GENETICS
DEFINE THE FOLLOWING TERMS AND PROVIDE ONE EXAMPLE FOR EACH.
1. Complete dominance:
2. incomplete dominance:
3. codominance:
MULTIPLE CHOICE
4. The appearance of an organism is its:
A. Genotype
B. phenotype
C. molecular make-up
D. popularity
5. A monohybrid cross of two individuals that are heterozygous for a trait would probably result in a
phenotypic ratio of:
A. 4:0
B. 1:3
C. 3:1
D. 1:1
6. To determine the genotype of an individual that shows the dominant phenotype, you would cross that
individual with one that is:
A. heterozygous dominant
B. homozygous recessive
C. homozygous dominant
D.heterozygous recessive
7. An organism that is homozygous dominant for a flower color would have the genotype:
A. RR
B. Rr
C. rr
D. Red
8. In guinea pigs, black fur is dominant. A black guinea pig is crossed with a white guinea pig. If the litter
contains a white offspring, the genotype of the black-haired parent is probably:
A. homozygous dominant
B. heterozygous
C. homozygous recessive
D. none of the above
9. If two parents with dominant phenotypes produce an offspring with a recessive phenotype, then
probably:
A. both parents are heterozygous
B. one parent is heterozygous
C. both parent are homozygous
D. one parent is homozygous
10.Suppose you have found a new species of plant. Some of the plants have yellow flowers, and some
have red flowers. You cross a red-flowering plant with a yellow-flowering plant. All of the
offspring have orange flowers. Suggest a possible genotype for the offspring.
A. RR
B. Rr
C. RR’
D. Rr
MATCHING: Write the letter of the definition that best fits with the term.
______1. Homozygous
A. an allele that can mask another allele
______2. Genotype
B. diagram to predict traits of potential offspring
______3. Gene
C. each of several alternative forms of a gene
______4. Phenotypic ratio
D. genetic makeup of an organism
______5. Recessive
E. both alleles in a gene pair, code for the same trait
______6. Heterozygous
F. a short segment of DNA that codes for a trait
______7. Genotypic ratio
G. number of time each phenotype appears in the offspring
______8. Phenotype
H. cross between individuals that involves one pair
of contrasting traits.
______9. Dominant
I. physical appearance of an organism
______10. Punnett square
J. two alleles in a gene pair, that don’t code for the same trait
______11. Allele
K. number of times each genotype appears in the offspring
L. an allele that can by masked by another allele
FOR QUESTIONS 12 & 13 ASSUME THE FOLLOWING: Tall is dominant (T) to short (t).
12. If an organism is heterozygous, what is its genotype? Phenotype?
13. If an organism that is homozygous dominant mates with a recessive organism, give the genotypic
& phenotypic ratios. SHOW ALL YOUR WORK.
14. If brown eyes are dominant to blue eyes, is it possible for 2 brown eyed people to produce a blue
eyed child? JUSTIFY YOUR ANSWER.