To survive and reproduce, organisms require a supply of materials from…

The idea

Every organism needs matter and energy to stay alive and produce offspring. Materials come from two sources: the non-living surroundings and other living organisms. Plants take carbon dioxide from the air and water and mineral ions from the soil, using light energy to make glucose by photosynthesis. Animals cannot photosynthesise, so they obtain energy and building materials by eating other organisms; they also take in oxygen for respiration and water for transport. These materials are used for growth, repair, movement and reproduction. For example, a caterpillar eats leaves for energy and materials, then uses them to grow and eventually reproduce as a butterfly. If any required material is in short supply, growth and reproduction are limited, which is why competition matters.

What earns the marks

• State that organisms need materials for survival, growth, repair and reproduction.
• Identify the surroundings as a source of materials, such as carbon dioxide, water, oxygen and mineral ions.
• Identify other living organisms as a source of materials, such as food for animals and hosts for parasites.
• Give a named example of an organism obtaining materials from both sources.
• Explain that a shortage of a required material limits growth or reproduction.
• Link the need for materials to the processes of photosynthesis, respiration and growth.

Common mistakes and how to put them right

• Saying organisms need food only for energy.

  Put it right: Food also supplies materials for growth and repair.

• Forgetting that plants obtain materials from both the air and the soil.

  Put it right: Name carbon dioxide from the air and water and mineral ions from the soil.

• Assuming all organisms obtain materials in the same way.

  Put it right: Plants photosynthesise, whereas animals and fungi obtain materials from other organisms.

Exam tips

• Name the specific material and its source, for example carbon dioxide from the air or mineral ions from the soil.
• Link the material to its use, such as glucose for respiration or amino acids for growth.
• Use examples from both plants and animals to show the two sources of materials.