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Genetics Practice Questions:
1. Define the following Vocabulary Words:
 fertilization

haploid

diploid

chromosomes

Test cross

meiosis

gametes

inheritance

chromosome

phenotype

genotype

allele

gene

homozygous

heterozygous

recessive allele

dominant allele

co-dominant

Sex-linked gene

Non-sex-linked gene

independent assortment
1. How are a chromosome, DNA, and a gene interrelated. Draw a picture to support your answer.
2. Below Given the Haploid number of chromosomes write down the diploid number of chromosomes:
Haploid Number
Diploid Number
30
12
7
3. What type of cells have a haploid number?
.
4. What type of cells have a diploid number?
.
5. What type of cells a formed through the process of meiosis?
.
6. How many chromosomes does human sperm cell contain?
.
7. Cross two heterozygous tall plants.
T=tall
t=short
i.
Write the cross described above. ________X_________
ii.
Draw a Punnett Square to represent the cross.
iii.
iv.
v.
What percent of the offspring will be tall? __________
If T= Tall plant and t= short plant what would be the phenotype for a heterozygous plant?
___________________
Organisms that have 2 identical genes such as TT or tt are said to be_________________.
8. W=Widow’s peak, w=No widow’s peak
i.
What is the genotype for a person that is heterozygous? What is the phenotype?
a. Genotype ____________
b. Phenotype ____________
9. In corn, dark kernels are dominant to light. Show the cross between a heterozygous plant and a pure homozygous
dominant plant. Please include the following: the symbols, the cross, , the Punnet square, and the genotypic and
phenotypic ratios.
a. The symbols ____________
b. The cross ____________
c. The Punnet square:
d. What percent are dark?
10. In rabbits, brown fur is dominant to white fur and long ears are dominant to short. Cross two brown long-eared
rabbit that are heterozygous for both traits. Include the following: the symbols, the cross, the Punnet square, and
the phenotypes of the offspring.
a. The symbols ____________
b. The cross ____________
c. The Punnet square:
d. The phenotypes:
.
11. Hemophilia is a sex-linked trait. Write the cross for a hemophiliac man and a woman that is a carrier.
a. The Cross:___________________
b. Make the punnet square:
c. What percent of the males do you expect to be hemophiliacs? ______
d. What percent of the females do you expect to be hemophiliacs? ______
e. What percent of the females do you expect to be carriers? ______
Pedigree Practice
12. Which members of the family above are afflicted with Huntington’s Disease?
**
13. There are no carriers for Huntington’s Disease- you either have it or you don’t. With this in mind, is Huntington’s
disease caused by a dominant or recessive trait? **
14. How many children did individuals I-1 and I-2 have? **
15. How many girls did II-1 and II-2 have? ** How many have Huntington’s Disease? **
16. The pedigree to the above shows the passing on of Hitchhiker’s Thumb in a family. Is this trait dominant or
recessive? **
17. How do you know? **
18. How are individuals III-4 and III-5 related? **
19. Name 2 individuals that have hitchhiker’s thumb. **
20. Name 2 individuals that were carriers of
hitchhiker’s thumb. **
21. Is it possible for individual IV-3 to be a carrier? **Why?
22. The pedigree to the above shows the passing on of colorblindness. What sex can ONLY be carriers of
a. colorblindness? **
23. Why does individual IV-7 have colorblindness? **
24. Why do all the daughters in generation II carry the colorblind
gene? **
25. List 2 IV generation colorblind males. **
26. What is a test cross? Select the best answer below:
A.
Crossing a possible heterozygote with a homozygous recessive
B.
Any genetic cross to determine genotype
C.
Crossing a possible homozygote with a homozygous dominant
D.
Crossing a possible heterozygote with another heterozygote
(Total 1 mark)
27. A parent organism of unknown genotype is mated in a test cross. Half of the offspring have the same phenotype as the
parent. What can be concluded from this result?
A.
The parent is homozygous dominant for the trait.
B.
The trait being inherited is polygenic.
C.
The parent is heterozygous for the trait.
D.
The parent is homozygous recessive for the trait.
28. A woman has a heterozygous genotype for blood group B. She is expecting a baby with a man who is
homozygous Group A. What are the possible blood groups for their baby? SHOW YOUR WORK/ PUNNET
SQUARE (genetic diagram)
29. If a man has blood group O and a woman has blood group AB, what is the probability that their child will be
blood group O? SHOW YOUR WORK/ PUNNET SQUARE (Genetic Diagram)
In Border Collies, black coat (B) is dominant to red coat (b). A breeder has a black male that
has won numerous awards. The breeder would like to use the dog for breeding if he is
purebred or BB. To learn this information, she test crosses him with a red female
(bb). Answer the following questions A, B, C, and D.
A. If the black male is BB, what kind of
gamete (sperm) can he produce?
Only
_________
B. If the red female is bb, what kind of gamete
(eggs) can she produce?
Only __________
C.
D.
If the black male is Bb, what kind(s) of gametes (sperm) can he produce? Either _______
or ______
If any of the puppies are red, what is the father's genotype?
Only __________
The gene that controls whether or not a person can produce the pigment melanin which
contributes to the color of skin, eyes and hair. Some people have the hereditary condition,
albinism; they are not able to produce melanin and have little or no pigment in their skin and
hair. Two different versions of the same gene are called alleles. One allele of this gene codes for
melanin production and normally pigmented skin and hair; it is symbolized by A. Another allele
of this gene codes for albinism; it is symbolized by a.
Both parents are heterozygous for albinism.
Complete the Punnett square (right) that
illustrates this marriage.
What are the phenotypes of the children?
What is the probability that a child will
have albinism?
10. The ability to curl your tongue up on the sides (T, tongue rolling) is dominant to not being
able to roll your tongue. A woman who can roll her tongue marries a man who cannot. Their first
child has his father's phenotype. What are the genotypes of the mother, father, and child?