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Chapter 3 Summary Notes Complete summary of chapter 3, including all topics covered in lecture in depth, with definitions, and explanations. Cuts all the excess fluff in the textbook, straight to the point biology

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Diane Williams

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3.1 Biodiversity
measured as the umber of species of organisms
reflects the reality that life on Earth exists from the ocean floor to well into the
cell > multicellular organism > population (all same species, same area) >
community (populations in same area) > ecosystem (group of communities interacting
in shared environment) > biosphere (all regions of earths crust, waters and atmosphere
that sustains life)
when grouping organisms, consider how organisms obtain carbon because it is the
“backbone” of all organic molecules synthesized by an organism
Heterotrophs obtain carbon from organic molecules, either from living hosts or from
organic molecules in the products, wastes, or remains of dead organisms.
Autotrophs synthesize organic carbon molecules using inorganic carbon (CO2)
Chemotrophs obtain energy by oxidizing inorganic or organic substances
(chemoautotrops found in some bacteria and archaeans; not found in eukaryotes.
Chemoherterotrophs found in some bacteria and archaeans, and also in protists,
fungi, animals and plants)
Phototrophs obtain energy from light (Photoautotrops found in some photosynthetic
bacteria, in some protists and in plants, Photoheterotrophs found in some
photosynthetic bacteria)
3.2 Selection
Selection occurs when some force or phenomenon affects the survival of individual
selection occurs when a large population if individuals is exposed to a lethal factor and
only resistant individuals survive to reproduce.
the key factors behind selection are a selective force (pressure) and the capacity for
explosive population growth, as well as an inheritable trait or genetic variation.
3.3 Evolution
a gradual change in the characteristics of a population of organisms over time, can be
the result of selection
all organisms alive today descended from a common ancestor
explains why all organisms share features such as the use of adenosine triphosphate
(ATP) as a cellular energy source, DNA as a genetic material and plasma membranes
composed of lipid bilayers
Darwin’s Theory Summary
individual organisms in a population vary in many heritable traits
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