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CONCEPTS OF BIOLOGY 07
1. Figure 7.2 If a mutation occurs so that a fungus
is no longer able to produce a minus mating type,
will it still be able to reproduce?
Yes, it will be able to reproduce asexually
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CONCEPTS OF BIOLOGY 07
2. What is a likely evolutionary advantage of sexual reproduction over asexual reproduction?
sexual reproduction involves fewer steps
less chance of using up the resources in a given environment
sexual reproduction results in greater variation in the offspring
sexual reproduction is more cost-effective
sexual reproduction results in greater variation in the offspring
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CONCEPTS OF BIOLOGY 07
3. Which type of life cycle has both a haploid and diploid multicellular stage?
an asexual life cycle
diploid-dominanty
haploid-dominant
alternation of generations
alternation of generations
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CONCEPTS OF BIOLOGY 07
4. Which event leads to a diploid cell in a life cycle?
meiosis
fertilization
alternation of generations
mutation
fertilization
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CONCEPTS OF BIOLOGY 07
5. Meiosis produces ________ daughter cells.
two haploid
two diploid
four haploid
four diploid
four haploid
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CONCEPTS OF BIOLOGY 07
6. At which stage of meiosis are sister chromatids separated from each other?
prophase I
prophase II
anaphase I
anaphase II
anaphase II
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CONCEPTS OF BIOLOGY 07
7. The part of meiosis that is similar to mitosis is ________.
meiosis I
anaphase I
meiosis II
interkinesis
meiosis II
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CONCEPTS OF BIOLOGY 07
8. If a muscle cell of a typical organism has 32
chromosomes, how many chromosomes will be in
a gamete of that same organism?
8
16
32
64
16
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CONCEPTS OF BIOLOGY 07
9. The genotype XXY corresponds to:
Klinefelter syndrome
Turner syndrome
Triplo-X
Jacob syndrome
Klinefelter syndrome
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CONCEPTS OF BIOLOGY 07
10. Abnormalities in the number of X chromosomes tend to be milder than the same abnormalities in autosomes because of ________.
deletions
nonhomologous recombination
synapsis
X inactivation
X inactivation
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CONCEPTS OF BIOLOGY 07
11. Aneuploidies are deleterious for the individual because of what phenomenon?
nondisjunction
gene dosage
meiotic errors
X inactivation
gene dosage
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CONCEPTS OF BIOLOGY 07
12. Explain the advantage that populations of sexually reproducing organisms have over asexually reproducing organisms?
The offspring of sexually reproducing organisms are all genetically unique.
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sexually reproducing organisms may have more successful survival of offspring in environments that
change than asexually reproducing organisms, whose offspring are all genetically identical.
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the rate of adaptation of sexually reproducing organisms is higher, because of their increased variation...
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...This may allow sexually reproducing organisms to adapt more quickly to competitors and
parasites, who are evolving new ways to exploit or outcompete them
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CONCEPTS OF BIOLOGY 07
13. Describe the two events that are common to all sexually reproducing organisms and
how they fit into the different life cycles of those organisms.
- The two events common to all sexually reproducing organisms
- are meiosis and fertilization. Meiosis reduces a diploid cell to a haploid state. The haploid cell may divide
- mitotically to produce an organism, some of whose cells will combine during fertilization, or the haploid
- cells produced by meiosis may immediately combine in fertilization to produce a diploid cell that divides
- to produce an organism
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CONCEPTS OF BIOLOGY 07
14. Explain how the random alignment of homologous chromosomes during metaphase I contributes to variation in gametes produced by meiosis.
- Random alignment leads to new combinations of traits. The chromosomes that
- were originally inherited by the gamete-producing individual came equally from the egg and the sperm. In
- metaphase I, the duplicated copies of these maternal and paternal homologous chromosomes line up across
- the center of the cell to form a tetrad. The orientation of each tetrad is random. There is an equal chance
- that the maternally derived chromosomes will be facing either pole. The same is true of the paternally
- derived chromosomes. The alignment should occur differently in almost every meiosis. As the homologous
- chromosomes are pulled apart in anaphase I, any combination of maternal and paternal chromosomes will
- move toward each pole. The gametes formed from these two groups of chromosomes will have a mixture
- of traits from the individual’s parents. Each gamete is unique.
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CONCEPTS OF BIOLOGY 07
15. In what ways is meiosis II similar to and different from mitosis of a diploid cell?
- The two divisions are similar in that the
- chromosomes line up along the metaphase plate individually, meaning unpaired with other chromosomes
- (as in meiosis I). In addition, each chromosome consists of two sister chromatids that will be pulled apart.
- The two divisions are different because in meiosis II there are half the number of chromosomes that are
- present in a diploid cell of the same species undergoing mitosis. This is because meiosis I reduced the number
- of chromosomes to a haploid state.
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CONCEPTS OF BIOLOGY 07
16. Individuals with trisomy 21 are more likely to survive to adulthood than individuals with trisomy
Based on what you know about aneuploidies
from this module, what can you hypothesize about
chromosomes 21 and 18?
- The problems caused by trisomies arise because the genes on the
- chromosome that is present in three copies produce more product than genes on chromosomes with only two
- copies. The cell does not have a way to adjust the amount of product, and the lack of balance causes problems
- in development and the maintenance of the individual. Each chromosome is different, and the differences in
- survivability could have to do with the numbers of genes on the two chromosomes. Chromosome 21 may
- be a smaller chromosome, so there are fewer unbalanced gene products. It is also possible that chromosome
- 21 carries genes whose products are less sensitive to differences in dosage than chromosome 18. The genes
- may be less involved in critical pathways, or the differences in dosage may make less of a difference to those
- pathways.
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