UNIT 9 - MENDELIAN GENETICS STUDY GUIDE - You must show ALL work to receive credit on ANY problem!
U9P1 - Define: a) hybrid b) genes c) principle of dominance d) principle of independent assortment
e) dominant f) recessive g) homozygous h) heterozygous i) incomplete dominance j) homologous
chromosomes k) nondisjunction
U9P2 – MONOHYBRIDS
1. Below are the genotypes for some of the characteristics of the organisms in your area. Decide whether the
genotypes are heterozygous (Tt) or homozygous (tt). Record your answers below.
AA_____
Ff_____
HH_____
Rr_____
aa _____
hh_____
Hh _____
rr_____
Aa_____
ff_____
FF_____
RR_____
2. Which of the genotypes in number 1 would be purebred (homozygous)?_________________
3. Which of the genotypes in number 1 could be a hybrid (heterozygous)? ________________
4. Use the information below to determine the possible phenotypes of Billy Bird.
Green body (A) is dominant to yellow (a) body color.
AA _______________
Aa _________________
aa________________
Long feathers (F) are dominant to short feathers (f)
FF _______________
Ff__________________
ff_________________
5. Use the information below concerning phenotype to determine all of the possible genotypes for Anna
Aves.
Short legs (H) are dominant to long legs (h)
Short legs = ____________________ Long legs= ______________________
Long beak (R ) is dominant to short beaks (r )
Long beak= ____________________ Short beak=______________________
6. Billy Bird and Anna Aves met and fell in love. Billy Bird is homozygous dominant for a green body but Anna
Aves has a yellow body. Use a Punnett square to show the possible offspring that would result from a mating
between Billy Bird and Anna Aves. (Be sure to show your work). Give the genotypic & phenotypic ratios for
the offspring.
7. Billy Bird and Anna Aves are both heterozygous for feather length. What would the genotype be for Billy
and Anna? Give the genotypic & phenotypic ratios for the offspring.
8. All of Billy’s family has short beaks. Anna has a short beak. Give the genotypic & phenotypic ratios for the
offspring. Would the offspring be considered purebred or hybrid?
9. If Billy Bird is heterozygous for body color is he purebred or hybrid?
10. If Anna has a genotype of AA for body color is she purebred or hybrid? What is her body color?
11. Use a Punnett square to show a cross between Billy Bird with a heterozygous genotype for body color and
Anna’s genotype AA for body color.
U9P3 – MONOHYBRIDS PART 2
1. In a cross between homozygous blue & homozygous white Smurfs in which blue (B) is dominant to white
(b), what are the genotypic & phenotypic ratios for the children?
2. In Garfield’s family, black fur (B) is dominant to yellow fur (b). Determine the expected genotypic ratios &
phenotypic ratios resulting from crossing: a) homozygous black & yellow b) 2 heterozygous black
c) heterozygous black & yellow.
3. Suppose that in outer space there exists creatures whose traits are inherited by Mendel’s laws. You find
that purple eyes (E) are dominant to yellow eyes (e). Two purple-eyed creatures mate & produce six offspring,
four of them have purple eyes & 2 have yellow eyes. What are the genotypes of the parents? What are the
genotypes of the offspring?
4. If the ability to fly is recessive & if Superman marries Lois Lane, what are the chances that a child will be
able to fly is Lois is heterozygous?
5. Black hair is dominant over blond hair. If Lucy is homozygous dominant for black hair & Pig Pen is
heterozygous for black hair, what are the genotypic & phenotypic ratios for their children?
6. In rabbits, spotted coat color (T) is dominant to solid coat color (t). Cross a homozygous spotted rabbit with
a homozygous solid color rabbit & give the genotypic & phenotypic ratios for the children.
7. The long hair of Persian cats is recessive to short hair. If a pure long-haired cat is mated with a pure shorthaired cat, what will be the genotypic & phenotypic ratios?
8. In horses, black coat (B) is dominant while white coat (b) is recessive. Cross 2 heterozygous horses & give
the genotypic & phenotypic ratios.
9. In chickens, the allele for rose comb (R) is dominant to the allele for single comb (r). Cross a heterozygous
chicken with a single combed chicken & give the genotypic & phenotypic results.
10. The long wings of fruit flies are dominant over short wings. What are the genotypic & phenotypic ratios of
a cross between 2 hybrid long-winged fruit flies?
11. The ability to roll the tongue (R) in humans is dominant over non-tongue rollers. Cross two non-tongue
rolling parents. What are the genotypic & phenotypic ratios?
12. The gene for inflated pod shape (I) in peas is dominant over the gene for constricted pod shape (i). Cross
a heterozygous inflated pea with a constricted pea. What are the genotypic & phenotypic ratios?
13. Curly hair is dominant (H) to straight hair (h). Bob & Sue both have straight hair. How many of their
children will have curly hair?
14. 3 separate problems – NOT multiple choice - In peas, yellow seed (G) producing plants are dominant to
green seed (g) producing plants. What will be the proportion of each color in each offspring from a cross of: a)
2 heterozygous yellow plants, b) a heterozygous yellow with a green, & c) a green with a green.
U9P4 – DIHYBRIDS
1. In pigs, mule hoof is controlled by a dominant allele (H), while its recessive allele (h) gives rise to cloven
hoof. Belted coat pattern (B) is dominant to solid (b). Give the F2 genotypic & phenotypic ratios resulting
from the cross of a pure-breeding mule hoof, belted boar & a cloven hoof, solid sow.
2. In the F2 generation of the preceding problem, what proportion of the cloven-hoofed, belted pigs would be
homozygous?
3. How many & what types of the F2 in problem #1 are homozygous?
4. In peas, a gene for tall plants (T) is dominant over its allele for short plants (t). The gene for smooth peas
(M) is dominant over its recessive allele for wrinkled peas (m). Calculate both phenotypic & genotypic results
for the results of the following crosses: a) TtMm x TtMm b) Ttmm x ttmm c) TtMm x Ttmm d) TTmm x
ttMM
Below is a chart listing various traits found in an alien species. Use the information in the chart to solve the
genetics problems that follow.
Trait
Dominant Phenotype
Recessive Phenotype
Body color
(B) purple
(b) red
# of Eyes
(E) 2
(e) 1
Vision
(V) 20/20 - no glasses required
(v) glasses needed
Size of Lips
(L) thin
(l) thick
Hair
(H) absent
(h) present
Diet / Type of Teeth
(D) pointed = carnivore
(d) blunt = herbivore
Location of Nostrils
(N) front of head, above mouth
(n) top of head, between eye
stalks
# of Tentacles
(T) 8
(t) 4
Tentacle Suckers
(S) present
(s) absent
5. A carnivorous male with 4 tentacles mates with an 8-tentacled female who also eats meat. The male is
heterozygous for the diet trait. The female's tentacle genotype is hybrid but her diet genotype is pure. What
is the chance this couple will produce a carnivorous baby with 8 tentacles?
6. A red male with thin lips mates with a thin-lipped purple female. The female is heterozygous for the body
color trait. As for the lips, both aliens are heterozygotes. What is the chance that their baby will be red and
have thick lips?
7. A blunt toothed male with hair and glasses mates with a hairless female who wears glasses and has pointed
teeth. The male's entire genome is pure. The female does not have hair but does carry the hair allele. She is
homozygous for the tooth shape. What is the chance of this couple having a hairless baby with pointed teeth
that needs glasses?
U9P5 – INCOMPLETE DOMINANCE
Sammy Skunk loves to grow flowers in his garden. He wants to grow flowers that come in three colors: Red,
Blue, and Purple.
1. The red allele is R. The blue allele is r. What are the genotypes for the following:
Red= _________
Purple=__________ Blue= __________
2. What would the possible offspring be of a cross between red flowers and purple flowers? Give the
genotypic & phenotypic ratios.
3. What would the possible offspring be of a cross between a purple and blue flower? Give the genotypic &
phenotypic ratios.
4. What would happen if Sammy Skunk crossed two plants with purple flowers? Give the genotypic &
phenotypic ratios.
5. In radishes, the shape may be long (LL), oval (Ll), or round (ll). The color of radishes may be red (RR), purple
(Rr) or white (rr). Give the F2 genotypic & phenotypic ratios resulting from the cross of a long red radish with
a round white radish.
6. In cattle the gene for horned (h) is recessive for the gene for polled (H) or hornless. The color is controlled
by incompletely dominant genes RR for red, rr for white, Rr for roan. If 2 heterozygous polled-roan cattle are
mated, what kind of offspring will be produced?
7. In carnations, red (R) or white (r) phenotypes depend on homozygous conditions, while the heterozygous
form is pink. Give the F1 & F2 genotypic & phenotypic ratios resulting from the cross of a red with a white.
8. Is it possible to establish a pure-breeding line of pink carnations?
9. Starting with only a red variety, is it possible to develop a white-flowered variety without either
outbreeding or encountering a mutation? Explain.
U9P6 – CODOMINANCE
1. Give the results of the following blood type crosses: a) heterozygous type A x homozygous type B
b) Type O x heterozygous type B c) type AB x homozygous type A d) Type AB x type O
2. If a man with blood type B, one of whose parents had blood type O, marries a woman with blood type AB,
what will be the theoretical percentage of their children with blood type B?
The chart below lists the blood phenotypes of 8 individuals on a soap opera. Use the information in the chart
to solve the genetics problems that follow.
Females
Blood Type
Males
Blood Type
Anne
Type O
Charlie
Type A
Mallory
Type B
Scott
Type AB
Susan
Type AB
Larry
Type O
Patricia
Type A
Keith
Type B
3. Larry has a son with type B blood. Which of the females listed above could be this child's biological
mother?
4. Anne is pregnant with Scott's child. What is the chance that the baby will have type A blood?
5. Because her daughter has type B blood, Patricia insists that Keith is the father. Keith claims that Scott is the
father of Patricia's baby girl. Is it possible that Scott is the baby's father?
6. Keith and Mallory have a 4-year old with type O blood. How is this possible?
7. Susan is the mother of Charlie's first two children. The oldest, Dawn, has type AB blood while her sister,
Kate, has type B blood. Charlie is now expecting a baby with Anne. What is the chance that this child will have
type O blood?
8. Erin, Patricia and Larry's daughter, is married to Jeff. Jeff was in a serious car accident and needs a
transfusion but Erin is told that Jeff cannot be given her blood. Based on this information, provide Erin's blood
genotype and blood phenotype.
9. Scott and Susan's son, Paul, is willing to donate blood to a young girl with leukemia. If the recipient has
type O blood, will Paul be able to donate to her?
U9P7 – SEX-LINKED
1. In a cross between a white-eyed female fruit fly and red-eyed male, what percent of the female offspring
will have white eyes? (White eyes are X-linked, recessive)
2. In a cross between a pure bred, red-eyed female fruit fly and a white-eyed male, what percent of the male
offspring will have white eyes? (white eyes are X-linked, recessive)
3. Hemophilia in humans is due to an X-chromosome mutation. What will be the results of mating between a
normal (non-carrier) female and a hemophilac male?
4. A human female "carrier" who is heterozygous for the recessive, sex-linked trait causing red-green color
blindness, marries a normal male. What proportion of their male progeny will have red-green color blindness?
Below is a chart listing some sex-linked traits for an alien species. Use the information in the chart to solve the
genetics problems that follow.
Trait
Body color
Dominant
Phenotype
Chromosome
X
(P) purple
Recessive
Phenotype
(p) pink
Ear shape
X
(H) pointed
(h) round
Eye color
X
(E) yellow
(e) red
Foot color
X
(F) matches body
(f) mismatch to body
Size of nose
X
(N) small
(n) large
Eyebrows
Y
eyebrows present
Extra arms
Y
extra arms present for 4 arms total
5. A male with yellow eyes mates with a red-eyed female. What is the chance that this couple will have a
baby boy with red eyes?
6. A female, heterozygous for the body color trait, mates with a pink male. What is the chance that these
aliens will give birth to a purple-skinned girl?
U9P8 – 1. Why did Mendel choose pea plants to study genetics? 2. Describe Mendel’s theory of heredity.
3. If you cross red flowers with white flowers, all of the offspring are red. Why? 4. How are the principles of
probability used in genetics? 5. How many different gametes result from the following: a) AABb b) AaBb
c) AABB d) aaBB? 6. Do Mendel’s laws of genetics apply to all living things or only plants? 7. According to
the principle of independent assortment, is it genes, alleles, or chromosomes that are distributed?
U9P9 - 1. What are linked genes? 2. How can you determine if genes are linked? 3. How many
chromosomes are in a normal karyotype? 4. What type of chromosomes are shown in a karyotype?
5. What type of genetic abnormalities can be seen in a karyotype? 6. What is the combination of sex
chromosomes for a male? For a female? 7. What is the percentage chance that a baby will be a boy?