Characteristics of
Life
Essential Questions:
What are the major characteristics of life?
How do we determine if something is living or non-living?
How can we organize this data to help us in our study of
biology?
Explore: The Biology Song!
• Watch the short YouTube video called “The Biology
Song.” (Why is it called the biology song?)
• Record any descriptions you see/hear about what
makes something living or a living organism.
• The Biology Song
Write your ideas in
The box on your
Notes sheet.
1. Composed of Cells
• All living things are composed of one
(unicellular) or more (multicellular)
cells.
• This leads to levels of organization in
more complex living things…
–
–
–
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Cells are organized into tissues.
Tissues are organized into organs.
Organs are organized into organ systems.
Organ systems comprise an Organism!
• Organism – Displays all characteristics of
life and considered by biologists to be
alive.
2. Require Energy
• Living organisms require energy; in
the most basic form of ATP.
– Obtained through the breakdown of
food and nutrients. (Heterotrophs)
– Obtained through inorganic sources
(Photosynthesis, Chemosynthesis)
– Obtained through “stealing” ATP from
other organisms. (Microorganisms)
• This energy is used to carry out
cell/life functions: metabolism,
locomotion, growth/development
or cell division, etc.
3. Reproduce
• All living things reproduce to carry on their
species.
• Some plants and bacteria reproduce
individually via asexual reproduction.
– Upon maturity split into two organisms
(budding).
– Offspring are genetically identical to parent.
• Some plants and animals reproduce
through another member of their species
via sexual reproduction.
– Upon maturity exchange eggs and sperm
(externally or internally) to create 1 or more
offspring.
– Offspring are not genetically identical to
parent/s: a unique blend of recombined DNA.
– May or may not have parental care
depending on reproductive strategy.
4. Display Heredity
• Living organisms inherit
traits from their parent(s)
via DNA and/or RNA.
• DNA/RNA are the codes or
sequences that get
translated into all types of
proteins.
• These are found
in the nucleus of
eukaryotic
organisms.
5. Respond to Stimuli
• living things respond to changes in light,
heat, sound, and chemical and
mechanical contact.
• To detect stimuli, many organisms have
means for receiving information, such as
skin, eyes, ears, and taste buds (the
sensory organs)
• Once a stimulus has been received by
the organism, that triggers a response.
– Lower organisms (lacking complex sensory
organs) undergo types of taxis.
• Phototaxis, Hydrotaxis, Chemotaxis, Geotaxis,
Thigmotaxis, Magnetotaxis, etc.
– Higher organisms (with complex sensory
organs) undergo behaviors often using
chemical messengers (called hormones.)
• Conditioning, Imprinting, Insight learning, etc.
6. Adapt to their Environment
• Organisms and Species adapt to
their environment in order to
survive.
• Adaptation occurs to best suit
the habitat, and may or may
not be reversible.
– Add fat/fur in the wintertime.
– Changing coat colors to elude
predators.
– Learned behaviors to avoid harm.
7. Maintain Homeostasis
• All organisms maintain a stable internal balance, also known as homeostasis.
• This ensures that body systems work at their best levels.
– Temperature, pH, Water/Osmotic Pressure, Salt balance
• This is accomplished by various types of feedback loops.
– Positive Feedback loop: accelerates or enhances the output created by a stimulus that
has already been activated.
• Blood clotting, Oxytocin release during birth
– Negative Feedback loop: reducing the output or activity of any organ or system back to
its normal range of functioning
• Shivering/Sweating, Blood Pressure
8. Evolve (over time)
• All organisms as a population (not
individually) evolve to the changing
environment over time.
• Occurs via changes in DNA
sequences (mutations) that code for
proteins (known as traits)
– Those with beneficial mutations will
survive and reproduce in the
changing environment and pass
them on to future offspring.
– Those without beneficial mutations
will not survive and not reproduce in
the changing environment.
Example: Antibiotic resistant bacteria!
Reflect: The Biology Song!
• Re-watch the short
YouTube video called
“The Biology Song.”
• Did you hear anything
different this time?
• Why is it called the
Biology song?
• The Biology Song
What am I? Living or Non-Living?
• In the following slides, you will see a picture of an
object.
– Observe the object. (Quantitative and Qualitative)
– Feel free to ask questions about the object.
• Identify the aspect of living things it represents.
– (Remember, it must meet all criteria to be considered
a living organism!)
• Determine if it is Living or Non-Living!
…We’ll start of easy…
What am I?
What am I?
What am I?
What am I?
What am I?
What am I?
What am I? (Super Tricky)
Protocell Circus - Video
Your Turn! Mind Mapping
• To conclude today,
you will create a
bubble map on the
back of your notes.
• Flip over and look
at the diagram.
Describe the 8
major
characteristics of
life.