Evolution and the Foundations of Biology
Overview: Inquiring About Life
•	An organism’s inherited characteristics that allow it to be well adapted for its environment are the result of evolution
•	Evolution is the process of change (over MANY GENERATIONS )that has transformed life on Earth

Concept 1.1: Studying the diverse forms of life reveals common themes

Theme: New Properties Emerge at Successive Levels of Biological Organization
•	Life can be studied at different levels, from molecules to the entire living planet

Theme: New Properties Emerge at Successive Levels of Biological Organization
•	Reductionism:
•	 complex systems are reduced to simpler components to make them more manageable to study
•	Emergent properties result from the arrangement and interaction of parts within a system 
•	Emergent properties characterize nonbiological entities as well
•	For example, a functioning bicycle emerges only when all of the necessary parts connect in the correct way
•	Biologists today combine reductionism with systems biology, the exploration of a biological system by analyzing the interactions among its parts
•	The systems approach poses questions such as
•	How does a drug for blood pressure affect other organs?
•	How does increasing CO2 alter the biosphere?
Structure and Function
•	At each level of the biological hierarchy we find a correlation between structure and function
•	Analyzing a biological structure can give clues about what it does and how it works
The Cell: An Organism’s Basic Unit of Structure and Function
•	All cells share certain characteristics, such as being enclosed by a membrane
•	The two main forms of cells are prokaryotic and eukaryotic
•	A eukaryotic cell contains membrane-enclosed organelles, including a DNA-containing nucleus
•	Prokaryotic cells lack a nucleus or other membrane-bound organelles and are generally smaller than eukaryotic cells
•	Figure 1.5

Theme: Life’s Processes Involve the Expression and Transmission of Genetic Information
•	Chromosomes contain most of a cell’s genetic material in the form of DNA (deoxyribonucleic acid)
DNA Structure and Function
•	A DNA molecule holds hundreds or thousands of genes, each a stretch of DNA along the chromosome
•	Genes are the units of inheritance that transmit information from parents to offspring
•	As cells grow and divide, the genetic information encoded by DNA directs their development
•	Figure 1.8
•	DNA provides blueprints for making proteins, the major players in building and maintaining a cell
•	Genes control protein production indirectly, using RNA as an intermediary
•	Gene expression is the process of converting information from gene to cellular product

Theme: Life Requires the Transfer and Transformation of Energy and Matter
•	Input of energy, mainly from the sun, and transformation of energy from one form to another make life possible
•	Plants and other photosynthetic organisms convert the energy of sunlight into the chemical energy of sugars 
•	This chemical energy of these producers is then passed to consumers that feed on the producers
•	Figure 1.9

Theme: Organisms Interact with Other Organisms and the Physical Environment
•	Every organism interacts with physical factors in its environment
•	Both organisms and their environments are affected by the interactions between them
•	For example, a tree takes up water and minerals from the soil and carbon dioxide from the air; the tree releases oxygen to the air, and roots help form soil
•	Figure 1.10

Concept 1.2: The Core Theme: Evolution accounts for the unity and diversity of life
•	Similar traits among organisms are explained by descent from common ancestors
•	Differences among organisms are explained by the accumulation of heritable changes
•	The remarkably diverse forms of life on this planet arose by evolutionary processes

Classifying the Diversity of Life: The Three Domains of Life
•	Humans group diverse items according to their similarities and relationships to each other
•	Careful analysis of form and function has been used to classify life-forms
•	Recently, new methods of assessing species relationships, especially comparisons of DNA sequences, have led to a reevaluation of larger groupings
•	Biologists currently divide the kingdoms of life into three domains: Bacteria, Archaea, and Eukarya
•	Domains Bacteria and Archaea are prokaryotes
•	Domain Eukarya includes three multicellular kingdoms: Plantae, Fungi, and Animalia
•	Plants produce their own food by photosynthesis
•	Fungi absorb nutrients
•	Animals ingest their food
•	Figure 1.11

Charles Darwin & The Theory of Natural Selection
•	Darwin made two main points 
•	Species showed evidence of “descent with modification” from common ancestors
•	Natural selection is the mechanism behind “descent with modification”
•	Darwin’s theory captured the duality of unity and diversity
•	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
•	Darwin inferred that
•	Individuals that are best suited to their environment are more likely to survive and reproduce
•	Over time (Within each New Generation), more individuals in a population will have the advantageous traits
•	In other words, the environment “selects” for the propagation of beneficial traits
•	Darwin called this process natural selection
•	Figure 1.15

The Tree of Life
•	The forelimb of a human, foreleg of a horse, flipper of a whale, and wing of a bat all share a common skeletal architecture
•	The shared anatomy of mammalian limbs reflects inheritance of a limb structure from a common ancestor
•	The diversity of mammalian limbs results from modification by natural selection over millions of years

•	Darwin proposed that natural selection could cause an ancestral species to give rise to two or more descendent species
•	For example, the finch species of the Galápagos Islands are descended from a common ancestor
•	Evolutionary relationships are often illustrated with treelike diagrams (Cladogram) that show ancestors and their descendants grouped by traits/ characteristics
•	Figure 1.16