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Chromosomes and
Inheritance
Supplemental Instruction
Iowa State University
Leader:
Course:
Instructor:
Date:
Chelsey
BIO 211 (3)
Colbert
Wednesday 11/9/11
1. What are the three similarities between chromosome behavior and Mendel’s factors?
a) Both are present in pairs in diploid cells
b) Homologous chromosomes separate and factors segregate during meiosis
c) Fertilization restores the paired condition of both factors and chromosomes
2. The ___________ theory of ___________ was developed by ___________.
a) Hereditary, chromosomes, Sutton
b) Chromosomes, Inheritance, Sutton and Boveri
c) Chromosomes, Inheritance, Mendel
d) Hereditary, chromosomes, Mendel
e) Chromosomes, Inheritance, Boveri
3. What did Thomas Hunt Morgan use to test the theory that genes are on chromosomes?
a) Fruit flies
b) Grasshoppers
c) Pea plants
d) Crickets
4. Relate the following terms in a sentence or two: chromosomes, nuclei, genes, alleles.
Within a nucleus of a cell there are multiple chromosomes (46 in humans); on
each chromosome there are many genes which consist of one of the possible
alleles (usually only two possible alleles) for a given character.
5. There are about ____ different genes and an average of ____ different genes on each
chromosome.
a) 1 million, 22000
b) 1 million, 30000
c) 30000, 22000
d) 1300, 400
e) 30000, 1300
6. When will genes exhibit dependent assortment versus independent assortment?
Dependent assortment – the genes are the same chromosome, they’re “linked”
Independent assortment – the genes are on different chromosomes
7. What is the expected phenotypic ratio for two genes that are linked but have undergone
some crossing over? (For example, 1:1:1:1 etc.)
Between 1:1:1:1 and 1:1:0:0
8. What is the relationship between the frequency of crossing over and the distance between
two linked genes on a chromosome?
As the distance between the gene loci increases, the likelihood of crossing over
increases. Genes at opposite ends of a chromosome virtually assort independently.
Supplemental Instruction
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9.
Which gene along with the white gene will
most likely produce a phenotypic ratio of 1:1:1:1?
a) Red
b) Purple
c) Green
10. In cattle, the hornless condition (H) is dominant and the horned condition (h) is
recessive. A bull without horns is crossed with a cow with horns. Of the four offspring,
one is horned and three are hornless. Determine the genotype of the bull and the cow.
Hh x hh
11. In humans, free ear lobes (E) are dominant over attached ear lobes (e), and brown eyes
(B) are dominant over blue eyes (b). A man with free ear lobes and brown eyes marries a
woman with attached ear lobes and brown eyes. Of four children, one has free ear lobes
and brown eyes, one has free ear lobes and blue eyes, one has attached ear lobes and
brown eyes, and one has attached ear lobes and blue eyes. Determine the genotypes of the
parents.
EeBb x eeBb
12. Hemophilia is a sex-linked recessive trait. A normal woman whose father was a
hemophiliac marries a normal man. Determine the genotype of the woman and the man.
Determine the possible genotypes for their children. What percent of male and female
children would be hemophiliacs? What percent normal? Would any be carriers?
Parents: XHXh x XHY
Children Genotypes: XHXh, XHXH, XHY, XhY
0% of females will have hemophilia, 50% of males will have hemophilia, Overall
75% of their children will be normal, 50% of females will be carriers
13. A young man has type AB blood and his sister has type O blood. What are their
genotypes and the genotypes of the parents?
Man: IAIB
Sister: ii
Parents: IAi x IBi
14. Which of the following genetic crosses would be predicted to give a phenotypic ratio of
9:3:3:1?
a) SSYY x ssyy
b) SsYY x SSYy
c) SsYy x SsYy
d) SSyy x ssYY
e) ssYY x ssyy
15. In Mendel's experiments, the spherical seed character (S) is completely dominant over the
dented seed character (s). If the characters for height were incompletely dominant, such
that TT are tall, Tt are intermediate and tt are short, what would be the phenotypes
resulting from crossing a spherical-seeded, short (SStt) plant to a dented-seeded, tall
(ssTT) plant?
a) All the progeny would be spherical-seeded and tall.
b) 1/2 would be spherical-seeded and intermediate height; 1/2 would be spherical-seeded
and tall.
c) All the progeny would be spherical-seeded and short.
d) You cannot predict the outcome.
e) All the progeny would be spherical-seeded and intermediate height.