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The Science of LifeThe Science of Life

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Biology – The Study of LifeBiology – The Study of Life Life arose more

than 3.5 billion years ago

First organisms (living things) were single celled

Only life on Earth for millions of years

Organisms changed over time (evolved)

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New organisms arose from older kinds ( millions of species)

Inhabit almost every region of Earth today

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Themes of BiologyThemes of Biology Cell structure and

function Stability and

homeostasis Reproduction and

inheritance Evolution Interdependence of

organisms Matter, energy, and

organization

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Cell Structure and Cell Structure and FunctionFunction

Cell basic unit of life All organisms are

made of and develop from cells

Some composed of only a single cell (unicellular) Virtually identical

to parent

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CellsCells Most composed of

many cells (multicellular) Cells are different

(undergo differentiation)

Cells are small Cells are highly

organized

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Cells contain specialized structures (organelles) that carry out the cell’s life processes

Many different kinds of cells

All cells surrounded by a membrane

Contain a set of instructions (genetic information)

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Stability and Stability and HomeostasisHomeostasis

Maintain very stable internal conditions

Temperature, water content, chemical content, etc.

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Reproduction and Reproduction and InheritanceInheritance All organisms produce new

organisms like themselves Organisms transmit hereditary

information to their offspring (reproduction)

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DNADNA Information in the form

of DNA (Deoxyribonucleic Acid)

DNA contains instructions for traits (genes)

Make the structures and complex chemicals necessary for life

DNA in every body cell (somatic) is exactly alike

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Sexual ReproductionSexual Reproduction Hereditary information

from two parts of same organism or two different organisms of the same species are combined

Egg and sperm zygote (fertilized egg)

Zygote contains hereditary information from both parents

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Asexual ReproductionAsexual Reproduction Hereditary Hereditary

information from information from different organisms is different organisms is NOT combinedNOT combined

Resulting cells contain Resulting cells contain identicalidentical hereditary hereditary informationinformation

Genetic information Genetic information from from single parentsingle parent

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EvolutionEvolution Populations of

organisms change (evolve) over generations (time)

Explains how many different kinds of organisms came into existence

Explains how modern organisms are related to past organisms

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Explains why organisms look and behave the way they do

Provides a basis for exploring the relationships among different groups of organisms

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Natural SelectionNatural Selection Natural selection

is the driving force in evolution

Organisms that have certain favorable traits are better able to successfully reproduce than organisms that lack these traits

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Natural SelectionNatural Selection Survival of

organisms with favorable traits cause a gradual change in populations over many generations

Known as “descent with modification”

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Interdependence of Interdependence of OrganismsOrganisms

Interaction of organisms with one another and with their environment (Ecology)

Single species – observing individuals of the species and their interactions with each other and their environment

Multiple species – large ecological studies of environments and communities (ecosystems)

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All organisms need substances such as nutrients, water, and gases from the environment

The stability of the environment depends on the healthy functioning of organisms in that environment

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Matter, Energy and Matter, Energy and OrganizationOrganization Living things are highly organized Requires a constant supply of

energy to maintain their orderly state

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EnergyEnergy Almost all energy comes from the

sun (directly or indirectly) Photosynthesis is the process by

which some organisms capture the energy from the sun (solar) and transform it into energy (chemical) that can be used by living things

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AutotrophsAutotrophs Organisms that make

their own food are called autotrophsPhototrophs – use solar energy (photosynthesis) to get energy Convert H2O and CO2 into sugar and O2

Chemotrophs – use different chemical processes to get energy

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HeterotrophsHeterotrophs Organisms that must take in

food to meet their energy needs are called heterotrophs

Consume autotrophs (herbivores), other heterotrophs (carnivores) or both (omnivores) for their energy needs

Complex chemicals are broken down and reassembled into chemicals and structures needed by organisms

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The World of BiologyThe World of Biology

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Characteristics of LifeCharacteristics of Life

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Cells All living things are

composed of cells In multicellular

organisms many are specialized to perform specific functions

Cells are always very small

The size of multicelled organisms depends on the number of cells NOT their size

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Organization Organized at both the

molecular and cellular levels

Take in substances from the environment and organize them in complex ways

Specific cell structures (organelles) carry out particular functions

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In multicellular organisms, cells and groups of cells (tissues) are organized by their function Cells

tissues Tissues

organs Organs

systems

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Energy UseEnergy Use Use energy in a process called

metabolism Sum of all chemical processes

Require energy to maintain their molecular and cellular organization, grow and reproduce

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HomeostasisHomeostasis Maintain stable internal conditions

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GrowthGrowth Grow as the result of cell division

and cell enlargement Cell division is the formation of

two cells from a preexisting cell New cells enlarge as they mature

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The process by which an adult organism arise is called development Repeated cell divisions and cell

differentiation

DevelopmentDevelopment

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ReproductionReproduction All species have the ability to

reproduce and produce viable offspring. Not essential to survival of

individual but is essential for continuation of a species

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ResponsivenessResponsiveness Respond to stimuli in

the external environment

Detect and respond to changes in light, heat, sound and chemical and mechanical contact

Coordinates it’s responses

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EvolveEvolve Ability to adapt to their

environment through the process of evolution

Favorable characteristics are selected for and passed on to offspring

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Scientific MethodScientific Method

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ObservationObservation Employing your five senses to

perceive objects or events

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Asking a Question Based on observations; one or

more questions are generated

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HypothesizingHypothesizing Explanation for what you have

seen and recorded An educated guess Can be tested

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Forming a HypothesisForming a Hypothesis Statement is testable if evidence

can be collected that either does or doesn’t support it

Often must be revised if it is NOT supported by the testing data

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PredictingPredicting To test hypothesis it is necessary

to make predictions that logically follows from the hypothesis

A statement made in advance that states the results that will be obtained from testing the hypothesis

Often in the form of an “if-then” statement

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ExperimentingExperimenting Testing a hypothesis or prediction

by gathering data under controlled conditions – conducting a controlled experiment

Based on a comparison of a control group with an experimental group

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Both groups are identical except for one factor (independent variable)

Observations and measurements are taken for a particular factor (dependent variable) in both groupsDriven by or results from independent variable

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Collecting DataCollecting Data Includes any and

all information that scientist gather in trying to answer their questions

Includes all measurements & observations made during the experiment

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MeasuringInvolves quantitative data that can be measured in numbers

SamplingTechnique of using a sample – a small part – to represent the entire population

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Organizing DataOrganizing Data Involves placing observations and

measurement (data) in order Graphs, charts, tables, or maps

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Analyzing DataAnalyzing Data Collected and organized data must

be analyzed Process of determining whether

data are reliable or whether they support or do not support a hypothesis or prediction

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InferringInferring Conclusions made on the basis of

facts or premises rather than on direct observations Often drawn from data gathered

from a study or experiment and previous knowledge

Not directly testable

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Forming a TheoryForming a Theory A theory may be formed

after many related hypotheses have been tested and supported with experimental evidence

A broad and comprehensive statement of what is thought to be true

Supported by considerable evidence

Ties together related hypotheses

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CommunicationCommunication Share the results of

their studies with other scientists

Publish findings in journals or at scientific meetings

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CommunicationCommunication Sharing of information is

essential to scientific process Subject to examination and

verification by other scientists

Allows scientists to build on the work of others

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Microscopy and Microscopy and MeasurementMeasurement Microscopes – produce an enlarged

image of an object Used to study organisms, cells,

and cell parts Increase in apparent size is called

magnification The ability to show details clearly

is called resolution Microscopes vary in both

magnification and resolution

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Microscopes

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Light Microscopes Light Microscopes (compound)(compound) Specimen

mounted on a glass slide on stage

Must be thinly sliced or very small

Pair of lenses Ocular lens (eye

piece) – 10X Objective lens

(nose piece)

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Focusing a MicroscopeFocusing a Microscope On low power,

use the Coarse adjustment knob to focus

On high power, use the fine adjustment knob to focus

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Carrying and StorageCarrying and Storage Carry a microscope with one

hand on the arm & the other hand under the base

Store microscopes on low power, light off, slide removed, and covered

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Magnification determined by multiplying power of the ocular lens with the objective lens.

Low 4 x10=40Medium 10 x10=100High 40 x10=400

Maximum magnification is around 2000X for the best microscopes

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Electron MicroscopeElectron Microscope Transmission EM

Uses a beam of electrons to produce an enlarged image of very thinly sliced specimen on screen or photographic plate

Image focused by magnetic lenses

200,000X magnification Cannot be used to view

living specimens

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Scanning EMScanning EM 3D image Specimens not sliced

for viewing Surface sprayed with

fine metal coating Also uses electron

beam and fluorescent screen or photographic plates

100,000X magnification Cannot be used to view

living specimens

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Scientific Scientific MeasurementsMeasurements

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MeasurementsMeasurements Scientists use SI units or metric

system Based on units of ten

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Base Units of Measurement Length – Meter Volume – Liter Mass – Gram Time – Second Temperature - oC

Always read the Meniscus (bottom of the curve)

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Common Metric Prefixes Common Metric Prefixes used in Biologyused in Biology

Kilo- means 1000 Centi- means 1/100th

Milli- means 1/1000th

Micro – means 1/100,000th

Nano- means 1/100000000th

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Other Metric PrefixesOther Metric Prefixes

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