Ap Biology Essay 1992

Presentation on theme: "The Scaffolding Process Example:  AP Bio Essay on Osmosis & Diffusion 1992 - Question # 1  What do students need to know to get to this point?  What."— Presentation transcript:

1 The Scaffolding Process Example:  AP Bio Essay on Osmosis & Diffusion 1992 - Question # 1  What do students need to know to get to this point?  What labs in earlier grades would lay the foundation for answering this question?

2 AP Bio Osmosis & Diffussion Lab Which molecules have moved where & WHY Part 1

3 AP Bio Osmosis & Diffussion Lab At what molarity is dynamic equalibrium reached? Part 2

4 Part 3 AP Bio Osmosis & Diffussion Lab What is the osmotic potential of the sucrose solution? What is the potato’s molarity? Explain your results using the concept of free energy = - I C R T where I = the ionization constant (for sucrose this is 1 because sucrose does not ionize in water); C = osmotic molar concentration R = pressure constant T = temperature  K Graph the results with a “best- fit” line

5 The Scaffolding Process 2.Read the California Science Standard for Investigation and Experimentation: “Science as a Process.”  What would labs look like in earlier grades that would lay the foundation for proficiency?

6  Science relies on reproducible observations  Hypotheses provide models to explain observations  Hypotheses are created w/creativity & insight  Differences between observed & expected observations detect flaws in hypotheses  Data that agree with predictions DO NOT PROVE a hypothesis: they only fail to disprove it. Students should explore & comprehend: California Standard: Science as a Process

7 Grow & measure plants; measure daily temp Become skilled with basic lab equipment Design simple experiments, collect data, collaborate & analyze results Measure masses and volume of substances Make data tables and graphs, including “best fit” lines Use graphs to interpolate & predict Foundation Level Examples California Standard: Science as a Process

8 Generate data by measuring pressure vs. volume of a gas Calculate spring constant of an inertial balance from relationship between its period as mass Measure O 2 consumption by animals at different temps vs. DO 2 at different levels of a lake Intermediate Level Examples California Standard: Science as a Process

9 Generate data by measuring Cl 2 content of seawater via titration of AgNO 3 Find the total charge in a capacitor by integrating current passed through as a function of time Determine the action spectrum of photosyn or % transmittance from pooled class data Analyze human pop growth vs. time for the past century Advanced Level Examples California Standard: Science as a Process


Presentation on theme: "AP Biology Lab Review AP Biology Lab 1: Diffusion & Osmosis."— Presentation transcript:

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2 AP Biology Lab Review

3 AP Biology Lab 1: Diffusion & Osmosis

4 AP Biology Lab 1: Diffusion & Osmosis  Description  dialysis tubing filled with starch- glucose solution in beaker filled with KI solution  potato cores in sucrose solutions  determining solute concentration of different solutions

5 AP Biology Lab 1: Diffusion & Osmosis  Concepts  semi-permeable membrane  diffusion  osmosis  solutions  hypotonic  hypertonic  isotonic  water potential

6 AP Biology Lab 1: Diffusion & Osmosis  Conclusions  water moves from high concentration of water (hypotonic=low solute) to low concentration of water (hypertonic=high solute)  solute concentration & size of molecule affect movement through semi-permeable membrane

7 AP Biology Lab 1: Diffusion & Osmosis ESSAY 1992 A laboratory assistant prepared solutions of 0.8 M, 0.6 M, 0.4 M, and 0.2 M sucrose, but forgot to label them. After realizing the error, the assistant randomly labeled the flasks containing these four unknown solutions as flask A, flask B, flask C, and flask D. Design an experiment, based on the principles of diffusion and osmosis, that the assistant could use to determine which of the flasks contains each of the four unknown solutions. Include in your answer: a.a description of how you would set up and perform the experiment; b.the results you would expect from your experiment; and c.an explanation of those results based on the principles involved. Be sure to clearly state the principles addressed in your discussion.

8 AP Biology Lab 2: Enzyme Catalysis

9 AP Biology Lab 2: Enzyme Catalysis  Description  measured factors affecting enzyme activity  H 2 O 2  H 2 O + O 2  measured rate of O 2 production catalase

10 AP Biology Lab 2: Enzyme Catalysis  Concepts  substrate  enzyme  enzyme structure  product  denaturation of protein  experimental design  rate of reactivity  reaction with enzyme vs. reaction without enzyme  optimum pH or temperature  test at various pH or temperature values

11 AP Biology Lab 2: Enzyme Catalysis  Conclusions  enzyme reaction rate is affected by:  pH  temperature  substrate concentration  enzyme concentration calculate rate?

12 AP Biology ESSAY 2000 The effects of pH and temperature were studied for an enzyme-catalyzed reaction. The following results were obtained. a. How do (1) temperature and (2) pH affect the activity of this enzyme? In your answer, include a discussion of the relationship between the structure and the function of this enzyme, as well as a discussion of ho structure and function of enzymes are affected by temperature and pH. b. Describe a controlled experiment that could have produced the data shown for either temperature or pH. Be sure to state the hypothesis that was tested here. Lab 2: Enzyme Catalysis

13 AP Biology Lab 4: Photosynthesis

14 AP Biology Lab 4: Photosynthesis  Description  determine rate of photosynthesis under different conditions  light vs. dark  boiled vs. unboiled chloroplasts  chloroplasts vs. no chloroplasts  use DPIP in place of NADP +  DPIP ox = blue  DPIP red = clear  measure light transmittance  paper chromatography to separate plant pigments

15 AP Biology Lab 4: Photosynthesis  Concepts  photosynthesis  Photosystem 1  NADPH  chlorophylls & other plant pigments  chlorophyll a  chlorophyll b  xanthophylls  carotenoids  experimental design  control vs. experimental

16 AP Biology Lab 4: Photosynthesis  Conclusions  Pigments  pigments move at different rates based on solubility in solvent  Photosynthesis  light & unboiled chloroplasts produced highest rate of photosynthesis Which is the control?#2 (DPIP + chloroplasts + light)

17 AP Biology Lab 4: Photosynthesis ESSAY 2004 (part 1) A controlled experiment was conducted to analyze the effects of darkness and boiling on the photosynthetic rate of incubated chloroplast suspensions. The dye reduction technique was used. Each chloroplast suspension was mixed with DPIP, an electron acceptor that changes from blue to clear when it is reduced. Each sample was placed individually in a spectrophotometer and the percent transmittance was recorded. The three samples used were prepared as follows. Sample 1 —chloroplast suspension + DPIP Sample 2 —chloroplast suspension surrounded by foil wrap to provide a dark environment + DPIP Sample 3 —chloroplast suspension that has been boiled + DPIP Data are given in the table on the next page. a.Construct and label a graph showing the results for the three samples. b.Identify and explain the control or controls for this experiment. c.The differences in the curves of the graphed data indicate that there were differences in the number of electrons produced in the three samples during the experiment. Discuss how electrons are generated in photosynthesis and why the three samples gave different transmittance results.

18 AP Biology Lab 4: Photosynthesis ESSAY 2004 (part 2) Time (min) Light, Unboiled % transmittance Sample 1 Dark, Unboiled % transmittance Sample 2 Light, Boiled % transmittance Sample 3 028.829.228.8 548.730.129.2 1057.831.229.4 1562.532.428.7 2066.731.828.5

19 AP Biology Lab 8: Population Genetics random vs. non-random mating size of population & gene pool

20 AP Biology Lab 8: Population Genetics  Description  simulations were used to study effects of different parameters on frequency of alleles in a population  selection  heterozygous advantage  genetic drift

21 AP Biology Lab 8: Population Genetics  Concepts  Hardy-Weinberg equilibrium  p + q = 1  p 2 + 2pq + q 2 = 1  required conditions  large population  random mating  no mutations  no natural selection  no migration  gene pool  heterozygous advantage  genetic drift  founder effect  bottleneck

22 AP Biology Lab 8: Population Genetics  Conclusions  recessive alleles remain hidden in the pool of heterozygotes  even lethal recessive alleles are not completely removed from population  know how to solve H-W problems!  to calculate allele frequencies, use p + q = 1  to calculate genotype frequencies or how many individuals, use, p 2 + 2pq + q 2 = 1

23 AP Biology Lab 8: Population Genetics ESSAY 1989 Do the following with reference to the Hardy-Weinberg model. a. Indicate the conditions under which allele frequencies (p and q) remain constant from one generation to the next. b. Calculate, showing all work, the frequencies of the alleles and frequencies of the genotypes in a population of 100,000 rabbits of which 25,000 are white and 75,000 are agouti. (In rabbits the white color is due to a recessive allele, w, and agouti is due to a dominant allele, W.) c. If the homozygous dominant condition were to become lethal, what would happen to the allelic and genotypic frequencies in the rabbit population after two generations?

24 AP Biology Lab 11: Animal Behavior

25 AP Biology Lab 11: Animal Behavior  Description  set up an experiment to study behavior in an organism  Betta fish agonistic behavior  Drosophila mating behavior  pillbug kinesis

26 AP Biology Lab 11: Animal Behavior  Concepts  innate vs. learned behavior  experimental design  control vs. experimental  hypothesis  choice chamber  temperature  humidity  light intensity  salinity  other factors

27 AP Biology Lab 11: Animal Behavior  Hypothesis development  Poor: I think pillbugs will move toward the wet side of a choice chamber.  Better: If pillbugs prefer a moist environment, then when they are randomly placed on both sides of a wet/dry choice chamber and allowed to move about freely for 10 minutes, most will be found on the wet side.

28 AP Biology Lab 11: Animal Behavior  Experimental design s ample size

29 AP Biology Lab 11: Animal Behavior ESSAY 1997 A scientist working with Bursatella leachii, a sea slug that lives in an intertidal habitat in the coastal waters of Puerto Rico, gathered the following information about the distribution of the sea slugs within a ten-meter square plot over a 10- day period. a.For the data above, provide information on each of the following:  Summarize the pattern.  Identify three physiological or environmental variables that could cause the slugs to vary their distance from each other.  Explain how each variable could bring about the observed pattern of distribution. b.Choose one of the variables that you identified and design a controlled experiment to test your hypothetical explanation. Describe results that would support or refute your hypothesis. time of day12 mid4am8am12 noon4pm8pm12 mid average distance between individuals 8.08.944.8174.0350.560.58.0

30 AP Biology Lab 11: Animal Behavior ESSAY 2002 The activities of organisms change at regular time intervals. These changes are called biological rhythms. The graph depicts the activity cycle over a 48-hour period for a fictional group of mammals called pointy-eared bombats, found on an isolated island in the temperate zone. a.Describe the cycle of activity for the bombats. Discuss how three of the following factors might affect the physiology and/or behavior of the bombats to result in this pattern of activity.  temperature  food availability  presence of predators  social behavior b.Propose a hypothesis regarding the effect of light on the cycle of activity in bombats. Describe a controlled experiment that could be performed to test this hypothesis, and the results you would expect.

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