Download Genetics Unit Study Guide – Teacher Version

Genetics Unit Study Guide
Vocabulary:
1.
The principle that describes that genes segregate without influence on each others
inheritance:
Law of Independent Assortment
2.
During the formation of gametes, independent assortment occurs during Meiosis
3.
Mendel’s hypothesis that two factors for each trait are segregated during the formation of
gametes is explained by the law of
4.
Segregation
If a corn plant has a genotype of Ttyy, what are the possible genetic combinations that could
be present in a gamete (single grain of pollen) from this plant? Ty and ty
5.
The law of independent assortment states that the two alleles for each trait will separate
during meiosis
6.
The law of segregation states that
genes will separate during meiosis
7.
BR
Br
bR
Br
BR
BBRR
BBRr
BbRR
BbRr
Br
BBRr
BBrr
BbRr
Y
bR
BbRR
BbRr
X
Br
BbRr
Bbrr
A male guinea pig with black, rough hair (BbRr) was crossed with a female guinea pig with black, rough hair
(BbRr). The Punnett square contains the partial results from this mating. (B=black, b=white, R=rough,
r=smooth)
According to the figure above, what is the genotype for X?
bbRR
8.
Using the diagram above, explain the pattern of inheritance for hemophilia (a blood disease)
trait.
9.
Sex-linked inheritance
Above is a pedigree for the recessive trait, attached ears (aa). The dominant trait is
unattached ears (A). the black circles indicate people who have the recessive trait. Using the
chart, what would be the genotype of person I,2?
XH
Xh
Xh
X HX h
XhXh
Y
X HY
4
Aa
h = hemophiliac
H = normal
10.
Using the chart above, how many offspring will be hemophiliacs?
2
11.
The phenotype of box 4 is
12.
In fruit flies, the gene for red eyes (R) is dominant and the gene for sepia eyes (r) is
male hemophiliac
recessive. What are the possible combinations of genes in the offspring of two red-eyed
heterozygous flies (Rr)?
RR, Rr, rr
13.
The appearance of an organism is its
phenotype
14.
In a two-factor cross between an individual with the genotype RRYY and an individual with the
genotype rryy, all of the offspring will have the genotype RrYy
15.
A segment of DNA that controls a particular hereditary trait is called a gene
16.
The genetic makeup of an organism is called its
genotype
17.
Having two similar alleles for a trait is called
homozygous
18.
A cross between two plants that have pink flowers produced plants that have red, pink, or
white flowers. What is the most likely explanation for these results? Incomplete dominance
19.
An organism in which two alleles for a trait are different is
20.
Tallness (T) is dominant to shortness (t) in pea plants. What is the genotype of a pea plant
that is heterozygous for tallness?
21.
heterozygous
Tt
An individual heterozygous for a trait and an individual homozygous recessive for the trait are
crossed and produce offspring that are of how many different phenotypes? _2_
22.
A family has eight children. Six children have second toes that are longer than the big toe.
Two children have second toes that are shorter than the big toe. What are the most likely
genotypes of the parents?
Heterozygous
23.
A homozygous individual would have what possible genotype?
24.
If two parents with dominant phenotypes produce an offspring with a recessive phenotype,
what can you say about the parents?
25.
Homozygous dominant, homozygous recessive, or heterozygous
Which diagram above correctly illustrates the fusion of normal gametes that will most likely
produce a human male?
27.
They are heterozygous
In a monohybrid cross between two heterozygous parents, one would expect the offspring to
be
26.
Two dominant or two recessive
3 or 4
What is genetic engineering? _____manipulating dna using technology_______
28.
List the steps to genetically modify an organism (to make recombinant DNA).
A gene is cut from one organism’s DNA. Then, the second organism’s DNA is cut open so the gene
can be spliced into the DNA. Once the gene is in place, the DNA can be spliced back together.
29. What is a clone? ____An identical copy with the exact DNA________
30. What is recombinant DNA? _____artificially modified DNA___
31. What is the ethical issue with genetically modifying organisms?_______People are against
the idea of humans “playing God” by manipulating natural DNA______
Problems:
Show all your work on a separate sheet of paper.
32. Crosses between red and white shorthorn cattle result in roan offspring and is a result of
incomplete dominance. Is it possible to produce a true breed in strain of roan cattle? Why
or why not? No. Roan is a heterozygous condition, so it is not possible to be “purebred” or a
“true breed”.
33. Polydactyly (presence of an extra finger) is due to a dominant factor. When one parent is
polydactylous, but heterozygous, and the other parent is normal, what would be the
probability of their having a child without polydactylous? 50% or 2:2
Pp pp
Pp pp
34. Short hair is dominant over long hair in guinea pigs. A short-haired guinea pig, one of whose
parents was long-haired, was mated with a long-haired animal. What types of offspring could
be produced? In what ratio? It would not be possible to have two long-haired parents (hh)
to have a short-haired offspring.
35. Diabetes is thought to be inherited as a recessive (d) trait. Two people without diabetes
have a diabetic child. What are the genotypes of the parents and of the offspring? Dd and
Dd
36. Albinism occurs commonly in animals, and it is always recessive to the normal. Six brown and
five albino mice were born to parents who were likewise brown and albino. What is the
genotype of the brown parent? Heterozygous (Bb)
Aa aa
Aa aa
37. Supposing brown eyes in people (B) is dominant to blue (b), could a marriage between two
blue-eyed people produce a brown-eyed child? No. (bb x bb) Could a marriage between a
homozygous brown-eyed person and a blue-eyed person result in blue-eyed children? No. (BB
x bb) Could two brown-eyed people have a blue-eyed child? Yes. (Bb x Bb) Explain all of your
answers by supplying the proper genotype.
38. A woman with heterozygous type A blood and a man with type O blood want to know the
probability of having a child with type O blood. 50%
Ao oo
Ao oo
39. A man really wants to have a baby with type AB blood so he can brag to his friends that his
kid is rare. Is it possible for a baby to get type AB blood if the mom has type O blood?
Prove your answer showing all work. No.
Ao Bo
Ao Bo
40. Tay-Sachs disease is a fatal genetic disorder caused by a recessive allele. The pedigree
chart below shows the appearance of the disease in three generations of a family. Tell the
genotype or possible genotypes of each member of the family. Be sure to define your
variables.
Tt
Tt
Key:
TT or Tt
= Normal male
Tt
Tt
= Tay-Sachs male
tt
= Normal female
6
tt
= Tay-Sachs female
41. On a certain day in a local hospital, two male babies were born. Shortly after the mothers
returned home with their infants, Mrs. Robinson discovered a tag marked “K” on her baby.
The other mother, Mrs. Koffer, insisted she had her own baby and refused to exchange.
The matter came to court where all concerned agreed to submit to blood test. Here are
the results:
Mrs. Robinson – Type O
Mrs. Koffer – Type O
Mr. Robinson – Type O
Mr. Koffer – Type AB
Baby taken home by the Robinsons – Type A
Baby taken home by the Koffers – Type O
Did a switch occur? Explain using Punnett Squares to support your answer.
Yes.
oo oo
Ao Bo
oo oo
Ao Bo