BIO 100 Maricopa County Community The Terms Gene and Allele Questions

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Laboratory Exercise Questions

~~1. Distinguish between the terms gene and allele. (1 point)

~~2. Give an example of one genetic trait (gene) and two different alleles (allele phenotypes) for that gene. (3 points)

a. Genetic Trait

b. Allele phenotype #1

c. Allele phenotype #2

~~3. Compare and contrast the terms phenotype and genotype. (4 points)

~~4. List the allele combinations (gamete possibilities) that can be formed by an individual with the following genotype: AABB (1 point)

~~5. List the different allele combinations (gamete possibilities) that can be formed by an individual with the following genotype: AaBb. (4 points)

~~6. Given: P = purple flowers and p = white flowers and P is dominant over p.

a. What is the phenotypic ratio of offspring from a cross between Pp x pp? (2 points)

b. In a population with 100 individuals how many will be homozygous? (2 points)

c. In that same population, how many will be purple? (2 points)

~~7. Mendel’s laws:

a. Which of Mendel’s laws is illustrated in a dihybrid cross? (1 point)

b. What does this law mean, in your own words? (1 point)

~~8. A horticulturist has a purple plant and a white plant. The horticulturist knows that purple is dominant over white. When they are bred, all of the resulting offspring are purple. What is the most likely genotype of the parent or original purple plant? (2 points)

~~9. The horticulturist runs a test cross with an offspring (F₁ generation) purple plant from Question 8. The phenotypic frequencies of the resulting offspring are 50% white and 50% purple. What is the true genotype of this offspring (F₁ generation) purple plant? (2 points)

~~10. What is the probability of a cross resulting in purple offspring when two heterozygous purple pea plants (e.g. Pp x Pp) are bred? What is/are the genotype(s) for purple offspring resulting from this cross? (4 points)

~~11. Compare the real-world ratios calculated in Exercises 5 and 6 (coin toss activity) to Mendel’s ratios. Were they close? Pose a possible explanation for why the ratios may not be exactly the same. (4 points)

~~12. Refer to the data on the corn kernel color ratio from Part II of the lab. Note that big P is the dominant allele for purple coloring and small p is the recessive allele for yellow. Big S is the dominant allele for smooth texture and small s is the recessive allele for wrinkled texture.

a. What was the tallied frequency (phenotypic ratio) of purple to yellow kernels in Corn Cob 1 from Step 1? Which of the possible Mendelian ratios is the most similar to these actual results counted in corn cob 1? (2 points)

b. What was the tallied frequency (phenotypic ratio) of purple to yellow kernels in Corn Cob 2 from Step 2? Which of the possible Mendelian ratios is the most similar to these actual results counted in corn cob 2? (2 points)

c. What was the tallied frequency (phenotypic ratio) of purple and smooth, to purple and wrinkled, to yellow and smooth, to yellow and wrinkled kernels from Step 3? Which of the possible Mendelian ratios is the most similar to these actual results counted in corn cob 3? (2 points)

d. Explain why the real-world tallies from each corn cob do not exactly match any the predicted Mendelian ratios which are based upon probability. (2 points)

~~13. Recall from the background information that purple kernels are dominant and yellow kernels are recessive. The Corn Cob 2 was the result of crossing two heterozygous ears of corn (Pp x Pp). This is represented by the Punnett square below. Complete the Punnett square by writing the correct letters that correspond to each number indicated in the table. Report the predicted offspring genotypes below. (4 points)

	P	p
P	1	2
p	3	4

a. Genotype 1:

b. Genotype 2:

c. Genotype 3:

d. Genotype 4:

~~14. Once the Punnett square for Question 13 is complete, calculate the ratio of purple and yellow kernels. Recall that purple (P) is dominant to yellow (p).

a. What is the phenotypic ratio of purple to yellow kernels predicted by the Punnett square? (2 points)

b. How did this Mendelian ratio numerically compare to the ratio obtained from counting the corn kernels for ear number two in part II of the lab? (2 points)

~~15. Recall from the background information that purple kernels (P) are dominant and yellow kernels (p) are recessive. Also recall that smooth kernels (S) are dominant and wrinkled kernels (s) are recessive. Corn Cob 3 was the result of crossing a male ear of corn with the following genotype: PpSs, with a female ear of corn with the same genotype: PpSs. This is represented by the Punnett square, below. Complete the Punnett square by writing the correct letters that correspond to each number indicated in the table (for example, PPSS or ppss). (8 points)

	PS	Ps	pS	ps
PS	1	2	3	4
Ps	5	6	7	8
pS	9	10	11	12
ps	13	14	15	16

a. Genotype 1:

b. Genotype 2:

c. Genotype 3:

d. Genotype 4:

e. Genotype 5:

f. Genotype 6:

g. Genotype 7:

h. Genotype 8:

i. Genotype 9:

j. Genotype 10:

k. Genotype 11:

l. Genotype 12:

m. Genotype 13:

n. Genotype 14:

o. Genotype 15:

p. Genotype 16:

~~16. Once the Punnett square for Question 15 is complete, calculate the ratio of corn kernel varieties (recall that if the dominant trait is present, it will be expressed).

a. What is the ratio of kernels based on the Punnett square? (2 points)

b. How did this Mendelian ratio numerically compare to the ratio obtained from counting the corn kernels for ear number three in part II of the lab? (2 points)

~~17. What are the genotypic and phenotypic ratios for kernel color and kernel texture for a dihybrid cross between PpSs x ppss? (4 points)

a. genotypic ratio:

b. phenotypic ratio:

~~18. Using the results from the Punnett Square in Question 15, answer the following question: In a population of 800 corn kernels, how many will have smooth kernel texture? (2 points)

~~19. In a flower garden, a horticulturist is growing purple and white pansies. The horticulturist notices that a new pansy has sprouted. When it finally flowers, the pansy is lavender. Explain how this happened. (4 points)

~~20. With a botanist’s help, an individual decides to cross the lavender pansy with the white pansy. Will this result in any purple pansies? Explain. (4 points)

~~21. State an industrial concern/importance for knowing the genetic makeup of an organism. Explain why it is important in your example. (5 points)

Application Question

~~22. How might the information gained from this lab pertaining to genetics be useful to you, or how can you apply this knowledge to your everyday life as a non-scientist? The application will be graded according to the rubric below. (20 points)