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Biology = study of life

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Why is Biology Important to You?

• Global Warming• Ozone Depletion• Air & Water Pollution• Endangered Species• Acid Deposition• Non-renewable Resources• Overpopulation• Genetic Engineering• HIV/AIDS ………………………………..

Biology

Scientific study of life

Lays the foundation

for asking basic questions about

life and the natural

world

Why Study Biology?

• To learn how organisms are constructed, how they function, where they live, and what they do

• To help develop, modify, and refine ideas about life

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Life’s Underlying Unity

• Life’s organization extends from the molecular level to the biosphere

• Shared features at the molecular level are the basis of life’s unity

Levels of Organization

Atom

MoleculeCell

Tissue

Organ

Organ System

molecule

cell

tissue

organ

organ system

atom

Levels of Organization

Multicelled organism

Population

Community

Ecosystem

Biosphere

multicelledorganism

community

population

ecosystem

the biosphere

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Molecules of Life

• All things are made up of the same units of matter

• Living things are made up of a certain subset of molecules:– Nucleic acids– Proteins– Carbohydrates– Lipids

DNA (deoxyribonucleic acid)

• Signature molecule of life

• Molecule of inheritance

• Directs assembly of amino

acids

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DNA and Inheritance

• Inheritance– Acquisition of traits by way of

transmission of DNA from parent to offspring

• Reproduction – Mechanism by which an organism

produces offspring – Governed by instructions in DNA

Nothing Lives without Energy

Energy = capacity to do work

Metabolism = reactions by which cells acquire and use energy to grow, survive, and reproduce

Interdependencies among Organisms

ProducersMake their own food

ConsumersDepend on energy stored in tissues of producers

DecomposersBreak down remains and wastes

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Energy Flow

• Usually starts with energy from the sun

• Transfers from one organism to another

• Flows in one direction

• Eventually flows back to the environment

Producers

nutrient cycling

energy output(mainly metabolic heat)

energyinputfromsun

Figure 1.3Page 5

Consumers, Decomposers

Sensing and Responding

• Organisms sense changes in their environment and make responsesto them

• Receptors detect specific forms of energy (stimuli)

• Sensing and responding allows maintenance of homeostasis

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Unity of Life

All organisms– Consist of one or more cells– Have the capacity to reproduce based on

instructions in DNA – Engage in metabolism– Sense and respond to the environment

Study Skills

A = 4.0

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Lectures

• Listen, think and process• Take note of professor’s

“favorites” and “hints”• Use shorthand and abbreviations in

notes

Lectures

• Use tape recorder if necessary

• Make friends• Review, and mark unclear areas (>

15 min/lecture)

Time Management

• Prioritize your life

• Keep calendar of deadlines– note schedule crunches – study early (and mark it on the

calendar)

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Time Management

• Make use of all of your time– before classes begin– between classes

• Treat school like a job– take time off when necessary

Preparing for Exams

• Start early (> 1 week)• Use text book reading as a review

and refinement• Know layout of exam• ATTEND REVIEW SESSIONS

Preparing for Exams

• Remember professor’s “favorites” and “hints”

• Write prep exam questions and “practice”

• Teach someone else difficult topics

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Preparing for Exams

• Audio tapes• Flash cards

• Correct and review old exams for comprehensive preparation

Taking Exams

• Be mentally prepared• Go through exam, take a break, go

over exam again• Skip difficult ones 1st time through• Use entire exam time

Taking Exams

• Spend time on questions relative to their worth

• Try to answer every question• Ask professor to clarify questions

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Taking Exams

• Add extras to essays if possible

• Bring calculator• Neatness matters• Avoid scribbling!! Use erasable

pen or pencil (bring several)

Taking Exams

• Use complete sentences

• Discretely mark unknowns

• When “showing work”square/circle final answers

Making the Grade

• Freshman GPA is IMPORTANT!

• Record and track class grades throughout semester

• Determine grade necessary for each final exam and prioritize preparation time

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Life’s Diversity

• Millions of living species

• Millions more now extinct

• Each species has someunique traits

Classifying Life

DomainKingdom

PhylumClass

OrderFamily

GenusSpecies

Scientific Names

Two-part name– Humphead parrotfish is Scarus gibbus– First part (Scarus) is genus name– Second name designates a particular species

within the genus

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Classification Systems

• Organisms are grouped together based on descent from a shared ancestor

• Three domains exist:

Eubacteria(Bacteria)

Archaebacteria(Archaea)

Eukaryotes(Eukarya)

Origin of life

EubacteriaArchaebacteria

Eukaryotes

Protistans Plants Fungi Animals

Major Groups

• Single cells

• No nucleus • Smaller, less

complex• Archaebacteria,

eubacteria

Prokaryotic Organisms

Eukaryotic Organisms

• Single- or multicelled

• Nucleus• Larger, more complex• Fungi, protistans,

plants, animals

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Mutation: Source of Variation

• Mutation = change in structure of DNA

• Basis for the variation in heritable traits

• May be harmful, neutral, or beneficial

Evolution

• Heritable change in a line of descent over time

• Populations change, not individuals

Natural Selection • Individuals vary in some

heritable traits

• Some forms of heritable traits are more helpful under prevailing conditions

• Natural selection is an outcome of differences in survival and reproduction among individuals that vary in their traits

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Artificial Selection

• Breeders are selective agents

• Individuals exhibiting favoredtraits are bred

• Favored traits become morecommon in population

BiodiversityWhy is it Important?

• Diversity of genetic material = greater variety = greater adaptability to new conditions

• Biodiversity = foundation on which evolution operates

Evolution

• Charles Darwin (1859) – The Origin of Species• Change in the genetic makeup of populations over

time….change in the frequency of genes• gene: specific region of DNA which determines

the type of proteins to be made; --- DNA is a type of genetic material, passed on parent to offspring

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Descent with Modification

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Natural Selection vs.

Artificial Selection

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Scientific Evidence

• Fossil record

•Look at the fossil record…

Scientific Evidence

• Fossil record• Comparative anatomy of related species

– homologous features

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Scientific Evidence

• Fossil record• Comparative anatomy of related species

– homologous features• Similarity of developmental features

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Scientific Evidence

• Fossil record• Comparative anatomy of related species

– homologous features• Similarity of developmental features• Biogeography• Molecular comparisons• Experimental tests

What is Science?

• Common sense raised to a higher level and applied systematically

• A “way of knowing”• Observation-based…cannot “weigh-in-on”

supernatural phenomenon

Other “Ways of Knowing”

• Intuition• Belief/Faith/Religion• Arts/Philosophy

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Characteristics of Science

1) Guided by natural laws

2) Explained in reference to natural law

3) Things (results, conclusions) are falsifiable

4) Testable Data & Conclusions5) Regard findings & data as tentative results

Types of Science

1) Discovery Science

2) Hypothesis-Driven Science

Discovery Science

• Goal = find natural cause of natural phenomena; descriptions

• structure and process of observable things• e.g., mapping the human genome; finding

and describing a new species • relies on inductive reasoning• inductive reasoning: generalize after

many, many supporting findings

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Scientific Reasoning

• Induction: “…elementary my dear Watson….”

• Deduction: (hypothetico-deductive reasoning) = from general premise use “if..then” logic to make predictions

• If all organisms are made of cells ANDHumans are organisms, THENHumans are made of cells

Hypothesis-Driven Science

• Follows a set process (scientific method)• Relies on deductive reasoning• Relies on hypothesis formation &

experimentation

Process of Science

• Scientific method: means by which a scientist seeks to gain new knowledge or explain natural phenomenon

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Process of Science1) Observe a problem2) Recognize a problem3) State an hypothesis (tentative answer to

problem to which a prediction should follow)

4) Conduct an experiment (=test hypothesis)5) Postulate theory (a comprehensive

explanation for a pattern of broad scope based on large data set)

Fail to Reject

Reject

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Process of ScienceObservations

• snowberry flies mimics its predator = jumping spider

• Jumping spiders stalk flies & are highly territorial

Process of ScienceQuestion

• So what? …. Why would snowberry flies look like their predator?

Hypothesis

• Spiders avoid flies with spider markingsPrediction

• Flies with mimicry are attacked less than those without

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Why a Control Group?

• Allows honing into causative factors by reducing variance of other explanations

Experimental Design

• Control group – A standard for comparison– Identical to experimental group except for

variable being studied• Sampling error

– Nonrepresentative sample skews results– Can be minimized by using large samples

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Treatments

Treatmentstest theeffect of:

UntreatedZonosemata

Wing mark-ing plus wingwaving

Zonosematawith ownwings reglued

Operation

Zonosematawith housefly wings

Wing wavingbut no wing markings

Housefly withZonosematawings

Wing mark-ings but nowing waving

Untreatedhousefly

No wingmarking, nowing waving

Figure 1.11a

Process of Science

Hypothesis vs. Theory

* Gray wolves form packs to increase their efficiency in securing food.

* Pack formation in many species has evolved via natural selection.

Scientific Theory

• An explanation of the causes of a wide range of related phenomena

• Has wide-ranging explanatory power

• Still open to testing

• Example - Darwin’s theory of evolution by natural selection

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Limits of Science

• Scientific approach cannot provide answers to subjective questions

• Cannot provide moral, aesthetic, or philosophical standards

• May conflict with supernatural beliefs

Scientists Raise Questions

The external world, not internal conviction, must be the testing ground for scientific

beliefs