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Study Guide Genetics DOK 5
Name:
Key
Block: ___________
Define the following terms:
1. Dominant Trait-characteristics that are expressed if present in the genotype
2. Recessive Trait-characteristics that are masked by dominant traits unless there are two of them
3. Genotype-an organism’s inherited alleles (actual DNA code)
4. Phenotype-an organism’s inherited appearance (the way the DNA code makes the organism
look)
5. Heterozygous-Two different alleles for a trait. Ex. Bb
6. Homozygous-An allele is repeated (BB, bb)
7. Gene-sections of chromosomes that code for specific traits
8. Alleles-options or choices for specific genes
Answer the following questions:
9. How many chromosomes are in human body cells? 46
10. How many chromosomes are in human gametes (reproductive cells)? 23
11. What is the difference between dominant and recessive traits?
Dominant traits are always expressed if they are present. Recessive traits are only expressed if
there is NO DOMINANT trait.
12. What is the relationship between genotypes and phenotypes?
Genotype is an organism’s genetic makeup. Phenotype is what those genes look like on the
organism.
13. What is homozygous? Give an example using any letter. (There are two types)
Homozygous means that an allele (the letters) are repeated. (BB, bb)
14. What is heterozygous? Give an example using any letter.
Heterozygous means that there are two different alleles present. Bb
15. State the goal of mitosis. To create body cells for growth and repair.
16. State the goal of meiosis. To create gametes (sex cells) for sexual reproduction.
Study Guide Genetics DOK 5
17. Using the Venn diagram below, note the similarities and differences between mitosis and
meiosis.
Mitosis
Meiosis
Both
1.
2.
3.
4.
Body cells for growth
and repair
46 chromosomes in
original cell and each
of the daughter cells
Asexual reproduction
Produce identical
cells
1.
-Both create new
cells
2.
-DNA replication
happens once
-begins with 46
chromosomes
3.
4.
Makes gametes
for sexual
reproduction
46
chromosomes in
original cell and
23 in each of
the daughter
cells
Makes sex cells
for sexual
reproduction
Produces cells
with half the
DNA
18. Given the genotype Bb (brown is dominant and white is recessive), what is the phenotype?
brown
19. What could be a genotype for a phenotype of white if white is recessive and purple is dominant?
pp
20. What is the relationship between chromosomes, DNA, and genes?
Chromosomes are coiled structures of DNA that have genes on them.
21. How do genes and alleles relate to each other? Give one example.
Alleles are a specific choice for a gene. Ex. Gene=handedness, Alleles=right or left
Study Guide Genetics DOK 5
22. What are the genotypes of the parents for this Punnett square cross?
d
23.
d the.
D
D
Dd
Dd
Dd
Dd
24. Complete the following Punnett squares.
Square 1
Square 2
Rabbit fur
B=brown
b=white
B
_______
B
____
____
B
____
____
BB
Flower color
P=purple
p=white
b
_______
Bb
BB
Bb
p
____
____
p
____
____
P
_______
P
_______
Pp
Pp
Pp
Pp
Genotypic Ratio:
Genotypic Ratio:
BB: 50% Bb: 50% bb: 0%
PP: 0% Pp: 100% pp: 0%
Phenotypic Ratio:
Phenotypic Ratio:
Brown: 100% white: 0%
Purple: 100% white: 0%
Study Guide Genetics DOK 5
25. Determine the genotype of the parents using the following Punnett square.
R
R
r
RR
Rr
Genotypic Ratio:
RR: 25% Rr: 50% rr: 25%
Phenotypic Ratio:
r
rr
Rr
26. Label the picture below.
DNA
Gene
Chromosome
Round: 75% square: 25%
Study Guide Genetics DOK 5
27. Label the picture below.
Chromosome
Nucleus
Gene
Cell
DNA
28. The Green family has four daughters. What is the probability their next child will also be a girl?
50%
29. If a typical human body cell has 46 chromosomes, meiosis will produce sex cells with how many
chromosomes? 23
30. If a typical canine (dog) gamete has 39 chromosomes, how many chromosomes will be in the
body cells? 78
31. In a PARAGRAPH, explain the relationship between Genes, Alleles, DNA, and Chromosomes.
These elements should be in your paragraph:
 Chromosomes are made of coiled DNA
 Genes are sections of DNA that code for a particular trait
 Alleles are choices for genes
Study Guide Genetics DOK 5
32. Complete Punnett squares for ALL of the following crosses. Include the genotype and
phenotype ratios. The allele for a cleft chin, D, is dominant among humans.
a. Mom: DD, Dad: Dd
b. Dad: Dd, Mom: Dd
c. Mom: DD, Dad: dd
d. Dad: Dd, Mom: dd
Please draw Punnett square for each of the crosses and write the appropriate genotype and
phenotype ratios with them.