unifying themes of biologycell. nerve cell. tissue. nervous tissue. organ. brain. organelle....

UNIFYING THEMES OF BIOLOGY

Copyright © 2009 Pearson Education, Inc.

Cells are the structural and functional units of life

Two distinct groups of cells exist– Prokaryotic cells

– Simple and small

– Bacteria are prokaryotic

– Eukaryotic cells– Possess organelles separated by membranes

– Plants, animals, and fungi are eukaryotic


DNA(no nucleus)

Prokaryotic cell

Membrane

Eukaryotic cell

Nucleus(contains DNA)

Organelles

Cells are the structural and functional units of life (continued)

Unicellular organisms

Multicellular organisms


Cells are the structural and functional units of life (continued)

Form generally fits function– By studying a biological structure, you can determine

what it does and how it works (from molecules to organisms!)

– Life emerges from interactions of structures

– Combinations of structures (components) provide organization called a system


In life’s hierarchy of organization, new properties emerge at each level

Life’s levels of organization define the scope of biology Life emerges through organization of various levels With addition of each new level, novel properties

emerge—called emergent properties


Biosphere

EcosystemFlorida coast

CommunityAll organisms onthe Florida coast

PopulationGroup of brown

pelicans

Nucleus

Nerve

Spinal cord

CellNerve cell

TissueNervous tissue

OrganBrain

OrganelleNucleus Molecule

DNA

Atom

Organism Brown pelican

Organ systemNervous system

Brain

Reproduction and Inheritance

Organisms pass their traits from one generation to the next generation via reproduction.

DNA is the molecular basis of life (ALL life on Earth)

DNARNAProtein

The inheritance of genetic material through reproduction explains the continuity of life


Reproduction and Inheritance (continued)

Continuity of life is based on heritable information in the form of DNA DNA–the genetic

material–carries biological information from one generation to the next

EVOLUTION--THE CORE THEME OF BIOLOGY


“Nothing in biology makes sense except in the light of evolution.”

--Theodosius Dobzhansky

Evolution

Evolution explains the unity and diversity of life.

UnityWhat do organisms have in common?

Why do similarities exist?

DiversityAre there differences between organisms of the same

species?

Unity Shared genetic code

Evolutionary relationships

Connected through a common ancestor

Diversity Differences in DNA structure among organisms

Natural selection: selection of some DNA structures over others

Adaptations: naturally selected traits

Natural selection was inferred by connecting two observations Individuals within a population inherit different

characteristics and vary from other individuals

A particular population of individuals produces more offspring than will survive to produce offspring of their own

(Lamarckian evolution and giraffes)


Population with varied inherited traits1

Elimination of individuals with certain traits2

Reproduction of survivors3

In this example: • Dark-colored

beetles are selected for

• Light-colored beetles are selected against

• Predation is the selective agent

• Dark coloration becomes an adaptation for this population of beetles

Natural selection is an editing mechanism– It results from exposure of heritable variations to

environmental factors that favor some individuals over others

– Over time this results in evolution of new species adapted to particular conditions/environments

– Evolution is biology’s core theme and explains unity and diversity of life


The Three-Domain System

ProtistsPlantsFungiAnimals

Domain Eukarya

Kingdom AnimaliaKingdom Fungi

Archaea (multiple kingdoms)

Domain Archaea

Domain Bacteria

Bacteria (multiple kingdoms)

Protists (multiple kingdoms) Kingdom Plantae

Dr. R.M. Moody

YOU ARE HERE

THE PROCESS OF SCIENCE


Scientists use two main approaches to learn about nature

Two approaches are used to understand natural causes for natural phenomena– Discovery science—uses verifiable observations and

measurements to describe science

– Hypothesis-based science—uses the data from discovery science to explain science

– This requires proposing and testing of hypotheses


Scientists use two main approaches to learn about nature

There is a difference between a theory and a hypothesis– A hypothesis is a proposed explanation for a set of

observations

– A theory is supported by a large and usually growing body of evidence


With hypothesis-based science, we pose and test hypotheses

We solve everyday problems by using hypotheses– An example would be the reasoning we use to answer

the question, “Why doesn’t the flashlight work?”

– Using deductive reasoning we realize that the problem is either the (1) bulb or (2) batteries.

– The hypothesis must be testable

– The hypothesis must be falsifiable


Hypothesis #1:Dead batteries

Observations

Question

Hypothesis #2:Burned-out bulb

Hypothesis #1:Dead batteries

Hypothesis #2:Burned-out bulb

Prediction:Replacing batterieswill fix problem

Prediction:Replacing bulbwill fix problem

Test prediction Test prediction

Test falsifies hypothesis Test does not falsify hypothesis

BIOLOGY AND EVERYDAY LIFE


CONNECTION: Biology, technology, and society are connected in important ways

Many of today’s global issues relate to biology (science)– Many of these issues resulted from applications of

technology

– Science and technology are interdependent, but their goals differ

– Science wants to understand natural phenomena

– Technology applies science for a specific purpose


EVOLUTION CONNECTION: Evolution is connected to our everyday lives

How is evolution connected to our everyday lives?– It explains how all living species descended from

ancestral species– Differences between DNA of individuals, species, and

populations reflect evolutionary change

– The environment matters because it is a selective force that drives evolution

– An understanding of evolution helps us fight disease and develop conservation efforts


Individualvariation

Observations

Overproductionof offspring

Natural selection:unequal reproductive

success

Inferences

Evolutionof adaptationsin a population

Types of Inference (Reasoning)

INDUCTIVE INFERENCE: Arriving at a conclusion based on repeated observation. Repeated observation of the phenomenon supports

my hypothesis.

The sun came up yesterday and today, so I predict it will come up tomorrow.

Can only say that our conclusion is probablytrue.

Types of Inference (Reasoning)

DEDUCTIVE INFERENCE: Logical process of using accepted facts to draw conclusions. Expressed using syllogisms:

If A then B (Premise)A (Premise)

therefore, B (Conclusion)

Problem: If the premises are not true, then the conclusions might be wrong.

1. All men are mortal. Socrates is a man, therefore Socrates is mortal.

2. All mammals are warm-blooded. All dogs are warm-blooded. Therefore, all dogs are mammals.

3. All people sweat profusely after running a marathon. You are sweating a lot. Therefore, you must have just run a marathon.

Critical Thinking and Science

Critical thinking is the deliberate process of judging the quality of information before accepting it.

Critical thinking should be a part of your everyday life: When listening to the media

Surfing the internet

Listening to me, reading textbooks, etc.

HOWEVER: YOU MUST BE KNOWLEDGEABLE ABOUT A SUBJECT BEFORE YOU CAN EFFECTIVELY ARGUE OR DISCUSS IT!

Scientists use two main approaches to learn about nature:

Two approaches are used to understand natural causes for natural phenomena:– Discovery/observational science—uses verifiable

observations and measurements to describe natural phenomena (e.g., fossil record, astronomy, etc.)

– Hypothesis-based /Experimental science—uses the data from discovery science to explain natural phenomena.

– This requires proposing and testing hypotheses

Hypotheses

A HYPOTHESIS is a testable explanation for a natural phenomenon.

Hypotheses are:

Formed based on observation and current theory.

“Rejected” or “Not rejected”, never “Proven”

*Hypotheses guide the design of experiments*

Often stated as an “If…then…” statement

Example: Effects of fertilizer and light on plant growth

The Scientific Method: Testing Hypotheses Explore a phenomenon & make observations Construct a question to investigate based on your observations Construct a hypothesis State a prediction based on the evidence Plan and test the hypothesis with an experiment Analyze the data and evidence Form a conclusion based on your results and construct new knowledge

Was the hypothesis rejected or supported? Form an explanation (model) based on your conclusions and

supporting evidence Connect your new knowledge to your prior knowledge and the

knowledge of others (existing theories) Consider follow-up questions for investigations

Theories and Laws

LAWS describe how a system behaves (e.g., the law of gravity).

Biological Rules are Biological laws

Help describe patterns and relationships but not explain how they work.

THEORIES explain those laws.

Explains how laws work.

In our everyday use of the word, it often means “imperfect fact” or “speculation.”

Used similarly to a hypothesis

This is not accurate

In science, a theory is something VERY SPECIFIC!!!

https://en.wikipedia.org/wiki/Biological_rules

Theories and Laws

A SCIENTIFIC THEORY is something that has been tested many different times, in many different ways, and has not yet been refuted. Theories are supported or rejected by

testing hypotheses. Theories can change!

HOWEVER, theories are rejected ONLY when they: Are replaced by new theories that explain predictions

of the old theory AND make new predictions!

Societal Conflicts

Society’s traditional views of nature sometimes differ with scientific findings (e.g., Capernicus’ heliocentric model and Galileo).

You have to remember that science can only describe and attempt to explain the physical world.

Science vs Pseudoscience

“Pseudo” = false

The only way to spot a fake is to know as much as possible about the real thing!

Science vs PseudoscienceScience…

Results are verifiable and can be reproduced Clear what methods were used to reach conclusions Focus on failed predictions of a theory Progresses; more and more is learned about the process under study Convinces by appeal to evidence No conflicts of interest; no personal financial stake in results of scientific studies

Pseudoscience… Results are not verifiable and cannot be reproduced

Methods are often unknown

Failed predictions are ignored, excused, or even hidden and lied about

No progress is made; nothing concrete is learned

Convinces by appeal to belief or faith

Pseudoscientists often earn some or all of their living selling their “services”

Scientific Experiments

Used to test hypotheses

Conducted under carefully controlled conditions. where experimental variables can be controlled.

Ideally, conditions should be the same for all groups; only change the variable you are interested in.

Scientific Experiments

The INDEPENDENT VARIABLE is the variable the scientist changes in the experiment The DEPENDENT VARIABLE is what the scientist observes/measures in the experiment (the result) A CONTROL group is a group in which no changes are made. It used as a standard for comparison. A TREATMENT (experimental) group is subjected to the same conditions as the control group except for the variable(s) being studied.

Qualitative vs Quantitative Data QUALITATIVE DATA Deals with descriptions (qualitative = quality)

Data that can be observed but not measured

E.g.) colors, textures, smells, tastes, appearance, relative size, etc.

QUANTITATIVE DATA Deals with numerical descriptions (quantitative =

quantity)

Data that can be measured

E.g.) length, height, area, volume, mass, temperature, time, velocity, etc.

Fertilizer Experiment

1) State a hypothesis

2) State a prediction

3) Identify the experimental groups

4) What could be used as a control group?

5) Identify the dependent variable

6) Identify the independent variable

Sampling Error and Replication

It is important to conduct multiple trials with each independent variable. This is called replication.

Why replicate? What do you do with data from multiple trials/observations?

Researchers cannot measure every individual in a population; data collected from a sample of the population.

Sampling errors occur when conclusions inferred from the collected sample differ from the whole population.

Occurs when sample sizes are small. Sampling error can be reduced by using a larger sample size

Vitamin C and Cancer in Mice

It has been suggested that vitamin C supplements lower the risk of cancer in mammals. You are given 100 mice that have been bred to have an identical genetic make-up. You are asked to design an experiment to address the question of whether vitamin C lowers the risk of cancer in mice.

1)Form a hypothesis2)State a prediction3)Design an experiment to test your hypothesis4) Identify the following:

a) Control group; b) Treatment group, c) Independent variable, and d) Dependent variable

Graphs

Graphs help you interpret and communicate your results.

Graphs show the relationship between your dependent and independent variables. Independent variable (X-axis): What you change

Dependent variable (Y-axis): What is measured

Type of graph used depends on the type of data being presented: Continuous Data

Discrete (categorical) Data

Graphs

Include: Descriptive title

Axes labels

Appropriate scales

Change appearance of points/lines if plotting more than one data set on the same graph Use different colors

Solid vs dashed lines

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