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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?

Are We Alone?

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They both have water in large amounts

What are the basic characteristics that define life?

What evidence would you look for on one of these moons that would tell you that life may have existed on them in the past?

What does it tell us if we discover life on one of these moons and it has characteristics similar to those of life on Earth? What if it is very different?

Characteristics of Life

What characteristics are shared by living organisms?

Life is highly organized and made of cells

Reproduce and grow

Use materials and energy from the environment

Respond to internal and external stimuli

Maintain a relatively constant internal environment (homeostasis)

Evolve

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Composed of cells

• First organisms were single cells

• Basic unit of life

• Self-contained units

• Bacteria are single cells

• Multicellular organisms made of different specialized cells

Highly Organized

• Complex function

• Humans have tissues and organ systems

• Organization is required for function

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How are living things organized?

nervous system shoot system

leaf

photosynthetic tissue

plant cell

brain

nervous tissue

neuron

Biosphere

Regions of the Earth’s crust, waters, and atmosphere inhabited

by living things

Ecosystem

A community plus the physical environment

Community

Interacting populations in a particular area

Population

Organisms of the same species in a particular area

Organism

An individual; complex individuals contain organ systems

Organ System

Composed of several organs working together

Organ

Composed of tissues functioning together for a specific task

Tissue

A group of cells with a common structure and function

Cell

The structural and functional unit of all living things

Molecule

Union of two or more atoms of the same or different elements

Atom

Smallest unit of an element composed of electrons, protons, and neutrons

Figure 1.2 Levels of

biological organization.

Lower Level of Biological Hierarchy

• Atoms

• Molecules

– DNA and proteins

• Cells

– Many different types in higher organisms

• Tissues

– Made up of many cells

• Organs

– Heart and brains

Mid-level of Biological Hierarchy

• Organ systems

– Heart and blood vessels

– Work together to pump blood

• Individual organism

– Organ systems functioning together

– Each system supporting other systems

• Population

– Group of similar organisms

• All mice living in one field

Top Level of Biological Hierarchy

• Community

– Groups of different species or organisms

– Live and interact in a certain area

• Ecosystems

– Communities and their physical environment

• Biomes

– Large regions defined by distinctive characteristics

• Biosphere

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Importance of Biological Hierarchy

• Molecular level to biosphere level

– Intricate interactions that affect all living

things including us.

– Understanding the hierarchy helps us to understand the interactions.

What characteristics are shared by living organisms?

Life is highly organized and made of cells

Reproduce and grow

Use materials and energy from the environment

Respond to internal and external stimuli

Maintain a relatively constant internal environment (homeostasis)

Evolve

Reproduction via DNA

• Living organisms reproduce or replicate themselves

• Single-cell organisms – Produce two genetically identical

cells

• Multicellular organisms – Variety of ways

– Seeds, eggs and sperm, etc.

• Genetic material – Passed from parents to offspring

– DNA: deoxyribonucleic acid

Growth and Development

• DNA as a blueprint

– Organisms grow and propagate themselves

– Organisms develop and grow in complexity

What characteristics are shared by living organisms?

Life is highly organized and made of cells

Reproduce and grow

Use materials and energy from the environment

Respond to internal and external stimuli

Maintain a relatively constant internal environment (homeostasis)

Evolve

Capturing Energy

• Collect energy from their environment – Use energy to grow and develop

• Some use the energy of sunlight – Plants capture sun’s energy via

photosynthesis

– Convert solar energy to chemical energy in sugars

• Some use energy from other living organisms – Animals consume plants or animals

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The sun is the ultimate source of energy on Earth What characteristics are shared by living organisms?

Life is highly organized and made of cells

Reproduce and grow

Use materials and energy from the environment

Respond to internal and external stimuli

Maintain a relatively constant internal environment (homeostasis)

Evolve

Sense and Response

• Detect danger

• Many organisms have multiple senses – Smell, hear, taste, touch, and see

• Some senses different than human – Ultraviolet and infrared light

– Electrical and ultrasonic fields

– Some bacteria use magnetic particles to sense direction

What characteristics are shared by living organisms?

Life is highly organized and made of cells

Reproduce and grow

Use materials and energy from the environment

Respond to internal and external stimuli

Maintain a relatively constant internal environment (homeostasis)

Evolve

Homeostasis

• All organisms engage in maintaining homeostasis in some fashion.

What characteristics are shared by living organisms?

Life is highly organized and made of cells

Reproduce and grow

Use materials and energy from the environment

Respond to internal and external stimuli

Maintain a relatively constant internal environment (homeostasis)

Evolve

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All organisms Evolve!

What are the basic characteristics that define life?

What evidence would you look for on one of these moons that would tell you that life may have existed on them in the past?

What does it tell us if we discover life on one of these moons and it has characteristics similar to those of life on Earth? What if it is very different?

Fossilized Bacteria from Mars rock? NO!

What are the basic characteristics that define life?

What evidence would you look for on one of these moons that would tell you that life may have existed on them in the past?

What does it tell us if we discover life on one of these moons and it has characteristics similar to those of life on Earth? What if it is very different?

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Adaptation to Environmental

Conditions

Human

Evolutionary

History

Three Domains of Life

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Classification of Life How do we classify humans?

Human House cat

• Domain Eukarya Eukarya

• Kingdom Animalia Animalia

• Phylum Chordata Chordata

• Class Mammalia Mammalia

• Order Primates Carnivora

• Family Hominidae Felidae

• Genus Homo Felis

• Species sapiens domesticus

What distinguishes humans from other animals?

Cultural heritage or patterns of our behavior passed from one generation to the next – also seen in monkeys and some birds

Highly developed brains

Completely upright stance

Creative language skills

Varied tool use – many animals use tools including monkeys and birds among others!

Modification of our environment for our own purpose which may threaten the biosphere – other animals can engineer their habitat ex. beaver

Humans Negatively Impact Natural Systems

Way of knowing

Natural World

Objective Statistics

Conclusions Change

Process Scientific Method

Laws, Theories

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Scientific theories in biology

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Germ Theory of Disease: Koch’s Postulates

• The suspected pathogen (virus or bacterium) must be present in every case of the disease;

• The pathogen must be isolated from the host and grown in a lab dish;

• The disease must be reproduced when a pure culture of the pathogen is inoculated into a

healthy susceptible host; and

• The same pathogen must be recovered again from the experimentally infected host.

Scientific Method

Scientific Method Example Dr. Barry Marshall discovers the cause of

stomach ulcers

H. Pylori and ulcers

• Experimented on animals – Conclusion not accepted

• 1985, Marshall decided to perform the experiment on himself!

– He and another volunteer swallowed solution of H. pylori.

• Within the week, they felt sick and were vomiting up their stomach contents.

• Examination by endoscopy showed that their stomachs were now inflamed, and biopsies of the stomach lining contained the suspected bacterium.

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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.

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• Observations: Many patients had a particular

bacterium near their ulcers.

• Hypothesis: Helicobacter pylori is the cause of

gastritis and ulcers.

How the cause of ulcers was discovered:

The scientific method in action

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• Experiment/observations:

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

patients.

2nd – Humans swallowing a H. pylori solution

developed 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 (Koch’s Postulates) A controlled study in action

Figure 1.9 A controlled

laboratory experiment to

test the effectiveness of a

medication in humans.

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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.

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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.

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Reading a graph What information does this line graph convey?

Figure 1.10 The presentation of scientific data. 62

Statistical Significance

• When scientists conduct an experiment, there is always

the possibility that the results are due to chance or to

some factor other than the experimental variable.

• Investigators take into account several factors when they

calculate the probability value (p) that their results were

due to chance alone.

• If the probability value is low, researchers describe the

results as statistically significant.

• A probability value of less than 5% (usually written as p

< 0.05) is acceptable, but p values of <0.001 are

common in many studies.

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Does science have social

responsibilities?

• Science is a way of acquiring knowledge about

the natural world.

– It is a slightly different endeavor than technology.

– Collection of data is non-judgemental

– Bioethicists argue about the social issues

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Does science have social

responsibilities?

• Technology is the application of scientific

knowledge to human interests.

• Bioethics is the branch of ethics concerned

with the development and consequences of

biological technology.

- Genetic engineering (genetically modified crops)

- Threat to biodiversity

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Human Influence on

Ecosystems

• Humans tend to modify ecosystems for their own

purposes.

• Changes in human behavior and use of new

technology can result in new diseases (emerging

diseases).

• Human activities may attribute to climate change

(global warming).

Biologists work in many environments