1. Intro Notes: Themes in the Study of Life
AP Biology
Intro Notes: Themes in the Study of Life

2. Life’s Hierarchical Order
Each level of biological structure builds on the level below it
Atomscomplex biological molecules subcellular organellescellstissues organsorgan systems

3. Levels of Organization
Organism
Individual living
thing
Bison
Tissues, organs,
and organ systems
Groups of
Cells
Nervous tissue
Brain
Nervous system
Smallest functional
unit of life
Cells
Nerve cell
Groups of atoms;
smallest unit of
most chemical
compounds
Molecules
Water
DNA

4. Organism in a

5. There are levels of organization beyond the individual organism:
Population-localized group of organisms belonging to the same species
Community- populations of species living in the same area
Ecosystem-energy processing system of community interactions that include the abiotic factors in the environment

6. Biomes- large scale communities classified by predominant vegetation type and distinctive combinations of plants and animals
Biosphere- the sum of all the planet’s ecosystems

7. Levels of Organization, cont.
Biosphere
The part of Earth
that contains all
ecosystems
Biosphere
Ecosystem
Community and
its nonliving
surroundings
Hawk, snake, bison, prairie dog, grass, stream, rocks, air
Community
Populations that
live together in a
defined area
Hawk, snake, bison, prairie dog, grass
Population
Group of
organisms of one
type that live in
the same area
Bison herd

8. Emergent properties (pg. 5)
Each level of biological organization has emergent properties
These are properties that emerge as a result of interactions between components

9. Some emergent properties and processes associated with life are the following:
Order-organisms are highly ordered. Characteristics of life emerge from this complex organization.
Reproduction- organisms reproduce their own kind; Life comes only from life (biogenesis)

10. Growth and development-Inherited information in DNA directs species- specific patterns of growth and development
Energy Utilization-Organisms take in energy and transform it to do work, including maintaining their ordered state
Response to the environment- Organisms respond to environmental stimuli

11. Homeostasis- Regulatory mechanisms maintain an organism’s internal environment within tolerable limits, even though the external surroundings may change.
Evolutionary adaptations- Life evolves as a result of the interaction between organisms and their environments.

12. Cells are an organism’s basic unit of structure and function
All organisms are composed of cells
Cells exist as unicellular organisms, or as subunits of multicellular organisms
Cells are the lowest level of structure capable of performing all life activities.

13. Based on structural organization, there are two kinds of cells: prokaryotes and eukaryotes
Lack membrane-bound organelles and nucleus
Found only in archaebacteria and bacteria
Generally smaller than eukaryotic cells
Almost all have tough external walls

14. Eukaryotes: Found in protists, plants, fungi, and animals
Subdivided by internal membranes, forming organelles
Contains DNA separated from the rest of the cell; organized into chromosomes found in the nucleus
Plant cells have a cell wall; animal cells do not.

16. The continuity of life is based on inheritable information in the form of DNA
Biological instructions for an organism’s complex structure and function are coded in DNA
Each DNA molecule is made of 4 nucleotides: adenine, thymine, guanine, and cytosine
The linear sequence of these 4 nucleotides encode the information in a gene

17. Structure of DNA Nucleotide Hydrogen bonds Sugar-phosphate backbone
Section 12-1
Nucleotide
Hydrogen bonds
Sugar-phosphate backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)

18. Inheritance
Inheritance is based on a complex mechanism for copying DNA and passing the information on to offspring.
All forms of life use essentially the same genetic code.
Differences among organisms reflect differences in nucleotide sequence.

19. Structure and function are correlated at all levels of biological organization.
There is a relationship between an organism’s structure and how it works.
Knowing a structure’s function gives insight about its construction.
Example: aerodynamic design of a bird’s wing, internal bone structure, and muscle arrangement suitable for flight

20. Ecosystem dynamics include nutrient cycling and energy flow (Fig. 1.7)
Organisms are open systems that interact continually with their environment
Both the organism and the environment are affected by this interaction.
Ecosystem dynamics include nutrient cycling and energy flow (Fig. 1.7)

21. Regulatory mechanisms ensure a dynamic balance in living systems
Many biological processes are self-regulating (feedback regulation)
Positive feedback speeds a process up
Negative feedback slows a process down

22. Examples of Feedback Inhibition
Thermostat senses temperature change and switches off heating system
Heating system turns on
Room temperature decreases
Thermostat senses temperature change and switches on heating system

23. Evolution, Unity, and Diversity
Biological diversity is enormous. Estimates range from 5 million to over 30 million species.
About 1.5 million species have been identified and named, including approximately 260,000 plants, 50,000 vertebrates, and 750,000 insects.

24. Taxonomy
Taxonomy is the branch of biology concerned with naming and classifying organisms.
Taxonomic groups are ranked in a hierarchy from the most to least inclusive category: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species

26. Five Kingdoms (traditional classification)
Monera- prokaryotic organisms (Bacteria)
Protista- unicellular eukaryotes
Plantae-plants, photosynthetic organisms
Fungi-fungi, eukaryotic decomposers
Animalia- animals, most obtain food by ingestion

27. Unity
There is unity in the diversity of life forms at the lower levels of organization.
Unity of life forms is evident in a universal genetic code, similar metabolic pathways, and similarities of cell structure.

28. Evolution is the core theme of Biology
Life evolves as species change over time.
Species that are very similar share a common ancestor at a recent branch point on the phylogenetic tree.
Less closely related organisms share a more ancient common ancestor.
Natural selection is the mechanism of evolutionary change (survival of the fittest)

29. Science as a Process
Testable hypotheses are the hallmarks of the scientific process
Scientific method is the process which outlines a series of steps used to answer questions. (Controlled experiments)
Science is based on the conviction that natural phenomena have natural causes.
Evidence is required to solve problems

30. Scientific Hypotheses
Are possible explanations
Reflect past experience
Multiple hypotheses should be proposed whenever possible
Hypotheses must be testable using the hypothetico-deductive approach
Hypotheses can be eliminated but not confirmed with absolute certainty

31. Reznick and Elder research

32. Showed that selective predation resulted in evolution over a short time period

33. Science and technology
Science and technology are functions of society, and are interdependent.
Technology extends our ability to observe and measure so that scientists can work on new questions.
Science generates information to make technological inventions possible
Technology has improved our standard of living, but not without environmental and ethical consequences.

34. Biology is a muliti-disciplinary adventure
Biology integrates concepts from chemistry, physics, and mathematics, with influences from humanities and social sciences.
As a science, biology is an ongoing process. New research methods and technologies have led to an “information explosion”