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SC BIOL 101 - Exam #1

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1/14/14- Classification system- Karl Linnaeus 1756; living things are classified into categories:1. Domain- largest category 2. Kingdom- group of closely related phyla 3. Phylum- group of closely related classes4. Class- group of closely related orders5. Order- group of closely related families6. Family- group of closely related genera7. Genus/genera- group of closely related species; closely related because they have a relatively recent common ancestor 8. Species- only real thing; a population or populations of organisms that interbreed and are reproductively isolated from other such groups; (population is in relation to a particular place; can be defined by scientists); always have a two word designation: humans are homo sapiens, cats are felis domesticus, dogs are cavis fomidiaris (first word is the genus and the second word is the species name)o Domains and Kingdoms of Life:1. Archeae- prokaryotes; extremophiles: many occupy extreme environments; ex. Thermophiles (extreme hot water), halophiles (salty water)2. Bacteria- prokaryotes; include familiar bacteria and can cause illness; ex. e.coli, streptococcus pyrogenes3. Eukarya- all eukaryotes; include single cell organisms (amoeba) and also multi cellular organisms; 3 kingdoms of eukaryotes and one “group” Unicellular eukaryotes- group Protista; ex. amoeba; 9 kingdoms within this group Fungi- kingdom of eukarya; ex. mushrooms, athletes foot fungus; multicellular absorptive (release enzymes into the environment) chemoheterotrophs (get their energy from chemicals and must get their organic molecules- carbohydrates, proteins, etc., from another living thing) Animalia- kingdom of eukarya; ex. cats, dogs, humans, etc.; ingestive (has a mouth) multicellular chemoheterotrophs Plantae- kingdom of eukarya; multicellular photoautotrophs (get energy from sunlight to make ATP and can make organic moleculesfrom scratch)- Phylogeny- evolutionary history of a group- Dendrograms- depict phylogeny with a dendrogram (picture of a phylogeny, looks like a family tree) o How are they constructed: goal is to discover monophyletic groups- which is an ancestor and all of its decedents; to discover monophyletic group, look for apomorphic characters (derived characters, unique) more advanced, ex. hole in the hip bone of dinosaurs, mammalia all havethree middle ear bones and have a single bone in their lower jaw; opposite are pleiomorphic characters which are more primitive (uselessfor discovering a monophyletic group), ex. composed of cells - Challenges faced by living things o Amoeba- has to undergo respiration, takes in oxygen and releases carbon dioxide; lives in water; can exchange material with simple diffusion o Unicellular prokaryotes; microscopico Unicellular eukaryotes- ex. amoeba; microscopic o Single cell organisms consume each other resulting in natural selection resulting in larger body size; why are cells small? Solution to increasing body size is multicellularity Fick’s Law- describes the rate of diffusion; the rate of diffusion is directly proportional to the concentration gradient; steeper the gradient the faster the rate of diffusion Diffusion is powered by the temperature of the environment; rate is also directly proportional to temperature  Surface area- the rate of diffusion is directly proportional to the surface area; large surface area=faster diffusion Why cells are small More cytoplasm there is more oxygen a cell needs The surface area of a cell is the area of total area of membrane Ex. cell is shaped like a cube, surface area= 6 x s x s; volume= s^3; SA/V ratio As the cell gets bigger, volume increases faster than the surface area; as the cell gets bigger there is not enough surface area to provide enough oxygen to the cytoplasm  Molecular weight of diffusing substance- rate of diffusion is inversely proportional (one goes up the other goes down) to the molecular weight of the substance; molecule bigger=slower diffusion Distance the substance has to cross by diffusion- greater the distance=slower the rate; inversely proportional - Evolution of multicellularityo Colonial protists- showed first signs of multicellularity; however they were in a colony: all the cells are the same and the cells can survive on their own o Multicellular organisms are different from a colony because there are greater than one type of cells and the cells cannot survive alone 1/16/14- Fluid surrounding the cells of our body is interstitial fluid - Geological time scale o Our earth and solar system are very close to 4.6 billion years old o The earliest fossils discovered are about 3.5 billion years old; fossils ofprokaryotes o Life evolved about 3.8-3.9 billion years ago o Scale breaks down geological time (now to 4.6 billion years ago) into categories such as eras: Cenozoic- encompasses time from 0 to 70 million years ago Mesozoic- 70 to 230 million years ago (dinosaurs were the predominant life form) Paleozoic- 230 to 600 million years ago; Cambrian (period) explosion (possible explanation for this is the appearance of “hard parts”, O2, and UV light) at the beginning of this era which is the sudden appearance of fossils of organisms that we know today “Precambrian”- everything before Paleozoic: 600 to 4.6 billion years ago (85% of geological time)Chapter 22: Evolution- Charles Darwin- lived in the 1800s1. People believed the earth was several thousand years old2. Also believed the earth was populated by unchanging life formso Fossils- need hard parts to become a fossil; organisms that die need to be buried in sediment to fossilize - 3 types of rocks1. Igneous- form when molten lava solidifies; never contains fossils; ex. granite2. Sedimentary- form from sediments and show layers called strata/stratum; the sediments at the bottom are older than the sediments at the top 3. Metamorphic- are igneous or sedimentary rocks that have been exposed to tremendous heat and pressure (will destroy any fossils)o Hypothesis of catastrophism: used to explain the different strata; at the end of every stratum there was a catastrophe that caused a change from one strata to the nexto James Hutton- 1795; proposed hypothesis of gradualism:  Stated that the land forms we see today like mountain ranges or grand canyon or oceans were a result of slow but continuous processes; this idea about gradualism argues against the other hypothesis that the earth is very young o Charles Lyall- book called principles


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