Chapter 3: Selection, Biodiversity & Biosphere 10/21/2010 1:24:00 PM
Molecules Organelles Cells Organisms Ecosystems Biosphere
(Refer to Figure 3.1)
Biodiversity is the number of species that exist on the Earth. The different types of organisms that live
on Earth can be classified into taxonomic categories. You could consider the fact that all organism have
carbons found in their bodies, due to the fact, we use carbon to help in synthesizing of organic
EXAMPLE Autotrophs (auto =”self”; troph =”nourishing”) are mostly plants which synthesize
organic carbon molecules using CO2 (inorganic molecule). CO2 is considered inorganic
because it oxides with a carbon.
EXAMPLE Heterotrophs are all animals carbon from living hosts or from products,
wastes, or dead organisms
EXAMPLE Chemotrophs (chemo=”chemical”; troph=”nourishing”) obtain energy by CO2
EXAMPLE Phototrophs get energy from light.
Selection is when some type of force affects the survival of individual organisms. This occurs when a
large population is exposed to a lethal factor and only the resistant individuals can survive to reproduce.
The key factors to selection are (1) force/pressure and capacity for a fast population growth. It is a major
contributor for evolution and biodiversity. Genetic variation is a recurring theme in which some pressure
EXAMPLE Syphilis evolved through each generation from being a skin-to-skin interaction to
now a sex transferring bacterium.
EXAMPLE of genetic variation. Whales have a common ancestor with hippopotamus which
Is the Indohyus. Although the Indohyus used the water to avoid predation and a selection of
them also ate fish, this is the key evidence as to why they are commonly similar.
EXAMPLE Climbing plants, known as herbaeceous vines, readily wrap their leaves/stems
(tendrils) or modified roots around their support.
Evolution id the gradual change of a population of organisms over time, and is the key to understanding
the diversity of life on earth. The theory of evolution explains that all organisms of light have a common
ancestor and that over time natural selection occurs. This is where we all diverge because of selective
pressure in our environments = adaptive radiation.
Darwin’s theory surrounds the idea that (1) individual organisms vary in heritable traits, (2) individuals
can reproduce to large amount but due to limited resources its “survival to the fittest”, (3) some individuals have a advantage over other in local environments, and (4) favorable traits are inherited by
offspring allowing them to evolve.
EXAMPLE of adaptive radiation plants (waterland; attracting insects)
CONCLUSION This is how organis