<p> AP Biology Lab Review Great Review Website: http://www.phschool.com/science/biology_place/labbench/index.html</p><p>Lab 1 - Diffusion and Osmosis Water Potential = Pressure Potential + Solute Potential Water potential is measured in bars, and measures the tendency of water to move across a selectively permeable membrane. (We used pieces of potato to measure this) Dialysis tubing is used to measure osmosis in solutions of various molarity. Mass was taken before and after soaking. </p><p>Osmosis - The diffusion of water through a semi-permeable membrane Diffusion - The random movement of molecules from an area of higher concentration to lower concentration</p><p>Lab 2 - Enzyme Catalysis In this lab, we measured the rate of a reaction by measuring the accumulation of products or the disappearance of the substrate (reactant). The rate of reaction may be affected by pH, temp, substrate concentration, or enzyme concentration (be able to design an experiment to test any of these factors). When designing an experiment, be sure to only change the factor that you are testing while keeping all others the same. We used a strong acid to stop the reaction (by denaturing the enzyme). We used titration to measure the amount of substrate converted or product formed (we measured the amount of H2O2 left in a reaction). The results were graphed to determine the reaction rate.</p><p>Lab 3 - Mitosis and Meiosis Observed mitosis in onion root tips We counted the number of cells in each stage of mitosis, and calculated out which stage occurred the longest (based on which stage appears more often in the roots). % of cells in the stage X 1440 minutes = number of minutes in the stage (1440 is the # of minutes in 24hrs) We also measured the amount of times crossing over occurred in the asci of a fungus by observing dark and light. Through this we are able to determine cross over frequency. </p><p>Lab 4 - Plant Pigments and Photosynthesis We separated the various pigments out of the leaves of a spinach leaf through thin layer chromatography (TLC) We were able to determine the Rf values by measuring the distance the pigment travelled by the distance the solvent travelled More polar pigments stayed closer to the origin, while less polar pigments migrated farther up the chromatography paper We also measured the rate of photosynthesis using a spectrophotometer. To do this, we used the dye DPIP that accepted electron instead of NADP+. If DPIP is in an oxidized state, it will be blue, and the percentage of light transmitted will be low. If, on the other hand, chlorophyll's electrons have been excited and move on to reduce the DPIP, the sample will become progressively paler, allowing more light energy to pass through the sample. We can measure this change over time until the sample has been completely reduced, is almost colorless, and the percentage of transmittance is very high. We would calibrate the spectrophotometer using a blank, our control was an unboiled chloroplasts solution incubated in the dark, and 2 experimental tubes, one with unboiled chloroplasts incubated in the light, and one with boiled choloroplasts in the light. We would expect the unboiled chloroplasts in the light to have higher transmittance due to more electron becoming fixed to the DPIP. Lab 5 - Cell Respiration In this lab we constructed respirometers which consisted of a glass container, a one-holed rubber stopper, and a graduated pipette in order to measure the rate of cellular respiration. The 3 respirometers contained: 1. 25 Germinating peas 2. 25 Non Germinating peas with glass beads to keep volume constant 3. Glass beads only</p><p>Each vile contained cotton balls containing KOH for the purpose of consuming CO2 to make sure CO2 levels didn’t change results. The only factors to change results were consumption of oxygen, change in temperature, or change in atmospheric temperature. The experiment took place in environments with various temperatures to see how temperature effected respiration.</p><p>Lab 6 - Molecular Biology Part 1 - Transformation We mixed E. coli bacteria with a gene that is resistant to the antibiotic ampicillin and also heat shocked them to increase absorption of the gene. We then tested transformation by attempting to grow bacteria on plates that either have, or do not have ampicillin in the growth medium. Ideally we should see growth on both plates for the E. coli that underwent transformation and on the non-ampicillin plate for the non- transformed bacteria, while finding no growth on the ampicillin treated plate for the non-transformed E. coli.</p><p>Part 2 - Gel Electrophoresis We used a tracking dye as our known sample that would be used to compare unknown DNA samples to. We mixed the unknown DNA samples with a restriction enzyme and ran the gel. We compared the size of the RFLP’s to the tracking dye to determine size of each fragment. We were then able to determine which suspect committed a crime by finding matches.</p><p>Lab 7 - Genetics of Drosophila This point of this lab was to look at mutations in fruit flies and determine the inheritance pattern of each mutation. Depending on the number of mutations that turned up in each sex, we were able to determine if the trait was dominant, recessive, or sex linked. To determine the validity of our results, we would conduct a Chi Square test.</p><p>X2 = the sum of o = observed number of individuals e = expected number of individuals</p><p>Lab 8 - Population Genetics In this lab, we tested the Hardy-Weinberg Equilibrium in population in comparison to populations where selection took place against homozygous recessive individuals. We also tested small populations to illustrate genetic drift, as well as populations where heterozygote advantage was present. </p><p>Lab 9 - Transpiration In this lab we built potometers to measure the rate of transpiration in various environments. The results of the environments should have been as follows: Temperature - Increase in the temperature of liquied increases the kinetic energy of the water molecules which increases the rate in which water in converted to water vapor, thus increasing transpiration Humidity - An increase in humidity increases the water potential in the surrounding which causes the rate of transpiration to decrease Air Movement (fan) - Moving air removes recently evaporated water away from the leaf, which will decrease water potential in the air around the leaf, thus increasing transpiration Light Intensity - Some of the light energy will turn to heat energy, thus increasing the temperature and the rate of transpiration.</p><p>Lab 10 - Circulatory Physiology In the first part of this lab, blood pressure is measured using a sphygmomanometer. The blood pressure cuff is inflated so that blood flow through the brachial artery in the upper arm is stopped. As pressure in the cuff is released, a stethoscope is used to listen for the blood flow re-entering the artery by listening for popping sounds called ‘Korotkoff Sounds’. Determining blood pressure occurs as follows: Systolic Blood Pressure - Blood pressure generated by the ventricles - This is read by the sphygmomanometer when the Korotkoff are first heard in the stethoscope as the pressure cuff is slowly released Diastolic Blood Pressure - The blood pressure maintained by the arterial walls between ventricular contractions. It is read from the sphygmomanometer when the Korotkoff disappear. A systolic reading of 120 mm Hg and a diastocic reading of 75 mm Hg is recorded as 120/75.</p><p>Blood pressure changes would be observed when: When test subject moves from a reclining to a standing position Blood pressure and heart reate increase with body activity (jogging in place or jumping jacks) More fit individuals take less time to return to their normal blood pressures.</p><p>The second part of the lab measured heart rate of daphnia (poikilothermic organism) by counting heartbeats per minute at 2 temps. We measured the Q10 value which measure increase in metabolic activity resulting from a 10°C change in temp. Q10 = Heart rate at higher temp / Heart rate at lower temp.</p><p>Lab 11 - Animal Behavior We observed the movement of pill bugs throughout various environments when different factors were changed, as well as the courtship behaviors in fruit flies. Taxis - Movement in response to a stimulus Kinesis - Random movement Factors tested in the pill bugs included phototaxis (light), chemotaxis(chemicals, acids/bases), hydrotaxis (water). We wanted to find results that showed whether this was taxis or kinesis, by changing only one variable and observing movement.</p><p>Lab 12 - Dissolved Oxygen Primary production (photosynthesis) was measured in water samples in different light environments that were made using screens. First know that the amount of dissolved oxygen is dependent on many factors: Temperature - Dissolved oxygen decreases as temperature increases Salinity - Dissolved oxygen concentration decreases as salinity increases Photosynthesis - Photosynthetic activity produces oxygen and increase the amount of dissolved oxygen Respiration - Respiration consumes oxygen and reduces the amount of dissolved oxygen. Titration was used to measure the amount of oxygen present in each water sample. It should have been shown that with the more light present, the more oxygen was present due to constant photosynthetic activity of aquatic algae.</p>