This document provides an introduction to life on Earth and biology. It defines life and discusses its key characteristics, including complex structure, response to stimuli, homeostasis, acquiring material and energy, growth, reproduction, and evolution. It describes the hierarchical levels of biological organization from atoms to biosphere. Finally, it outlines the domains and kingdoms of life, distinguishing between prokaryotes and eukaryotes, unicellular and multicellular organisms, and their methods of obtaining nutrients.

1. Chapter 1
An Introduction to Life on Earth

2. What is Biology?
--- The science of living organisms
and life processes.

3. So what exactly is life?

4. Life: An evanescent phenomenon dependent for its continued existence, and
perpetuation, on cyclic enzymatic reactions in an environment consisting
principally of protein and water. Student Dictionary of Biology.
(1972) Van Nostrand Reinhold Company, New York.
Life: the property by which living organisms are distinguished from dead
Organisms or inanimate matter. Websters II New Riverside Dictionary.
These definitions suck terribly.
Neither of the Biology texts (for majors or non-majors) that we use
include the term “life” in their glossaries.

5. The characteristics of life:
1. Complex, organized structure
2. Response to stimuli
- a change outside (or
inside) leads to another
change
3. Homeostasis
- the ability to maintain the
structure and regulate the internal
environment.
4. Ability to acquire material and energy
-The material and energy are often
transformed
5. Growth
6. Reproduction - either sexual or asexual
DNA is genetic information, the
“blueprint” for the offspring
7. Ability to evolve - to change to fit the environment

6. Complex, organized structure
The complexity of life is built in levels.
Fig. 1-8

7. Each level has ingredients or components
which interact to make something greater
than the sum of the parts.
Emergent Properties
Example: NaCl (Sodium Chloride)
Sodium = solid metal
Chlorine = poisonous gas
Put them together = table salt

8. That part of Earth inhabited
Biosphere by living organisms; includes both
the living and nonliving
components Earth's surface
A community together with its
Ecosystem
nonliving surroundings
snake, antelope, hawk, bushes, grass, rocks, stream
Two or more populations of different
Community species living and interacting in
the same area
snake, antelope, hawk, bushes, grass
Very similar, potentially interbreeding
Species
organisms
Members of one species inhabiting
Population
the same area herd of pronghorn antelope
Fig. 1-1

9. Multicellular An individual living thing composed
Organism of many cells
pronghorn antelope
Organ Two or more organs working
together in the execution of
System a specific bodily function
the nervous system
A structure usually
Organ composed of several tissue
types that form a functional unit
the brain
A group of similar cells that perform
Tissue
a specific function
nervous tissue
Cell The smallest unit of life
nerve cell
Fig. 1-1

10. A structure within a cell that
Organelle
performs a specific function
mitochondrion chloroplast nucleus
Molecule A combination of atoms
water glucose DNA
The smallest particle of an element
Atom that retains the properties of
that element
hydrogen carbon nitrogen oxygen
Subatomic Particles that make up an atom
Particle
proton neutron electron
Fig. 1-1

11. If you put a plant in your window, the stem
will lean in the direction of the sun. This is
an example of which characteristic of life?
• Living things are organized.
• Living things respond to stimuli.
• Living things maintain homeostasis.
• Living things need energy.

12. Response to stimuli
Organisms react to external and
internal stimuli.
Some reactions are slow and can’t
be seen.

13. Our body works to keep our temperature at
about 98.6ºF. This is an example of which
characteristic of living things?
• Living things are organized.
• Living things respond to stimuli.
• Living things maintain homeostasis.
• Living things need energy.

14. Homeostasis
-the ability to maintain the structure and
regulate the internal environment.
In order to stay alive and function,
organisms must keep the
conditions within their bodies
fairly constant.

15. Ability to acquire material and energy
The material and energy are often
transformed .
Energy is used to maintain a high
level of complexity and
organization, to grow, and to
reproduce.

16. Organisms can take in nutrients (food) for
raw materials and energy (heterotrophs)
Or they can use sunlight for energy
(photosynthesis) to produce energy-
rich sugar molecules (autotrophs)

17. The word heterotroph means
“other-feeder” or:
• Able to photosynthesize.
• Able to make its own food.
• Must rely on other organisms for energy.
• Make its own energy.

18. Metabolism changes the raw material
and energy into the forms which are
needed for maintenance, growth,
reproduction, etc .
Metabolism is basically the sum total of
all of the chemical reactions that occur
within an organism.

19. Growth
All organisms grow during their life

20. Reproduction
Individuals reproduce their own kind.

21. The genetic information for “How to build an
offspring” is stored in the DNA of the parent(s)
and that information is passed on to the
offspring.
Fig. 1.6

22. Evolution
If the environment changes, then the
population of organisms must change
to fit the environment or face the
possibility of extinction.
This process of survival of the fittest is
natural selection

23. The evolutionary changes are usually slow,
taking several generations and occur by the
accumulation of DNA changes known as
mutations.

24. All life forms have these characteristics in
common, yet there is an amazing
diversity in the forms of life on the planet.

25. All living organisms are organized into
groups.
Each of the major organizational
groups are called domains

26. There are two prokaryotic domains;
Bacteria and Archaea and a eukaryotic
domain; Eukarya.
Fig. 1.11

27. In the figure, which organism is
most closely related to humans?
• Bacterium
• Protist
• Archaean
• Tree
Figure 1-11

28. Within the domains are at least 6 groups
known as kingdoms
Each kingdom has different attributes
which define them. (See table 1-1)

29. The first difference is cell type
PROKARYOTES EUKARYOTES
No nucleus or nuclear Nucleus with a nuclear
envelope envelope
Genetic material in a Genetic material within
“nucleoid region” the nucleus
No organelles or Contains cytosol with
internal membranes membrane-bound
organelles

30. Kingdom Cell Type
Bacteria Prokaryotic
Archaea Prokaryotic
Protista Eukaryotic
Fungi Eukaryotic
PlantaeEukaryotic
Animalia Eukaryotic

31. The next property is how many cells the
organism has
Single cell (unicellular) or many
cells (multicellular)

32. Kingdom Cell Type Cell Number
Bacteria Prokaryotic Unicellular
Archaea Prokaryotic Unicellular
Protista Eukaryotic Unicellular
Fungi Eukaryotic Multicellular
Plantae Eukaryotic Multicellular
Animalia Eukaryotic Multicellular

33. The third attribute in the classification of
organisms at the kingdom levels is how the
organism obtains nutrients/energy
Three basic methods
Make food using sunlight
- photosynthesis
Uptake of nutrients by absorption
Uptake by eating or ingestion

34. Kingdom Cell Type Cell Number Nutritional Method
Bacteria Prokaryotic Unicellular Absorp./photosyn.
Archaea Prokaryotic Unicellular Absorp./photosyn.
Protista Eukaryotic Unicellular Absorp./photosyn./ingestion
Fungi Eukaryotic Multicellular Absorption
Plantae Eukaryotic Multicellular Photosynthesis
Animalia Eukaryotic Multicellular Ingestion