Genetics Worksheet: Gregor Mendel's Experiments and Cancer Risk

This assignment delves into the core concepts of genetics, beginning with an exploration of Gregor Mendel's experiments and his observations on pea plant traits. The assignment requires students to explain Mendel's findings regarding dominant and recessive alleles and why certain traits appear in specific forms. The second part of the assignment involves the use of Punnett squares to predict the outcomes of genetic crosses, including genotypic and phenotypic ratios. Students are asked to analyze different crosses, including those involving heterozygous and homozygous plants. The assignment also includes a probability exercise involving coin flipping to simulate the ratios observed in genetic crosses. Finally, the assignment extends to the topic of cancer risk factors, requiring students to research various cancer types and identify personal risk factors, culminating in an essay discussing those risks and potential preventative measures.

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.
Your response must be at least 75 words in length. (Type your response in the blank area
below; it will expand as needed.)
Answer: Inheritance is characterized by the passing of genetic elements or traits to the offspring
from parents. Mendel’s factors are two forms of allele of one gene. Among them, one is
dominant in character and other is recessive allele. Dominant character will show its phenotypic
characteristics despite of the presence of recessive allele. In the case of recessive it will only
produce its phenotype when both the allele of the genotype will be of recessive in length (Wanjin
& Morigen, 2015).
The traits of the pea plants come in one form or another because the alleles of the
particular genes are fully expressed that is there is no occurrence of incomplete dominance or
linkages of these genes. The dominant trait is expressed when the genotype will be heterozygous
or homozygous both whereas recessive alleles are shown in the presence of homozygous
recessive genotype.
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.)
Answer: Dominant allele is one that expresses their characteristics despite of presence of one
copy of that allele. This effect is also called as heterozygous. One the other hand, recessive allele

is those which exert its features only there are two copies of alleles. If both the alleles are
dominant, it is known as co-dominance. In the parental generation, the color of the seed was
yellow that is purebred. After the cross-breeding, all the offspring were yellow in color. This
event is occurred as the yellow color in the parental generation is dominant in nature. It
suppresses the characteristics of recessive allele (yourgenome, 2020). Here, the alleles were not
both the dominant in type that result in equally expressed. So, the half-yellow and half-green are
not shown. Apart from this, there is no occurrence of incomplete dominance so that the mixture
of the colors is also not possible.
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
G G
g Gg Gg
g Gg Gg
What is the genotypic ratio of the offspring in Question 3?
Answer- The genotypic ratio will be 100% heterozygous plant. The genotype will be Gg.
What is the phenotypic ratio of the offspring in Question 3?
Answer- 100% of the offspring is Gg (heterozygous), the phenotype will be green. Since, the
green kernel is dominant over clear recessive allele, the green will be the phenotype of the kernel
of the corn plant.
4. Yellow seeds are dominant over green seeds in pea plants. Cross a heterozygous (yellow
seeded) plant with a green seeded plant.
Key: Y= yellow seeds, y= green seeds
Heterozygous yellow seed= Yy & Green seeded plant= yy
Genotype of parents: ____Yy______ x ___yy_______
Parent #1
Parent #2
Y y
y Yy yy
y Yy yy
What is the genotypic ratio of the offspring in Question 4?
The genotypic ratio of the offspring would be 50% Yy, and 50% yy that is 2Yy:2yy
What is the phenotypic ratio of the offspring in Question 4?

The phenotypic ratio will be two yellow seeds (Yy) and two green seeds (yy) that is 2 yellow: 2
green.
5. Now cross two of the heterozygous F1 offspring from question #2.
Parent #1
Parent #2
Y g
Y YY Yg
g Yg gg
What is the genotypic ratio of the offspring in Question 5?
The genotype for heterozygous allele for F1 is YG. If two of the heterozygous genes are crossed,
the genotypic ratio in offspring will be 25% YY, 50% YG, and 25% GG.
What is the phenotypic ratio of the offspring in Question 5?
The phenotypic ratio in the offspring will be 3 yellow seeded plants. 1YY (yellow):
2Yg(yellow): 1gg(green).
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) 26
Head/tails (ht) 42
Tails/tails (tt) 32
Ratio (hh:ht:tt) 26:42:32
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?
Answer: There are similarities in the resulting ratios among the result of crossing of two
heterozygous plants with coin flipping. From the crossing of two heterozygous parents the
obtained result is 25:50:25 and from the coin flipping exercise, the ratio is 26:42:32 which are
quite similar to that heterozygous experiment.
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.)
In the coin flipping exercise, the coin is flipped exactly half of the times that are 50 times. Then
it has been calculated as 100. So, there might be a chance of calculation error it has also been
regarded that more data consideration provides better accuracy to the result of the experiment.
Therefore, more data might be gathered for accuracy in the result.
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)

Answer-
Risk factors for different types of cancers -
Risk factor for any disease denotes that it may increase the chance of getting the disease. In this
situation, one imaginary character is chosen for describing the risk factors associated with
different types of cancers.
Risk factor for breast cancer-
Unlike other diseases, the breast cancer also possesses the risk factors. Certain breast cancer risk
includes personal behavior, such as diet, exercise. Other risk factors related to daily life
comprises of consumptions of medicines containing hormones.
Gender: The gender is the main factor for breast cancer. Female are more prone to this disease.
Since the patient is female, she has elevated risk of causing breast cancer. Although, breast
cancer is seen in males also, this is more common in female.
Race and ethnicity: The patient in this case belongs to African-American community. African-
American women have more probability of death from breast cancer irrespective of age.
Moreover, she started menstrual periods at early age which also increased the risk of breast
cancer. This increased risk may be because of longer lifetime exposure to the hormones estrogen
and progesterone.
The patient has history of consumption of alcohol. Drinking alcohol is associated with increased
risk of breast cancer. Women who have 2 to 3 drinks a day have elevated the 20% higher risk
than non-drinkers. Apart from this, she was obese. It will increase the chances of breast cancer
after her menopause.
For this, she might lower the consumption of alcohol. She might consult to a dietician and take
proper nutritious food for her well-being to decrease her weight.
For colorectal cancer: The patient has increased risk in development of colorectal cancer.
Since, she used to take more than 1 drink of alcohol that is linked with this cancer. She has also
habit of smoking. It is known to have causing this cancer too.
Obesity: obesity is increasing the chances of growing this cancer. Being obese, the patient has
larger waistline that is more likely to have this in both men and women.
Inflammatory bowel disease: She has a personal history of inflammatory bowel disease and
untreated. This untreated condition may lead to develop dysplasia. It is a condition of the cells
that line the colon or rectum of the cells and look abnormal. Gradually it will lead to cancer.

Poor diet: She has a poor diet habit such as consumption of processed meat like pork, beef, and
lamb. This has increased risk of causing this cancer.
For lowering risk, she might avoid consumption of alcohol and quit smoking. She might develop
a healthy diet and by this she might lose her weight especially in her waistline.
Lung cancer: She has increased risk of developing lung cancer as she has habit of smoking.
Smoking is directly related to the lung cancer and only way to lower the risk of this disease
includes avoiding smoking.
Skin cancer: since, the patient belongs to African-American society, she has increased risk of
causing melanoma. She has fair skin, freckling and light hair. Whites with red or blond hair and
fair skin that freckles or burns easily are highly susceptible for this disease (American Cancer
Society, 2020).

References
American Cancer Society. (2020). American Cancer Society | Information and Resources about
for Cancer: Breast, Colon, Lung, Prostate, Skin. Retrieved 6 April 2020, from
https://www.cancer.org/
Wanjin, X., & Morigen, M. (2015). Understanding the cellular and molecular mechanisms of
dominant and recessive inheritance in genetics course. Yi chuan= Hereditas, 37(1), 98-
108.
your genome. (2020). What are dominant and recessive alleles?. Retrieved 6 April 2020, from
https://www.yourgenome.org/facts/what-are-dominant-and-recessive-alleles