Edexcel IGCSE Biology: Double Science 复习笔记 1.1.2 Living Organisms: Nutrition & Respiration

• Organisms must obtain food to provide energy
  • Energy is necessary to carry out life processes e.g. movement, respiration and excretion

Nutrition in plants

• Plants use sunlight, carbon dioxide and water to produce oxygen and glucose in the process of photosynthesis
• Because plants create their own food for energy, they are described as being autotrophic

Nutrition in animals

• Animals consume other living organisms in order to obtain the energy they require
• They break down larger complex molecules into simpler molecules through the process of digestion
• As animals obtain their food from a range of different sources, they are described as being heterotrophic

Autotrophs make their own food whereas heterotrophs obtain it from a range of food sources

• Respiration is a chemical reaction carried out in all living organisms
• Energy is released from glucose either in the presence of oxygen (aerobic respiration) or the absence of oxygen (anaerobic respiration)
• The reactions ultimately result in the production of carbon dioxide and water as waste products
• Energy is transferred in the form of ATP

The equation for aerobic respiration