Name_________________________________
Due Thursday Oct 21, 2010
Ch 8 homework
1. Describe how cytokinesis differs in plants and animals.
2. When animal cells are grown in a petri dish, they typically stop dividing once
they have formed a single, unbroken layer on the bottom of the dish. This arrest
of division is an example of
a. cancer.
b. cell constraint.
c. density-dependent inhibition.
d. cell division repression.
e. growth factor desensitization.
3. Homologous chromosomes are…..
a. Identical chromosomes present in twins
b. Two chromosomes carrying the genes for the same characteristic at the
same loci
c. Two chromosomes carrying the same gene for the same characteristic at
different loci
d. Two sex chromosomes found in the same place at the same time
4. A chromosome fragment breaks off and then reattaches to the original
chromosome, but in the reverse direction, the resulting chromosomal
abnormality is called a(n) ____________________
5. Identify each stage of mitosis and describe what is happening to the
chromosome in each step. (2 points)
6. During meiosis, which of the following occurs in prophase 1 but not prophase 2?
a. crossing over
b. pairing of homologous chromosomes
c. disappearance of the nuclear envelope
d. crossing over and pairing of homologous chromosomes
e. crossing over, pairing of homologous chromosomes, and disappearance
of the nuclear envelope
7. Under what circumstances would a cell undergo meiosis? Mitosis?
8. Independent orientation of chromosomes at metaphase I results in an increase
in the number of
a. gametes.
b. homologous chromosomes.
c. possible combinations of characteristics.
d. sex chromosomes.
e. points of crossing over.
9. Explain what the cell cycle control system is and what happens when it fails
Ch 9 homework (1 point each)
1. Cystic fibrosis is a recessive genetic disorder. Ron is homozygous dominant (FF) and
Nancy is a carrier (Ff) of cystic fibrosis. Use a Punnett square to predict the probability
that one of their children will have cysticfibrosis. Include the probabilities for genotype
and phenotype of the offspring. Show all work and box your final answer. ** include
the punnet square, genotype and phenotype in your answer. For example 50% Tt
heterozygous dominant, 25% tt homozygous recessive and 25% TT homozygous
dominant. 75% tall, 25% short.
2. Patty is homozygous dominant for freckles (SS), while Charlie is homozygous for no
freckles (ss). Draw a Punnett square predicting the probability if their children will have
freckles. Include the probabilities for genotype and phenotype of the offspring, Show all
work and box your final answer. ** include the punnet square, genotype and
phenotype in your answer. For example 50% Tt heterozygous dominant, 25% tt
homozygous recessive and 25% TT homozygous dominant. 75% tall, 25% short.
3. Imagine that Patty and Charlie’s children (from Q 2) were separated at birth,
inadvertently met, fell in love and had children of their own. Draw a Punnett square
predicting the probability if their children will have freckles. Include the probabilities for
genotype and phenotype of the offspring, Show all work and box your final answer.
(1) ** include the punnet square, genotype and phenotype in your answer. For
example 50% Tt heterozygous dominant, 25% tt homozygous recessive and 25%
TT homozygous dominant. 75% tall, 25% short.
4. Define genotype and phenotype. Also, include an example where you tell me the
genotype and phenotype of an individual (it can be theoretical).
5. Sex-linked conditions are more common in men than in women because
A) men acquire two copies of the defective gene during fertilization.
B) men need to inherit only one copy of the recessive allele for the condition to
be fully expressed.
C) women simply do not develop the disease regardless of their genetic
composition.
D) the sex chromosomes are more active in men than in women.
E) the genes associated with the sex-linked conditions are linked to the Y
chromosome, which determines maleness.
6. All the offspring of a cross between a black-eyed fly and an orange-eyed fly have
black eyes. This means that the allele for black eyes is ________ the allele for orange
eyes.
A) codominant to
B) recessive to
C) more aggressive than
D) dominant to
E) better than
7. What are linked and sex-linked genes
8. What are homologous chromosomes, alleles and loci?
9. Explain Mendels law of independent assortment.
10. ____________________ is when a single characteristic that is influenced by many
genes whereas __________________ is when a single gene which affects many
phenotypic characteristics