1. 1.2.3. Characteristics of Life

2. Learning Objectives
Definition and identification of the "characteristics of life",
through fundamental principles and interactions of
Organisation, Nutrition, Excretion, Response and Reproduction.

3. How do we know if something is alive?
It has Organization – cells, tissues, organs, etc.
Nutrition : for Growth and development
Excretion
Reproduction
Responds and Adapts to the environment

4. Organisation Unicellular or multicellular Specialized structures
Cell is the basic unit of structure and function
If cell structure is damaged its function is also affected

5. Levels of organisation
Cell
Tissue
Organ
Organ system
Organism
Population
Community
Ecosystem
Biosphere

6. Learning check How do we know something is alive?
It has organization – cells, tissues, organs, etc.
Grows and develops
Excretes
Reproduces
Responds and Adapts to the environment

7. Growth and Development
Growth – increase in size
Development – change in form or shape
Amount of growth varies in different organisms
Nutrition maintains the organisation and growth of living organisms

8. Nutrition The way organisms obtain and use food
Food is needed for energy
Plants use sunlight and chemicals from their surrounding to make food = Photosynthesis
Animals take in food from other organisms

9. Sources of Nutrition
The sun is the basic source of energy for all nutrition.
**The energy in plants (producers) is passed on to animals (consumers) when they eat the plants.
energy
Sun Plants Animals

10. Excretion
Excretion - is the removal of the waste products of metabolism from the body
Many processes produce poisonous waste that could damage the organism if allowed to accumulate.
A balance must be maintained between their internal and external environments

11. Methods of excretion Various organised structures involved;
In Animals: the urinary system, skin, lungs
In Plants: the stomata

12. Learning check What is meant by nutrition?
It is the way an organism obtains and uses food.

13. Response and Adaptation
Response = reaction to a stimulus in environment
Adaptation – plants and animals change in response to long-term changes in the environment;
these may be passed on to future generations (Charles Darwin)

14. Methods of response
In Animals: organised structures respond to light, sound, touch, etc. (eyes, ears, skin, etc.)
Animals often respond by movement
In Plants: growth towards or away from a stimulus e.g. light, water, fertilisers, etc.
Plants respond slower and less obvious

15. Learning check What is Excretion?
It is the removal of the waste products of metabolism from the body.

16. Reproduction Reproduction is the production of new individuals.
Involves passing on genetic information to the next generation.
Necessary for the survival of the species
Offspring can be the same as or different from parent(s)

17. Methods of reproduction
Asexual: involves simple organisms splitting in two or more identical offspring. e.g. in Bacteria and Protista = Mitosis
Sexual:– involves the union of sex cells. Offspring will carry genes from both parents
e.g. in plants and animals

18. Learning check What is the purpose of reproduction?
To produce new individuals and pass on genetic information to the next generation.
Reproduction is necessary for the survival of a species.

19. Summary
One characteristic is not enough to qualify something as being alive.
Life involves an interaction between metabolism and continuity
Metabolism requires an interaction of organisation, nutrition, excretion and behaviour
Continuity requires organisation, nutrition, behaviour and reproduction

20. Need to know
Definition and identification of the "characteristics of life",
through fundamental principles and interactions of organisation
nutrition, excretion, response and reproduction.

21. END