Human BiologySylvia S. Mader

Michael Windelspecht

Chapter 1 Exploring Life and Science

Lecture Outline

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Points to ponder

• What is biology?

• What characterizes life?

• How do we classify life?

• Where do humans fit into the big picture?

• How do we study science?

• Where is scientific information published and what should you be aware of?

What characteristics are shared by living organisms?

• Organized from the atom to the biosphere• Use materials and energy from the environment• Reproduce offspring• Growth and development• Maintain a relatively constant internal

environment (homeostasis)• Respond to internal and external stimuli• Evolutionary history through which organisms

change over time

1.1 The characteristics of life

How are living things organized?1.1 The characteristics of life

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nervous system shoot system

leaf

photosynthetic tissue

plant cell

brain

nervous tissue

neuron

BiosphereRegions of the Earth’s crust,

waters, and atmosphere inhabitedby living things

EcosystemA community plus the physical environment

CommunityInteracting populations in a particular area

PopulationOrganisms of the same species

in a particular area

OrganismAn individual; complex individuals

contain organ systems

Organ SystemComposed of several organs

working together

OrganComposed of tissues functioning

together for a specific task

TissueA group of cells with a common

structure and function

CellThe structural and functional

unit of all living things

MoleculeUnion of two or more atoms

of the same or different elements

AtomSmallest unit of an element composed of

electrons, protons, and neutrons

How do we classify humans?

Human House catDomain Eukarya EukaryaKingdom Animalia AnimaliaPhylum Chordata ChordataClass Mammalia MammaliaOrder Primates CarnivoraFamily Hominidae FelidaeGenus Homo FelisSpecies sapiens domesticus

1.2 Humans are related to other animals

What distinguishes humans?

• Cultural heritage or patterns of our behavior passed from one generation to the next

• Highly developed brains• Completely upright stance• Creative language skills• Varied tool use• Modification of our environment for our own

purpose which may threaten the biosphere

1.2 Humans are related to other animals

What do we know about science?• Science is a way of knowing about the natural

world

• Science and scientists should be objective

• Scientific conclusions may change or be modified as our understanding and technology increase

• Science is studied using the scientific method

1.3 Science is a process

Scientific Theories in Biology

1.3 Science is a process

The steps of the scientific method1.3 Science is a process

The results are analyzed,and the hypothesis issupported or rejected.

Many experiments andobservations support a

theory.

The hypothesis istested by experiment

or further observations.

Input from various sourcesis used to formulate a

testable statement.

New observationsare made, and previous

data are studied.

Hypothesis

Observation

Experiment/Observations Conclusion

Scientific Theory

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• Observations: many patients had a particular bacterium near their ulcers

• Hypothesis: Helicobacter pylori is the cause of gastritis and ulcers.

• Experiment/observations:

1st – H. pylori was isolated and grown from ulcer patients

2nd – humans swallowing a H. pylori solution resulted in inflammation in their stomachs

• Conclusion: H. pylori was the cause of most ulcers and can be cured by antibiotics

How the Cause of Ulcers Was Discovered:

The scientific method in action

1.3 Science is a process

A controlled study• Variables:

• Experimental variable is the variable that is purposely changed or manipulated

• All other variables need to remain constant

• Groups:• Test group is a group of subjects that are exposed to

the experimental variable• Control group is a group for comparison that is not

exposed to the experimental variable

1.3 Science is a process

1.3 Science is a process

A controlled study in actionCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

a.

b.

c.

d.

Subjects weredivided intothree groups.

Perform Experiment:Groups were treated the same

except as noted.

Large numberof subjectswere selected.

State Hypothesis:Antibiotic B is a better treatment for

ulcers than antibiotic A.

Collect Data:Each subject was examinedfor the presence of ulcers.

Testgroup 2:receivedantibiotic B

Controlgroup:receivedplacebo

Testgroup 1:receivedantibiotic A

Conclusion:Hypothesis is

supported:Antibiotic B is

a bettertreatment forulcers thanantibiotic A.

ControlGroup

TestGroup 1

TestGroup 2E

ffec

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f T

reat

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10

60

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(a-b): © blickwinkel/Alamy; (c): © Phanie/ Photo Researchers, Inc.

80

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Reading about scientific information

• Scientific journals are considered the best source of information but can be difficult for the lay person to understand

• Often the lay person reads secondary sources and must be wary of information taken out of context

• Be careful of information on the Internet by using reliable sources such as URLs with .edu, .gov and .org

1.3 Science is a process

What should you look for when you read about science?

• Beware of anecdotal data

• Understand methodology and results

• Does the data justify the conclusions inferred by the scientists?

• Be able to read a graph

• Have some understanding of statistics

1.4 Making sense of a scientific study

Reading a GraphWhat information does this line graph convey?

1.4 Making sense of a scientific study

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standard error

130

120

100Site 1 Site 2 Site 3 Site 4

X-axis

Y-axis

Dia

met

er o

f T

rees

(cm

)

110Data

Does science have social responsibilities?

• Science is a way of acquiring knowledge about the natural world through a systematic process separating it from ethics, religion and aesthetics

• Technology is the application of scientific knowledge to human interests- Biotechnology (genetically modified bacteria and

genetically modified crops)- Gene technology (cloning of humans or gene therapy to

modify inheritance)- Use of stem cells from embryos (embryonic stem cells)

1.5 Science and social responsibility

Everyone is Responsible

• The Western world believes that science and technology improves our lives.

• All citizens should assume responsibility.

• Everyone needs to be involved in making value judgments about the proper use of technology.

• You will learn more about all of these as you venture through this text. Consider your opinions.

1.5 Science and social responsibility