Study Questions 10
Meiosis, Fertilization, and Mendelian Genetics

1. What is the "goal" of meiosis?

2. How are mitosis and meiosis similar? different?

3. Be able to follow chromosomes through both mitosis and meiosis and label the stages.

4. If you mixed a substance that prevented proper functioning of Na⁺ channels into some sperm and eggs, what would the consequences on the fertilization reaction be? Would the egg get fertilized?

 

5. What would happen if you injected some Ca⁺⁺ into an unfertilized sea urchin egg?

 

6. How do eggs floating around in the briny deep make sure that it is the sperm of the correct species that is fertilizing them?

 

7. The cortical reaction functions directly in the (Circle all correct answers)

a. formation of a fertilization membrane

b. fast block to polyspermy

c. release of hydrolytic enzymes from the sperm cell.

d. slow block to polyspermy

e. the fusion of the egg and sperm nuclei.

 

8. What do the following terms mean?

gene -

allele -

genotype -

phenotype -

dominant -

recessive -

homozygous -

heterozygous -

incomplete dominance -

co-dominance -

multiple alleles -

monohybrid cross -

dihybrid cross -

linkage -

crossing over -

9. How is a gene different from an allele?

10. What is an intercross? A testcross?

11. Be able to follow alleles through a monohybrid cross (from gamete generation in the parents to predicted genotype and phenotype ratios in the offspring).

 

12. How is a testcross valuable in genetic analysis?

13. What is the expected phenotypic ratio from a cross of two monohybrids when the alleles show complete dominance? incomplete or codominance?

 

14. What is the principle of independent assortment? Does it occur during mitosis or meiosis?

 

15. Assuming independent assortment and complete dominance, what is the expected phenotypic ratio from a cross of two dihybrids?

 

16. Assuming independent assortment and complete dominance, what is the expected phenotypic ratio from a testcross of a dihybrid?

 

17. How would the phenotypic ratio in the previous question change if the two genes were completely linked?

 

18. Having dimples and having an extra finger are both dominant traits. If a dimpled woman (with five fingers) marries a six-fingered man (without dimples), and they have an undimpled, five-fingered daughter ...

a. What are the genotypes of the parents?

b. What proportion of their kids would be expected to have both dimples and six fingers?

 

19. What do the following terms mean?

autosome -

X-linked gene -

Y-linked gene -

20. What sex chromosomes are present in a human female? a human male?

 

21. Can X-linked traits show up in both males and females? In which sex are recessive X-linked traits more likely to show up? What about dominant X-linked traits?

 

22. Can Y-linked traits show up in both males and females?