Download Chapter 1: An Introduction to Life on Earth

Chapter 1: An Introduction to Life on Earth
1.1
Why Study Biology?
A. Biology Helps You Understand Your Body
B. Biology Can Open Career Opportunities
C. Biology Can Enrich Your Appreciation of the World (Figures 1-1, 1-2)
1.2
How Do Biologists Study Life?
A. The Scientific Method Is the Basis for Scientific Inquiry
1.
Scientific Method (Figures 1-3, 1-4)
a.
Observation - observe a phenomenon and form a question
b.
Hypothesis - supposition based on previous observations that is offered as an explanation
c.
Experiment - designed to test hypotheses
d.
Conclusion - can be drawn based on results of experiments
2.
Variables - Factors that may affect the outcome of an experiment
3.
Controls - Control variables so that they remain constant
4.
Experiments are not always possible - must make predictions (Figure 1-5)
B. Life Can Be Studied at Different Levels of Organization (Figure 1-6)
1.
Cell - smallest unit of life; combine to form tissues (Figure 1-7)
2.
Tissues combine to form organs; many organs form basis of an organism
3.
Collection of organisms - population; many populations - community
C. Science Is a Human Endeavor
1.
Alexander Fleming’s observation of Penicillium mold (Figure 1-8)
2.
Used scientific method to discover first antibiotic
D. Scientific Theories Have Been Thoroughly Tested
1.
Theories result from extensive and reproducible testing
2.
Example of theory = theory of evolution
1.3 What Is Life?
A. Living Things ________________________ (Figure 1-9)
B. Living Things ________________________ (Figure 1-10)
C. Living Things Respond to ________________
1.
Plants grow toward light
2.
Bacteria can move away from poisonous chemical
D. Living Things Acquire and Use ______________________ (Figure 1-11)
1.
Metabolism - total of all life-sustaining chemical reactions
2.
Energy - ability to do work
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E. Living Things Use DNA to Store Information (Figure 1-12)
1. Deoxyribonucleic acid (DNA) - hereditary information
2. Gene - segment of DNA that contains set of instructions
1.4
Why Is Life So Diverse?
A. Evolution Accounts for Both Life’s Unity and Its Diversity
1.
Genetic variation - each generation is slightly different
2.
Inheritance of genetic variations
B. Natural Selection Causes Evolution
1.
Certain characteristics aid in survival and reproduction
2.
Individuals with favorable characteristics produce more offspring
C. Life’s Diversity Is Currently Threatened
1.
Biodiversity - array of species present in a given environment
2.
Interrelationships between humans and other species
Links to Life: The Life Around Us
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