The Science of Life pg 1 Biology unifies much of natural science Biological systems are the most complex chemical systems on Earth The complexity of living organisms is made possible by the Sun a constant source of energy The process of photosynthesis is one of the most beautiful and complex processes in physics and chemistry o Life defies simple definition Biology is the study of living things the science of life Characteristics of living organisms Cellular organization All organisms consist of one or more cells all bounded by a membrane that separates it from its surroundings Ordered complexity All living things are very complex and ordered Although nonliving things can be complex they do not compare to the complexity of living things Sensitivity Living things respond to stimuli o o Plants respond to light o Pupil size changes upon a change in darkness Growth development and reproduction all living organisms are capable of reproduction in which the offspring is the same species with the same hereditary traits Energy utilization Organisms take in energy and use it in some way Homeostasis a process in which organisms maintain constant internal conditions different from their environment o o Body temperature remains stable despite the environmental conditions Evolutionary adaptation Organisms interact with one another along with the nonliving environment They do this for their survival therefore organisms evolve adaptations to their environments o Living systems show hierarchical organization The Cellular Level Atoms the fundamental elements of matter Molecules a grouping of atoms into clusters Organelles Molecules assembled into tiny structures Cells membrane bound units o Considered the basic unit of life The Organismal Level Tissues groups of similar cells that act as a functional unit Organs groups of tissues Can also be composed of several different tissues Organ systems Organs group together o Example The nervous system Composed of sensory organs the brain and spinal cord and neurons The Populational Level same place Population a group of organisms of the same species living in the The Ecosystem Level Species populations of a particular kind of organism together Biological community consists of all the populations of different species living in one place together Ecosystem or ecological system a biological community o Example A mountain ecosystem consisting of soil water and the atmosphere interact with the biological community The Biosphere Biosphere The entire planet o Therefore Atoms Molecule Organelle Cell Tissue Organ Organ system Organism Population Species Community Ecosystem Biosphere o Emergent properties the changing of novel properties as one moves up the biological hierarchy above One cannot draw conclusions from the knowledge of a single component Example One cannot examine a single cell and determine that it is a o Science uses both deductive and inductive reasoning Deductive reasoning applies general principles to predict specific results Example If all mammals have hair and an animal is found that does NOT have hair one can conclude that the hairless animal is not a mammal Inductive reasoning applies specific principles to generate generic results Example If poodles have hair if Terries have hair then all dogs o Hypothesis driven science makes and tests predictions must have hair After making observations scientists construct a hypothesis a suggested explanation that accounts for the recorded observations Hypothesis can be iterative meaning that they can be changed based upon new data o Testing hypotheses Experiment the test of a hypotheses A successful experiment is one which hypotheses have been tested rejected and then discarded o Establishing controls Variable A factor that influences an outcome Often scientists try to giraffe The Nature of Science pg 4 isolate variable to test their hypotheses Test experiment When a variable is altered in an experiment in order to test a hypothesis Control experiment When the variable is left unaltered in an experiment o Reductionism breaks larger systems into their component parts In order for scientists to understand a large complex system they use the process called reductionism breaking the system down to its component parts This process is not easy because sometimes the components may act differently by themselves than they do as a system o The nature of scientific theories Several uses for the word theory A proposed explanation for some natural phenomenon Body of interconnected concepts explained by scientific reasoning and experimental evidence that explains facts in a specific area of study o Research can be basic or applied Basic research intended to extend the boundaries of what we know These individuals usually work in universities Applied research When people apply the findings from basic researching Individuals are employed in some type of industry such was manufacturing goods creating new drugs or testing environmental qualities Evolution Genetic change in a population of organisms Generally evolution change is from simple to complex o Darwin proposed natural selection as a mechanism for evolution Natural selection the differential reproduction of genotypes that is caused by factors in the environment which leads to evolutionary change Artificial selection Change in the genetic structure of populations due to interference with humans more appealing Often animals and crops are artificially selected in order to appear o The predictions of natural selection have been tested Darwin s theories have been tested many ways The fossil record Darwin predicted that fossils would yield links between groups of organisms such as fishes and amphibians Natural selection allows scientists to see the transitional forms of several organisms The age of earth Physicists argued that the Earth was only a few thousand years ago however Darwin proved them wrong through his theory of evolution Comparative anatomy o Homologous bones in species that have the same evolutionary origin however now they differ in structure An Example of Scientific Inquiry Darwin and Evolution pg 8 o The idea of evolution existed prior to Darwin Unifying Themes in Biology o Analogous Bones that have a similar function but differ in and function evolutionary origins o Cell theory describes the organization of living systems All organisms are composed of cells and they are the basics to human life Robert Hooke discovered cells in 1665 with one of the first
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