Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings What is Biology???? How...

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

What is Biology????

How does a scientist learn about living things????

Most scientists practice discovery science and hypothesis driven science.


• The lives of gray-headed flying foxes are closely entwined with the lives of the eucalyptus trees that form their habitat

– Eucalyptus trees provide food and roosting sites for the flying foxes

– Flying foxes aid in eucalyptus pollinationand help disperse the resulting seeds

Life in the Trees --- Discovery Science


• Flying foxes are becoming an endangered species, partly because of habitat destruction


• In discovery science, scientists describe some aspect of the world and use inductive reasoning to draw general conclusions

– Example: scientists have described how newborn flying foxes cling to their mother’s chest for the first weeks of life

– The scientists have made observations and reasoned to a generalization.

Figure 1.2


Discovery Science Utilizes Inductive Reasoning

Verifiable observations and measurements are the data of discovery science.

Discovery science can lead to important conclusions based on a type of logic called inductive reasoning.

This type of reasoning derives general principles from a large number of specific observations.

“All living things are made from cells.” That induction was made with over two centuries of observations in which

biologists discovered cells in every biological specimen they observed through microscopes.


Hypothesis Driven Science

• In hypothesis-driven science, scientists use the “scientific method”

– They propose a hypothesis

– They make deductions leading to predictions

– They then test the hypothesis by seeing if the predictions come true

– The use of “danger” calls by flying foxes helps them evade the tree climbing pythons that prey upon them.


If the flying foxes don’t call out “danger,” then they will be more subject to predation.


• Deductive reasoning is used in testing hypotheses

• Case study: flashlight failure

• Based on research and past experience…my hypothesis is that the batteries are dead.

• If a hypothesis is correct, and we test it, then we can expect a particular outcome

• If I replace the batteries then the flashlight should work.

• From general premises we extrapolate to the specific results we should expect if the premises are true.

Figure 1.3B


Hypothesis driven science utilizes deductive reasoning.

If all organisms are made of cells(premis 1), and humans are organisms (premis 2), then

humans are composed of cells (deduction about a specific case). This deduction can be tested by examining human tissue under the microscope.


SummaryScientists use two main approaches in their efforts to understand nature, In discovery

science, they describe some aspect of the world and use inductive reasoning to draw general conclusions. In hypothesis driven science,

scientists use the “Scientific Method.” They propose a hypothesis ( a tentative answer to a

question), make deductions leading to predictions, and then test the hypothesis by

seeing if the predictions come true.


The Tools of Hypothesis Driven Science

• Hypothesis driven science utilizes the scientific method.

• The scientific method uses the 5 senses to make observations.

• The most extensive work, while utilizing the scientific method, is the gathering of background information in order to formulate a hypothesis using acceptable premises.

• The scientific method uses deductive reasoning.


• The main steps of the scientific method

1.3 With the scientific method, we pose and test hypotheses

Observation

Search &Question

Hypothesis

Prediction

Test:Experiment or

additionalobservation

Test does notsupport hypothesis; revise hypothesis or

pose new one

Test supports hypothesis; make

additional predictions and test them

Figure 1.3A


• Experiments designed to test hypotheses must be controlled experiments

• Control groups must be tested along with experimental groups for the meaning of the results to be clear

• A control group and an experimental group differ by only one variable.

• The control group provides a basis for comparison, enabling researchers to draw meaningful conclusions from their experiments.


Zebra Jumping Spider


Snowberry fly


• Case study: spider mimicry by snowberry fly

Po

un

ce

ra

te (

% o

f tr

ials

in

w

hic

h s

pid

er

jum

pe

d o

n f

ly)

Control group(untreated flies)

Experimental group(wing markings masked)

jumping spider snowberry fly

Figure 1.3D

If the flies wing markings are masked with a dye then jumping spiders should pounce on the experimental flies more often than they do on control flies with normal wings.


• Another test of the spider mimic hypothesis: wing transplants from spider mimics (snowberry flies) to houseflies

Nu

mb

er o

f st

alk

and

atta

ck r

esp

on

ses

by

spid

ers

Wingmarkings

Normalspidermimic

Figure 1.3E

Wingwaving

Mimic withmimic wing transplant

Controls Experimentals

Mimic withhousefly

wing transplant

Housefly with

mimic wing transplant

(no waving)

Normalhousefly


The Tools of Science Include Technology

• Tools can be implements such as microscopes.

• Science and technology are an indivisible pair.


Science vs Technology• TECHNOLOGY

Goal: the creation of artfacts and systems to meet people's needs

• SCIENCEGoal: the pursuit of knowledge and understanding for its own sake

• “ . . . practical usable criteria for making sharp neat distinctions between science and technology do not exist.”

• “ . . . ‘contrivance’ technology exemplified by many gifted engineers in the last century who worked with no formal scientific understanding of their problems, and ‘applied science’ technology in which one increasingly needs to grasp the conceptual science even to understand the problem, let alone explore solutions "

• “Neither is sufficient on its own; some problems require more of one approach, some more of the other.”


• Biology is the scientific study of life

• Interactions between different kinds of organisms affect the lives of all

– Recall the example of flying foxes and eucalyptus trees

THE SCOPE OF BIOLOGY


• Organisms are made up of:

– organ systems

– organs

– tissues

– cells

– molecules

ECOSYSTEM LEVELEucalyptus forest

COMMUNITY LEVELAll organisms ineucalyptus forest

POPULATION LEVELGroup of flying foxes

ORGANISM LEVELFlying fox

ORGAN SYSTEM LEVELNervous system

ORGAN LEVELBrain

Brain Spinal cord

Nerve

TISSUE LEVELNervous

tissue

CELLULAR LEVELNerve cell

MOLECULAR LEVELMolecule of DNA

Figure 1.1


• A structural hierarchy of life, from molecules to ecosystems, defines the scope of biology

• An ecosystem consists of:

– all organisms living in a particular area

– all nonliving physical components of the environment that affect the organisms (soil, water)

1.1 Life’s levels of organization define the scope of biology


• At the top of life’s hierarchy is the ecosystem

• Ecosystems include:

– all the organisms in an area, which make up a community

– interbreeding organisms of the same species, a population

ECOSYSTEM LEVELEucalyptus forest

COMMUNITY LEVELAll organisms ineucalyptus forest

POPULATION LEVELGroup of flying foxes

ORGANISM LEVELFlying fox

ORGAN SYSTEM LEVELNervous system

ORGAN LEVELBrain

Brain Spinal cord

Nerve

TISSUE LEVELNervous

tissue

CELLULAR LEVELNerve cell

MOLECULAR LEVELMolecule of DNA

Figure 1.1

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings What is Biology???? How...

Documents

Transcript of Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings What is Biology???? How...