1. An Introduction to Biology
Unit One
An Introduction to Biology

2. Diversity of Life
Approximately 1.8 million species have been identified and named to date, and thousands more are identified each year
Estimates of the total number of species that actually exist range from 10 million to over 100 million
Levels of Organization – Biosphere, Biome, Ecosystem, Community, Population, Organism, Organ System, Organ, Tissue, Cells, Organelles, Molecules, Atoms
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3. The biosphere Tissues Ecosystems Organs and organ systems Communities
Figure 1.4
The biosphere
Tissues
Ecosystems
Organs and
organ systems
Communities
Figure 1.4 Exploring: Levels of Biological Organization
Cells
Organelles
Organisms
Atoms
Molecules
Populations

4. Many Themes in Biology Speciation Biotic and Abiotic interactions
Energy Flow
Structure and Function
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5. The Cell Is an Organism’s Basic Unit of Structure and Function
The cell is the lowest level of organization that can perform all activities required for life
All cells
Are enclosed by a membrane
Use DNA as their genetic information
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6. A eukaryotic cell has membrane-enclosed organelles, the largest of which is usually the nucleus
By comparison, a prokaryotic cell is simpler and usually smaller, and does not contain a nucleus or other membrane-enclosed organelles
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7. Nucleus (membrane- enclosed)
Figure 1.8
Prokaryotic cell
Eukaryotic cell
DNA
(no nucleus)
Membrane
Membrane
Cytoplasm
Figure 1.8 Contrasting eukaryotic and prokaryotic cells in size and complexity.
Nucleus (membrane- enclosed)
Membrane- enclosed organelles
DNA (throughout nucleus)
1 m

8. DNA Enables Life
Chromosomes contain a cell’s genetic material in the form of DNA (deoxyribonucleic acid)
A Chromosome is subdivided into sections called Genes
Genes are the units of inheritance that transmit information from parents to offspring
The ability of cells to divide is the basis of all reproduction, growth, and repair of multicellular organisms
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9. DNA Structure and Function
Each chromosome has one long DNA molecule with hundreds or thousands of genes
Genes encode information for building proteins
DNA is inherited by offspring from their parents
DNA controls the development (Meiosis) and maintenance of organisms (Mitosis)
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10. Fertilized egg with DNA from both parents
Figure 1.10
Sperm cell
Nuclei containing
DNA
Fertilized egg with DNA from both parents
Embryo’s cells with copies of inherited DNA
Egg cell
Offspring with traits inherited from both parents
Figure 1.10 Inherited DNA directs development of an organism.

11. Each DNA molecule is made up of two long chains arranged in a double helix
Each link of a chain is one of four kinds of chemical building blocks called nucleotides and nicknamed A, G, C, and T
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12. (b) Single strand of DNA
Figure 1.11
Nucleus A C
DNA
Nucleotide T A T T
Cell A C C G T
Figure 1.11 DNA: The genetic material. A G T A
(a) DNA double helix
(b) Single strand of DNA

13. Genes control protein production indirectly
DNA is transcribed into RNA then translated in order to manufacture proteins
DNA makes RNA which in turn makes Protein
Gene expression is the process of converting information from gene to cellular product
Nucleotides (A,T, C, & G) in specific combinations make up DNA; sections of DNA make up Genes; thousands of Genes make up a Chromosome; a specific number of Chromosomes result in a unique species
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14. Grouping Species: The Basic Idea
Taxonomy is the branch of biology that names and classifies species into groups of increasing breadth
Domains, followed by kingdoms, are the broadest units of classification
Phylogenetic Tree
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15. Ursus americanus (American black bear)
Figure 1.14
Species
Genus
Family
Order
Class
Phylum
Kingdom
Domain
Ursus americanus (American black bear)
Ursus
Ursidae
Carnivora
Mammalia
Chordata
Figure 1.14 Classifying life.
Animalia
Eukarya

16. The Three Domains of Life
Organisms are divided into three domains
Domain Bacteria and domain Archaea compose the prokaryotes
Most prokaryotes are single-celled and microscopic
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17. Domain Eukarya includes all eukaryotic organisms
Domain Eukarya includes three multicellular kingdoms
Plantae, which produce their own food by photosynthesis
Fungi, which absorb nutrients
Animalia, which ingest their food
Other eukaryotic organisms were formerly grouped into the Protist kingdom, though these are now often grouped into many separate categories
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18. (a) Domain Bacteria (b) Domain Archaea (c) Domain Eukarya 2 m 2 m
Figure 1.15
(a) Domain Bacteria
(b) Domain Archaea
2 m
2 m
(c) Domain Eukarya
Kingdom Animalia
100 m
Figure 1.15 The three domains of life.
Kingdom Plantae
Protists
Kingdom Fungi

19. Charles Darwin and the Theory of Natural Selection
Fossils and other evidence document the evolution of life on Earth over billions of years
Charles Darwin published On the Origin of Species by Means of Natural Selection in 1859
Darwin made two main points
Species showed evidence of “descent with modification” from common ancestors
Natural selection is the mechanism behind “descent with modification
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20. Darwin observed that
Individuals in a population vary in their traits, many of which are heritable
More offspring are produced than survive, and competition is inevitable
Species generally suit their environment
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21. Evolution occurs as the unequal reproductive success of individuals
Darwin inferred that
Individuals that are best suited to their environment are more likely to survive and reproduce
Over time, more individuals in a population will have the advantageous traits
Evolution occurs as the unequal reproductive success of individuals
In other words, the environment “selects” for the propagation of beneficial traits
Darwin called this process natural selection
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22. Population with varied inherited traits 2
Figure 1.20 1
Population with varied inherited traits 2
Elimination of individuals with certain traits 3
Reproduction of survivors 4
Increasing frequency of traits that enhance survival and reproductive success
Figure 1.20 Natural selection.

23. Intelligent Design
Science is defined as the quest for truth in how the universe arose and continues to function
Many scientist support the Theory of Evolution as the mode by which life began on Earth
Some scientists are investigating other hypotheses as to how life began on Earth: Intelligent Design

24. The Flexibility of the Scientific Method
The scientific method is an idealized process of inquiry
Hypothesis-based science is based on the “textbook” scientific method but rarely follows all the ordered steps: theory versus reality
1 state problem
2 form hypothesis
3 experiment
4 analyze data
5 conclusion
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25. The Role of Hypotheses in Inquiry
A hypothesis is a tentative answer to a well-framed question; educated guess
A scientific hypothesis leads to predictions that can be tested by observation or experimentation
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26. Types of Data
Data are recorded observations or items of information; these fall into two categories
Qualitative data, or descriptions rather than measurements
For example, Jane Goodall’s observations of chimpanzee behavior
Quantitative data, or recorded measurements, which are sometimes organized into tables and graphs
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27. Figure 1.23
Figure 1.23 Jane Goodall collecting qualitative data on chimpanzee behavior.

29. Experimental Controls and Repeatability
A control is a standard of comparison for checking or verifying the results of an experiment. In an experiment to test the effectiveness of a new drug, for example, one group of subjects (the control group) receives an inactive substance or placebo , while a comparison group receives the drug being tested
A supportable scientific experiment requires that a control group is used to cancel the effects of unwanted variables
In science, observations and experimental results must be repeatable
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30. Theories in Science In the context of science, a theory is
Broader in scope than a hypothesis
General, and can lead to new testable hypotheses
Supported by a large body of evidence in comparison to a hypothesis
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31. Scientific Laws
Accepted as fact by scientific community based on experimental repeatability
Newton’s laws of motion
Gravity
An object tends to stay at rest or in motion unless acted upon by another object

32. Science, Technology, and Society
The goal of science is to understand natural phenomena
The goal of technology is to apply scientific knowledge for some specific purpose
Science and technology are interdependent
Biology is marked by “discoveries,” while technology is marked by “inventions”
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