characteristics of life mrs. stewart honors biology i
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Characteristics of Life
Mrs. StewartHonors Biology I
Objectives Define life in terms of the scientific
characteristics that identify living organisms
Evaluate specimens for those characteristics
All living things are composed of cells that perform the necessary functions of life
Standard:
What is biology?
Bio logy
Life Study of
Define Life
Biologists have formulated a list of characteristics by which we can identify and classify living vs. non-living specimens
Characteristics of LifeCells and OrganizationHomeostasisResponse to StimuliMetabolismGrowth and DevelopmentReproductionChanges over time (adaptation)
***Organisms must have all seven characteristics in order to be considered alive***
Cells Basic units of structure
and function for all living things
Every organism consists of at least one cell
Organism = an individual that possesses all characteristics of life
Cells and Organization
Unicellular – made up of only one cell
Multicellular – consist of more than one cell
Levels of Organization - Living things have order and complexity not found in lifeless objects.
Living things are organized on several levels. Each level higher up on the hierarchy represents an increase in complexity.
Think – Pair - Share
Monkeys – summarize the heirarchy of organization found in complex organisms to your dog
Think – Pair - Share
Dogs – Both cells and organisms share the characteristics of life. Tell your monkey how cells and organisms different.
Response to stimuli Organisms respond to a stimuli in order
to maintain homeostasis Senses: make observations that lead to
responses
Reflexes: unconscious responses to
stimuli
Behaviors: learned and instinctive
responses to stimuli
Stimulus = a physical or
chemical change in the internal or
external environment.
LightTemperature
chemical
mechanical
Think – Pair – Share
Dogs Give an example of a reflex
response to stimuli
Monkeys Give an example of a
learned behavior response to stimuli
Homeostasis
Ability to maintain a stable internal environment
Examples: Heart rate Body temperature pH levels Water levels Others?
Homeostasis – body temperature explanation
Think – Pair – Share
Brainstorm together: why is homeostasis important for an organism’s survival?
Metabolism
The sum of all chemical reactions in the body
Some substances are broken down to yield energy and some substances are synthesized, which requires energy.
Metabolism (aka: energy use)
Organisms obtain energy by one of 2 methods:
Autotrophic – organisms that make their own food that they will then convert into energy (ex: photosynthesis)
Heterotrophic – organisms that must take in food from an outside source to convert into energy (examples???)
Growth
Growth occurs in two ways: 1) cell enlargement
– gets bigger 2) cell division
(reproduction) – cells split to produce more cells
Development
Development: process by which an organism becomes a mature adult through cell differentiation, or specialization.
Reproduction Process by which an organism produces
offspring
Asexual-One parent
-Genetically
identical offspring
(Examples:
budding & fission)
Sexual-requires 2 parents
-genetically different offspring
-sex cells from each
gender join
Heredity Living things
inherit traits from their parent(s)
Genes = basic unit of inheritance
DNA molecules contain genes that code for proteins which are important for proper functioning of an organism
Change through time
Adaptations – changes made by a population in response to the environment in order to survive.
Why do organisms adapt?
SURVIVAL
Assignment Characteristics of life Scavenger Hunt
Reflection - Exit Ticket Which of the 7 characteristics do you
think is the most important one to define life.
Explain your choice.