Chapter 2.1 : What is Life
Characteristics of Living
Things
(Things that all living organisms share)
1. Cellular Organization
Cell: The basic unit of
structure and function in
living things, a membrane
covered structure that
contains all materials
necessary for life.
Organisms are made up
of either one cell
(unicellular) or more
than one cell
(multicellular)
Though cells perform some of the same
functions, cells do not all look the same
2. Chemicals of Life
All living things are composed of various chemicals
such as carbohydrates, proteins, lipids, and nucleic
acids (DNA)
3. Energy Use
- Organisms use energy to carry out the activities
of life which include making food, breaking down
food, building cells, etc.
Metabolism: The total of all chemical activities
that an organism performs
4. Response to Surroundings.
Stimulus: A change in an organism’s
environment that changes the organism’s
activity, which is called the response.
Stimulus
Response
- scared/surprised
- fight or flight
- sight/sound of food
- bright light
- mouth waters
- pupil opening becomes
smaller
- shiver/put on a jacket
- cold temperature
Homeostasis: Maintenance of stable internal
environment by means of self-regulation.
ex. body temp, blood sugar
5. Growth and Development
- All organisms grow and develop
during periods of their lives.
Growth: increasing
the number or size of
cells
Development: passing
through different stages,
becoming more complex
(teenager to adult)
6. Reproduction
- Organisms produce other organisms like
themselves
Asexual Reproduction: A single parent
produces offspring identical to the parent
Pro’s:
Con’s
- Faster (more offspring in less time)
-- All
All of
of parent’s
parent’s genetics
genetics are
are passed
passed on
on
-- Offspring
genetically
Do not need
a mate identical to parent
Example: Hydra, Yeast, Liverwort
Sexual Reproduction: Usually requires two parents
to produce offspring. Offspring are a combination of
the parents’ traits. (most organisms reproduce by
this method)
Con’s:
Pro’s:
- Requires
Populationa is
mate/not
diverse all
because
males reproduce
offspring share
and they
genetics
waste
resources
from both parents
- Takes
Some a
oflot
theofpopulation
energy/time
should survive
-environmental
Wastes half ofchange
parents(variability)
genes
Life Comes From Life
It may seem obvious to
us now that living things
arise from living things
through reproduction
(biogenesis), but that was
not always the case.
Spontaneous generation : The idea that life could
arise from nonliving sources.
Flies came from rotting meat.
Mice came from cloth and grain.
Francesco Redi and
Louis Pasteur conducted
experiments that finally
convinced people that
spontaneous generation
did not occur.
The Needs of
Living Things
1. Food:
Food provides organisms with the
energy and raw materials to carry out
life activities
Auto troph (producers) Organisms that produce
their own food. (ex. plants)
self
feed/nourish
Photosynthesis Equation
Water + Carbon Dioxide + Sun Energy
Food (Glucose) + Oxygen
Heterotroph:
other
Organisms that rely on other organisms
for food
Consumer: eat(consume) other
organisms for food (ex. humans)
Decomposer: break down dead
organisms or waste to get food
(ex. fungus, bacteria)
2. Water
Required for the chemical reactions of metabolism
Living things are made up of about 70% water
Humans can go about 3 days without water, we get
water from both fluids and foods
3. Air
Organisms require gasses found in the air
ex. Oxygen is needed for respiration
carbon dioxide is needed for photosynthesis
4. Living Space
Organisms require space in which to live. The
size of the space differs with the size and needs
of the organism
Chapter 2.2
Classifying Organisms
Classification:
Arrangement of organisms into orderly groups
based on similarities. Classifying organisms makes
it easier for people to study and answer questions
about the organism
Taxonomy:
Science of identifying, classifying, and naming
living things.
Aristotle (384-322 B.C.)
• Greek philosopher
and scientist.
• Classified living
things into two
broad categories of
plants and animals
based on such
things as where
they lived and size.
Swedish
botanist/physician who
The naming system is called
created a new system
binomial Nomenclature (two
of classification
Names)
(1750s) that still is
used today.
Linnaeus categorized
organisms based on
shared characteristics,
and he gave each animal
a unique two-part
scientific name.
Scientific Names
But
Scientists
each ofuse
these
scientific
“robins”
names to
has
identify
a unique
scientific
organisms
name
to avoid
that
sets
confusion
it apart
and
from
mistakes
the
others.
caused by language
differences.
The common name
“robin” is used in
different parts of the
world to describe
different species.
This could lead to
confusion.
The scientific name has two parts, the genus and species.
The scientific name is given in Latin because it is a dead
language and will not change meaning over time.
Example:
Elphus maximus (scientific name
is italicized or underlined)
genus species - The genus name is
capitalized and the species begins
with a lower case letter
Levels of Classification
Organisms are put into a series of groups that are
progressively more exclusive.
1. Kingdom
Largest
2. Phylum
3. Class
4. Order
5. Family
6. Genus
7. Species
Smallest
Taxonomy in Action : Let’s take a look at how this
group of organisms is sorted by the classification
levels
Kingdom Animalia : contains all the different phyla
of animals
Phylum Chordata: contains animals with a hollow
nerve cord
Class Mammalia : contains animals that have a
backbone and nurse their young
Order Carnivora : contains animals with a backbone,
that nurse their young, and whose ancestors had special
teeth for tearing meat.
Family Felidae : contains animals with a backbone,
that nurse their young, have well developed claws and
teeth for tearing meat, and are cats
Genus Felis : contains animals with a backbone, that
nurse their young, have well developed claws and teeth
for tearing meat, are cats, and cannot roar-only purr.
Species Felis domesticus : contains only one kind of
animal, the common house cat. It has all the
characteristics of all the levels above it, but it has other
unique characteristics
Domains and Kingdoms
A three-domain system is commonly used to
classify organisms. Organisms are placed into
domains and kingdoms based on their cell type,
their ability to make food, and the number of
cells in their bodies.
Domains
Bacteria
Kingdoms Eubacteria
Archaea
Eukarya
Archaeobacteria
Animalia
Plantae
Fungi
Protista
Dichotomous Key: Specialized guides used to aid in the identification
of an unknown species.
Step 1:
MAKE OBSERVATIONS
• Make sure they are observations, not
inferences (color, child/adult…).
• Make similar observations on each specimen
so you can compare them.
• Divide your sheet into a grid for easy reading.
Step 2:
Make a Web
The object has
three sides
The object does not
have three sides
The object
has 3
equal angles
The object
does not
have 3
equal angles The object
is blue.
What could you ask here?
The object
is not blue.
Dichotomous Key: Specialized guides used to aid in the identification
of an unknown species.
Step 3: Make a dichotomous key