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Name _____________________Hour:________
PUNNETT SQUARE SHOW WHAT YOU KNOW!
Attach Genetics notes to this review
TERMS TO KNOW:
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What is a gene?________________________________________
What is a genotype?_____________________________________
How is a genotype written?______________________
What is a phenotype?____________________________________
Write an example of a heterozygous genotype.__________
What are these two different forms of the same gene called?______
Hybrid = ___________ (one word)
Write an example of a homozygous genotype:____________
Purebred = ____________ (one word)
_____________ is the father of genetics.
11. What do the letters on the sides of every Punnett Square represent?______________________
12. What do the letters inside every Punnett Square represent?______________________
CROSSES IN PEA PLANTS:
Height Gene
Flower Color Gene
Pod Color Gene
Alleles: Tall (T)
Short (t)
Alleles: Green pods (G)
Yellow pods (g)
Alleles: Purple flowers (F)
White flowers (f)
Consider just the gene for flower color.
1. What is the genotype of a plant that is heterozygous for height ?______
What possible gamete genotypes would this plant make in meiosis? ______ _____
2. Cross two plants that are heterozygous purple. Show the Punnett square:
a) What is the fraction of their possible offspring that could have a purple
phenotype?_________
b) What is the fraction of their possible offspring that could have a homozygous
recessive genotype?_________
Consider two genes, one for flower color and one for pea plant height.
3. What is the genotype of a plant that is heterozygous for flower color and pod color?________
What possible gamete genotypes would this plant make in meiosis? REMEMBER THE FOIL
METHOD WHEN CONSIDERING TWO GENES! ONE COPY OF BOTH GENES MUST BE
PRESENT!
______ _____ _____ _____
4. Cross a plant that is short with white flowers with one that is homozygous for the tall
trait and purple flower trait. Show the Punnett square below if needed.
a) What is the percent probability that these two plants will have tall, purple
offspring?________
b) What is the percent probability that these two plants will have short, purple
offspring?_______
5. Cross a plant that is heterozygous for height and pod color with one that is
homozygous recessive for both traits. Show the Punnett square below
a) What are the possible genotype fractions of this cross?
1/4___TtGg___ 1/4__________ 1/4____________ 1/4___________
b) What are the possible phenotype fractions of this cross?
¼ Tall Green, ______________,
______________,
______________
6. Cross two plants that are heterozygous for both height and flower color. Show the Punnett
square below.
a) What is the most common phenotype of their offspring?________________
b) What is the phenotype ratio of their offspring?
9_tall,_purple flowers___:3_____________:3___________:1_____________
c) What is the percent chance they will have a tall offspring? __________
OTHER CROSSES:
Consider one gene for hair length in guinea pigs
7. Short hair in guinea pigs is dominant to long hair. If a litter of pigs has 5 short haired and 5 long
haired, and one of the parents has long hair, what are the genotypes of both parents?
_____________ and ______________.
Consider two genes in aliens, one for teeth shape and one for intelligence level.
8. In a far away galaxy, there is a small planet known as “jackflub,” it is the home to small creatures
known as the jackflubbies (I’m sure you have heard of them). Anyway, what you probably aren’t
aware of is their arch-enemies, “the nibflibs!!!” The nibflibs are grotesque creatures that eat
jackflubby children and build shopping malls out of their bones.
Just like the jackflubbies, nibflibs have a few traits of their
own. Here are a few of the traits nibflibs have……
a) Sharp teeth (E) (used for tearing flesh off baby jackflubby bones)
Dull teeth (e)
b) Intelligent (I) (someone has to design the malls…right?)
Moron (i)
Questions….
a.) Can two sharp toothed, moronic nibflibs have an intelligent baby?______
Prove your answer.
b.) What is the chance that a dull toothed, moronic nibflib can have an
intelligent baby with another dull toothed, moronic nibflib?_______
Prove your answer.
c.) A baby nibflib is born and has the following genotype… EEii
- What is the phenotype of this baby?_________________
- Can its mother have the genotype EEII?_______
Explain your answer.