1. The Characteristics of Life

2. History: Spontaneous Generation or Abiogenesis- 1 st proposed by Aristotle held that complex, living organisms are generated by decaying organic substances, e.g. that mice spontaneously appear in stored grain or maggots spontaneously appear in meat.

3. The Characteristics of Life History: Was widely believed until the 19 th century. Several scientists performed experiments that disproved spontaneous generation Francisco Redi Lazzaro Spallanzani Louis Pasteur

4. Redi’s Experiment Francisco Redi 1668

5. Spallanzani’s Experiment Lazzaro Spallanzani 1746

6. Pasteur’s Experiment Louis Pasteur 1859

7. The Characteristics of Life History: Biogenesis- is the process of life forms producing other life forms e.g. a spider lays eggs, which form into spiders. The term is also used for the assertion that life can only be passed on by living things.

8. The Characteristics of Life How can you tell if something is alive?

9. The Characteristics of Life Biologists have devised a list of 5 characteristics that define life. Something can be considered alive ONLY if it displays ALL 5 of the characteristics.

10. The Characteristics of Life Anything that possesses all 5 of the characteristics of life is called an organism.

11. The 5 characteristics of life are: 1.Cellular Organization cell  tissue  organ  system  organism 2. Growth & Development 3. Reproduction 4. Adaptation to environment – response to a stimulus 5. Maintenance of Homeostasis

12. The Characteristics of Life Organization: All living organisms have an organized structure Ex.-Cells form tissues -Tissues form organs -Organs form organ systems

13. The Characteristics of Life All living organisms grow and develop during their life spans. Growth & Development:

14. The Characteristics of Life Growth: an increase in the size of an organism due to an increase in the size and number of cells Development: all of the changes that take place throughout the life span of an organism

15. The Characteristics of Life Reproduction: All living organisms are able to produce live offspring.

16. The Characteristics of Life Adaptation to environment: All living organisms are able to adapt to their surroundings. They are able to react, or respond to an environmental condition, or stimulus.

17. The Characteristics of Life Maintenance of Homeostasis: All living organisms are able to maintain a relatively constant internal environment. Homeostasis: The regulation of an organism’s internal environment to maintain conditions suitable for life.

18. The Characteristics of Life Are bacteria alive? How about viruses?