Section 1 : The World of Biology
 Biology- the study of life
 How is biology important to a person’s daily
life and to human society?
Knowledge of biology allows us to make informed
decisions and know about our health, technology, the
food we eat, pollution, diseases, and the environment.
Characteristics of Life
 1. Organization and Cells
 2. Response to Stimuli
 3. Homeostasis
 4. Metabolism
 5. Growth and Development
 6. Reproduction
 7. Change Through Time
1. Organization and Cells
 Organization- the high degree of order within an
organism’s internal and external parts and in its
interactions with the living world
 Organs- structures that carry out specialized jobs
within an organ system; made of tissues
Tissues- groups of cells that have similar abilities
Cell-the smallest unit that can perform all life’s
processes
 Organelles- tiny structures that carry out functions necessary
for the cell to stay alive
Examples: mitochondria &
Golgi Apparatus
Biological molecules- the chemical compounds that
provide physical structure and enable other cellular
functions and biological molecules are made of
ATOMS
Organization also includes:
Unicellularity-
Multicellularity-
 Single-celled
 More than one cell
2. Response to Stimuli
 An organism’s response to a stimulus (a physical or
chemical change in the environment)
 Examples: pupil dilation in response to bright light
What are some other examples of an
organism responding to a stimulus?
3. Homeostasis
 Homeostasis- the maintenance of a stable level of
internal conditions even though environmental
conditions are constantly changing.
 Examples: burning calories to stay warm
:Birds fluffing up feathers to
keep warm
4. Metabolism
 Metabolism- the sum of all the chemical reactions
that take in and transform energy and materials from
the environment; getting energy from the food we eat
 Or……………….
photosynthesis
5. Growth and Development
 *All living things grow and increase in size.
 Growth in living things occurs by cell division and
not accumulation of matter such as occurs in crystals
 (nonliving)
 Development- the process by which an organism
becomes a mature adult
6. Reproduction
 Producing offspring
 *NOT essential to the survival of an individual
 DNA transmits heredity information from parent to
offspring
 Gene- a short segment of DNA that contains the
instructions for a single trait of an organism
 Why is reproduction an important
characteristic of life?
 *Reproduction is essential to the continuation of a
species*
Types of Reproduction
Asexual
Sexual
 One parent; produces identical
 2 parents produce offspring
offspring
 Ex. bacteria
that contain genetic material
from both parents; a different
individual
7. Change Through Time
Evolution- changes in a
The ability of populations
population over time
of organisms to change
over time is important for
survival in a changing
world.
Also, it explains the
diversity of life-forms
found on earth today.