Cellular respiration is a metabolic pathway that breaks down glucose and produces ATP. The stages of cellular respiration include glycolysis, pyruvate oxidation, the citric acid or Krebs cycle, and oxidative phosphorylation.
During cellular respiration, a glucose molecule is gradually broken down into carbon dioxide and water. Along the way, some ATP is produced directly in the reactions that transform glucose. Much more ATP, however, is produced later in a process called oxidative phosphorylation. Oxidative phosphorylation is powered by the movement of electrons through the electron transport chain, a series of proteins embedded in the inner membrane of the mitochondrion. These electrons come originally from glucose and are shuttled to the electron transport chain when they gain electrons.
As electrons move down the chain, energy is released and used to pump protons out of the matrix, forming a gradient. Protons flow back into the matrix through an enzyme called ATP synthase, making ATP. At the end of the electron transport chain, oxygen accepts electrons and takes up protons to form water. Glycolysis can take place without oxygen in a process called fermentation. The other three stages of cellular respiration—pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation—require oxygen in order to occur. Only oxidative phosphorylation uses oxygen directly, but the other two stages can't run without oxidative phosphorylation.). As electrons move down the chain, energy is released and used to pump protons out of the matrix, forming a gradient. Protons flow back into the matrix through an enzyme called ATP synthase, making ATP. At the end of the electron transport chain, oxygen accepts electrons and takes up protons to form water. Glycolysis can take place without oxygen in a process called fermentation. The other three stages of cellular respiration—pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation—require oxygen in order to occur. Only oxidative phosphorylation uses oxygen directly, but the other two stages can't run without oxidative phosphorylation.
When several flower ovaries or receptacle of a flower with many separate carpels joins together they form aggregate fruit. Each ovary has a single ovule that converts into a seed after fertilization.
Aggregate fruit can be formed without the involvement of accessory parts called true aggregate fruit or with the involvement of additional floral parts called accessory aggregate fruit. Strawberry is also an accessory aggregate fruit because the different ovaries in the strawberry develops into achenes over the surface of flower receptacles.
The cells of living things also get energy by "burning." They "burn" glucose in the process called cellular respiration. Inside every cell of all living things, energy is needed to carry out life processes. Energy is required to break down and build up molecules and to transport many molecules across plasma membranes.
