How is chemical energy stored in substances such as fuels? How can the chemical energy be released from fuels to produce heat energy? What is the name of the process by which chemical energy in food is released in living things? People who lived in the cold Arctic regions used to eat a lot of whale fat called blubber.
Suggest a reason why that food was very useful. Are you consuming any chemical energy when you are using an electric stove for cooking? What are the main sources of chemical energy in the world? Aerobic respiration requires oxygen, while anaerobic respiration does not. The release of energy is necessary to fuel the activities of the cells, such as biochemical synthesis, repairing the body, and reproduction.
ATP, or adenosine triphosphate, is the key molecule that is utilised by the cells in various metabolic processes. Virtually all activities of the cells require energy. These cellular activities are called metabolism, which can be divided into two categories:. The release of chemical energy from food is a catabolic process.
But before cells can release energy, the food must first be digested, reduced to its basic constituents, absorbed by the cells, and stored. During aerobic respiration, oxygen reacts with the basic constituents of food, like carbohydrates, fats, and proteins. These are consumed as reactants to create ATP molecules. For example, ATP is produced when glucose reacts with oxygen during aerobic cellular respiration. An energy transfer then occurs, which is used to break the molecular bond of ADP in order to add a third phosphate group, forming ATP molecules.
The simplified chemical reaction is as follows:. Anaerobic respiration, on the other hand, is the main metabolic path in many species of bacteria and archaebacteria. Since bacteria do not have specialised organelles , anaerobic respiration occurs in the cytoplasm.
Instead of oxygen, anaerobic respiration uses sulfate, nitrate, sulfur, or fumarate as electron acceptors. The chemical energy stored in food is released by cells through the process of respiration. This process has four steps , and mainly produces ATP as the energy-carrying molecule that can be used by cells in their metabolic activities. The four steps of the process are:. The total ATP yield of respiration is 30 or 32 per glucose molecule.
Although the theoretical yield is 38 ATP molecules per glucose molecule, some are lost because of being spent in moving pyruvate from glycolysis, phosphate and ADP into the mitochondria.
Chemical energy is stored in food because of the various molecular bonds in food and the electrochemical gradients that they create. Depending on the type of food, these bonds may either be easy or difficult to break. The constituents of food, such as carbohydrates, fibres, minerals, fats, and proteins, act as reactants. As it strikes the nail, it slows down and loses its kinetic energy. The energy does not disappear, however. Some of it goes to split the wood to make way for the nail, some passes into the wood as heat energy, and some is converted into sound.
This is the energy involved in chemical reactions, when elements join together into compounds. This energy is stored inside the compounds as chemical potential energy. The stored energy can be released by further chemical reactions. The food we eat stores energy that is released by digestion. Energy can also be released by burning the chemicals in a process called combustion.
Fuels are chemical compounds that release heat energy by combustion. Fuels such as charcoal are hydrocarbons, chemical compounds made mainly from hydrogen and carbon. When a fuel burns in air, the hydrocarbons break up into simpler compounds. The chemical potential energy they contain is then released as heat energy. Light energy is produced at the same time and this is what makes a fire glow as it burns. When humans or other animals eat food, they use its stored energy to keep warm, maintain and repair their bodies, and move about.
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