Living things show similar characteristics of life
Living things use food, water and oxygen
Living things use food for energy, respond to stimuli, expel materials they no longer need, can reproduce and eventually die
EXAMPLE QUESTIONS
How can you tell something is alive?
What do you think living things need to survive?
How can you tell if something is not a living thing?
LIVING THINGS SHOW SIGNS OF LIFE
Living things show the same characteristics of life.
They respire, need food and water, and get rid of materials they no longer need.
They are sensitive and react to stimuli.
They grow reproduce and eventually die.
LIVING THINGS NEED FOOD
Green plants produce their own food by photosynthesis.
This is a process requiring carbon dioxide, water, light and a green colored pigment called chlorophyll.
The food (a simple sugar manufactured by a plant through photosynthesis) is used by the plant itself, by animals that eat either the plant or other animals that have eaten the plant.
LIVING THINGS RESPIRE
We are familiar with the way animals breathe, but it is more difficult to observe plants breathing.
Breathing simply means taking in oxygen and giving out carbon dioxide and other gases.
Living things need energy to enable their bodily processes to work (for example, moving and growing).
The energy comes from green plants which change carbon dioxide and water to sugar in the presence of light energy and chlorophyll.
Energy-rich foods, such as fats, starches and sugars, have energy ‘locked’ in them.
The key to unlocking this energy is in the oxygen breathed by both animals and plants.
The unlocking or energy is called respiration.
Because animals, in general, are much more active than plants, they need more energy.
Respiration is a chemical process that releases energy from sugar and gives off carbon dioxide and water as waste products.
LIVING THINGS EXPEL MATERIALS THEY NO LONGER NEED
Respiration produces carbon dioxide and water.
Other chemical processes in the body of living things produce material that are not used.
These are expelled or excreted (for example, urine and faeces in mammals).
LIVING THINGS SHOW MOVEMENT
In some living things, movement is so slow or in such small increments that it is impossible to observe.
For example, it is difficult to see plants moving as they respond to light or gravity.
Usually, the movement of animals is easily observed.
Both animals and plants move in response to stimuli such as light and heat.
