Organism classification and the scientific method 9/1

Organism classification and the scientific method

From the last class-Themes in biology

1.Life is organized in a hierarchy from DNA molecules to the biosphere2.Living organisms interact with their environments, exchanging matter and energy3.Cells are the structural and functional units of life4.All life has common features

Three Domains of Life

Prokaryotes•Single-celled (mostly)•No organelles•No membrane-bound nucleus

Eukaryotes•Single or multi-cellular•Membrane-bound

nucleus•Organelles

Bacteria (multiple kingdoms)

Small in size!

Bacteria (multiple kingdoms)

The most diverse protists!

Extreme environments!Archaea (multiple kingdoms)

Colony of archaea composed of many cells

100oC and pH of 0

Archaea (multiple kingdoms)And not-so-extreme

environments…

Protists (multiple kingdoms)

Two major groups we will look at in this course

AlgaeProtozoans

Plants, Fungi and Animals can be distinguished by how they get their nutrients

Kingdom PlantaeDiverse, successful, produce their own food

and have cell walls made of cellulose

Molds, yeasts and mushrooms

Decomposers that recycle nutrients

Kingdom Animalia

Ingest other organisms for food

900,000+ species of insects may account for ~80% of all animal diversity

1.6 Evolution explains the unity and diversity of life

Evolution is a theory. So what does this mean?

Theory-an idea that has been rigorously tested, supported and generally accepted to be true.

Theories are supported by hypothesis-driven research and results.

• In 1859, Charles Darwin published On the Origin of Species by Means of Natural SelectionThe book accomplished two things

1. Presented evidence to support the idea of evolution2. Proposed a mechanism for evolution called natural

selection

Darwin proposed natural selection by connecting two observations1. Individuals within a population inherit different

characteristics and vary from other individuals2. Populations tend to produce more offspring

than can survive to reproduce themselves

Natural selection is an editing mechanismHeritable variations in populations respond to

environmental factors this favors some individuals over othersOver (evolutionary) time this results in

evolution of new species adapted to particular environments

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

Individualvariation

Observations

Overproductionof offspring

Natural selection:unequal reproductive

success

Inferences

Evolutionof adaptationsin a population

Common Evolutionary Misconceptions

1. Evolution occurs in a population, not in an individual

Mutations happen in an individual2. Organisms do not choose to adapt

Changes occur at random

Populations develop diverse characteristics as a result of their response to the environment, mutations and exchange with other populations

Population with varied inherited traits1

Elimination of individuals with certain traits2

Reproduction of survivors3

Evolution can not occur if:

1. There are no differences between individuals of a population.

2.Mortality is not selective.3.There are no differences in reproduction

within a population.

Pangolin

Killer whale

Two examples of adaptive evolution, from a common ancestor

Pangolin

Killer whale

THE PROCESS OF SCIENCE

1.7 Scientists use two main approaches to learn about nature

Two approaches are used to understand natural causes for natural phenomena

1. Discovery science—uses verifiable observations and measurements to describe science

2. Hypothesis-based science—uses the data from discovery science to explain ideas

This requires proposing and testing of hypotheses

Inquiry is the heart of science

Examples of Discovery Science

The Human Genome Project

Exploration to discover new species

Discovery Science: A lost cause?

Absolutely not!

Here, we make a distinction between theory and 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 and is accepted by most scientists

Lab experiments- The most controlled. Researchers can control most if not all variables.

Field experiment- One variable is changed, but the natural environment determines the outcome.

Natural experiment- Evolution is a natural experiment. We have very little control over the outcome…or do we?

There’s ‘more than one way to skin a cat’

1.8 With hypothesis-based science, we pose and test hypotheses

We solve everyday problems by using hypothesesAn 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 (i.e. Can we design an

experiment to directly support our hypothesis?)The hypothesis must be falsifiable (i.e. If it truly is false, can we

test it in a way that demonstrates this?)

Hypothesis #1:Dead batteries

Observations

Question

Hypothesis #2:Burned-out bulb

Observations

Question

Prediction:Replacing batterieswill fix problem

Prediction:Replacing bulbwill fix problem

Test prediction Test prediction

Observations

Question

Test falsifies hypothesis Test does not falsify hypothesis

Observations

Question

Test falsifies hypothesis Test does not falsify hypothesis

Important! Each hypothesis involved only one factor, or variable.

Why wouldn’t we test both hypotheses together by changing the batteries AND light bulb at the same time?

1.8 Case Study

Another hypothesis: Mimicry helps protect nonpoisonous king snakes from predators where poisonous coral snakes also live

The hypothesis predicts that predators learn to avoid the warning coloration of coral snakes

Mimicry – a resemblance of one organism to another, usually in an attempt to evade predators.

• Experimentation supports the prediction of the mimicry hypothesis—nonpoisonous snakes that mimic coloration of coral snakes are attacked less frequently

– The experiment has a control group using brown artificial snakes for comparison

– The experimental group is artificial snakes with the red, black, and yellow ring pattern of king snakes

Eastern Coral Snake (poisonous)

Scarlet king snake (non-poisonous)

Red on yellow, kill a fellowRed on black, friend of Jack.

Coral snake range-blue Eastern king snake range-red

Predators here do not interact with coral snakes (poisonous)

Predators here see both snakes

Non-poisonous snakes that mimic coloration of coral snakes are attacked less frequently

Control group- brown snake (non-threatening)

Experimental group- artificial snakes with the red, black, and yellow ring pattern of king snakes

Scientific testing can include assumptions:What might some assumptions of this

study be?

1. Predators cannot tell a scarlet from a king snake2. Predators would be interested in the brown snake

Artificialking snakes

Artificialbrown snakes

Coral snakesabsent

Coral snakespresent

Y-axis (dependent variable)(i.e. The data depends on what the experimental variables are)

X-axis (independent variable)(i.e. What the researcher chooses to test; the experimental variables)

Artificialking snakes

Artificialbrown snakes

Coral snakesabsent

Coral snakespresent

BIOLOGY AND EVERYDAY LIFE

1.9 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 phenomenaTechnology applies science for a specific purpose

1.10 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 changeThe environment matters because it is a selective

force that drives evolutionAn understanding of evolution helps us fight disease

and develop conservation efforts

You should now be able to

1. Describe life’s hierarchy of organization2. Describe living organisms’ interactions with their

environments3. Describe the structural and functional aspects of cells4. Explain how the theory of evolution accounts for the unity and

diversity of life 5. Distinguish between discovery science and hypothesis-based

science6. Describe ways in which biology, technology, and society are

connected

has changedthrough the process of

Biology

is the study of

mechanism is

accountsfor

depends on

DNA(genetic code)

accountsfor

codes foris evidence of

seen invariations in seen in

common propertiesof living organisms

cells as basicunits of life

diversity of life

seen in

leads to

No rewardFood reward

0 1 2 3 4 5 6

In this experiment, mice learn to run through a maze. Based on the graph, what is the hypothesis the researchers were testing?

Concept Check

Darwin proposed the theory of natural selection. For the most part, natural selection acts as a filtering agent at the ___________level of life’s hierarchy.– Community– Population – Individual – Organ

AnswerDarwin proposed the theory of natural selection. For the most part, natural selection acts as a filtering agent at the ___________level of life’s hierarchy.

2) Population

Concept CheckNot all scientific discoveries are reached through the “scientific method.” Which of the following would best be described as discovery science?– Looking for a live specimen of an organism found in the

fossil record.– Describing a new bird species from the Philippines. – A project to find preserved specimens of the probably

extinct Rocky Mountain locust frozen in glaciers . – All of the above.

Answer

Not all scientific discoveries are reached through the “scientific method.” Which of the following would best be described as discovery science?

4) All of the above.

Interpreting Data•These two snakes look remarkably similar to each other. The coral snake (right) is very poisonous to vertebrates. Hypotheses:•H1: The coral snake’s bright color pattern serves to warn off potential predators.•H2: The the king snake suffers less predation because it mimics or looks like the coral snake. •H3: The protection that king snakes receive by mimicking coral snake will depend on the presence of coral snakes.

Interpreting Data•A team of scientists designed an investigation that used artificial snakes to test the previous hypotheses. Which of the previous hypotheses are supported by the results displayed at the right?

1) H1: The coral snake’s bright color pattern serves to warn off potential predators.

2) H2: The the king snake suffers less predation because it mimics or looks like the coral snake.

3) H3: The protection that king snakes receive by mimicking coral snake will depend on the presence of coral snakes.

4) Both 2 and 3

Answer•A team of scientists designed an investigation that used artificial snakes to test the previous hypotheses. Which of the previous hypotheses are supported by the results displayed at the right?

4) Both 2 and 3

Interpreting Data

Biologists placed artificial snake mimics in two different localities to test the hypothesis that looking like a poisonous snake only works where the poisonous snake is found:1. Outside of the coral snake range—only king snakes present.2. Inside the coral snake range—both coral and king snakes are present.

Interpreting Data

•The data graphed at the right __________ the hypothesis that the effectiveness of mimic coloration depends upon the presence of the poisonous model is:– supports– does not support – is irrelevant to

Answer

•The data graphed at the right __________ the hypothesis that the effectiveness of mimic coloration depends upon the presence of the poisonous model is:– supports

Interpreting Data

Based on this data which of the following is a logical hypothesis or prediction?– King snakes outside of the range of

coral snakes will more closely resemble coral snakes than populations of king snake living within the range of coral .

– King snakes outside of the range of coral snakes will not resemble coral snakes as closely as populations of king snakes that live within the range coral snakes.

– Neither prediction is valid.

AnswerBased on this data which of the following is a logical hypothesis or prediction?

2) King snakes outside of the range of coral snakes will not resemble coral snakes as closely as populations of king snakes that live within the range coral snakes.

Biology and Society

Even a cursory glance at the news media reveals that scientific progress is an essential part of modern society. Still, many people are very skeptical of science. Do you think that an informed citizen needs a firm foundation of understanding of science to effectively participate in a representative society?

Disagree Agree

Strongly A B C D E Strongly

Biology and Society

Even a cursory glance at the news media reveals that scientific progress is an essential part of modern society. Still, many people are very skeptical of science. Do you think that scientists should take a more active role in helping society to understand and apply their findings?

Disagree Agree

Biology and Society

Religion and science are often at odds. Some feel that religion and science are two powerful but separate ways of human understanding. Most importantly these people do not feel that science and religion are in conflict. •Do you think that an individual can hold devout religious beliefs, while at the same time support scientific understanding?

Disagree Agree

Isn’t evolution just a theory?http://www.youtube.com/watch?v=85diEXbJBIk

How does evolution really work?http://www.youtube.com/watch?v=Pf9P0lrpgLk

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