Monohybrid Crosses Practice Exercises Complete the following Punnett Squares for the questions below. Find the genotype as well as the phenotype ratios for the possible offspring. Question 1: Long haired fur is dominant to short haired fur in dogs. Show a cross between a purebred homozygous long haired dog and a purebred homozygous short haired dog. Use the following template as a guide. P generation: LEGEND Homozygous long Heterozygous long Homozygous short - __________ X __________ Results of a _____ x _____ cross F1 genotypes: F1 phenotypes: Question 2: Show a cross between a heterozygous (hybrid) long haired dog with a purebred short haired dog. Question 3: Solid Green watermelon skin is dominant to striped watermelon skin. Show a cross between a heterozygous solid green watermelon and a homozygous striped watermelon. Find the possible offspring. Question 4: Black guinea pigs are dominant to white guinea pigs. Find the possible offspring produced as a result of a cross between a hybrid (heterozygous) black guinea pigs and another hybrid (heterozygous) black guinea pig. Question 5: Tongue rolling is dominant in humans over non tongue rolling. Show a cross between a homozygous tongue roller and a homozygous non tongue roller. Find the possible offspring. Question 6: Red eyes are dominant to white eyes in fruit flies. Find the ratio of the offspring produced in the following fruit fly cross: Hybrid red eyes with purebred white eyes. Question 7: In humans, unattached earlobes are dominant to attached earlobes. Find the result for the offspring produced between heterozygous unattached earlobes with another who is also heterozygous for unattached earlobes. Question 8: Round seeds are dominant to wrinkled seeds in pea plants. Find the results when a hybrid round seed plant is crossed with a pure trait wrinkle seed plant. Question 9: White flowers are recessive to red flowers some species of carnations. Show a cross between two white flowering plants. Question 10: Curly hair is dominant to straight hair in humans. Show a cross between a heterozygous curly haired parent with a pure homozygous straight haired parent. Bikini Bottom – Dihybrid Crosses Name ________________________________ Use the chart to identify the genotypes of the following traits: 1. Heterozygous round eyes, blue body ________ 2. Hybrid eye shape, purebred roundpants ________ 3. Purebred roundpants, heterozygous long nose ________ Trait Body Shape Body Color Eye Shape Nose Style Dominant Gene Squarepants (S) Yellow (Y) Round (R) Long (L) Recessive Gene Roundpants (s) Blue (y) Oval (r) Stubby (l) 4. SpongeBob’s aunt, who is a roundpants, has a cute stubby nose. She has finally found the sponge of her dreams and is ready to settle down. Her fiancé always comments on how adorable her nose is (he says it reminds him of his mother’s – aww, how sweet!). They wonder what the chances are of that trait being passed on. Her fiancé is a purebred squarepants and is a hybrid for his long nose. A. Identify the genotypes of the aunt and her fiancé. Aunt = Roundpants, Stubby Nose = ________ Fiancé = Purebred Squarepants, Long Nose = ________ B. What are the possible gamete combinations for each person? Aunt = ______________________________ Fiancé = ______________________________ C. What are the possible genotypes for their children? ______________________________________ 5. As we know, SpongeBob is heterozygous for his yellow body color and his squarepants, while his wife SpongeSusie is blue and has roundpants. Use this information to answer the following questions. A. Give the genotypes for each. SpongeBob = __________________ SpongeSusie = _______________ B. What are the possible gamete combinations for each person? SpongeBob = __________________ SpongeSusie = __________________ C. Complete the Punnett square based on the information provided in #5. ____________ ____________ ____________ ____________ ____________ ____________ ____________ ____________ D. Answer the questions based on your Punnett square. What is the chance of a blue baby? _____ What is the chance of a blue squarepants? _____ What is the chance of a squarepants? _____ What is the chance of a purebred recessive for both traits? _____ Contributed by Andrea Stonebraker 6. In starfish, pink body color (P) is dominant to orange (p), and thick eyebrows (T) are dominant over thin (t) ones. Patrick, who is heterozygous for body color but purebred for thick eyebrows, has met Patti, who is recessive for both traits. A. What is Patti’s phenotype? _______________________________ B. Is it possible for the new couple to have offspring that resemble their mother? Explain. ___________________________________________________________________________ ___________________________________________________________________________ C. Before Patrick commits to this relationship, he would like to guarantee that his offspring would have his thick eyebrows as he thinks they make him smarter! You need to provide evidence for or against the marriage with regards to eyebrows ONLY. 7. While Squidward’s family boasts about being a purebred line for dominant light blue skin color, they are also purebred for a less distinguished trait: the recessive trait of baldness. Lack of hair causes Squidward some self-esteem issues that he does not want his children to face. He would like to ensure that his offspring have hair AND with his blue skin color. What traits should he look for in a bride? A. Must she have hair? Explain. _____________________________________________ _______________________________________________________________________ B. Must she be blue? Explain. _______________________________________________ ________________________________________________________________________ Squidward Traits: Skin Color Blue = B, Green = b Hair Hair = H, Bald = h C. Squidward has found a potential bride prospect with the green squid Octavia. While Octavia has does not. Determine the chances of their child being blue and having hair. hair, her father Squidward's Genotype = __________ Octavia's Genotype = __________ D. Use the genotypes in above to complete the Punnett square below and then answer the questions. ____________ ____________ ____________ ____________ ____________ ____________ ____________ E. Answer these questions based on your Punnett square. For which traits, if any, is it possible for their offspring to be purebred? What is the probability of their children being heterozygous for both traits? ________ Contributed by Andrea Stonebraker ____________ Bikini Bottom Genetics Incomplete Dominance Name ________________________________ SpongeBob loves growing flowers for his pal Sandy! Her favorite flowers, Poofkins, are found in red, blue, and purple. Use the information provided and your knowledge of incomplete dominance to complete each section below. 1. Write the correct genotype for each color if R represents a red gene and B represents a blue gene. Red - _____ Blue - ______ Purple - _____ 2. What would happen if SpongeBob crossed a Poofkin with red flowers with a Poofkin with blue flowers. Complete the Punnett square to determine the chances of each flower color. (a) Give the genotypes and phenotypes for the offspring. (b) How many of the plants would have red flowers? _____% (c) How many of the plants would have purple flowers? _____ % (d) How many of the plants would have blue flowers? _____ % 3. What would happen if SpongeBob crossed two Poofkins with purple flowers? Complete the Punnett square to show the probability for each flower color. (a) Give the genotypes and phenotypes for the offspring. (b) How many of the plants would have red flowers? _____% (c) How many of the plants would have purple flowers? _____ % (d) How many of the plants would have blue flowers? _____ % 4. What would happen if SpongeBob crossed a Poofkin with purple flowers with a Poofkin with blue flowers? Complete the Punnett square to show the probability for plants with each flower color. (a) Give the genotypes and phenotypes for the offspring. (b) If SpongeBob planted 100 seeds from this cross, how many should he expect to have of each color? Purple flowers - ______ Blue flowers - ______ Red flowers - ______ SpongeBob and his pal Patrick love to go jellyfishing at Jellyfish Fields! The fields are home to a special type of green jellyfish known as Goobers and only really great jellyfishermen are lucky enough to catch some on every trip. Many of the jellyfish are yellow (YY) or blue (BB), but some end up green as a result of incomplete dominance. Use this information to help you complete each section below. 5. What would happen if SpongeBob and Patrick crossed two “goobers” or green jellyfish? Complete the Punnett square to help you determine the probability for each color of jellyfish. (a) Give the possible genotypes and phenotypes for the offspring. (b) What percentage of the offspring would be yellow? _____% (c) What percentage would be blue? _____ % (d) What percentage would be “goobers” (green)? _____ % 6. What would happen if they crossed a yellow jellyfish with a goober? Complete the Punnett square to help you determine the probability for each color of jellyfish. (a) Give the possible genotypes and phenotypes for the offspring. (b) What percentage of the offspring would be yellow? _____% (c) What percentage would be blue? _____ % (d) What percentage would be “goobers” (green)? _____ % 7. What would happen if they crossed a blue jellyfish with a yellow jellyfish? Complete the Punnett square to help you answer the questions. If 100 jellyfish were produced from this cross, how many would you expect for each? Yellow - _____ Blue - _____ Goobers - ______ 8. What would happen if they crossed a blue jellyfish with a goober? Complete the Punnett square to help you answer the questions. If 100 jellyfish were produced from this cross, how many would you expect for each? Yellow - _____ Blue - _____ Goobers - ______ Codominance Worksheet (Blood types) Name ______________________________ Human blood types are determined by genes that follow the CODOMINANCE pattern of inheritance. There are two dominant alleles (IA and IB) and one recessive allele (i). Blood Type (Phenotype) Genotype O ii AB A B 1. Can donate blood to: A,B,AB and O (universal donor) IAIB IAIA or IAi B B I I or IAi O, AB AB, A AB,B Can receive blood from: O A,B,AB and O (universal receiver) O,A O,B Write the genotype for each person based on the description: a. b. c. d. e. f. g. Homozygous for the “B” allele Heterozygous for the “A” allele Type O Type “A” and had a type “O” parent Type “AB” Blood can be donated to anybody Can only get blood from a type “O” donor ______ ______ ______ ______ ______ ______ ______ 2. Pretend that Brad Pitt is homozygous for the type B allele, and Angelina Jolie is type “O.” What are all the possible blood types of their baby? 3. Draw a Punnett square showing all the possible blood types for the offspring produced by a type “O” mother and an a Type “AB” father 4. Mrs. Clink is type “A” and Mr. Clink is type “O.” They have three children named Matthew, Mark, and Luke. Mark is type “O,” Matthew is type “A,” and Luke is type “AB.” Based on this information: a. Mr. Clink must have the genotype ______ b. Mrs. Clink must have the genotype ______ because ___________ has blood type ______ c. Luke cannot be the child of these parents because neither parent has the allele _____. 5. Two parents think their baby was switched at the hospital. Its 1968, so DNA fingerprinting technology does not exist yet. The mother has blood type “O,” the father has blood type “AB,” and the baby has blood type “B.” a. Mother’s genotype: _______ b. Father’s genotype: _______ c. Baby’s genotype: ______ or ________ d. Punnett square showing all possible genotypes for children produced by this couple e. Was the baby switched? Two other parents think their baby was switched at the hospital. The mother has blood type “A,” the father has blood type “B,” and the baby has blood type “AB.” a. Mother’s genotype: _______ or ________ b. Father’s genotype: _______ or ________ c. Baby’s genotype: ______ d. Punnett square that shows the baby’s genotype as a possibility: e. Was the baby switched? Based on the information in this table, which man could not be the father of the baby? Justify your answer with a Punnett square. 6. 7. Name Mother Baby Blood Type Type A Type B Sammy the player George the sleeze The waiter The cable guy Type O Type AB Type A Type B 8. Explain why blood type data cannot prove who the father of a baby is, and can only prove who the father is not. Codominance Worksheet (Blood types) Name ______________________________ Human blood types are determined by genes that follow the CODOMINANCE pattern of inheritance. There are two dominant alleles (IA and IB) and one recessive allele (i). Blood Type (Phenotype) Genotype O ii AB A B 1. Can donate blood to: A,B,AB and O (universal donor) IAIB IAIA or IAi B B I I or IAi O, AB AB, A AB,B Can receive blood from: O A,B,AB and O (universal receiver) O,A O,B Write the genotype for each person based on the description: a. b. c. d. e. f. g. Homozygous for the “B” allele Heterozygous for the “A” allele Type O Type “A” and had a type “O” parent Type “AB” Blood can be donated to anybody Can only get blood from a type “O” donor ______ ______ ______ ______ ______ ______ ______ 2. Pretend that Brad Pitt is homozygous for the type B allele, and Angelina Jolie is type “O.” What are all the possible blood types of their baby? 3. Draw a Punnett square showing all the possible blood types for the offspring produced by a type “O” mother and an a Type “AB” father 4. Mrs. Clink is type “A” and Mr. Clink is type “O.” They have three children named Matthew, Mark, and Luke. Mark is type “O,” Matthew is type “A,” and Luke is type “AB.” Based on this information: a. Mr. Clink must have the genotype ______ b. Mrs. Clink must have the genotype ______ because ___________ has blood type ______ c. Luke cannot be the child of these parents because neither parent has the allele _____. 5. Two parents think their baby was switched at the hospital. Its 1968, so DNA fingerprinting technology does not exist yet. The mother has blood type “O,” the father has blood type “AB,” and the baby has blood type “B.” a. Mother’s genotype: _______ b. Father’s genotype: _______ c. Baby’s genotype: ______ or ________ d. Punnett square showing all possible genotypes for children produced by this couple e. Was the baby switched? Two other parents think their baby was switched at the hospital. The mother has blood type “A,” the father has blood type “B,” and the baby has blood type “AB.” a. Mother’s genotype: _______ or ________ b. Father’s genotype: _______ or ________ c. Baby’s genotype: ______ d. Punnett square that shows the baby’s genotype as a possibility: e. Was the baby switched? Based on the information in this table, which man could not be the father of the baby? Justify your answer with a Punnett square. 6. 7. Name Mother Baby Blood Type Type A Type B Sammy the player George the sleeze The waiter The cable guy Type O Type AB Type A Type B 8. Explain why blood type data cannot prove who the father of a baby is, and can only prove who the father is not. Lethal alleles Worksheet Name ______________________________ Alleles that cause an organism to die only when present in homozygous condition are called lethal alleles. 1. Cystic fibrosis is caused by a recessive lethal gene and can be detected by an excess concentration of chloride in sweat. If a sweat test reveals a man to be heterozygous and his wife to be homozygous normal, what are the chances that their children will have the disease? Could any of their grandchildren have the disease? 2. In humans, sickle-cell anemia is caused by a recessive lethal allele Hbs; individuals who are HbaHbs have sickle-cell trait, but are healthy. a. What is the probability of two heterozygous individuals giving birth to a child with sickle-cell trait? b. What is the probability of two heterozygous individuals giving birth to a child with sickle-cell anemia? c. If a normal HbaHba individual receives a blood transfusion from a HbaHbs individual (heterozygous for sickle cell) what are the chances that the HbaHba man and his HbaHba wife will have HbaHbs children? 3. Albinism in corn plants is caused by a recessive lethal gene that results in death before maturity. What will the adult phenotypic ratio be for the F1 generation of heterozygous parents? 4. Huntington's chorea is a dominant lethal in humans. The disease does not appear until later in life, so that afflicted individuals may already have produced children. What are the F1 genotypic and phenotypic ratios of parents who are homozygous dominant and heterozygous?
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