Genetics Review Questions
Name______________
1. If “R” represents the gene for round seeds and “r” represents the gene for wrinkled seeds,
which is a hybrid?
a. Rr
b. RR
c. rr
d. none of these
2. What is the basic unit of heredity? genes
3. Who studied the inheritance patterns of pea plants and is the “Father of Genetics”? Mendel
4. A gene that masks or hides other genes is called dominant.
5. Recessive traits are not expressed unless the offspring inherit a recessive gene from each parent.
6. Dominant genes are represented by a capital letter, while a recessive gene is represented by a
lowercase letter.
7. PP and pp represent a purebred organism.
8. A hybrid gene pair is also referred to as heterozygous.
9. Offspring inherit one gene from each parent.
10. Pp has genes that are different and represent a hybrid organism.
11. What did Karl Correns discover? incomplete dominance
12. The likelihood that an event may or may not take place is called probability.
13. What is the probability that a child will be male? 50% or 1 in 2
14. In a punnett square, what does each square represent? possible combinations of alleles that can
result from a genetic cross
15. Visible characteristics are called traits (I would also accept phenotype).
16. The actual gene make-up of an organism is called a genotype.
17. If B represents the dominant gene for brown fur, what would be the genotype for a guinea pig that
is heterozygous for brown fur? Bb
18. How is it possible for tall-stemmed parent plants to produce offspring that are short-stemmed?
Both parents would have to be hybrids (Tt x Tt).
19. If a smooth pea pod is represented by an “S” and a pinched pea pod by an “s”, what is the
phenotype of an “Ss” pea pod? smooth
20. Define codominance and give an example. It occurs when neither gene in a gene pair masks
the other, instead both traits are present. Example: Red cow X White bull = Roan offspring
21. Define incomplete dominance and give an example. It occurs when neither gene in a gene pair
masks the other, instead the two traits blend together to make a new trait.
Example: Red flower X White flower = Pink flower
22. Why did Mendel study pea plants? (3 reasons)
a) variety of traits
b) grow and reproduce quickly
c) crossed and bred easily
23. What is pollination? transfer of pollen from male structure to female structure
24. What is self-pollination? pollen from a flower lands on the pistil of the same
plant
25. What is cross-pollination? pollen from a flower lands on the pistil of another
plant
26. List 4 things Mendel concluded from his experiments. (pg. 113)
a) Individual factors control the inheritance of traits.
b) These “factors” exist in pairs.
c) The female parent contributes on factor, and the male parent contributes
one factor.
d) One factor in a pair can mask or hide the other factor.
27. Different forms of a gene are called? alleles
28. How would you write two dominant alleles for tall stems? TT
29. How would you write two recessive alleles for short stems? tt
30. How would you write a hybrid genotype for tall stems? Tt
31. Does probability predict what will definitely occur? No, it only predicts
possibilities.
32. Each time you toss a coin, what 2 ways can it land? heads or tails How do you
write this in mathematical terms? ½ or 50%
33. If the genes of a gene pair result in both traits being expressed, the genes are said
to show codominance.
34. How are codominant alleles written? both letters are capitalized
35. If a homozygous white-haired guinea pig (WW) is crossed with a heterozygous
white-haired guinea pig (Ww), what percentage of their offspring will be black?
0% will be white