2. True or false: Diploid eukaryotic organisms have two sets of chromosomes, one from each parent.

a. true
b. false

3. An egg produced by the human female contains

a. two Y chromosomes
b. two X chromosomes
c. one Y chromosome
d. one X chromosome
e. none of the above

4. Down syndrome is the result of

a. independent assortment
b. genetic linkage
c. crossing-over
d. incomplete dominance
e. nondisjunction

a. true
b. false

5. Number of chromosomes in human sex cells?

a. 1
b. 2
c. 22
d. 23
e. 46

6. Number of X chromosomes in a human female?

a. 1
b. 2
c. 22
d. 23
e. 46

7. The environmentally and genetically determined observable physical appearance of an organism.

a. Allele
b. Gene
c. Genotype
d. Phenotype
e. Homozygous trait

8. An example of a heterozygous condition is

a. aa
b. AA
c. Aa
d. all of the above
e. none of the above

9. The probability of parents w. genotypes Ss x Ss having an offspring w. the genotype ss is

a. zero
b. 25%
c. 50%
d. 75%
e. 100%

10. Both alleles for the trait are identical.

a. Homozygous trait
b. Allele
c. Dominant allele
d. Recessive allele
e. Heterozygous trait

12. An allele that expresses itself and masks the effects of the other allele for the trait (this allele masks the homologous allele).

a. Homozygous trait
b. X-linked allele
c. Dominant allele
d. Recessive allele
e. A, C, and D