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This activity will simulate what occurred in the population of peppered moths during the -trial Revolution and you will answer questions and make inferences about it.

 

The Industrial Revolution was a time in Europe when there was a massive increase in industry and factories. Methods of production shifted from handicraft to machine, along with the use of new materials like iron and steel, and new energies like coal, steam engines, electricity, and combustion engines. The large number of new factories put out large quantities of smoke and created a dramatic rise in pollution.

 

The Peppered Moth population was significantly affected by the Industrial Revolution. Prior to this time period peppered moths used to be white and lightly colored and were only rarely peppered or black in color. These moths lived in a forest full of Aspen trees with light colored bark, and their light coloring allowed them to camouflage for protection. After the Industrial Revolution, scientists noticed there was a drastic increase in the number of peppered and black moths and a decrease in the number of white moths. The Industrial Revolution caused a change in the habitat of the peppered moths, and the makeup of their population shifted as a result. Scientists believe that this is due to natural selection.

 

For this assignment you will count the number of each type of moth in a set of images and then make inferences about what you notice. You will answer questions about the images and the possible causes of the shift in coloration of the peppered moth.

 

Submission:

Answer the questions for each image as well as the discussion questions and submit your work. A grading rubric is included below the questions for this assignment.

 

Overview:

In this assignment you will review Punnett squares and their use in predicting the genetic makeup of offspring. Then you will be given three different scenarios and use Punnett squares to predict the likelihood of the genotypes and phenotypes of the offspring.

 

Probability is the likelihood that an event will occur. Geneticists use Punnett squares to determine the probability that each potential genotype will occur in a genetic cross. A specific genetic trait has both a genotype and a phenotype. The genotype represents the genes that are present for a specific trait. The phenotype is the physical representation of that trait.

 

The genotype of specific traits represents both dominant and recessive alleles. An allele is a form of a specific gene found at the same point on a strand of DNA. A dominant allele is represented as a capital letter and a recessive allele is represented by a lowercase letter. A dominant trait means that it will mask or cover a recessive trait. An organism's genetic traits contain two alleles because one is inherited from each parent. If an organism has two of the same alleles, then their genotype is called homozygous. A trait with two dominant alleles would be called homozygous dominant. Two recessive alleles would be called homozygous recessive. If an organism has two different alleles, their genotype is called heterozygous, which means one allele is dominant and one allele is recessive.

 

There are cases where heterozygous alleles don't completely mask one another. Incomplete dominance is where a mixture of the trait for each allele is present in the phenotype. Codominance is where both alleles are present in the phenotype.

 

In this activity, you will review Gram stains and apply your knowledge of this process to draw conclusions from images of Gram-stained bacteria. You will then answer some discussion questions about bacteria.

Gram Staining is a process of using different stains to identify bacteria based on the thickness of their cell walls. These stains stick to the peptidoglycan in the cell wall. After fixing bacteria to a slide there are four different stains used in this process. Crystal Violet is added to the slide and absorbed by the cell walls. lodine is then added and binds with the crystal violet in the cell wall, making it insoluble in water. Alcohol is used as a decolorizer so that any extra stain is removed. For bacteria with thin cell walls, this causes all the colored pigment from the crystal violet to run off. For bacteria with thick cell walls, the pigment becomes dehydrated and crystalizes in the cell. Since bacteria with thin cell walls now have no color, safranin is added to give the cell a pink color and make it visible. If the bacteria have a thick cell wall the Gram stain will turn out purple and if they have a thin cell wall it will be pink. After staining, bacterial cells can be classified as Grampositive or Gram-negative.

 

Gram-positive bacteria have a thick cell wall and stain purple from the crystal violet. Streptococcus, staphylococcus, and S. epidermidis are examples of Gram-positive bacteria.

 

Gram-negative bacteria have a thin cell wall and stain pink from safranin. E. coli, pneumonia, and cholera are examples of Gram-negative bacteria.