Biology Chapter 1 Notes
How Do You Define Life?
• Anything that is complex and made of chemicals
• Something that needs to eat food.
• Life cannot be defined.
The Scope of Life
• Biology is the study of life.
• What is life?
➢ It defies a simple, one-sentence definition.
• Life is recognized by what living things do.
➢ They have order.
➢ They regulate themselves.
o Called homeostasis: “maintaining a steady state”
➢ They grow and develop.
➢ They use energy.
➢ They respond to the environment.
➢ They reproduce.
➢ Populations evolve.
Theme 1: The Scope of Life and Emergent Properties
• Life consists of a vertical hierarchy
➢ Molecules Biosphere
• Novel properties emerge at each step due to the…
➢ ….of the components
• Emerging properties are difficult to predict when you look at the properties
at the lower levels of the hierarchy.
Example of an Emergent Property
• Put all the molecules required for photosynthesis in a test tube
➢ Expose to light
• Photosynthesis will not occur
• The specific orientation of the molecules is missing.
Theme 2: Organisms Exchange Matter and Energy Within Ecosystems
• Every organism interacts with its environment
➢ Both are affected.
o Ex. Plants use CO2 to make food.
o All 02 in the atmosphere comes from photosynthesis.
➢ Nutrients are recycled
➢ Energy flows from sunlight to producers to consumers o Energy exists as heat
Theme 3: Cells Are An Organism’s Basic Unit
• Cells are the lowest level of organization that can perform all the activities of
• All cells…
➢ Are enclosed by a membrane.
➢ Use DNA as the recipe for the process of life.
➢ 2 kinds of cells:
o Prokaryotic and Eukaryotic
Theme 4: The Continuity of Life is Based on the Information in DNA
• Chromosomes contain most of a cell’s genetic material in the form of DNA
• DNA is the substance of genes
• Genes are the units of inheritance that transmits from parents to offspring.
Theme 5: Diversity is the Hallmark of Life and Diverse Forms of Life Fit Their
• There are three main groups of life – called domains
Living Organisms Can Be Classified
• Eukaryote: organisms with a true nucleus
➢ Most are unicellular but some of them are multicellular organisms, it is a
very diverse group consisting of algae, kelp, protozoa, slime molds
• The structure and the function of the diverse components of life are related
Theme 6: Evolution
• Heritable changes in populations over generatins
• Biology’s core theme
➢ The scientific explanation for both
o The unity of life
o The diversity of life
• The word science is derived from a Latin verb meaning “to know”
• Its is both:
➢ A way of knowing
➢ A body of knowledge Scientists use two main forms of inquiry
1. Discovery science
➢ Describes natural structures and processes
2. Hypothesis based science
➢ Observations lead to questions
➢ Questions lead to hypotheses
o Tentative answers to a well framed questions
▪ Should be specific
▪ Usually “if, then” statements
o Tested by observation or experimentation
➢ Failure to falsify a hypothesis does not “prove” it
o Ex. you replace your flashlight bulb
o It now works
o Supports the hypothesis that your bulb was burnt out,
o But does not prove it
▪ Perhaps the first bulb was inserted incorrectly
• Cholera Outbreak in 1954, London
➢ Did not know that caused cholera
➢ Did not know how cholera spread
➢ Cholera was/is a killer
Scientific Method: Observation
• Dr. John Snow observed that most cases of cholera were located near a water
pump on Broadway Street
• Cholera affected the digestive tract causing severe diarrhea
• Residents who drank from the pump contracted cholera
• Visitors who drank from the pump contracted cholera
• People who drank beer (not water) did not get cholera
Scientific Method: Hypothesis
• A hypothesis is a tentative explanation for an observation
• What would be an acceptable hypothesis for the observations made by Dr.
Scientific Method: Experiment
• Design an experiment appropriate to test Dr. snow’s hypothesis.
Scientific Method: Results
• What was the result of Dr. Snow’s testing?
Scientific Method: Conclusions
• What conclusion did Dr. Snow make concerning the results of his
• Now….. it is known that
➢ Cholera is caused by a bacteria that lives in feces
➢ The bacteria is spread through unsafe sanitary conditions – water
➢ Deaths are due to severe dehyd