Practice Makes Perfect! Punnett Squares Worksheet

Practice Makes Perfect! Punnett Squares Worksheet

“PRACTICE MAKES PERFECT! ” PUNNETT SQUARES WORKSHEET

**LOOK**  ALL ANSWERS (including 1-16 on the back ) MUST be answered on your own sheet of paper!

You must include a KEYfor each problem, a CROSS for each Punnett square, and you must SHOW all work!

Once Upon A Time….

  1. Snow White has a special fondness for apples. Her favorites are the true-breeding red delicious apples produced by the seven dwarfs. Doc, the scientist of the group, has recently tried crossing the red delicious apples loved by Snow White, with a true-breeding group of golden delicious apples. In apples, red color is dominant and golden is recessive.
  1. Construct a Punnett square to show F1. What are the expected genotype and phenotype ratios?
  2. Construct a Punnett square to show F2. What are the expected genotype and phenotype ratios?
  3. If Doc collects a dozen apples from the F2 generation for Snow White, how many red and how many golden apples would be in the basket?
  1. A missing persons report has been filed on a young woman named Rapunzel, rumored to have been kidnapped and held captive in a tower. When detectives storm and search the tower, Rapunzel is gone, but they find a footprint left behind. The footprint clearly shows a loop pattern on the big toe. A loop pattern is a recessive trait. Detectives question Rapunzel’s family to determine if the footprint might belong to Rapunzel. The investigation provides the following information:
  2. Rapunzel’s dad does not have the foot loop (not fruit loop, but foot loop!) pattern
  3. Rapunzel’s mom does not have the foot loop pattern
  4. Rapunzel’s sisters do not have the foot loop pattern
  5. Rapunzel’s brother does have the foot loop pattern
  1. What is the genotype of Rapunzel’s mother? Rapunzel’s father?
  2. Construct a Punnett square to determine if the footprint could belong to Rapunzel.
  3. What is the probability that Rapunzel has a foot loop pattern?
  1. Count Dracula is looking for a mate. He comes from a pure-line family with the dominant trait of very sharp fangs. It is important to Dracula to find a wife who shares the same family background. In the world of vampires, not only are sharp fangs considered extremely attractive, their ability to survive depends on them!  He has met someone that he thinks could be the vampire of his dreams (or would that be nightmares?!). Dolly has fangs as sharp as razor blades, but Dracula wants to make sure they have no chance of producing baby vampires with dull fangs. When Dracula visits Dolly’s house, he snoops and discovers the highly-prized certificate of pure-line sharp fangs awarded to Dolly’s father, but he is horrified to discover that Dolly’s mother has dull fangs!
  1. What are the genotypes of Dolly’s parents?
  2. What is Dolly’s genotype?
  3. Construct a Punnett square to determine the expected genotypes and phenotypes if Dolly and Dracula marry and have children.
  1. Sleeping Beauty is known throughout the kingdom for her beautiful homozygous ruby red lips and golden hair. The prince that has awakened her from her slumber has heterozygous red lips and heterozygous black hair. Red lips are dominant and pink lips are recessive. Black hair is dominant and blonde hair is recessive.
  1. Construct a dihybrid cross to determine what their children might look like.
  2. What are the expected genotype and phenotype ratios of their offspring?
  1. In ghosts, white color is dominant over gray color, and a rounded-head is dominant over a pointed head. If a gray ghost with a pointed head marries a ghost heterozygous for body color and head shape, determine the expected genotype and phenotype ratios in the ghostettes (little ghosts) produced.

More Practice…..

  1. Cinderella is so happy! She is marrying her Prince Charming and preparations are underway for the wedding ceremony. She wants everything to be perfect, right down to the flowers. Her favorite colors are pink and red, but alas – only pink roses are available. Not only is Cinderella an excellent housekeeper, she also has a background in Biology, so she directs the palace gardeners to cross pink roses with pink roses. She knows that roses show incomplete dominance and that pink roses have a heterozygous genotype, while one homozygous genotype shows red roses and the other homozygous genotype shows white roses.
  1. Construct a Punnett square for the cross of pink roses X pink roses.
  2. What is the expected phenotype ratio? Will Cinderella have pink and red roses for her wedding?
  1. Wolves are sometimes observed to have black coats and blue eyes. Assume that these traits are controlled by single genes that arelocated on two different chromosomes. Assume further that normal coat color is dominant to black coat color and that brown eyes are dominant to blue eyes. Suppose a male wolf with a black coat and blue eyes mates with a female wolf heterozygous for bothnormal coat color and brown eyes.
  1. Construct a Punnett square to see what the resulting pack might look like.
  2. What is the expected phenotype and genotype ratio?
  1. In monsters, eye color is a trait that exhibits co-dominance. Monsters that are RR have red eyes, those that are YY have yellow eyes, and monsters that are heterozygous have red AND yellow freckled eyes.
  1. If a yellow-eyed monster marries a monster with red AND yellow freckled eyes, what are the expected genotype and phenotype ratios of their mini-monsters (children)?
  2. Mortimer and Matilda Monster have three children, Mavis has red AND yellow freckled eyes, Mabel has redeyes, and Mort Jr. has yellow eyes. Use the phenotypes of the children to determine the genotypes of theparents, Mortimer and Matilda.
  1. In Kingwood Texas, there is a creature known as a panther. It comes in three colors, yellow, green, and blue. This trait is controlledby a single gene with incomplete dominance. A homozygous (YY) individual is yellow, a homozygous (Y’Y’) individual is blue, and aheterozygous (YY’) individual is forest green.
  1. What would be the genotypic and phenotypic ratios of the offspring if a yellow panther were crossed with a blue one?

Matching - Answers must be on your own paper! You must write out the question and the correct answer.

1. Combination of alleles that contains a dominant and recessive

2. Study of heredity

3. Haploid reproductive cells

4. Humans have 23 pair of these

5. Unit on a chromosome that codes for a trait

6. Type of allele that is always expressed when present

7. Separation of alleles when homologous pairs separate

8. Having two of the same alleles

9. Traits passed on from parents to offspring

10. Outward appearance of an organism

11. Characteristic that distinguishes one individual from another

12. Different forms of a gene

13. Type of allele that is masked when there is only one present

14. Genetic composition of an organism

15. Cell that contains pairs of chromosomes, 2n

16. Fertilized ova

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