Can you anyone help me with a couple of my biology quiz?

[DisneyPrincess1]

Which defines an organism that is homozygous for a trait?
A has two different alleles for a trait
B has two different genes for a trait
C has two of the same alleles for a trait
D has two of the same genes for a trait

7. White-flowered plants crossed with red-flowered plants to produce pink-flowered offspring is an example of ___________
A codominance
B complete nce.
C dominance.
D incomplete nce.

8. Which is the correct expression of a heterozygous genotype for a recessive genetic disorder?
A a
B A
C aa
D Aa

9. A nt genetic disorder will be expressed if an individual has?
A one allele for the disorder
B one gene for the disorder
C two alleles for the disorder
D two genes for the disorder

10. What is the genotype of a woman with red-green color blindness?
A Xb Xb
B XB XB
C Xb Y
D XB Y

11. What is the effect of sickle-cell anemia?
A blocked respiratory pathways
B decreased neurological functions
C inefficient oxygen transportation
D susceptibility to contracting malaria

12. Why is Down Syndrome referred to as trisomy 21?
A The person has 21 pairs of chromosomes instead of 23.
B The person has an abnormal gene on chromosome 21.
C The syndrome is caused by having 21 pairs of autosomes.
D The syndrome results from an extra chromosome 21.