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# Respiration Respiration is one of the most important life processes. It's worth learning well. ## Respiration is a Chemical Reaction 1. Respiration happens in every cell of every living organism. 2. Respiration is the process of releasing energy from glucose (a sugar). 3. The energy released by...

# Respiration Respiration is one of the most important life processes. It's worth learning well. ## Respiration is a Chemical Reaction 1. Respiration happens in every cell of every living organism. 2. Respiration is the process of releasing energy from glucose (a sugar). 3. The energy released by respiration is used for all the other chemical reactions that keep you alive. For example, the reactions involved in building proteins, muscle contraction, and keeping warm. ## Aerobic Respiration Needs Plenty of Oxygen 1. Aerobic respiration is respiration using oxygen. It takes place in the mitochondria (see page 2) of animal and plant cells. 2. In aerobic respiration, glucose and oxygen react to produce carbon dioxide and water. This reaction releases lots of energy. 3. Here's a word equation to show what happens in the reaction: glucose + oxygen → carbon dioxide + water + ENERGY ## Anaerobic Respiration Takes Place Without Oxygen 1. Anaerobic respiration is respiration without oxygen. 2. Anaerobic respiration is less efficient than aerobic respiration, so it releases less energy. 3. Because of this, anaerobic respiration usually only happens when cells can't get enough oxygen, eg. if your body can't get enough oxygen to your muscle cells when you exercise, they start to respire anaerobically. ## Anaerobic Respiration is Different in Different Organisms 1. In humans, anaerobic respiration produces a substance called lactic acid: glucose → lactic acid + ENERGY Lactic acid can build up in your muscles during exercise and can be painful. 2. In microorganisms like yeast, anaerobic respiration produces carbon dioxide and ethanol (alcohol): glucose → carbon dioxide + ethanol + ENERGY When anaerobic respiration produces ethanol, it's called fermentation. Fermentation is the process used to make beer. ## Two types of Respiration There are two types of respiration. Learning the difference can be tricky but it just means turning glucose into energy. Make sure you've learnt those equations - cover the book and write them down. **Note**: The image also contains warm-up and practice questions, likely for a student, but these have been excluded as they are not needed to answer the question `Tell me about this instrument`.