Respiration and Breathing
Energy Content per gram of food (J) = 4.2 x temp. Rise x 20/ mass of food
Respiration
In I/GCSE biology, there are two types of respiration;
- Aerobic Respiration
- Anaerobic Respiration
Aerobic Respiration takes place in living cells, inside the mitochondria, so is not present in bacteria or viruses.
Anaerobic Respiration takes place in skeletal muscles, (in arm or leg muscles), and in yeast cells.
Respiration happens so that the following functions can occur;
- Movement,
- Growth,
- Sensitivity,
- Excretion,
- Reproduction,
- Nutrition.
We know that respiration has occurred when;
- CO2 is produced - breathe into limewater to tell whether it is present.
- Heat is produced.
- Glucose/ oxygen are used up.
Aerobic Respiration
In IGCSE biology, you need to understand that:
Respiration is a process that takes place in all living cells. Respiration transfers energy from food molecules in animals and in plants. The energy from respiration is used to make smaller molecules from large ones, to let muscles contract, and to keep a constant muscle temperature. Respiration releases energy from food molecules in cells.
Glucose + Oxygen --> CO2 + water + energy
Anaerobic Respiration
Anaerobic respiration occurs in the skeletal muscle cells. The main difference between them is that Aerobic respiration uses oxygen, while anaerobic respiration doesn’t
Glucose --> Lactic Acid + a little energy
You respire anaerobically when you are exercising hard, and your muscles struggle to get the oxygen to do aerobic respiration. (the heart and lungs struggle to put oxygen in the blood, and then pump it around the blood.
Without the oxygen, the glucose transfers to lactic acid, with a little energy. The problem is that the lactic cid builds up, and doesn’t let the muscles contract correctly, meaning that you get a ‘stitch’.
This lactic acid is poisonous, and must be removed. This is done by the body moving it to the liver, and then breaking it down using oxygen. This is called oxygen debt.
End of this topic!
