Cellular respiration
All organisms respireThe process of carrying out chemical reactions in cells to release energy from glucose. in order to release energy to fuel their living processes. The respiration can be aerobic, which uses glucose and oxygen, or anaerobic which uses only glucose. Respiration must happen all of the time so that the organism can survive.
Releasing energy in the form of ATP
Respiration releases energy - it is an exothermicReaction in which energy is given out to the surroundings. The surroundings then have more energy than they started with so the temperature increases. process. The energy is stored in molecules of ATPStands for 'adenosine triphosphate' which is the high-energy chemical that transfers chemical energy in cells.. ATP can be broken down in other processes in cells to release the stored energy.
photosynthesisA chemical process used by plants to make glucose and oxygen from carbon dioxide and water, using light energy. Oxygen is produced as a by-product of photosynthesis. Algae subsumed within plants and some bacteria are also photosynthetic. is the process by which plants, and some bacteria, synthesise food molecules - which they then use, in addition to other things, for respiration. The process of photosynthesis requires energy - it is endothermicReaction in which energy is taken in..
Don't confuse respiration with breathing, which is ventilationBreathing in and out.. Respiration happens inside cells. Breathing is the movement of air into and out of the respiratory system, which involves organs like the lungs.
Why organisms need energy in the form of ATP
- To drive the chemical reactions needed to keep organisms alive - the reactions to build complex carbohydrateFood belonging to the food group consisting of sugars, starch and cellulose. Carbohydrates are vital for energy in humans and are stored as fat if eaten in excess. In plants, carbohydrates are important for photosynthesis., proteinOrganic compound made up of amino acid molecules. One of the three main food groups, proteins are needed by the body for cell growth and repair. and lipidFat or oils, composed of fatty acids and glycerol. from the products of photosynthesisA chemical process used by plants to make glucose and oxygen from carbon dioxide and water, using light energy. Oxygen is produced as a by-product of photosynthesis. Algae subsumed within plants and some bacteria are also photosynthetic. in plants, and the products of digestionThe breakdown of large insoluble food molecules to smaller soluble ones. in animals, require energy.
- Movement - in animals, ATP is needed to make muscles contract, while in plants, it is needed for transport of substances in the phloemThe tissue in plants that transports the products of photosynthesis, including sugars and amino acids..
All organisms need ATP to live.
Respiration is only around 40 per cent efficient. As animals respire, heat is also released.
In birds and mammals, this heat is distributed around the body by the blood. It keeps these animals warm and helps to keep a constant internal temperature.
ATP is also required:
- For cell division.
- To maintain constant conditions in cells and the body. This is called homeostasisThe maintenance of steady conditions. The ability of the body to maintain a constant internal environment, eg temperature and blood glucose concentration..
- To move molecules against concentration gradients in active transportThe transport of molecules against their concentration gradient from a region of low concentration to a region of high concentration..
- For the transmission of nerve impulsesElectrical signals that travel along the nerve fibre from one end of the nerve cell to the other..