B09) RESPIRATION
An organism will receive all the energy it needs for living processes as a result of the energy transferred from respiration | For movement | | To enable muscles to contract in animals. |
For keeping warm | | To keep a steady body temperature in a cold environment. | |
For chemical reactions | | To build larger molecules from smaller one. |
Respiration
Aerobic respiration | |
Respiration with oxygen. Occurs inside the mitochondria continuously | |
Glucose is oxidised by oxygen to transfer the energy the organism needs to perform it’s functions. | |
C6H12O6 + O2 CO2 + H2O | glucose + oxygen carbon dioxide + water |
Aerobic respiration releases a large amount of energy from each glucose molecule
Cellular respiration is an exothermic reaction which is continuously occurring in all living cells
cytoplasm
mitochondria
animal cell
plant cell
Anaerobic respiration |
Respiration when oxygen is in short supply. Occurs during intensive exercise |
During hard exercise, muscle cells are respiring so fast that blood cannot transport enough oxygen to meet their needs. Glucose is partially oxidised to produce lactic acid which builds up in muscle tissue causing them to become painful and fatigued. |
glucose lactic acid |
Electron micrograph of a mitochondrion
Anaerobic respiration releases a much smaller amount of energy than aerobic respiration.
The incomplete oxidation of glucose causes a build up of lactic acid and creates an oxygen debt
Anaerobic respiration in plant and yeast cells |
The end products are ethanol and carbon dioxide. Anaerobic respiration in yeast cells is called fermentation |
glucose ethanol + carbon dioxide |
This process is economically important in the manufacture of alcoholic drinks and bread.
Response to exercise
During exercise the human body reacts to increased demand for energy | Heart rate increases | Top pump oxygenated blood faster to the muscle tissues and cells. |
Breathing rate and breath volume increase | This increases the amount of oxygen entering the blood stream. |
During long periods of vigorous activity muscles become fatigued and stop contracting efficiently
The extra amount of oxygen required to remove all lactic acids from cells is called the oxygen debt
Response to exercise HT only
Lactic acid builds up in the muscles cells during exercise
Blood flows through the muscle cells and transports the lactic acid to the liver
The liver oxidises the lactic acid and converts it back to glucose
Metabolism
Metabolism is the sum of all the reactions in a cell or the body
Metabolism | The energy transferred by respiration in cells is used by the organism for the continual enzyme controlled processes of metabolism. | Conversion of glucose to starch, glycogen and cellulose. |
The formation of lipid molecules from a molecule of glycerol and three molecules of fatty acid. | ||
The use of glucose and nitrate ions to form amino acids which in turn are used to synthesise proteins. | ||
Respiration | ||
Breakdown of excess proteins to form urea for excretion. |