5 Steps to a 5 AP Biology, 2014-2015 Edition

Laboratory Review ❮ 257

❯ Rapid Review

Investigation 1: Artificial Selection

• To demonstrate evolution in a plant population, choose which traits are selected for and
  cross-pollinate only between those selected plants. Once the offspring (seeds) are planted
  and grown, check this trait to see if it is more prevalent in the new population.


• This is an example of directional selection, when members of a population at one end of
  a spectrum are selected for, whereas the trait at the other end of the spectrum becomes
  rarer.
  Investigation 2: Mathematical Modeling: Hardy-Weinberg


• The Hardy-Weinberg equation is used to check the frequencies of alleles in a population
  that is not evolving. This “snapshot” of the population is used as a point of comparison,
  to see if evolution does occur (and changes the allelic frequencies).


• For a given gene, there is the p allele and the q allele. Therefore, p+q=1.


• For that same gene, organisms can be homozygous dominant (pp), homozygous reces-
  sive (qq), or heterozygous (pq or qp). Therefore, p^2 + 2 pq+q^2 =1.


• By altering any of the five conditions required for a non-evolving Hardy-Weinberg pop-
  ulation, you can cause a change in your population’s gene pool.
  Investigation 3: Comparing DNA Sequences to Understand Evolutionary Relationships with
  BLAST


• BLAST is a computer program used to compare specific genes from different organisms.


• The more similar the nucleotide base sequence between two genes, the closer the evolu-
  tionary relationship.


• A cladogram is a visual representation of the evolutionary relatedness of a species.
  Investigation 4: Diffusion and Osmosis


• Water flows from hypotonic(low solute) to hypertonic(high solute).


• To measure diffusion and osmosis, take dialysis bags containing solutes of varying con-
  centrations, place them into beakers containing solutions of various concentrations, and
  record the direction of flow during each experiment.
  Investigation 5: Photosynthesis


• To experimentally determine the photosynthetic rate of various plants in various envi-
  ronments, first remove the air from leaf disk samples and add the samples to water con-
  taining sodium bicarbonate (a source of carbon dioxide). They will sink to the bottom
  of the cup.


• As the leaf tissue photosynthesizes, oxygen is released, causing the disks to rise to the
  surface. Expose different plant samples to different environmental conditions, measure
  how much photosynthesis occurs (ET 50 ), and then compare.
  Investigation 6: Cell Respiration


• To experimentally determine the rate of respiration in peas, use a respirometer to calcu-
  late the change in volume that occurs around the peas. Set up (1) a control group of

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