Aerobic Respiration

Respiration is the process by which cells release energy from glucose. This process occurs in the mitochondria within the cytoplasm of cells in all living organisms, including animals and plants.

It’s easy to mix up respiration with breathing, also known as ventilation. However, breathing is actually about inhaling and exhaling air to supply oxygen and remove waste, while respiration is a cellular process.

There are two types of respiration:

  • Aerobic respiration – requires oxygen and produces a large amount of energy
  • Anaerobic respiration – does not require oxygen and produces a smaller amount of energy

So if there’s plenty of oxygen around, aerobic respiration takes place. When oxygen is scarce, cells switch to anaerobic respiration.

Aerobic Respiration

The word equation for aerobic respiration is:

Glucose + Oxygen Carbon Dioxide + Water

In other words, glucose is reacting with oxygen to form carbon dioxide and water. This reaction releases energy, so sometimes the equation may show energy in brackets.

For example, when we run:

A graphic representation of a running human silhouette positioned between two columns. On the left, titled "What goes in", arrows point towards the silhouette indicating the intake of "Oxygen (Air)" and "Glucose (food)". On the right, titled "What comes out", arrows emanate from the silhouette showcasing the outputs: "Carbon dioxide (in air we exhale)", "Energy (energy that keeps our bodies running)", and "Water". The background is divided into a yellowish hue for the intake and a bluish hue for the output.

Relating Respiration and Photosynthesis

Respiration and photosynthesis are opposite processes that are essential for the survival of living organisms. Respiration involves the breakdown of glucose to release energy. In contrast, photosynthesis is the process by which plants use energy from sunlight to convert carbon dioxide and water into glucose and oxygen.

Plants and other organisms use the glucose and oxygen produced during photosynthesis for respiration.

An illustrative diagram showcasing the relationship between photosynthesis and cell respiration. At the top left, the Sun emits "Light energy" towards a green chloroplast labelled "PHOTOSYNTHESIS". Water and CO2 are shown as inputs to this process. The chloroplast then produces O2 and Glucose as outputs. Below, an orange mitochondrion is labelled "CELL RESPIRATION", receiving the O2 and Glucose and subsequently converting them into "Chemical Energy". The background is a gradient from brown at the top to a deeper shade at the bottom.

Plant respiration takes place in the dark and in the light. However, photosynthesis only takes place in the light.

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