Meiosis/Dihybrids Review
1. What type of cell undergoes meiosis?
Gamete cells
or Somatic cells
2. What does Spermatogenesis make? What does Oogenesis make? What sex does each process occur in?
3. For each of the following state if the cell is haploid or diploid.
Sperm cell =
Liver cell =
Egg cell =
Stomach cell =
4. If the diploid number in a liver cell of an organism is 34, how many chromosomes are there in the egg of this
organism?
5. During meiosis, the chromosome number:
a) is doubled
b) is reduced
c) remains the same
d) becomes diploid
6. Cells starting mitosis & meiosis begin with a (haploid or diploid) set of chromosomes.
7. How many times do cells divide during meiosis?
8. Draw 2 Chromososmes crossing over. What does this process cause?
9. How many cells form at the end of meiosis and how do they compare, genetically, to each other?
10. A sperm cell is a (gamete or zygote), and is (haploid or diploid).
11. Which of the following best describe the term “crossing over”?
a.)
b.)
c.)
d.)
An exchange of information between two homologous chromosomes
A molecular interaction between two sister chromatids
A molecular interaction between two non-sister chromatids
A separation of two sister chromatids
Figure 1
12. Which letter in Figure 1 represents meiosis? Why?
13. Which letter in Figure 1 represents mitosis? Why?
14. Which letter in Figure 1 represents fertilization? Why?
16. What is the ultimate goal/purpose of Meiosis?
17. What is the difference between a chromosome, sister chromatids, and homologous chromosomes? You may
draw a picture as your answer.
19. What is the difference between a haploid, diploid, and zygote?
20. Give 3 examples how meiosis differ from mitosis.
21. If the sperm cell of an organism contains 14 chromosomes, how many chromosomes are in a somatic cell of
this organism?
DIHYBRID PUNNETT SQUARE PRACTICE PROBLEMS
Problem A: Suppose that black hair (B) is dominant over blonde hair (b) and brown eyes (E) are dominant over
blue eyes (e). The father has black hair (heterozygous) and brown eyes (heterozygous) and the mother has blonde
hair and blue eyes.
1. What percent of the offspring will be totally heterozygous?
2. What is the phenotype ratio?
3. What percent of the offspring will have blonde hair and blue eyes?
Problem B: Using the same traits as above, cross a completely recessive person with a blonde hair and
homozygous brown eyed person.
1. What percent of the offspring will be totally heterozygous?
2. What is the phenotype ratio?
3. What percent of the offspring will have blonde hair and blue eyes?