What is life?
Prentice Hall: Life Science
(2005), pp. 34-41
Objective(s): I can
List the characteristics all
living things share.
Explain where living things
come from.
Identify what all living
things need to survive.
Key terms
Organism
Development
Cell
Unicellular
Spontaneous
generation
Multicellular
Autotroph
Stimulus
Heterotroph
Response
Homeostasis
Key Concepts
What characteristics do
all living things share?
What do living things
come from?
What do living things
need to survive?
Introduction
Organisms are living things.
Organisms include: plants,
dogs, sharks, sting rays,
moss, bacteria, humans,
worms, spiders, etc.
Living things in an
environment are also
referred to as biotic factors.
The Characteristics
of
Living
Things
Living things share important
characteristics.
Characteristic- a feature or
quality that makes somebody
or something recognizable
All living things have a cellular
organization, contain similar
chemicals, use energy, respond
to their surroundings, grow and
develop, and reproduce.
Cellular Organization
All organisms are made of small building
blocks called cells.
Cells are the basic units of structure and
function in all living things.
Unicellular = one celled organism
Multicellular = hundreds to trillions of cells
working together
Cells are the
building blocks of life.
The Chemicals of Life
Carbohydrates
C, H, O
Provide energy
Water
Proteins
Chemical
Reactions
Build & repair
cells
H, O
Most
abundant
Organism
Lipids
Mostly C, H
Fats & Oils
Store energy
Nucleic Acids
Transfer genes
Produce
proteins
Living things obtain and
use energy
Energy is the ability
to do work and cause
change
• Walking
•Talking
•Thinking
•Breathing
All require
energy!
•Playing
•Studying
Where do living organisms get
their energy?
Response to environment
Organisms respond to the
environment around them. What
are some common responses to
your environment?
Stimulus: A
change in the
environment
that occurs and
causes a
reaction.
Response: The
way an organism
reacts to the
stimulus
Growth and Development
Growth is the process of
becoming larger.
Development is the
process of change that
occurs during an organism’s
life to produce a more
complex organism.
Living things all grow and change.
Whether talking about a person or a
tree changes will take place as long
as the organism is alive.
Reproduce
Asexual Reproduction: single
organism reproduces without the
aid of another
Sexual Reproduction: two cells
from different individuals unite to
produce the first cell of the new
individual
All organisms must
reproduce-offspring are
the result of
reproduction.
Eliminate Waste
An organism may not
use all the nutrients from
their energy sources.
The excess materials are
eliminated/removed from
the organism.
Life comes from Life
 Living things arise from living things
through reproduction.
 At one time people believed that life could
appear from nonliving material.
 This mistaken idea that living things can
arise from nonliving sources is called
spontaneous generation.
 It took hundreds of years to convince
people that spontaneous generation does
not occur.
http://www.dreamstime.com/stock-photo-large-fly-on-a-wallimage10562960
Redi’s Experiment
• An Italian doctor
• Helped disprove
spontaneous
generation during
1600s
• Designed a
controlled
experiment to
show flies don’t
arise from
decaying meat
Pasteur’s
Experiment
• A French
Chemist
• Designed
controlled
experiments
that finally
rejected
spontaneous
generation in
the mide1800s
The Needs of Living Things
Though surprising, flies, bacteria,
and all other living things have the
same basic needs as you.
All living things must satisfy their
basic needs for water, food, living
space, substances found in air, and
stable internal conditions.
Water
All living things need water to
survive.
Most organisms can live for
only a few days without water.
Organisms need water to obtain
chemicals from their
surroundings, break down food,
grow, move substances within
their bodies, and reproduce.
http://www.hickerphoto.com/waterfall-pictures-4109-pictures.htm
Food
Organisms need a source of energy
to live.
Food is used as the energy source.
Some organisms, such as plants,
capture the sun’s energy and use it
to make food.
Organisms that make their own food
are called autotrophs. Auto- means
“self” and –troph means “feeder.”
Food
Organisms that cannot make their own
food are called heterotrophs. Heteromeans “other.”
Heterotrophs obtain their energy by
feeding on others.
Some heterotrophs eat autotrophs and use
the energy I the autotroph’s stored food.
Other heterotrophs consume heterotrophs
that eat autotrophs.
Therefore, heterotroph’s energy source is
also the sun- but in an indirect way.
Living Space
All organisms need a living space- a
place to get food and water and find
shelter.
Whether an organism lives in the
freezing Antarctic or the scorching
desert, its surrounding must provide
what it needs to survive.
Because there is a limited amount of
space on Earth, some organisms
must compete for space.
Stable Internal Conditions
Organisms must be able to keep the
conditions inside their bodies stable,
even when conditions in their
surroundings change significantly.
The maintenance of stable internal
conditions is called homeostasis.
Homeostasis keeps internal
conditions just right for cells to
function.
Stable Internal Conditions
Think about your need for water
after a hard workout.
When water levels in your body
decrease, chemicals in your body
send signals to your brain,
causing you to feel thirsty.
Other organisms have different
mechanisms for maintaining
homeostasis.
Homeostasis
Summary
All living things share common
characteristics.
All living things have basic
needs in order to survive.
Redi and Pasteur designed
experiments to disprove
spontaneous generation.
Life comes from life.