This definitions covers Key Definitions within Respiration for GCSE Biology. Topic 2: Respiration It is section 8 of 14 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
Topic position
Section 8 of 14
Practice
15 questions
Recall
20 flashcards
📖 Key Definitions
Aerobic respiration: The chemical process in which glucose and oxygen are broken down in the mitochondria to release energy (ATP), producing carbon dioxide and water as waste products. It is the main energy-releasing pathway in most organisms.
Anaerobic respiration: The release of energy from glucose without oxygen. In animals it produces lactic acid; in plants and yeast it produces ethanol and carbon dioxide. It releases much less energy per glucose molecule than aerobic respiration.
Mitochondria (singular: mitochondrion): Membrane-bound organelles found in the cytoplasm of eukaryotic cells. They are the site of the later stages of aerobic respiration and are therefore most abundant in cells with high energy demands (e.g., muscle cells, liver cells).
Oxygen debt: The amount of extra oxygen the body must absorb after a period of anaerobic exercise, above the resting rate of oxygen consumption, in order to break down accumulated lactic acid and restore muscles to their normal state.
Lactic acid: The product of anaerobic respiration in animal cells. It builds up in muscles during intense exercise, causing fatigue and the characteristic burning sensation. It is transported to the liver, where it is converted back to glucose when oxygen becomes available again.
Fermentation: The form of anaerobic respiration that occurs in yeast and plant cells, producing ethanol and carbon dioxide from glucose. It is exploited commercially in brewing, bread-making, and biofuel production.
Exothermic reaction: A chemical reaction that releases energy to the surroundings as heat. Respiration is exothermic — it transfers chemical energy stored in glucose into heat energy and ATP, which cells use to do work.
ATP (adenosine triphosphate): The universal energy currency of cells. Energy released from respiration is stored in ATP molecules. When cells need energy (for movement, active transport, protein synthesis), ATP is broken down and the energy is released.