-Biology is the scientific study of life
-Over ½ of a million new research articles are published annually-We are a part of the global development
of science
Explore life from the microscopic to the Global Scale
A. A Hierarchy of Biological Organization
 There are several key properties of life (See Figure 1.3)
1. Order
2. Evolutionary Adaptation
3. Response to Environment
4. Regulation
5. Energy Processing
6. Growth and Development
7. Reproduction
 There are several levels of biological organization, with each level of biological
structure building on the level below it.
1. Individual organism-species-population-community-ecosystem-biomebiosphere
2. Atoms-Complex Biological molecules-subcellular organelles-cells-tissuesorgans-organ systems-complex organism
B. A Closer Look at Ecosystems
 Organisms interact continuously with their environment, both with the Biotic
(living) and Abiotic (nonliving) factors. Can you give an example?
 The dynamics of an ecosystem include two major processes:
1. The Cycling of Nutrients
2. The flow of Energy through an ecosystem: from sunlight to producers
(plants and other photosynthetic organisms that convert light energy to
chemical energy) to consumers (organisms that feed on producers and/or
other consumers). (See Figure 1.5)
 Energy conversion-The exchange of energy between an organism and its
surroundings is required for organisms to perform work (Think Photosynthesis and
C. A Closer Look at Cells
 Lowest level of structure capable of performing all functions of life is the cell.
Cells are the basic units of structure and function. All organisms are composed of
cells. May exist singly as unicellular organisms or as subunits of multicellular
 Cells contain heritable information, in the form of DNA (deoxyribonucleic acid).
DNA is the substance of genes, the units of inheritance that transmit information
from parents to offspring (See Figure 1.10)
o All forms of life have essentially the same genetic code. The entire library
of genetic instructions that an organism inherits is called its genome.
The discovery of cells was credited to Robert Hook who saw cells of a cork
(stopper). Later, Antonie van Leeuwenhok observed organisms, blood, and sperm
in a microscope and identified different types of cells.
There are two main forms of cells:
1. Prokaryotic Cell=Cell lacking membrane-bound organelles and a
membrane-enclosed nucleus.
2. Eukaryotic Cell=Cell with a membrane-enclosed nucleus and membraneenclosed organelles
Biological Systems are much more than the sum of their parts
A. The emergent properties of systems
 Emergent properties are novel properties that emerge at each level of biological
order. Emergent properties are found everywhere.
B. The Power and limitations of Reductionism
 Holism= The principle that a higher level of order cannot be meaningfully
explained by examining component parts in isolation (a whole is greater than the
sum of its parts)
 Reductionism= The principle that a complex system can be understood by studying
its component parts (a powerful strategy in biology). This takes complex systems
and breaks them into parts that can be studied.
 Scientists need to balance these two principles.
C. Systems Biology
 Systems Biology is used to model the dynamic behavior of a whole biological
system. It is where Biology is turning—is this holistic or reductionist?
D. Feedback Regulation in Biological Systems
 In feedback regulation, the output, or product, of a process regulates that very
process. This ensures a dynamic balance in living systems.
1. Positive feedback-the end product speeds up its production (like blood
clotting). (See Figure 1.13)
2. Negative feedback-the accumulation of an end product slows that process.
This is the most common form of regulation. (See Figure 1.13)
Biologists explore life across its great diversity of species
 Diversity is a hallmark of life!!!! There are currently 1.8 million identified
species Five to 30 million species are expected to be on Earth!
A. Grouping Species: The Basic idea
 DOMAIN-Kingdom-Phylum-Class-Order-Family-Genus-Species
B. The Three Domains of Life (Figure 1.15)
1. domain Bacteria-Prokaryotic
2. domain Archaea-Prokaryotic
3. domain Eukarya-Eukaryotic (Protists, Plants, Fungi, and Animals)
C. Unity in the Diversity of Life
 Diversity and unity are the dual faces of life on Earth. All living things are both
similar and different (See Figure 1.16)
Evolution accounts for life’s unity and diversity
 Charles Robert Darwin-Published On the Origin of Species by Natural
Selection in 1859 and changed science forever. (See Figure 1.18) There were two
main points made by Darwin:
1. Contemporary species arose from a succession of ancestors a.k.a. “Descent
with Modification”
2. The mechanism for descent with modification is called Natural Selection.
(See Figures 1.20 and 1.21).
Biologists use various forms of inquiry to explore life
 Inquiry is a search for information and explanation, often focusing on specific
questions. The inquisitive mind is the engine that drives all progress in Biology.
There are two processes of scientific inquiry:
1. Discovery Science: describes natural structures and processes as accurately
as possible through careful observation and analysis of data (recorded
observations). Discovery science uses inductive reasoning, in which
generalizations are made based on a number of specific observations.
2. Hypothesis-Based Science: explains nature using the proposing and testing
of hypothetical explanations. A hypothesis is a tentative answer to a wellframed question. Hypothesis-based research uses deductive reasoning,
where an inference is made from general premises to specific results. This
takes the form of “If….then”. (See Figure 1.24). Always remember that a
hypothesis is never proven, it can only be supported or rejected
 A controlled experiment is a designed experiment where an experimental group is
compared with a control group. The environment is kept constant except for the
variable being tested.
 A scientific theory is a broad statement that is generally supported by a massive
body of evidence.
 Science is a very social activity that is dependent upon technology. Good
Scientists are people who:
1. Ask Questions about nature and believe those questions are answerable
2. Are curious, observant, and passionate in their quest for discovery
3. Are creative, imaginative, and intuitive
4. Are generally skeptics
 Science and technology are interdependent.
 A better understanding of nature must remain the goal of science
A set of themes connects the concepts of biology
 In order to make sense of the complexities of life, there are broad themes that
pervade all of biology. The eight themes of the A.P. Biology Curriculum are:
1. Science as a Process
2. Evolution
3. Energy Transfer
4. Continuity and Change
5. Relationship of Structure to Function
6. Regulation
7. Interdependence in Nature
8. Science, Technology, and Society