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Chapter 3

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York University
BIOL 1000
Michael Gadsden

Chapter 3: Selection, Biodiversity & Biosphere 10/21/2010 1:24:00 PM 3.1 Biodiversity 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 molecules. 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. 3.2 Selection 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 is involved. 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. 3.3 Evolution 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 (waterland; attracting insects) CONCLUSION This is how organis
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