Biology Lab Review Chapter 1 The Discovery Process A theory is not an educated guess nor is it an article of faith A theory is a unifying explanation that has withstood many attempts to falsify it through scientific investigation over prolonged period of time There are four unifying theories in biology o The Cell Theory all organisms are made of cells that store hereditary information in DNA o The Gene Theory DNA sequences may be altered by mutation or by crossing over and segregation during meiosis o The Theory of Hereditary Changes in DNA sequences produce individual heritable variation o The Theory of Evolution Evolution is simply genetic change over time Scientific Problem Solving 1 Observe and Formulate Questions 2 Reflect on the Implications 3 Propose a Hypothesis 4 Test the Hypothesis o Dependent variable represents the response to the factor that changes o Independent Variable factor that changes o Other variables may affect the results and must be controlled whenever possible 5 Analyze the Result o Support or Refute the Hypothesis o Results are neither right nor wrong o Experiments that refute a hypothesis may be more useful that those that support the current understanding of a problem 6 Support Reject or Modify the Hypothesis Termite workers are sterile and lack compound eyes The dissecting microscope is the best choice to view larger 3D or opaque specimens such as live termites Dissecting microscopes use transmitted and reflected light whereas compound microscopes use just transmitted lights Dissecting microscopes have lower magnification but greater resolution through the magnification range when compared to compound microscopes Dissecting microscopes use our ability to see in three dimensions by incorporating a separate objective for each ocular This allows you to make a 3D examination Dissecting Microscope Transmitted light passes through a specimen Reflected light bounces off the surface of a specimen Scientific Method 1 Make Observations 2 Develop Hypothesis 3 Design an Experiment 4 Collect Data 5 Analyze the Data 6 Share Results 7 Refine the Investigation Class Discussion Symbiotic association mutualism mutually beneficial association Termites and their symbionts are important decomposers of organic material Compound Microscope Flagella are hair like projections that help organisms move flagellated protists Ocular magnify objects 10 times The total magnification of a specimen equals the ocular power multiplied by the objective power The space between the objective and slide is the working distance The field of view is the visible area The depth the microscope focuses is the depth of field Magnification and depth of field are Parfocal means a specimen that is in focus with a low power objective remains roughly focus when inversely proportional a higher power objective is used Parcentric means a specimen centered over the condenser using a low power objective remains centered when a higher power objective is rotated into place Resolution is the ability to discern close objects The smaller the distance between two visible objects the greater the resolution The human eye distinguishes objects 0 1mm apart A light microscope resolves objects 1 000 times closer or about 0 1 m apart Although resolution increases with magnification the relationship is not linear Resolution does not increase as much as magnification Chapter 2 The Properties of Water Osmosis and Diffusion Water is the most plentiful chemical constituent of living cells Water is the only natural substance that occurs as a liquid solid and gas at temperatures that support life Although a water molecule carries a neutral charge the oxygen atom attracts negatively charged electrons making it slightly negative while the hydrogen atoms are slightly positive This polar nature causes water molecules to weakly bond together which explains how water remains liquid when other molecules of similar size are gases This attraction to other molecules is called cohesion Adhesion occurs when water molecules are attracted to other materials A covalent bond forms when two atoms share two electrons within a molecule they may be polar or nonpolar and are very strong A hydrogen bond occurs between two molecules when a positively charged hydrogen atom bonds with a negatively charged oxygen fluorine or nitrogen atom Surface Tension the cohesion of water molecules causes water to pull itself into the shape with the smallest surface area Plants rely on capillary action to pull water from the soil into the roots Water molecules form hydrogen bonds not only with other water molecules but with cellulose molecules in the cell walls of plant transport tissues called xylem Plants transport water from the roots through the rest of the plant by a process called transpiration which relies on the cohesive property of water Some call water the universal solvent because of its importance in transporting essential dissolved materials and its ability to dissolve more different materials than other solvent Solutions are characterized by interactions between the solvent and solute molecules or ions A solution is a homogeneous mixture composed of a solute dissolved in a solvent Water as a polar solvent interacts with the ionic bonds of many molecules Ionic bonds occur when an electro is completely transferred from one atom to another to form a positively charged cation while the atom that gains its electron becomes a negatively charged anion The process by which the components of a mixed solution are separated along a matrix is called a chromatography Water has low viscosity as opposed to something with high viscosity such as honey Low viscosity makes it easy for substances to diffuse through water while it also protects surfaces This is a result of the high thermal capacity of water Water absorbs a lot of heat before it starts to get hot and retains heat once warmed Since it takes a lot of energy to change the temperature of a body of water bodies of water tend to moderate air temperatures This is one reason coastlines tend to have more moderate weather than inland locations The thermal capacity of water also drives the weather Water absorbs heat energy and vaporizes in high temperatures This releases heat energy causing water to condense and precipitate as temperatures cool Most liquids contract when they freeze Water contracts until it reaches 4 degrees Celsius and then expands until it becomes a solid This makes it less dense in its solid
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