Genetics and Heredity Test
1. In an organism’s genotype, a capital letter stands for a _________ allele.
a. Recessive
b. Dominant
c. Homozygous
d. Heterozygous
2. What occurred in the P generation of Mendel’s pea plant experiment?
a. He crossed a purebred tall plant with a purebred short plant
b. He crossed a hybrid tall plant with a hybrid short plant
c. He saw that all tall offspring were produced
d. He saw that 3 out of 4 offspring were tall and 1 out of 4 were short
3. Why did all of Mendel’s pea plants show up as tall in the F1 generation?
a. The allele for the short trait disappeared.
b. No alleles for the short trait were present
c. The recessive allele for the short trait was hidden by a dominant allele
d. The dominant trait for the short trait was hidden by a recessive allele
4. Which of the following represents a homozygous recessive genotype?
a. TT
b. Tt
c. tt
d. Tr
5. Which of the following represents a correct heterozygous genotype?
a. TT
b. Tt
c. tt
d. Tr
6. Finish the following sentence: A recessive allele _______________.
a. Always shows up in an organism’s phenotype
b. Can be hidden if a dominant allele is present
c. Can hide a dominant allele
d. Cannot be passed on to an organism’s offspring
7. If T = tall and t = short in pea plants, which of the following is TRUE?
a. A short pea plant can only have the hybrid genotype Tt
b. A short pea plant can only have the purebred genotype TT
c. A short pea plant can only have the purebred genotype tt
d. A short pea plant can have the genotypes TT or Tt
8. What does a Punnett square show?
a. All the probable outcomes, or potential offspring, of a genetic cross
b. Only the offspring that will definitely be produced by a genetic cross
c. Only the dominant traits produced in a genetic cross
d. All of Mendel’s discoveries about genetic crosses
9. An organism’s physical appearance is its ___________.
a. Genotype
b. Phenotype
c. Allele
d. Gene
10. The different forms of a gene are called alleles. Why do organisms have two alleles for each trait?
a. The organism’s mother contributes both alleles
b. The organism’s father contributes both alleles
c. The organism’s mother contributes one allele in her egg and the father contributes the other in his
sperm
d. The statement is false. Organisms have four alleles for each trait.
11. Tay-Sachs is a fatal disease in which fat builds up in the brain. If T = no disease and t = Tay-Sachs, which
genotype represents a person with the disease?
a. TT
b. tt
c. Tt
d. Both b and c
12. Amy and Kevin both have brown eyes, but their son Sam has blue eyes. How is this possible?
a. The parents are both homozygous recessive
b. The parents are both homozygous dominant
c. The parents are both heterozygous
d. Sam cannot be their son
True/False
13.
14.
15.
16.
17.
Dominant alleles are always expressed.
Heterozygous offspring will show the dominant trait in their phenotype.
An organism can be heterozygous for some traits and homozygous for other traits.
In a cross between two Tt plants, 25% of the offspring will be Tt.
A purebred organism can be represented by the genotype Rr.
Matching. You will use the terms MORE than once.
a. Down Syndrome
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
b. sickle cell disease
c. hemophilia
d. Klinefelter's
e. Turner
Extra chromosome on the 21st pair of chromosomes
Male with XXY
Lacks a protein which allows for blood clotting
Red blood cells cannot carry oxygen because of their shape
Female with only one X chromosome
Effects mostly males because it is carried on the X chromosome
Male may not develop facial hair, cannot have children, tends to be overweight
Results in intellectual disability, heart problems, poor vision
Females are short, have wide bodies/neck, cannot have children
Clots of red blood cells prevent blood from flowing through blood vessels
Occurs mostly in African American populations
Punnett Squares. Complete the Punnett on your scratch paper using the method you learned in class.
29. In guinea pigs, black fur (B) is dominant to white fur (b). Cross a heterozygous black guinea pig with a
homozygous white guinea pig. What percent of offspring will be black?
30. In rats, brown fur (B) is dominant to white fur (b). Cross a homozygous dominant rat with a homozygous
recessive rat. What percentage will be white?
31. In flowers, yellow petals (Y) are dominant to purple (y). Cross two heterozygous flowers. What percentage will
be yellow?
32. Unattached ear lobes (E) are dominant to attached ear lobes (e). Cross a homozygous recessive person with a
homozygous dominant person. What percentage will have unattached ear lobes?
33. R = round eyes r= narrow eyes. Cross two heterozygous parents. Which of the following is TRUE?
a. Offspring must have Rr to have round eyes
b. Offspring must have RR to have narrow eyes
c. Offspring with at least one R allele will have round eyes
d. Offspring with at least one R allele will have narrow eyes
Key:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
b
a
c
c
b
b
c
a
b
c
b
c
a
a
a
b
b
a
d
c
b
e
c
d
a
e
b
b
c