Learning about Human Biology

Chapter 1

1.1 The Characteristics of Life

Focus: Several basic characteristics allow us to distinguish between

living things and nonliving objects.

The Characteristics of Life

Living things take in energy and materials Energy: the capacity to do work

Living things sense and respond to changes in the environment

Living things reproduce and grow

Living things consist of one or more cells

Living things maintain homeostasis

Humans Take in Energy by Eating Food

Cells Are the Basic Units of Life

Summary of Life’s Characteristics

1.2 Our Place in the Natural World

Focus: Human beings arose as a distinct group of animals during an

evolutionary journey that began billions of years ago.

Humans Have Evolved over Time

Evolution – change in the body plan and functioning of organisms through the generations• Began billions of years ago• Continues today

Where do we fit in?• Primates• Vertebrates

Classification of living organisms• Three domains of life• Five kingdoms of life – changing as we speak!

Animation: Life’s diversity

Humans Are Related to Earth’s Other Organisms

Humans Have Some Distinctive Characteristics

Mammalian features• Hair• Mammary glands

Distinctive PRIMATE features• Manual dexterity• Brain

• Size• Capacity for sophisticated language and analysis• Development of various social behaviors

1.3 Life’s Organization

Focus: Nature is organized on many levels, starting with nonliving

materials and eventually including the whole living world.

Fig. 1-5a, p. 4

Fig. 1-5b, p. 5

Animation: Life’s levels of organization

Animation: Building blocks of life

Organisms Are Connected through the Flow of Energy and Cycling of Materials

Solar energy and photosynthesis

Interconnections among organisms• Producers• Consumers• Decomposers

• bacteria and fungi

The Flow of Energy and the Cycling of Materials Maintain Nature’s Organization

Animation: One-way energy flow and materials cycling

1.4 Using Science to Learn about the Natural World

Focus: Science basically is a way of thinking about the natural world by making and testing predictions they

search for evidence that may disprove or support a proposed explanation.

Science Is a Systematic Study of Nature

Scientific method• Observe some aspect of nature• Ask a question about the observation or identify

a problem to explore• Develop a hypothesis• Make a prediction• Test the prediction• Repeat the tests or develop new ones• Analyze and report the test results and

conclusions

Scientists Do Research in the Laboratory and in the Field

Animation: Sampling error

Example Experiment:

Hypothesis: Olestra® causes intestinal cramps

• Variables• Independent• Dependent• Standardized

• Groups• Control• Experimental

Fig. 1-8, p. 7

HypothesisOlestra® causes intestinal cramps.

PredictionPeople who eat potato chips made with Olestra will be more likely to get intestinal cramps than those who eat potato chips made without Olestra.

Experiment Control Group Eats regular potato chips

Experimental Group Eats Olestra potato chips

Results 93 of 529 people get cramps later (17.6%)

89 of 563 people get cramps later (15.8%)

Conclusion

Percentages are about equal. People who eat potato chips made with Olestra are just as likely to get intestinal cramps as those who eat potato chips made without Olestra. These results do not support the hypothesis.

Science Never Stops

Is more research needed on Olestra?

Olestra reformulated to reduce side effects?

Examples of Scientific Theories

Animation: An example of the scientific method

1.5 Critical Thinking in Science and Life

Focus: To think critically, we must evaluate information

before accepting it.

A Guide to Critical Thinking

Evaluate the Source of Information

Let credible scientific evidence, not opinions or hearsay, do the convincing

Question credentials

Question motives

Evaluate the Content of Information

Fact versus opinion

Cause versus correlation• Ice cream & crime

1.6 Science in Perspective

Focus: A scientific theory explains a large number of

observations.

What the Word “Theory” Means in Science

Supported by tens of thousands of experiments

May be modified or even rejected upon further investigations• Science is tentative!

Science Has Limits

External world is testing ground for scientific views• Natural world only (not supernatural)

Culture and society: NOT a part of science!• Morals• Esthetics• Religious beliefs

1.7 Living in a World of Infectious Disease

Focus: Humans have always lived with countless health threats. Today

we are locked in an escalating global battle with bacteria, viruses,

parasites, and other pathogens -agents that can cause disease.

Black Death

Infections Are a Threat Because They Disrupt Homeostasis

Infection – pathogen enters cells or tissues and reproduce

Disease – when the pathogen overwhelms the host’s defense systems

Effect on homeostasis• Major versus minor disruptions

What Do Pathogens Look Like?

Bacteria

Viruses

Fungi

Parasitic protists

Parasitic worms

A Wide Variety of Pathogens May Live on or in the Human Body

Emerging Diseases Present New Challenges

Causative agents of emerging diseases• West Nile virus: encephalitis• SARS virus: severe acute respiratory syndrome• Ebola virus: hemorrhagic fever• Borrelia burgdorferi bacterium: Lyme disease

The SARS and Ebola Viruses

Antibiotics Are a Double-Edged Sword

Discovered in the 1940s

Organisms that produce antibiotics • natural chemicals that can destroy bacteria

Antibiotic resistance is a major health threat• Caused by abuse or improper use

Scientific Method Review

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