4.4.2 Respiration Flashcards
Respiration
Is an enzyme-controlled reaction that breaks down glucose to release energy, in the form of a substance called ATP
Exothermic reaction
What is respiration for in animals and plants
Animals:
Powering chemical reactions, e.g biosynthesis
Muscle contractions
Regulating body temperature
Plants:
Active transport
Aerobic respiration word and symbol equation
Glucose + oxygen -> carbon dioxide + water
C6H12O6 + 6CO2 -> 6CO2 + 6H2O
Anaerobic respiration in animals
When insufficient oxygen is present, e.g muscles during vigorous exercise, so glucose cannot be fully oxidised
Produces lactic acid
Drawbacks of anaerobic respiration in muscles
Glucose is not fully oxidised, therefore less energy is released
Lactic acid builds up which can be toxic to cells in high concentrations and causes MUSCLE FATIGUE
Anaerobic respiration in plants and yeast word equation
Glucose -> carbon dioxide + ethanol
(Fermentation)
Effect of exercise
More blood is delivered to the muscles every minute
So more O2 carried by haemoglobin in RBCs and glucose carried through plasma are delivered to the muscles
So the muscles can carry out a faster rate of aerobic respiration
And prevent anaerobic respiration from happening
So more energy is released allowing the muscles to continue contracting
And more carbon dioxide is removed from the muscles
How does increased breathing rate help the body in its response to exercise
Increased breathing rate means increased oxygen taken into the lungs, which then diffuses into the bloodstream
Then it can be delivered to cells of the body for increased rate of respiration
Oxygen debt
After respiring anaerobically, lactic acid must be transported to the liver where it is converted back into glucose, using oxygen.
The extra oxygen required to react with the lactic acid is oxygen
How do muscles have access to glucose during exercise
There may not be a sufficient supply of glucose—cells have a limited supply
So muscle cells store glycogen which can be rapidly converted to glucose during exercise
Metabolism definition and examples
All chemical reactions in cells
Food eaten:
Glucose—respiration, makes glycogen, makes starch
Fatty acids and glycerol—lipids
Amino acids—makes protein, makes urea which is then excreted
Other processes:
Photosynthesis
Production of amino acids from glucose and nitrate ions
Role of liver in metabolism—substance: poisonous substances, e.g ethanol
Detoxifies substances - makes sure they are removed from blood
Role of liver in metabolism—substance: excess amino acids
breaks down excess amino acids into ammonia which gets turned into the less harmful substance urea
Role of liver in metabolism—substance: red blood cells
Breaks down old/dead red cells and stores the iron until it is needed to make more RBCs
Role of liver in metabolism—substance: lactic acid
Lactic acid produced by muscles travels to the liver which converts it back to glucose (glycogen)
