Welcome to our free-to-use Q&A hub, where students post questions and get help from other students and tutors.

Follow the trail of responses and if you have anything to add please sign up or sign in.

You can ask your own question or look at similar Biology questions.

All cells release energy. 

All cells must have energy to function. Glucose and other sugars are cell food—they are the power source for cell activities in almost all living things. When glucose is stored as glycogen or taken in as starch, it must be broken down into individual molecules before cells are able to use it. Chemical energy is stored in the bonds of sugars. When the bonds of a sugar molecule are broken, a burst of energy is released that the cell can use. Cells can release energy in two basic processes: cellular respiration and fermentation. Cellular respiration requires oxygen, but fermentation does not. In addition, cellular respiration releases much more usable energy than does fermentation.

Cellular Respiration

 In cells use oxygen to release energy stored in sugars such as glucose. In fact, most of the energy used by the cells in your body is provided by cellular respiration. Just as photosynthesis occurs in organelles called chloroplasts, cellular respiration takes place in organelles called mitochondria. Remember that mitochondria are in both plant cells and animal cells, so both kinds of cells release energy through cellular respiration. Like photosynthesis, cellular respiration is a process that changes starting materials into new products. The starting materials of cellular respiration are sugars—such as glucose—and oxygen. The process begins when glucose in the cytoplasm is broken down into smaller molecules. This releases a small amount of energy. These molecules then move into the mitochondria. At the same time, oxygen enters the cell and travels into the mitochondria. As the smaller molecules are broken down even further, hydrogen is released along with a large amount of energy. The hydrogen combines with oxygen to make water. The products are energy, carbon dioxide, and water. Some of the energy produced during cellular respiration is transferred to other molecules, which then carry the energy where it is needed for the activities of the cell. The rest of the energy is released as heat. Carbon dioxide formed during cellular respiration is released by the cell. 

 Aerobic respiration is the chemical reaction used to release energy from glucose. It is called aerobic because oxygen from the air is also needed.

glucose + oxygen → carbon dioxide + water (+ energy)

Plant cells respire, just as animal cells do. If they stop respiring, they will die. Remember that respiration is not the same as breathing, so take care - plants do not breathe.

Also, respirstion and photosynthesis are two different things i.e. Respiration uses oxygen and produces carbon dioxide. Photosynthesis uses carbon dioxide and produces oxygen.Plants respire all the time, whether it is dark or light. They photosynthesise only when they are in the light.

    • Aerobic Respiration
    Aerobic RespirationSeptember 18, 20170 CommentsWhat Is Respiration?

    Respiration is one of the important chemical processes in all the living organisms. It could happen either in the presence of oxygen (aerobic) or the absence of Oxygen (anaerobic-mainly in single-celled or multicellular organisms). For instance, human beings undergo the process of respiration by inhaling oxygen and exhaling carbon dioxide. Many living organisms whether plants or animals undergo this process to use their food energy.

    The general diagram of this process is as shown below-


    Respiration is of two types, namely aerobic respiration, and anaerobic respiration.

    Aerobic Respiration

    Aerobic respiration is a process in which the food glucose is converted into energy in the presence of oxygen. The general equation of aerobic respiration as a whole is as given below-

    Glucose + oxygen ==Carbon-dioxide+ Water+ Energy

    In the above equation, energy is released by the breaking up of glucose by oxygen and as a result of this, the water and the carbon-dioxide are being produced as one of the resultant of the reaction. When one molecule of glucose is broken,  2900 kJ of energy is released. This is used in-turn to create a new type of energy molecule called as the ATP of the Adenosine Triphosphate. The body uses this ATP generated as the energy for various purposes.

    Aerobic respiration process also takes place in animals, plants and other living organisms. Firstly the oxygen enters the cells of plants with the help of stomata. Plants produce their food with the aid of photosynthesis process and thus release energy from it through the respiration process. The below equation describes the process of photosynthesis or the aerobic respiration in plants.

    Carbon-dioxide + water== Glucose + Oxygen

    Anaerobic Respiration

    Anaerobic, the word itself would say about what the process is. Anaerobic respiration is a process which takes place due to the lack of oxygen. In this process, the energy is obtained by the breakdown of glucose in the absence of oxygen. One of the well-known examples of anaerobic respiration is fermentation in yeast

    Aerobic Respiration in plants is exactly the same in plants as it is in humans. This still uses the same organelle (the mitochondria) and releases the same products at the end- CO2 and water. However, as we need to consume glucose to form a reactant for respiration, plants can make it themselves through photosynthesis, therefore these reactants and products become interdependant on each other in a kind of cycle. Respiration in plants still goes through the same stages as in humans as in Glycolysis,Link Reaction, Krebs and Oxidative Phosphorylation. 

    Hope this helps.  

    Aerobic respiration happens when there is plenty of oxygen (normal level in air is 21%). Anaerobic respiration happens where there is less oxygen than this.

    Respiration is the process of producing energy from glucose in the mitochondria inside cells.

    oxygen + glucose ---------->  carbon dioxide + water + (energy)

    All living things have to do this. The difference between plants and animals is that plants can make the glucose themselves through photosynthesis, and animals have to eat food for a source of glucose.

    Releasing the energy from glucose is a multi-step process that involves several different enzymes and a change in the structure of glucose. The equation above is the simplified version that is taught in school. At A-Level and above you would learn the more complicated version.

    In simplified terms the energy is released when the bonds are broken in the molecules.

    Aerobic respiration involves oxygen. The consumption of oxygen and glucose leads to the production of carbon dioxide, water and energy. This is respiration. At the same time (during the day) plants also perform photosynthesis, which is basically the same process in reverse: carbon dioxide, water and energy (via sunlight) produce glucose and oxygen. This only happens during the day, and at night the plant only undergoes respiration, not photosynthesis.

    Footer Graphic