Genetics Study Guide Key
1. This trait is masked when the dominant allele is present. recessive trait
2. Different forms of genes are called alleles
3. He is considered the "father of modern day genetics." Gregor Mendel
4. Passing of traits from parents to offspring is called heredity.
5. This trait will always show up if the allele for this trait is present dominant trait.
6. If two different alleles for a trait are present the item is considered a hybrid.
7. If an organism has two identical alleles for a trait (example TT or tt) it is said to be
homozygous.
8. A chart used to track which members of a family will have a particular trait is
pedigree.
9. If an organism has two different alleles for a trait example (Tt) it is said to be
heterozygous.
10. A chart that shows all the possible genetic outcomes of a cross is a
punnett square.
11. The likelihood an event will occur is probability.
12. When alleles are not dominant or recessive. Both alleles are expressed in the subject.
codominance.
13. Genes found on the X or Y chromosomes are sex linked genes.
14. A person who has an allele for a disease but does not show symptoms of the disease.
carrier.
15. Hemophilia, sickle cell and cystic fibrosis are considered genetic disorder.
16. Chromosomes are composed mostly of DNA.
17. A double helix (shaped like a twisted ladder) is made up of four different nitrogen
bases.
18. The process of meiosis is when each parent's cell divides twice to produce sex cells
that have only half the number of chromosomes.
19. In the punnett square, is the gene within the star dominant or recessive?
Answer: recessive
T
t
T
TT
Tt
Tt
tt
t
20. Which gene in the punnett square is homozygous?
Answer: AA
A
A
a
AA
Aa
a
Aa
Aa
21. What are the physical traits displayed in an organism? Phenotype
22. TT is what type of allele? Dominant or recessive? dominant
23. DNA is the genetic makeup or allele combination an organism has.
24. tt is what type of allele? Dominant or recessive? recessive
25. Dominant alleles can be seen in the offspring when present.
26. Recessive alleles can be hidden by the presence of a dominant allele.
Use the image below to help you answer the following questions.
27. In a double helix, Adenine is paired with Thymine.
28. In a double helix, Cytosine is paired with Guanine.
29. What is the name of the following chart?
pedigree chart