American Military University Biology Genetics Worksheet

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fUnit II Assignment—Genetics Worksheet Gregor Mendel’s Experiments, Theories, and Findings 1. Mendel observed that pea plants had traits, such as color, that were either “one or the other,” never something in between. In your own words, discuss the correlation between Mendel’s factors, what they might be, and why pea plant traits come in one form or another—e.g., gray or dark red—rather than blended. Your response must be at least 75 words in length. (Type your response in the blank area below; it will expand as needed.) 2. Let’s imagine that we are studying only one trait, that of green- or yellow-colored seeds. Mendel bred his peas until they either produced seeds of one color or the other. These purebred plants he called the p generation (“p” for parental generation). He then cross bred green plants with yellow ones and discovered that all the offspring were yellow-colored. Mendel called the offspring of the purebred plants the F1 generation. In your own words, explain why all the offspring in the F1 generation were yellow instead of half being yellow and half green, or some other mix of the colors. Hint: Remember that Mendel coined the terms dominant and recessive. Your response must be at least 75 words in length. (Type your response in the blank area below; it will expand as needed.) Punnett Squares Reginald Punnett was a British geneticist who developed the Punnett square to explain how the chromosomes of parents cross and produce offspring. In order to solve genetics problems using a Punnett square, it is necessary to a) understand the associated vocabulary and b) understand some of the rules for solving the problems. • Before you continue with the problems below, review the meaning of the terms allele, dominant, recessive, homozygous, heterozygous, genotype and phenotype. • You should also review the Punnett Square Basics video linked in the unit lesson. In this first problem (question #3), the key and genotype of the parents will be done for you as an example. For problems #4 and #5, you will fill in those details based on the information in the question. Remember, when asked for the genotypic ratio, it may be expressed as 25%(GG):50%(Gg):25%(gg), for example. Or, you may write it more succinctly as 1GG:2Gg:1gg. Either way will be correct. The phenotypic ratio will use descriptive terms, for example, 3(Green):1(clear), 2(Green):2(clear), or whatever it may be depending on the results of your cross. 3. In corn plants, the allele for green kernels (G) is dominant over clear kernels (g). Cross a homozygous dominant plant with a homozygous recessive plant. Fill in the Punnett square below and give the ratios for each question beneath the Punnett Square. Key: G = green kernels, g = clear kernels Genotype of parents: _GG_ x _gg_ Parent #1 Parent #2 What is the genotypic ratio of the offspring in Question 3? What is the phenotypic ratio of the offspring in Question 3? 4. Yellow seeds are dominant over green seeds in pea plants. Cross a heterozygous (yellow seeded) plant with a green seeded plant. Key: __________ Genotype of parents: __________ x __________ Parent #1 Parent #2 What is the genotypic ratio of the offspring in Question 4? What is the phenotypic ratio of the offspring in Question 4? 5. Now cross two of the heterozygous F1 offspring from question #4. Parent #1 Parent #2 What is the genotypic ratio of the offspring in Question 5? What is the phenotypic ratio of the offspring in Question 5? 6. Consider the resulting ratio of crossing the two heterozygous pea plants in question #5. We will use this ratio in a short activity exploring probability. Keep in mind that crossing two individuals that are heterozygous for a certain trait is similar to flipping two coins. Each coin has two sides (we might think of each side as an “allele”) and the chances of flipping heads/heads, heads/tails or tails/tails should be similar to the ratio we see when crossing two heterozygotes. For this simple activity, you will need two coins (pennies, nickels, dimes, quarters, or a mix of any of those). Alternatively, you may google a coin-flipper simulator that will allow you to flip two coins at once. You will also need a piece of scratch paper and a pen or pencil. Directions: Flip the two coins simultaneously at least 50 times. For each flip of the pair of coins, you will record the results on a piece of scratch paper. You might set up a table like the one below to record your results. Once you have flipped the coins at least 50 times, enter the number of heads/heads, heads/tails and tails/tails in Table 1 below. Now determine the ratio for your results. You will do this by dividing the number for each result by the total number of flips, and then multiply by 100. (Example: If the number of heads/heads is 9 then 9/50 = .18, .18x100 = 18%), Repeat this mathematical procedure for heads/tails and tails/tails) Table 1 Heads/heads (hh) Head/tails (ht) Tails/tails (tt) Ratio (hh:ht:tt) Compare the resulting ratio from the question #5 cross of two heterozygous parents to the ratio from the coin flipping exercise. Are there similarities? If so, what are they? What might be done to make the ratio from the coin flipping exercise become more similar to the ratio from question #5? (Hint: Consider that more data equals better accuracy.) Cancer Risk Factors 6. This question deals with cancer and risk factors. Begin by going to the website http://www.cancer.org/ Click “Cancer A-Z” in the upper left corner. The page that comes up will provide links to information on breast cancer, colon and rectal cancer, lung cancer, prostate cancer, and skin cancer. Review the information for each these cancers. Next, write an essay that discusses your own risk factors for each type of cancer and steps you might take to decrease those risk factors. Be sure to address all five types of cancer. You do not have to disclose any actual personal information if you do not wish to do so. You may create a fictional character and discuss his or her risk factors instead. Be sure to address all five types of cancer. Your response must be at least 300 words in length. (Type your response below)
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Unit II Assignment—Genetics Worksheet

Gregor Mendel’s Experiments, Theories, and Findings
1. Mendel observed that pea plants had traits, such as color, that were either “one or the other,” never
something in between. In your own words, discuss the correlation between Mendel’s factors, what they
might be, and why pea plant traits come in one form or another—e.g., gray or dark red—rather than
blended.
The peas exhibited Mendelian inheritance, where each gene is typically composed of two
alleles that can possess either a dominant or recessive trait. A gene composed of two dominant
alleles would express the dominant trait, and a gene containing two recessive alleles would
express the recessive trait. However, if a gene is composed of one dominant allele and one
recessive allele, the dominant trait will be expressed over the recessive trait. This is the reason
why pea plant traits only come in one form or another rather than being blended.
2. Let’s imagine that we are studying only one trait, that of green- or yellow-colored seeds. Mendel bred
his peas until they either produced seeds of one color or the other. These purebred plants he called the p
generation (“p” for parental generation). He then cross bred green plants with yellow ones and discovered
that all the offspring were yellow-colored. Mendel called the offspring of the purebred plants the F1
generation.
In your own words, explain why all the offspring in the F1 generation were yellow instead of half being
yellow and half green, or some other mix of the colors. Hint: Remember that Mendel coined the terms
dominant and recessive.
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Offspring inherit one allele from each parent. Since each offspring gets an allele from each
parent, it means that the gene of all the offspring would contain one dominant allele and
one recessive allele. According to Mendel’s Law of Dominance, a heterozygous gene will
express the dominant trait. In this case, yellow is the dominant trait, and green is the
recessive trait for color. Therefore, since yellow is the dominant trait, all the offspring in
the F1 generation were yellow.

Punnett S...