Name:______________________________________________ Unit 5 Genetics Problems
Directions: Answer each of the following questions. You may need to draw a Punnett square to
solve some of the questions.
1. As a result of a short life cycle and few chromosomes, ideal organisms for experimental studies in
genetics are
(1) garden peas
(2) humans
(3) fruit flies
(4) maple trees
2. The genes located at corresponding positions on homologous chromosomes are known as
(1) autosomes
(2) homozygotes
(3) alleles
(4) heterozygotes
3. An individual possesses two identical genes for a certain trait. For this trait, the individual is said to
be
(1) dominant
(2) hybrid
(3) homozygous
(4) heterozygous
4. The outward appearance (gene expression) of a particular trait in an organism is referred to as
(1) a genotype
(2) A phenotype
(3) an allele
(4) a chromosome
5. The phenotype of a pea plant can be most easily determined by
(1) looking at it
(2) crossing it with a recessive plant
(3) crossing it with a similar plant
(4) looking at the parents
6. Which pair of terms is most alike in meaning?
(1) segregation, dominance
(2) heterozygous, hybrid
(3) phenotype, genotype
(4) recessiveness, blending
7. What is the probability that a hybrid tall pea plant will produce a gamete carrying a gene for
tallness?
(1) 0%
(2) 25%
(3) 50%
(4) 75%
8. With respect only to the alleles G and g, a heterozygous female could normally produce how many
different kinds of egg cells?
(1) 1
(2) 2
(3) 3
(4) 4
9. In guinea pigs, rough hair is dominant over straight hair. If heterozygotes are crossed, the largest
number of any one genotype of offspring would probably be
(1) homozygous straight hair
(2) homozygous rough hair
(3) heterozygous rough hair
(4) intermediate between rough hair and straight hair
10. A cross is made between two organisms, both of which have the genetic makeup Bb for a
particular trait, and two offspring are produced. The first offspring exhibits the dominant trait. What
is the probability that the second offspring will exhibit the recessive trait?
(1) ¼
(2) ½
(3) ¾
(4) 0
11. A black guinea pig crossed with an albino guinea pig produces 12 black offspring. When the
albino is crossed with a second black one, 7 blacks and 5 albinos are obtained. What is the best
explanation for this genetic situation? ________________________ (hint: it is one of Mendel’s laws)
Write the genotypes for the parents, gametes and offspring using the letter B.
Parent 1 Genotype: ____________________
Parent 2 Genotype: _______________
Parent 1 Gametes: _______ and ________
Parent 2 Gametes: _______ and _____
First mating (12 black offspring) Genotypes: ___________________________________
Second mating (7 black and 5 albino) Genotypes: _______________________________
_______________________________________________________________________
12. In sesame plants, the one-pod condition (P) is dominant to the three-pod condition (p). Determine
the genotypes for the two parents for all possible matings producing the following offspring:
318 one-pod : 98 three-pod
Genotype of Parent 1: _____________
Genotype of Parent 2: _____________