Unit 1 Notes To date about 1 8 million species have been identified and named With so many different species there are many different unifying similarities 1 Evolution is a central theme in biology The ability to evolve is built into organisms Evolution is a change in the genetic makeup DNA of a population over time as a result of natural selection A single individual cannot evolve populations evolve Evolution can happen at different speeds for different types of organisms Natural selection is the driving force behind evolution It means that evolution is not a level playing field organisms are not equally suited to reproduce certain individuals are more suited than others to reproduce Evolution is based on two principles variation and competition individuals will struggle to survive o If individuals are different one has a better change of surviving than the other Think of a race one is more suited to run faster than the other o Giraffe example the ones who already had slightly longer necks were able to survive because they could reach their food The giraffes with the shorter necks died out thus leaving the longer giraffes to reproduce and create more giraffes with longer necks There are variations within every species e g some are tall some are short Means some are better suited to survival natural selection aka survival of the fittest Variability comes from genes and genes are inherited Conclusion more good genes survive and therefore the population changes You cannot straighten your hair and expect your children to have straight hair because you are not altering your genetic makeup 2 Life Contains an order of structural levels with each level building on the levels beneath it Hierarchy of biological organization within a living thing there are simple levels of organization that combine to make more and more complex levels of organization 1 Biosphere all of the environments on Earth that are inhabited by life land water and several layers of atmosphere A biosphere is made up of several ecosystems 2 Ecosystems all living things in a particular area along with non living environmental components with which life interacts soil water air components light Example in a classroom the ecosystem is all the people chairs walls air etc 3 Community the entire array of living organisms inhabiting a particular ecosystem An ecosystem is made up of communities 4 Population individuals of a species living within the bounds of a particular area 5 Organism individual living things A population is made up of organisms 6 Organ System and Organ body part consisting of 2 or more tissues which carries out a specific function within an organism e g liver kidney etc 7 Tissue group of cells from similar embryonic origins that combine to form organs Tissue is made up of cells 8 Cell the fundamental unit of structure and function in life e g neuron hepatocyte The smallest living thing on the planet is a single cell organism A virus is not a living thing it is a nucleic acid because it has no cells 9 Organelle various functional components that make up cells e g chloroplast mitochondria 10 Molecule chemical structure consisting of 2 or more atoms e g chlorophyll in plants 11 Atom basic unit of matter e g hydrogen Matter includes living and non living things everything is made up of atoms 12 Subatomic particle all units of matter small than the atom e g protons neurons electrons and lots of others 3 Each level of biological organization has emergent properties Emergent property a property that emerges as a result of interactions between components as complexity increases Think of it as taking apart your house the wiring cement cabinets etc are not interacting in a specific way if you pile all the materials together They are not creating the organism your house until they are put together If you mix all of the components of a chloroplast together in a test tube photosynthesis will not occur o The molecules must interact in a specific way With each step up in biological hierarchy new emergent properties are seen For example if you take sodium and chlorine you have table salt The table salt is the emergent property because it was not found in either of the individual substances 4 Life has the ability to acquire material and energy All living things must obtain energy The material and energy are often transformed Energy the ability to do work All levels of biological organization are thermodynamically open systems o Exchanging energy heat and work and matter with their environment The sun is necessary to provide the energy for the producers in our ecosystem If there were a nuclear explosion there would be so much dust and dirt lingering in the air that sunlight wouldn t be able to penetrate the dust and reach the earth If something were able to survive the explosion it would either die of starvation or because of the drop in temperature There must be an exchange of energy between an organism and its environment See figure 1 5 about energy flow and transformation in the ecosystem o The sun gives energy to the producers plants and other photosynthetic organisms The energy is lost in heat and chemical energy The chemical energy affects the organisms on earth animals 5 Structure and function are related Form dictates function An objects shape makes it ideal for the function it does If you change something s shape you run the risk of altering its function as well Form and Function o Just as a tool such as a hammer is crafted to perform a certain task the anatomy of plants and animals determine the task that they perform o Plant leaves thin and flat to maximize sunlight absorption o Bird wing bones inner structure like a honeycomb Both lightweight and strong allows the bird to fly 6 Living things reproduce and cells are the basic unit of structure and function Prokaryotic cells are cells which lack internal cellular membranes no Eukaryotic cells are cells which have a membrane enclosed nucleus and nucleus or organelles membrane enclosed organelles Cells for life Cells are the lowest level of organization that performs all activities required Cell division is the basis for reproduction and for growth and repair of multicellular organisms 7 DNA is the basis of heritable information The passing of DNA from one generation to another is the basis of inheritance Inheritance the acquisition of traits by transmission of DNA from parent to offspring This process of transmitting the DNA to new generations is built into the
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