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B4 G) Respiration
B4 G) Respiration
Respiration is the process of transferring energy from glucose, and it is one of the most important chemical reactions involved in life. Respiration reactions happen in all plant and animal cells all of the time. There are two different types of respiration reactions. These are:
Respiration reactions give out energy, which means that they are exothermic reactions. Exothermic reactions are where the products have less energy than the reactants.
Animals and plants use the energy from respiration for a variety of different activities, such as:
You are only required to know the word equations for the following reactions; you are not required to know the chemical equations.
- Aerobic respiration – with oxygen
- Anaerobic respiration – without oxygen
Respiration reactions give out energy, which means that they are exothermic reactions. Exothermic reactions are where the products have less energy than the reactants.
Animals and plants use the energy from respiration for a variety of different activities, such as:
- Building larger molecules from smaller molecules; for example, building proteins from amino acids
- Mammals and birds use the energy to regulate their body temperature (keep themselves warm)
- Animals use the energy to make muscles contract, which allows them to move
- Animals use the energy for nerve impulses
- Plants and animals use the energy for active transport (moving substances against a concentration gradient; from low concentration to high concentration)
You are only required to know the word equations for the following reactions; you are not required to know the chemical equations.
Aerobic Respiration – With Oxygen
Aerobic respiration breaks down glucose in the presence of oxygen. It is the most efficient way to transfer energy from glucose. The word and chemical equations are shown below:
Aerobic respiration breaks down glucose in the presence of oxygen. It is the most efficient way to transfer energy from glucose. The word and chemical equations are shown below:
Aerobic respiration happens all of the time in animals and plants, and it is essential for the activities that were listed above. Most of the aerobic respiration reactions happen inside the mitochondria in cells and this is why the mitochondria are sometimes referred to as the powerhouse of cells.
Anaerobic Respiration – Not Enough Oxygen
Anaerobic respiration is used when there is not enough oxygen present. For example, during exercise, you may be unable to supply your muscle cells with enough oxygen, which will mean that your muscle cells will have to switch from aerobic respiration to anaerobic respiration. Anaerobic respiration is the incomplete breakdown of glucose without oxygen. Anaerobic respiration releases a relatively small amount of energy compared to the amount of energy released by aerobic respiration.
Anaerobic respiration in animals is slightly different to anaerobic respiration in plants and yeast.
Anaerobic Respiration in Animals – Muscle Cells
In animals, anaerobic respiration is the incomplete breakdown of glucose without oxygen, resulting in lactic acid and energy. The word and chemical equations for anaerobic respiration are shown below:
Anaerobic respiration is used when there is not enough oxygen present. For example, during exercise, you may be unable to supply your muscle cells with enough oxygen, which will mean that your muscle cells will have to switch from aerobic respiration to anaerobic respiration. Anaerobic respiration is the incomplete breakdown of glucose without oxygen. Anaerobic respiration releases a relatively small amount of energy compared to the amount of energy released by aerobic respiration.
Anaerobic respiration in animals is slightly different to anaerobic respiration in plants and yeast.
Anaerobic Respiration in Animals – Muscle Cells
In animals, anaerobic respiration is the incomplete breakdown of glucose without oxygen, resulting in lactic acid and energy. The word and chemical equations for anaerobic respiration are shown below:
Anaerobic respiration releases less energy than aerobic respiration. This is because the glucose in anaerobic respiration is not fully oxidised/ broken down properly (it is not combined/ reacted with oxygen). However, despite not releasing as much energy, anaerobic respiration is still useful in emergencies because it allows your muscles to continue working for a little bit longer.
Anaerobic Respiration in Plants and Yeast
Plants and yeast can respire anaerobically (without oxygen) too, but the products are slightly different; glucose becomes ethanol and carbon dioxide. The word and chemical equations for anaerobic respiration are shown below:
Plants and yeast can respire anaerobically (without oxygen) too, but the products are slightly different; glucose becomes ethanol and carbon dioxide. The word and chemical equations for anaerobic respiration are shown below:
Anaerobic respiration in yeast is known as fermentation. Yeast is used to make bread rise and to make beers and wines alcoholic.
The yeast in the bread respires anaerobically, which produces carbon dioxide and ethanol. The carbon dioxide produced will make the bread/ dough rise (when you make bread at home, you make the dough, wrap the dough in clingfilm to prevent oxygen getting in and then leave the dough somewhere to rise. After a certain amount of time, the dough will have risen, and it is the carbon dioxide from the yeast anaerobically respiring that has caused the dough to rise). The ethanol that has been produced by anaerobic respiration will evaporate away when the bread is cooked; this is why bread does not contain alcohol.
In addition to making bread, yeast undertaking fermentation reactions is used to produce many alcoholic drinks. The yeast and beer solution are placed in an oxygen free environment. As there is no oxygen present, it means that the yeast respires anaerobically and produces ethanol (the alcohol) and carbon dioxide. The carbon dioxide that is produced results in beer having a slight fizz (brewers may add more carbon dioxide to make the beer or ciders fizzier).
The yeast in the bread respires anaerobically, which produces carbon dioxide and ethanol. The carbon dioxide produced will make the bread/ dough rise (when you make bread at home, you make the dough, wrap the dough in clingfilm to prevent oxygen getting in and then leave the dough somewhere to rise. After a certain amount of time, the dough will have risen, and it is the carbon dioxide from the yeast anaerobically respiring that has caused the dough to rise). The ethanol that has been produced by anaerobic respiration will evaporate away when the bread is cooked; this is why bread does not contain alcohol.
In addition to making bread, yeast undertaking fermentation reactions is used to produce many alcoholic drinks. The yeast and beer solution are placed in an oxygen free environment. As there is no oxygen present, it means that the yeast respires anaerobically and produces ethanol (the alcohol) and carbon dioxide. The carbon dioxide that is produced results in beer having a slight fizz (brewers may add more carbon dioxide to make the beer or ciders fizzier).