Chapter 1Chapter 1Introduction: The Scientific Study of Introduction: The Scientific Study of

LifeLife

BiologyBiology: : The study of life.The study of life.

Greek origin:Greek origin:

BioBio: Life: Life

LogosLogos: Study of: Study of

I. Life is based on many structural levelsI. Life is based on many structural levels

Levels of biological organization:Levels of biological organization: AtomsAtoms Molecules Molecules Subcellular organellesSubcellular organelles CellsCells TissuesTissues** OrgansOrgans** Organ systemsOrgan systems** OrganismOrganism: May consist of a single cell or a : May consist of a single cell or a

complex multicellular organism.complex multicellular organism.* Level of organization not found in all organisms* Level of organization not found in all organisms

Levels of organization beyond organism:Levels of organization beyond organism:

PopulationPopulation: Group of organisms of the : Group of organisms of the samesame species species that interact with one another.that interact with one another.

CommunityCommunity:: Several different populations living Several different populations living together in same area (e.g.: lake, forest, jungle).together in same area (e.g.: lake, forest, jungle).

EcosystemEcosystem: Interactions of community with non-living : Interactions of community with non-living environment (air, water, soil).environment (air, water, soil).

EcosphereEcosphere: All ecosystems on planet earth. Includes: : All ecosystems on planet earth. Includes: • BiosphereBiosphere: All biological communities on earth.: All biological communities on earth.

• Atmosphere Atmosphere (air)(air)

• HydrosphereHydrosphere (water) (water)

• LithosphereLithosphere (crust) (crust)

Common features of all organisms:Common features of all organisms:1. Cells:1. Cells: Basic structural and functional unit of Basic structural and functional unit of

life. Genetic information contained in DNA.life. Genetic information contained in DNA.

2. Growth and Development:2. Growth and Development: Growth:Growth: Occurs by an increase in cell size, cell Occurs by an increase in cell size, cell

number, or both.number, or both. DevelopmentDevelopment: Changes that take place during an : Changes that take place during an

organism’s life.organism’s life.

3. Energy use and metabolism:3. Energy use and metabolism: All organisms must take in and transform energy to All organisms must take in and transform energy to

do work, to live.do work, to live. MetabolismMetabolism: All chemical reactions and energy : All chemical reactions and energy

transformations essential for growth, maintenance, transformations essential for growth, maintenance, and reproduction. and reproduction.

4. Regulation4. Regulation External environment may change, but internal External environment may change, but internal

environment remains fairly constant.environment remains fairly constant.• Homeostasis: Homeostasis: OOrganisms constantly strive to maintain a rganisms constantly strive to maintain a

“steady state” (e.g.: constant body temperature or blood pH) “steady state” (e.g.: constant body temperature or blood pH) despite changes in the internal and external environment.despite changes in the internal and external environment.

• Metabolism is regulated by Metabolism is regulated by homeostatichomeostatic mechanisms. mechanisms.

5. Movement:5. Movement: Internal movement: Characteristic of all life.Internal movement: Characteristic of all life. Locomotion: Self-propelled movement from point A to Locomotion: Self-propelled movement from point A to

point B. Not observed in all life forms.point B. Not observed in all life forms.

6. Respond to environmental stimuli6. Respond to environmental stimuli: Organisms : Organisms respond to internal and external changes (visual respond to internal and external changes (visual stimuli, temperature, light, sound, pressure, etc.).stimuli, temperature, light, sound, pressure, etc.).

7. Order: 7. Order: Organisms are highly organized, Organisms are highly organized, when compared to nonliving environment.when compared to nonliving environment.

8. Reproduction:8. Reproduction: Organisms come from other Organisms come from other organisms. Reproduction may be sexual or organisms. Reproduction may be sexual or asexual.asexual.

9. Evolutionary adaptation:9. Evolutionary adaptation: Populations, not Populations, not individuals, “evolve” or change over many individuals, “evolve” or change over many generations so they can survive in a changing generations so they can survive in a changing world.world.

The cell is the basic unit of lifeThe cell is the basic unit of life Lowest level of structure capable of Lowest level of structure capable of

performing all of life’s activitiesperforming all of life’s activities

All organisms are composed of cellsAll organisms are composed of cells

VIRUSES:VIRUSES: Not considered living organisms by Not considered living organisms by most biologists because they lack:most biologists because they lack:

• CellsCells

• Self-regulated metabolismSelf-regulated metabolism

May exist as May exist as unicellular unicellular or or multicellularmulticellular organismorganism

Comparison of Cells and Viruses

Charles Darwin (1809-1882)Charles Darwin (1809-1882)

Evolution Explains the Unity and Diversity of Life

Evolution is the core theme of biologyEvolution is the core theme of biology Charles DarwinCharles Darwin:: Wrote Wrote “On the Origin of “On the Origin of

Species by Means of Natural Selection” Species by Means of Natural Selection” (1859) (1859) in which he proposed the theory of evolution.in which he proposed the theory of evolution.

Evidence that led to the principle of evolution:Evidence that led to the principle of evolution:

FossilsFossils: Most species that ever existed are : Most species that ever existed are extinct; appear to be gradual progressionextinct; appear to be gradual progression

Artificial selectionArtificial selection of domestic/farm animals of domestic/farm animals

AdaptationsAdaptations: Organisms appear uniquely : Organisms appear uniquely suited to their environment (especially in suited to their environment (especially in Galapagos).Galapagos).

Darwin’s finches Darwin’s finches are a classic exampleare a classic example

The theory of evolution by natural selection:The theory of evolution by natural selection:

1. Genetic Variation:1. Genetic Variation: Due to genetic differences Due to genetic differences there is variation within a population (size, color, there is variation within a population (size, color, structure, etc.). These differences can be passed structure, etc.). These differences can be passed on to an individual’s offspring.on to an individual’s offspring.

2. Overproduction:2. Overproduction: Many more organisms are Many more organisms are born, than those that survive and reproduce.born, than those that survive and reproduce.

3. Limits on population Growth:3. Limits on population Growth: Limited Limited resources (food, water, space, sunlight, etc.) resources (food, water, space, sunlight, etc.) creates competitioncreates competition

4. Differential reproduction:4. Differential reproduction: Organisms with Organisms with features that help them compete will be more features that help them compete will be more likely to survive and reproduce.likely to survive and reproduce.

Natural Selection Changes Populations

Theory of evolution by natural selection:Theory of evolution by natural selection:

Consequences of natural selectionConsequences of natural selectionOver time, the characteristics of a population Over time, the characteristics of a population

will “evolve” and assume those features will “evolve” and assume those features that are “naturally selected”.that are “naturally selected”.

What is the heritable molecule with the What is the heritable molecule with the blueprints for the traits of an organism?blueprints for the traits of an organism?

DNA:DNA: Deoxyribose nucleic acid Deoxyribose nucleic acid

All life can be classified taxonomicallyAll life can be classified taxonomically TaxonomyTaxonomy: The branch of biology concerned : The branch of biology concerned

with naming and classifying organismswith naming and classifying organisms

Most Biologists Recognize Five Kingdoms:Most Biologists Recognize Five Kingdoms: Monera, Protista, Plantae, Fungi, and AnimaliaMonera, Protista, Plantae, Fungi, and Animalia

However, biologists have recently discussed a However, biologists have recently discussed a new classification system:new classification system:

Domain BacteriaDomain Bacteria Domain ArchaeaDomain Archaea Domain EukaryaDomain Eukarya

All life can be classified taxonomicallyAll life can be classified taxonomically

1. Kingdom Monera (Procaryotae): Most 1. Kingdom Monera (Procaryotae): Most widespread organisms. widespread organisms. Procaryotes (“Before nucleus”):Procaryotes (“Before nucleus”):

• Lack nuclear membrane around DNA.Lack nuclear membrane around DNA.

• Lack membrane bound organelles (mitochondria, Lack membrane bound organelles (mitochondria, chloroplast, golgi, endoplasmic reticulum).chloroplast, golgi, endoplasmic reticulum).

Unicellular: Single celled organisms.Unicellular: Single celled organisms. Have a cell wall.Have a cell wall.

Include: Bacteria.Include: Bacteria.

Kingdom Prokaryotae: Bacteria lack nucleus and membrane bound organelles

Five Kingdoms of Living World:Five Kingdoms of Living World:2. Kingdom Protista:2. Kingdom Protista:

Eucaryotes (True nucleus)Eucaryotes (True nucleus)::• Have nuclear membrane around DNA.Have nuclear membrane around DNA.

• Have membrane bound organelles (mitochondria, Have membrane bound organelles (mitochondria, chloroplast, golgi, endoplasmic reticulum).chloroplast, golgi, endoplasmic reticulum).

Unicellular or simple multicellular. Unicellular or simple multicellular. Most are larger and more complex than bacteria. Most are larger and more complex than bacteria. Some have cell walls, others don’t.Some have cell walls, others don’t. Some make their own food (Some make their own food (phothosyntheticphothosynthetic)), ,

others must eat other organisms.others must eat other organisms. IncludeInclude: Protozoa, algae, slime molds.: Protozoa, algae, slime molds.

Kingdom Protista: Eucaryotic Unicellular or Simple Multicellular Organisms

Five Kingdoms (Continued): Five Kingdoms (Continued): 3. Kingdom Fungi:3. Kingdom Fungi:

Most are multicellular. Most are multicellular. EucaryotesEucaryotes: :

• Have nuclear membrane around DNA.Have nuclear membrane around DNA.

• Have membrane bound organelles (mitochondria, Have membrane bound organelles (mitochondria, chloroplast, golgi, endoplasmic reticulum).chloroplast, golgi, endoplasmic reticulum).

Have cell walls.Have cell walls. HeterotrophsHeterotrophs: Obtain food from other organisms.: Obtain food from other organisms. Most are Most are decomposersdecomposers, which , which absorbabsorb food from food from

dead organisms.dead organisms. IncludeInclude: Mushrooms, yeasts, and molds.: Mushrooms, yeasts, and molds.

Five Kingdoms (Continued):Five Kingdoms (Continued):4. Kingdom Plantae:4. Kingdom Plantae:

Complex multicellular organisms. Complex multicellular organisms. Cellulose cell walls.Cellulose cell walls. EucaryotesEucaryotes: Have nuclear membrane around DNA : Have nuclear membrane around DNA

and membrane bound organelles.and membrane bound organelles. AutotrophsAutotrophs: Convert sunlight, water, and carbon : Convert sunlight, water, and carbon

dioxide into food through dioxide into food through photosynthesisphotosynthesis.. Other features:Other features:

• Waxy cuticle that prevents water loss.Waxy cuticle that prevents water loss.

• Multicellular sex organs.Multicellular sex organs.

• Openings in leaves and stems for gas exchange (stomata).Openings in leaves and stems for gas exchange (stomata).

IncludeInclude: Trees, flowering plants, and mosses.: Trees, flowering plants, and mosses.

Five Kingdoms (Continued):Five Kingdoms (Continued):5. Kingdom Animalia:5. Kingdom Animalia:

Complex multicellular organisms. Complex multicellular organisms. Lack cell walls.Lack cell walls. EucaryotesEucaryotes: Have nuclear membrane around DNA : Have nuclear membrane around DNA

and membrane bound organelles.and membrane bound organelles. HeterotrophsHeterotrophs: Obtain chemical energy from living : Obtain chemical energy from living

sources. Eat other organisms for nourishment.sources. Eat other organisms for nourishment. Features of complex animals:Features of complex animals:

• High degree of tissue specialization and body High degree of tissue specialization and body organization.organization.

• Locomotion.Locomotion.

• Well developed sense organs, nervous system, and Well developed sense organs, nervous system, and muscles.muscles.

IncludeInclude: Sponges, worms, insects, and vertebrates.: Sponges, worms, insects, and vertebrates.

Interdependence of Biological GroupsInterdependence of Biological Groups1. Producers or Autotrophs1. Producers or Autotrophs::

Self-nourishing organisms (plants, algae, etc.). Self-nourishing organisms (plants, algae, etc.). Produce food from simple raw materials.Produce food from simple raw materials. Most carry out photosynthesis:Most carry out photosynthesis:

COCO22 + H + H22O + Sunlight -----> Food + OxygenO + Sunlight -----> Food + Oxygen Depend on nonproducers for carbon dioxideDepend on nonproducers for carbon dioxide

2. Consumers2. Consumers Mainly animals.Mainly animals. Heterotrophs that obtain food directly or indirectly Heterotrophs that obtain food directly or indirectly

from producers.from producers. Carry out cellular respiration:Carry out cellular respiration:

Food + Oxygen -----> COFood + Oxygen -----> CO22 + H + H22O + ENERGYO + ENERGY

Gas exchange between producers and consumers helps Gas exchange between producers and consumers helps maintain balance of life-sustaining gases in atmosphere.maintain balance of life-sustaining gases in atmosphere.

Interdependence of Biological SystemsInterdependence of Biological Systems3. Decomposers3. Decomposers::

Some bacteria, fungi, and animals. Some bacteria, fungi, and animals. Recycle nutrients by breaking down products and Recycle nutrients by breaking down products and

bodies of dead organisms.bodies of dead organisms. Process is vital because makes nutrients available Process is vital because makes nutrients available

for use by other organisms.for use by other organisms.

All organisms All organisms interactinteract with each other and with each other and the the environmentenvironment they live in. they live in.

Interactions betweenInteractions between producers, producers, consumers, consumers, andand decomposers decomposers are essential are essential to maintain proper conditions for life on to maintain proper conditions for life on earth.earth.

Relationships Between Producers, Consumers, and Decomposers

Nutrient Cycling and Energy Flow in an Ecosystem

SCIENCE AS A METHOD OF INVESTIGATION SCIENCE AS A METHOD OF INVESTIGATION

Scientia (Latin):Scientia (Latin): To know To know

Science is a systematic way of thinking, answering Science is a systematic way of thinking, answering questions, and solving problems.questions, and solving problems.

Steps of scientific method:Steps of scientific method:

1. Observations1. Observations

2. Question2. Question

3. Hypothesis3. Hypothesis

4. Predictions4. Predictions

5. Test predictions (5. Test predictions (ExperimentsExperiments))

Results of experiments may:Results of experiments may: Support (but not prove) hypothesisSupport (but not prove) hypothesis Disprove hypothesis -----> Change hypothesis.Disprove hypothesis -----> Change hypothesis.

Scientific method (Continued):Scientific method (Continued):

Hypothesis:Hypothesis: Proposed explanation for observationsProposed explanation for observations An “educated guess”, should be consistent with established factsAn “educated guess”, should be consistent with established facts Capable of being tested, should generate predictions.Capable of being tested, should generate predictions. Falsifiable, may be proven false (but not proven true).Falsifiable, may be proven false (but not proven true).

Variables in an ExperimentVariables in an Experiment Dependent VariableDependent Variable: What a scientist measures.: What a scientist measures. Independent variableIndependent variable: What a scientist controls or manipulates.: What a scientist controls or manipulates. Standardized variablesStandardized variables: What remains the same throughout : What remains the same throughout

experiment. E.g.: Age, sex, race, nutrition, health, etc.experiment. E.g.: Age, sex, race, nutrition, health, etc.

Control Treatment:Control Treatment: Independent variable is eliminated or set at a standard value.Independent variable is eliminated or set at a standard value.

Levels of TreatmentLevels of Treatment Values set for the independent variable.Values set for the independent variable.

Scientific method:Scientific method:

ReplicationReplication Experiments are repeated numerous times.Experiments are repeated numerous times. Consistent results increases confidence in results.Consistent results increases confidence in results. Sample sizeSample size: Larger sample sizes are generally better.: Larger sample sizes are generally better.

Theory:Theory: Hypothesis supported by a large body of observations and Hypothesis supported by a large body of observations and

experiments.experiments. Good theories relate previously unrelated facts and grow as new Good theories relate previously unrelated facts and grow as new

information is obtained.information is obtained.

Principle:Principle: A theory that over time has yielded true predictions.A theory that over time has yielded true predictions. Almost universally accepted.Almost universally accepted.

Law:Law: A principle of great basic importance.A principle of great basic importance. Law of gravity or biogenesis.Law of gravity or biogenesis.

Biology is connected to our lives in many Biology is connected to our lives in many waysways Birth, development, reproduction, aging, and Birth, development, reproduction, aging, and

deathdeath Disease and infectionsDisease and infections Human populationHuman population Nutrition & exerciseNutrition & exercise AgricultureAgriculture Biodiversity and endangered speciesBiodiversity and endangered species Genetic engineering and reproductive technologyGenetic engineering and reproductive technology Pollution and environmentPollution and environment