What is Life?What is Life?

Characteristics Characteristics

OfOf

Living ThingsLiving Things

OrganismsOrganisms• Any living thingAny living thing

All Living Things:All Living Things:

•Have cellular organizationHave cellular organization

•Contain similar chemicalsContain similar chemicals

•Use energyUse energy

•Grow and developGrow and develop

•Respond to the environmentRespond to the environment

•ReproduceReproduce

Cellular Cellular OrganizationOrganization•Unicellular-single celled Unicellular-single celled

organisms such as bacteriaorganisms such as bacteria

•Multicellular-organisms Multicellular-organisms which are composed of which are composed of many cellsmany cells

UnicellularUnicellular

MulticellularMulticellular

Chemicals of LifeChemicals of Life

•Water-H2OWater-H2O

•Carbohydrates-sugarsCarbohydrates-sugars

•ProteinsProteins

•Lipids-fatsLipids-fats

•Nucleic Acids-DNANucleic Acids-DNA

Energy UseEnergy Use

•All living things use energy All living things use energy for growth and cell repairfor growth and cell repair

•Energy is used for work-for Energy is used for work-for example digesting food, example digesting food, pumping blood and pumping blood and exchanging gases (breathing)exchanging gases (breathing)

Growth and Growth and DevelopmentDevelopment

•Growth is the process of Growth is the process of becoming largerbecoming larger

•Development is the process Development is the process of change that occurs during of change that occurs during an organism’s life-such as an organism’s life-such as healing and specializationhealing and specialization

Response to Response to EnvironmentEnvironment• Stimulus-a Stimulus-a

change in an change in an organisms organisms environment that environment that causes an causes an organism to react organism to react (such as changes (such as changes in temperature, in temperature, light sound, etc.)light sound, etc.)

• Response-an Response-an action or change action or change in behavior in behavior (such as (such as flinching, flinching, shivering, a shivering, a plant bending plant bending toward the light)toward the light)

ReproductionReproduction

•Producing offspring that are Producing offspring that are similar to the parent similar to the parent organisms (birds lay eggs, organisms (birds lay eggs, plants make seeds, bacteria plants make seeds, bacteria divide into two exact replicas divide into two exact replicas of the original bacteria)of the original bacteria)

Life Comes From LifeLife Comes From Life

• Spontaneous generation- the Spontaneous generation- the mistaken idea that living things arise mistaken idea that living things arise from nonliving thingsfrom nonliving things

• Francesco Redi-designed a controlled Francesco Redi-designed a controlled experiment to disprove spontaneous experiment to disprove spontaneous generationgeneration

• Louis Pasteur-designed an Louis Pasteur-designed an experiment to show that experiment to show that microorganisms live in the airmicroorganisms live in the air

Francesco Redi’s Francesco Redi’s ExperimentExperiment• Redi Placed meat in jars, one was left Redi Placed meat in jars, one was left

uncovered and one was covered with clothuncovered and one was covered with cloth• He left the jars out for a few daysHe left the jars out for a few days• The jar that was left open had maggotsThe jar that was left open had maggots• The jar that was covered didn’t have any The jar that was covered didn’t have any

maggotsmaggots• He concluded that the flies he had seen He concluded that the flies he had seen

had laid eggs on the meathad laid eggs on the meat• His experiment helped to disprove His experiment helped to disprove

spontaneous generationspontaneous generation

Louis Pasteur’s Louis Pasteur’s ExperimentExperiment• Pasteur placed broth in two flasks which Pasteur placed broth in two flasks which

had curved necks which allowed air to had curved necks which allowed air to enter but not bacteria in the airenter but not bacteria in the air

• He boiled one flask but not the other oneHe boiled one flask but not the other one• The flask which had been boiled remained The flask which had been boiled remained

clear, but the other one spoiledclear, but the other one spoiled• His experiment showed not only that His experiment showed not only that

bacteria is everywhere, but also that bacteria is everywhere, but also that boiling can kill most bacteria and that boiling can kill most bacteria and that bacteria only form when other bacteria are bacteria only form when other bacteria are presentpresent

EnergyEnergy

•Autotrophs-organisms, such Autotrophs-organisms, such as plants, which can make as plants, which can make their own foodtheir own food

•Heterotrophs-organisms that Heterotrophs-organisms that cannot make their own food, cannot make their own food, they have to ingest foodthey have to ingest food

AutotrophsAutotrophs

HeterotrophsHeterotrophs

WaterWater

•All living things need waterAll living things need water

•Water is able to dissolve Water is able to dissolve more chemicals than any more chemicals than any other substance on earthother substance on earth

•Makes up 92 percent of your Makes up 92 percent of your body weightbody weight

HomeostasisHomeostasis

•The maintenance of stable The maintenance of stable internal conditions despite internal conditions despite changes in its surroundings changes in its surroundings (like sweating when your hot, (like sweating when your hot, shivering when your cold, or a shivering when your cold, or a plant which goes dormant in plant which goes dormant in the winter)the winter)