Chapter 1: An Introduction to Life on Earth

Characteristics of Living Things

• Living Things are Both Complex and Organized

• Living Things Grow and Reproduce• Living Things Respond to Stimuli

• Living Things Acquire and Use Materials and Energy

• Living Things Use DNA to Store Information

The unifying characteristic of ALL living things is the universal presence of DNA.

Evolution accounts for both life’s

unity and its diversity

Natural selection is the primary mechanism of evolution. Organisms that are able to adapt to their environments become

the dominant form of the species, while those that cannot adapt die out.

Earth’s biodiversity is currently threatened. The greatest threat comes from a single species – modern man.

So What is Biology?• Biology is the science of life

• Biologists attempt to answer questions about life, such as– Where did we come from?– What causes cancer?– Why are certain populations shrinking?– How does HIV cause AIDS?– What happens when egg and sperm meet?– How can diseases be prevented?

To answer these and other questions, biologists use the Scientific Method

• Observation – Scientists wonder “what,” “why,” or “how”

• Hypothesis – They formulate ideas that may answer those questions

• Experiment – well-designed experiments incorporate controls and isolate variables to make results more accurate

• Conclusion – Scientists then analyze the results of their experiments, and draw conclusions

• Then, although not a formal part of the Scientific Method, scientists communicate and share results

Life Can be Studied at Different Levels of Organization

• Cellular biologists study the smallest unit of life• Some biologists concentrate on specific body

systems• A collection of different organs forms the basis of

an organism. Some biologists specialize in populations of specific organisms

• Others study a collection of different populations, or communities

Some Benefits to the Study of Biology

• A greater understanding of ourselves and our bodies

• Advances in medicine (i.e., penicillin, the polio vaccine)

• A deeper appreciation for the diversity of our world

• A better understanding of the need to take care of the Earth

References and Resources

Webshotswww.webshots.com

SchoolWorld’s Endangered Species Projecthttp://www.schoolworld.asn.au/species/reports.html

Textbook – “Life on Earth” Custom Edition for Fayetteville State University, Audeskirk, Audeskirk, & Byers

Bioresearchhttp://bioresearch.ac.uk/text/