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AP Biology

Explore artificial selection, Hardy-Weinberg equilibrium, and DNA sequence comparisons in AP Biology labs centered on evolution and genetic concepts. Conduct analysis, calculate frequencies, and examine the evolutionary relationships between species using BLAST. Dive deep into genetic drift, fitness, and more!

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AP Biology

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  1. AP Biology Lab Review Based on the PPT from Ms. Foglia

  2. Big Idea 1: Evolution

  3. Lab 1: Artificial Selection • Concepts: • Natural selection = differential reproduction in a population • Populations change over time  evolution • Natural Selection vs. Artificial Selection

  4. Lab 1: Artificial Selection • Description: • Use Wisconsin Fast Plants to perform artificial selection • Identify traits and variations in traits • Cross-pollinate (top 10%) for selected trait • Collect data for 2 generations (P and F1)

  5. Sample Histogram of a Population

  6. Lab 1: Artificial Selection Analysis & Results: • Calculate mean, median, standard deviation, range • Are the 2 populations before and after selection (P and F1) actually different? • Are the 2 sub-populations of F1 (hairy vs. non-hairy) different? • Are the means statistically different? • A T-test could be used to determine if 2 sets of data are statistically different from each other; these are often used in examples where the sample size is small

  7. Lab 2: Mathematical Modeling:Hardy-Weinberg • Concepts: • Evolution = change in frequency of alleles in a population from generation to generation • Hardy-Weinberg Equilibrium • Allele Frequencies (p + q = 1) • Genotypic Frequencies (p2+2pq+q2 = 1) • Conditions: • large population • random mating • no mutations • no natural selection • no migration

  8. Lab 2: Mathematical Modeling:Hardy-Weinberg Analysis & Results: • Null model: in the absence of random events that affect populations, allele frequencies (p,q) should be the same from generation to generation (H-W equilibrium) • Analyze genetic drift and the effect of selection on a given population • Manipulate parameters in model: • Population size, selection (fitness), mutation, migration, genetic drift

  9. Lab 2: Mathematical Modeling:Hardy-Weinberg • Real-life applications: • Cystic fibrosis, polydactyly • Heterozygote advantage (Sickle-Cell Anemia)

  10. Lab 2: Mathematical Modeling:Hardy-Weinberg 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 (brownish). (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?

  11. a. Indicate the conditions under which allele frequencies (p and q) remain constant from one generation to the next. • large population • random mating • no mutations • no natural selection • no migration • 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 (brownish). (In rabbits the white color is due to a recessive allele, w, and agouti is due to a dominant allele, W.) • 25,000/ 100,000 = .25 so .25 = q2(a)q = .5 and (A) p = .5 • Homozygous Rec = .25 = 25,000 • Homozygous Dom (agouti) = p2 = .25 = 25,000 • Heterozygous (agouti) = 2(p)(q) = 2(.5)(.5) = .5 = 50,000 • 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? The frequency of the ‘A’ allele would decrease and the frequency of the ‘a’ allele would increase.

  12. Lab 3: Comparing DNA Sequences using BLAST  Evolutionary Relationships • Concepts: • Bioinformatics: combines statistics, math modeling, computer science to analyze biological data • Genomes can be compared to detect genetic similarities and differences • BLAST = Basic Local Alignment Search Tool • Input gene sequence of interest • Search genomic libraries for identical or similar sequences

  13. Lab 3: Comparing DNA Sequences using BLAST  Evolutionary Relationships • Description: • Use BLAST to compare several genes • Use information to construct a cladogram (phylogenetic tree) • Cladogram = visualization of evolutionary relatedness of species

  14. Lab 3: Comparing DNA Sequences using BLAST  Evolutionary Relationships

  15. Lab 3: Comparing DNA Sequences using BLAST  Evolutionary Relationships • Use this data to construct a cladogram of the major plant groups

  16. Lab 3: Comparing DNA Sequences using BLAST  Evolutionary Relationships • Fossil specimen in China • DNA was extracted from preserved tissue • Sequences from 4 genes were analyzed using BLAST

  17. Lab 3: Comparing DNA Sequences using BLAST  Evolutionary Relationships • Analysis & Results: • BLAST results: the higher the score, the closer the alignment • The more similar the genes, the more recent their common ancestor  located closer on the cladogram

  18. Lab 3: Comparing DNA Sequences using BLAST  Evolutionary Relationships

  19. Answer is C

  20. Big Idea 2: cellular processes: energy and communication

  21. Lab 4: Diffusion & Osmosis • Concepts: • Selectively permeable membrane • Diffusion (high  low concentration) • Osmosis (aquaporins) • Water potential () •  = pressure potential (P) + solute potential (S) • Solutions: • Hypertonic • hypotonic • isotonic

  22. Lab 4: Diffusion & Osmosis

  23. Lab 4: Diffusion & Osmosis • Description: • Surface area and cell size vs. rate of diffusion • Cell modeling: dialysis tubing + various solutions (distilled water, sucrose, salt, glucose, protein) • Identify concentrations of sucrose solution and solute concentration of potato cores • Observe osmosis in onion cells (effect of salt water)

  24. Lab 4: Diffusion & Osmosis

  25. Potato Cores in Different Concentrations of Sucrose

  26. Lab 4: Diffusion & Osmosis • Conclusions • Water moves from high water potential ( ) (hypotonic=low solute) to low water potential () (hypertonic=high solute) • Solute concentration & size of molecule affect movement across selectively permeable membrane

  27. Answer is A

  28. Answer is B

  29. Lab 4: 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 description of how you would set up and perform the experiment; • the results you would expect from your experiment; and • an explanation of those results based on the principles involved. Be sure to clearly state the principles addressed in your discussion.

  30. 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 description of how you would set up and perform the experiment; • the results you would expect from your experiment; and • an explanation of those results based on the principles involved. Be sure to clearly state the principles addressed in your discussion. Think about our lab that we did…. Talk about putting a cell (potato) in each of the solutions – mass before and then mass after and see in which solution did it gain/lose the most weight. The principle involved is simple osmosis. The potato will lose weight in hypertonic solutions and gain weight in the hypotonic solutions. Based on how much weight is gained/lost in each of the solutions, you would be able to put them in order. 0.8 M – potato will lose the most mass 0.6 M – potato will lose the second most mass 0.4 M – potato will remain mostly the same with losing just a bit 0.2 M – potato will gain mass *potatos are about 0.3 molarity

  31. Lab 5: Photosynthesis • Concepts: • Photosynthesis • 6H2O + 6CO2 + Light  C6H12O6 + 6O2 • Ways to measure the rate of photosynthesis: • Production of oxygen (O2) • Consumption of carbon dioxide (CO2)

  32. Lab 5: Photosynthesis • Description: • Paper chromatography to identify pigments • Floating disk technique • Leaf disks float in water • Gases can be drawn from out from leaf using syringe  leaf sinks • Photosynthesis  O2 produced  bubbles form on leaf  leaf disk rises • Measure rate of photosynthesis by O2 production • Factors tested: types of plants, light intensity, colors of leaves, pH of solutions

  33. Plant Pigments & Chromatography

  34. Floating Disk Technique

  35. To make comparisons between experiments, a standard point of reference is needed. Repeated testing of this procedure has shown that the point at which 50% of the disks are floating (the median or ET50) is a reliable and repeatable point of reference. In this case, the disks floating are counted at the end of each time interval. The median is chosen over the mean as the summary statistic. The median will generally provide a better estimate of the central tendency of the data because, on occasion, a disk fails to rise or takes a very long time to do so. A term coined by G. L Steucek and R. J Hill (1985) for this relationship is ET50, the estimated time for 50% of the disks to rise. That is, rate is a change in a variable over time. The time required for 50% of the leaf disks to float is represented as Effective Time = ET50.

  36. Lab 5: Photosynthesis • Concepts: • photosynthesis • Photosystems II, I • H2O split, ATP, NADPH • chlorophylls & other plant pigments • chlorophyll a • chlorophyll b • xanthophylls • carotenoids • experimental design • control vs. experimental

  37. Answer is A

  38. Answer is D

  39. Lab 6: Cellular Respiration • Concepts: • Respiration • Measure rate of respiration by: • O2 consumption • CO2 production

  40. Lab 6: Cellular Respiration • Description: • Use respirometer • Measure rate of respiration (O2 consumption) in various seeds • Factors tested: • Non-germinating seeds • Germinating seeds • Effect of temperature • Surface area of seeds • Types of seeds • Plants vs. animals

  41. Lab 6: Cellular Respiration

  42. Lab 6: Cellular Respiration

  43. Lab 6: Cellular Respiration • Conclusions: • temp = respiration • germination = respiration • Animal respiration > plant respiration •  surface area =  respiration Calculate Rate

  44. Lab 6: Cellular Respiration

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