasing carbon dioxide and water. The chemical equation is C6H12O6 + 6O2 → 6CO2 + 6H2O. Anaerobic respiration breaks down glucose without oxygen, producing less energy. In yeast, the equation is C6H12O6 → 2C2H5OH + 2CO2. During vigorous exercise, lactic acid builds up and is later removed as the oxygen debt is repaid during recovery.

1. Respiration

2. LO:
• State the uses of energy in the body of
humans: muscle contraction, protein
synthesis, cell division, active transport,
growth, the passage of nerve impulses and
the maintenance of a constant body
temperature
• State that respiration involves the action of
enzymes in cells

3. LO:
• Define aerobic respiration as the chemical
reactions in cells that use oxygen to break down
nutrient molecules to release energy
• State the balanced chemical equation for aerobic
respiration as
C6 H12 O6 + 6O2 → 6CO2 + 6H2 O
• Investigate the uptake of oxygen by respiring
organisms, such as arthropods and germinating
seeds
• Investigate the effect of temperature on the rate
of respiration of germinating seeds

4. LO:
• Define anaerobic respiration as the chemical
reactions in cells that break down nutrient
molecules to release energy without using
oxygen
• State the balanced chemical equation for
anaerobic respiration in the microorganism yeast
as C6 H12 O6 → 2C2 H5 OH + 2CO2
• State that anaerobic respiration releases much
less energy per glucose molecule than aerobic
respiration

5. LO:
• State that lactic acid builds up in muscles and
blood during vigorous exercise causing an
oxygen debt
• Outline how the oxygen debt is removed
during recovery

6. LO: define the term respiration
• the set of chemical reactions that break down
nutrient molecules in living cells to release
energy
• Definition: respiration is the release of energy
from food substances, and goes on in all living
cells
• respiration involves the action of enzymes in
cells

7. Energy
= capacity for doing work
- Needed for life
- Source of energy = sun
- Energy conversions:
- First conversion = photosynthesis
- Second conversion = respiration

8. • Growth (proteosynthesis) – protein synthesis
• Maintenance of a constant body temperature
• Active transport
• Cell division
• Movement – muscle contraction
• The passage of nerve impulses

9. LO: Know the form of energy found in human body
Adenosine triphosphate
• Small packet of energy which can drive the
reactions in a cell
• Short-term store of energy

10. LO: Define aerobic respiration ;State the balanced chemical equation
for aerobic respiration
• the release of a relatively large amount of energy
in cells by the breakdown of food substances in
the presence of oxygen
• chemical reactions in cells that use oxygen to
break down nutrient molecules to release energy
• Takes place in mitochondria
• Some energy is lost as heat

11. LO: Define anaerobic respiration; state the word equation
• the release of a relatively small amount of energy
by the breakdown of food substances in the
absence of oxygen
Word equation:
• in muscles during hard exercise
glucose → lactic acid
• microorganism yeast
glucose → alcohol + carbon dioxide

12. LO: State the balanced chemical equation for anaerobic
respiration in the microorganism yeast as
• balanced chemical equation for anaerobic
respiration in the microorganism yeast
C6 H12 O6 → 2C2 H5 OH + 2CO2
• Glucose alcohol and carbon dioxide

15. • Anaerobic respiration releases
much less energy per glucose
molecule than aerobic
respiration!!!

16. LO: State that lactic acid builds up in muscles and blood during
vigorous exercise causing an oxygen debt
• Lactic acid produced by muscles during
anaerobic respiration is carried out of the
muscles in the blood
• It is transported to the heart, liver and kidneys
and is oxydated to pyruvate
• Heart, liver and kidneys need extra oxygen to
get rid of the lactic acid, provided by the deep
fast breathing that follows hard exercise

17. • HOMEWORK:
• Pages 52-53 Describe the role of anaerobic
respiration in yeast during brewing and bread-
making.