iGCSE Biology (Combined) Edexcel

Characteristics of Living Organisms

Characteristics of Living Organisms

All living organisms share certain characteristics that distinguish them from non-living things. These include:

• Movement: All organisms move in some way. This can be obvious, as animals do when they walk or swim, or less evident, as with plants that turn towards light (phototropism) or whose flowers and leaves open or close in response to environmental stimuli.

• Respiration: This is the process by which organisms release energy from food. It occurs in every living cell.

• Sensitivity: All living organisms respond to changes in their environment. This is also known as responsiveness or irritability.

• Growth: Organisms grow by increasing in size and/or number of cells. It happens throughout the life of an organism.

• Reproduction: This characteristic is about the ability to produce offspring. Reproduction can be sexual (requiring two parents and the joining of special cells, gametes) or asexual (requiring only one parent).

• Excretion: This is the removal of waste products from the metabolism of cells. Examples of excretions include sweat in humans, carbon dioxide from respiration, and oxygen from photosynthesis in plants.

• Nutrition: This involves taking in nutrients which are organic substances and mineral ions, absorbing them, and assimilating them into the body. This includes eating and digestion in animals, and photosynthesis in plants.

Remember, all living organisms will display these seven characteristics at some stage of their existence, even though they may be carried out in different ways in different groups of organisms.