Genetics Study Guide Answers
1. Phenotype: physical characteristics (tall,
brown)
2. Genotype: genetic combination (Gg, GG, gg)
3. Genes: a segment of DNA, located on the
chromosome, factors that control traits
4. Dominant Allele: an allele whose traits always
show up if the allele is present (T)
5. Recessive Allele: an allele whose traits are
masked by a dominant allele and only show
up if two recessive alleles are present (t).
6. Heredity: the passing of traits from parents
to offspring
7. Trait: a characteristic that a parent can pass
to its offspring
8. Genetics: the study of heredity
9. Selective Breeding: selecting parents with
traits that you want their offspring to have
10.Punnett Square: a chart that shows all of the
possible combinations of alleles that can
result from a genetic cross.
11.Probability: the likelihood a particular event
will occur
12. Tall, brown eyes
13. Tt, TT, tt
14.Codominance is neither DOMINANT nor
RECESSIVE. Therefore if you cross a dog with
white fur and a dog with black fur the puppies
will have WHITE and BLACK fur.
15.Purebred and HOMOZYGOUS both mean same
(TT or tt).
16.Heterozygous and HYBRID both mean
DIFFERENT (Tt).
17.GREGOR MENDEL is considered “the father of
genetics” and studied PEA PLANTS.
18.Purebred tall and purebred short
19.Heterozygous tall
20. ¾ tall, ¼ short
21.A Punnett Square shows all of the possible
combinations of a genetic cross.
22.Mitosis creates new BODY cells for growth and
repair. (ex. Skin, blood, muscle, bone, etc.)
23.Meiosis creates new SEX cells for
reproduction.(sperm, egg)
24.How are Meiosis and Mitosis similar? They both
produce new cells
25.After Mitosis occurs, the new cells will have the
SAME number of chromosomes.
26.After Meiosis occurs, the new cells will have HALF
the number of chromosomes.
27.What two people could have identical DNA?
IDENTICAL TWINS
28.What is the point of mitosis? TO PRODUCE
BODY CELLS
29.What is the product of meiosis? TO PRODUCE
SEX CELLS
30.GENES are located on CHROMOSOMES which
are found inside the nucleus of the cell.
31. Label the following as dominant or recessive
a. Aa DOMINANT
b. AA DOMINANT
c. aa RECESSIVE
32. Label the following as purebred recessive, purebred
dominant, or hybrid dominant.
a. Aa Hybrid Dominant
b. AA Purebred Dominant
c. aa Purebred Recessive
33. Label the following as homozygous recessive,
homozygous dominant, or heterozygous dominant.
a. Aa Heterozygous Dominant
b. AA Homozygous Dominant
c. aa Homozygous Recessive
34. In humans, the allele for dimples (D) is
dominant. A woman with the genotype (dd) has
children with a man with the genotype (Dd). If the
couple has ten children, how many children would
you logically expect to have a dimples?
D
d
d
Dd
d
Dd
dd
dd
Dd (dimples) 50%
dd (no dimples) 50%
Half of their children will have dimples (5).
35. Linda has 10 children. She is heterozygous for
her dimples and her husband has a homozygous
dominant genotype. What is the probability that
their 11th child will have dimples?
D
D
D
DD
DD
d
Dd
Dd
DD 50%, Dd 50%
Dimples 100% 4/4
All of her children will have dimples, so the 11th
one will too. 4/4
36. A cat with solid fur and one with purebred
spotted fur had offspring, called the F1 generation.
In time, two of the offspring from the F1 generation
mated and produced offspring’s called the F2
generation. What percentage of F2 generation
would be born with spotted fur?
F Spotted
F1:
f
Solid Fur
F
F
f
Ff
Ff
f
Ff
Ff
F2:
F
f
F
FF
Ff
f
Ff
ff
FF: 25%
Ff: 50%
Ff: 25%
Spotted (75%)
Solid (25%)
37.In humans, dimples (D) are dominant over no
dimples (d). A man with dimples marries a
woman without dimples and they have three
children, two of which have dimples and one
that does not have dimples. If no dimples are
recessive, what must the man’s genotype be?
d
d
D
Dd
Dd
D
Dd
Dd
d
d
D
Dd
Dd
d
dd
dd
Dd (all dimples) WRONG
Dd (dimples)
dd (no dimples)
Dad has to be Dd
38. Cross a heterozygous tall pea plant with a
homozygous short pea plant. Use “T” for tall and “t”
for short.
•
•
•
•
•
•
t
T
Tt
t
tt
t
Tt
tt
What is the probability of the above offspring to be Tt? 2/4
What is the probability of the above offspring to be tt? 2/4
What is the probability of the above offspring to be TT? 0/4
What percentage of the offspring will be tall? 50%
What percentage of the offspring will be short? 50%
List all of the possible genotypes of the offspring. Tt (50%), tt
(50%)
• List all of the possible phenotypes of the offspring. Tall (50%),
Short (50%)