1. Properties that we share with all other living things…
Defining Life
Properties that we share with all other living things…

2. Biology is the scientific study of life
Biologists are moving closer to understanding:
How a single cell develops into an organism
How plants convert sunlight to chemical energy
How the human mind works
How living things interact in communities
How life’s diversity evolved from the first microbes

3. How would YOU define life?
A human definition…
Growing
Thinking
Moving
Life is ACTIVE! (well, usually…)

4. Can you tell what’s living? LIVING = biotic NONLIVING = abiotic

10. You get the idea… All living things share certain properties… In order to be considered living, ALL FIVE properties must be present. What are they???

11. Property #1: CELLULAR ORGANIZATION
ALL living things are composed of one or more cells (can have 1 to trillions of cells).
All cells grow and reproduce

12. Property #2: METABOLISM
Living things need energy!
To grow
To move
To process information
Metabolism= sum of chemical reactions carried out by an organism

13. Property #3: HOMEOSTASIS
Living things maintain stable internal conditions.
Examples: body temperature and blood sugar.
What is the temperature that the human body maintains?
A. 95.4
B. 98.6
C. 99.5

14. Information Normal affects condition disturbed STIMULUS:
RECEPTOR
Information
affects
Normal
condition
disturbed
Thermometer
STIMULUS:
Room temperature
rises
CONTROL CENTER
(Thermostat)
HOMEOSTASIS
Normal
room
temperature
RESPONSE:
Room temperature
drops
20o
30o
40o
Normal
condition
restored
EFFECTOR
Sends
commands to
Air conditioner
turns on
Figure 1-3
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Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

15. Property #4: REPRODUCTION
No living thing is immortal (lives forever) so…
It must be able to reproduce from one generation to the next – or there would be no life left!

16. Property #5: HEREDITY
DNA is inside cells coding to direct growth and development of all living things
Parents pass on characteristics to their offspring through their genes.

17. Which property of life is most important??
A. cellular organization
B. homeostasis
C. heredity
D. reproduction
E. metabolism
Be prepared to argue WHY!!!

18. Why can’t we just choose one characteristic to define life?
Do any non-living things possess any of the characteristics of life?

19. Life’s basic characteristic is a high degree of order
Each level of biological organization has emergent properties

21. Biologists explore life from the microscopic to the global scale
The study of life extends from molecules and cells to the entire living planet
Biological organization is based on a hierarchy of structural levels

22. A Hierarchy of Biological Organization
Biosphere: all environments on Earth
Ecosystem: all living and nonliving things in a particular area
Community: all organisms in an ecosystem
Population: all individuals of a species in a particular area
Organism: an individual living thing

23. A Hierarchy of Biological Organization (continued)
6. Organ systems: groups of organs functioning together
Organs: specialized body parts made up of tissues
Tissue: a group of similar cells
Cell: life’s fundamental unit of structure and function
Organelle: a structural component of a cell
Molecule: a chemical structure consisting of atoms

24. Organs and organ systems Organisms
The biosphere
Organelles
1 µm
Cell
Ecosystems
Cells
Atoms
Molecules
10 µm
Communities
Tissues
50 µm
Populations
Organs and organ systems
Organisms