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Biology Exploring Life
All forms of life share common properties
Life is defined by what living things do. 7 major processes/properties associated with living things Have order (all living things are either single cells or
made of many cells)- atoms, molecules, organelles, cells, tissues, organs, organ systems, organisms
Reproduce: make more of their own (cell division/sexual reproduction)
Grow and develop: increase in size, go through a series of changes (development) controlled by DNA
Process energy: use energy to carry out all life functions and to maintain homeostasis (internal balance)
Respond to the environment: stimulus/response (migration, movement toward light, etc.)
Regulation: have processes that regulate a constant internal environment (homeostasis) (shivering,
Hierarchy of Organization
At each level of organization new properties arise that were not present at the preceding level. (Emergent Properties)
Living organization begins at the cellular level. All living things are made of cells. Cells are made of atoms, molecules, and organelles-but these are not considered living. DNA is an important molecule, but it is not a living thing Organelles are tiny “organs” that perform a specific function
for a cell, but alone they are not considered living
A group of similar cells that perform a specific function are tissues-tissues are considered living
A group of tissues form an organ (heart)
A group of organs form an organ system (circulatory system)
A group of organ systems form an organism (an individual living thing)
A group of organisms of the same species form a population
A group of populations form a community (plants and animals, fungi, bacteria)
A group of communities form and ecosystem
Groups of ecosystems form the biosphere (all of the ecosystems on earth that support life.)
Cells are the structural and functional units of life
Cells are the level of organization at which the properties of life emerge
All organisms are composed of cells. They occur singly or as the subunits of multicellular organisms.
Two main characteristics of cells 1. All cells are enclosed in a membrane that regulates
what enters and leaves the cell 2. All cells use DNA as genetic information
2 types of cells: 1. Prokaryotic: DNA is not enclosed in a membrane
bound nucleus. No membrane bound organelles. Smaller in size Have existed on Earth for longer (evolved around the first
1.5 billion years of life on Earth 2. Eukaryotic: DNA contained within a membrane
bound nucleus. Contains membrane bound organelles. Larger in size Evolved about 2.1 billion years ago
The properties of life emerge from the ordered arrangement and interaction of the structure of cells.
A system is the combination of the parts forming a more complex organization.
Because of the complexity of biological systems, biologists use an approach called systems biology which uses models to study the dynamic behavior within a system. Systems biology is based on the study of the individual parts of the system to explain the whole system.
Cells also help explain the correlation between structure and function. A cells structure gives us clues as to it’s function (nerve cells)
All activity from movement to metabolism takes place at the cellular level.
Organisms Interact with their Environment
This interaction includes all living and non-living parts.
There are two major processes that are involved in this interaction 1. Recycling of chemical nutrients
producersconsumersconsumersdecomposers producers
Nurtients are recycled through the ecosystem
2. The flow of energy SunlightProducerschemical
heatConsumerheatDecomposterheat There must be a constant source of sunlight and
heat is given off in each step in the flow of energy through the system. This means that each step has less available energy than the previous step.
The Unity of Life is Base on DNA and a Common
Genetic Code
DNA is the chemical substance of genes. Genes are the units of inheritance and all cells have DNA
The molecular structure of DNA controls the transmittance of information from parents to offspring and controls the activities of the cell.
The diversity of life arises from the differences in the DNA sequence of nucleotides
DNA stand for Deoxyribonucleic Acid
DNA is composed of long chains of nucleotides
Nucleotides A ribose sugar A phosphate group A nitrogen base
The Diversity of Life is Arranged into Three
Domains
Life is not only organized within the biosphere from molecules to the biosphere, life is organized according to the diversity of living things.
Living things are grouped according to similarities. This grouping process (taxonomy) names and classifies species into a hierarchy of broader and broader groups: genus, family, order, class, and phylum to kingdom
Historically, biologists grouped all living things into 5 kingdoms
Using evolutionary relationships we now group all living things into one of three domains Domain Bacteria (Prokaryotes, very diverse group) Domain Archaea (Prokaryotes, live in very harsh
environments-salty lakes, boiling hot springs) Domain Eukarya (Eukaryotes, range from single cell
protists to multicellular organisms)
Evolution explains the Unity and Diversity of Life
Fossils document the history of the changing Earth Life has existed on Earth for billions of years The Earth has been inhabited by an evolving cast of
life forms
Evolution accounts for life’s: Kinship(Similarities) and Diversity Differences
Charles Darwin
Published On the Origin of Species by Means of Natural Selection in 1859 Provided evidence to support the idea of evolution
and that species living today are descendants of ancestral species (descent with modification)
Natural Selection is the mechanism for evolution
Darwin made two observations: 1. Individuals in a population vary in their traits,
many of which are passed from parent to offspring 2. A population can produce more offspring than the
environment can support
From these observations, Darwin inferred: 1. Individuals with heritable traits best suited to the
environment are more likely to survive and reproduce than less well-suited individuals
2. This unequal reproductive success over many generations will increase the proportion of individuals in the population with the advantageous traits
3. This will result in an evolutionary adaptation. The accumulation of favorable traits in a population over time.
The Process of Science
Science: derived from the Latin verb “to know”
Scientists use inquiry: search for information and explanation 1. Discovery Science 2. Hypothesis-based Science
Discovery Science Describes nature through observation and analysis
of data Data = recorded observations
(quantitative/qualitative) Inductive reasoning: generalizations derived from
specific observations
Hypothesis-Based Science Uses deductive reasoning: propose an explanation
for a set of observations. Logic flows from general to specific.
Hypothesis: predictions that can be tested by observing or experimenting.
AP Biology will use: “If…., then ….. because” when writing our hypotheses.
A hypothesis must be testable and falsifiable
Experimental Design
Hypothesis
Use control (the group in the experiment you will compare your results to) and experimental (the group that contains the factor you will be testing or observing) Controlled Experiment
Design: Independent variable (IV) A variable that is changed intentionally to observe
its affect on the dependent variable Dependent variable (DV) What you measure in the experiment, what is
affected during the experiment Control Constants # of trials
Example: You are interested in how stress affects heart rate in humans. Your independent variable would be the stress and the dependent variable would be the heart rate. You manipulate stress levels in your subjects and measure how those stress levels change heart rate.
Hypothesis
Explanation to a specific question
Tested by experimentation or continued observation
Can be disproven (falsified) but cannot be proven true
Theory
Summarizes a group of hypotheses supported by repeated testing
Broader in scope
New hypotheses can be generated from it
Supported by massive body of evidence
Law
Statement of Fact
Explains things but doesn’t describe them
Generally accepted to be true and universal
Basis for scientific method
Science is a social activity with most scientists working in teams
Scientists share information
Science seeks natural causes for natural phenomena Limited to the study of structures and processes that wen
can directly observe and measure Hypotheses about supernatural forces or explanations are
outside the bounds of science because they generate untestable hypotheses
Biology and Everyday Life
Biology, technology, and society are connected.
Issues facing society are related to biology and most involve expanding technology
The goals of science and technology differ The goal of science is to understand natural
phenomena The goal of technology is to apply scientific
knowledge for a specific use
Technology advances stem from scientific research Scientific research benefits from new technology
Evolution is a core theme in biology Evolution is useful in medicine, agriculture,
forensics, and conservation
Human caused environmental changes are powerful selective forces that affect the evolution of many species Antibiotic resistant bacteria Pesticide resistant pests Endangered species and extiction