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 classes 4 Class group of closely related orders 5 Order group of closely related families 6 Family group of closely related genera 7 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 pyrogenes 3 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 molecules from 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 groupswhich 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 have three middle ear bones and have a single bone in their lower jaw opposite are pleiomorphic characters which are more primitive useless for 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 microscopic o 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 multicellularity o 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 of prokaryotes 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 1800s 1 People believed the earth was several thousand years old 2 Also believed the earth was populated by unchanging life forms o Fossils need hard parts to become a fossil organisms that die need to be buried in sediment to fossilize 3 types of rocks 1 Igneous form when molten lava solidifies never contains fossils ex granite 2 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 next o 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 of geology Charles Darwin read this book and influenced him greatly ideas are in the category of uniformitarism The geological processes that formed the landforms of today are the same as they were at the beginning of the earth also argue against the idea