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CPBiology
IntroductiontoGenetics
Name_____________________________________ Date_____________________
Review:IntroductiontoGenetics
Meiosis
1. What is the meaning of diploid number and haploid number? Name some
examples of human cells that are diploid and human cells that are haploid?
Diploid means at least one copy of one chromosome from each parent (mom and dad).
Haploid means at least one copy of one chromosome from either parent (mom or dad).
Sex cells are the only cells in the body that are haploid (eggs and sperm). All the rest
are diploid.
2. For cats, the normal chromosome number in a body cell is 38 chromosomes.
What is the haploid chromosome number?
19
3. Why does meiosis produce daughter cells different from the parent cell?
The daughter cells are haploid, whereas the parent cells are diploid. Also, crossing
over and independent assortment take place, which both change the genetic makeup of
the daughter cells.
4.
Define gonad. Provide examples of gonads.
The reproductive organ. In males the gonads are the testes. In females the gonads are
the ovaries.
5. Define gamete. Provide examples of gametes.
Reproductive or sex cell. In males the gametes are sperm. In females the gametes are
eggs.
CPBiology
IntroductiontoGenetics
6.
Explain how fertilization restores the normal number of chromosomes to an
organism. You may use a diagram to help you.
A haploid egg plus a haploid sperm produces a diploid zygote. The organism’s diploid
number is its normal chromosome number.
(Insert drawing of sperm fertilizing egg to make zygote here, as drawn in POGIL)
7. What is crossing over? When in meiosis does it happen? What does crossing
over do to the genetic information contained in cells?
Crossing over is when parts of homologous chromosomes are exchanged during
meiosis. It happens during Prophase 1. It increases the genetic variation in the
gametes, because parts of the mother chromosomes have been exchanged with the
father’s chromosomes.
8.
How many chromosomes are in a human diploid cell? How many chromosomes
are in a human cell produced by meiosis?
9.
How do the parent cells compare to the cells produced at the end of meiosis II?
46
23
The cells at the end of meiosis 2 have half the number of chromosomes as the parent
cells at the beginning of meiosis.
10. Why are the offspring of organisms that reproduce sexually NOT genetically
identical to either of the parents?
Crossing over and independent assortment in Prophase 1 make the offspring
genetically different from their parents. This sorting and recombination of genes makes
the offspring not genetically identical to either parent.
CPBiology
IntroductiontoGenetics
11. List all the phases of meiosis and describe what happens in each phase.
See Meiosis worksheet, question 11
12. What is nondisjunction? What impact does nondisjunction have on a zygote
produced from an egg or sperm that underwent nondisjunction?
Nondisjunction is when homologous chromosomes fail to separate, either in anaphase 1
or anaphase 2 in meiosis. The consequence of this lack of separation is that the zygote
formed from these gametes could have too many chromosomes or too few, depending
on which gamete formed the zygote.
(See errors in meiosis notes for visual)
CPBiology
IntroductiontoGenetics
FertilizationandDevelopment
13. What is fertilization? Where does it take place in humans?
Fertilization is the union of egg and sperm to produce a zygote. In humans it takes
place in the fallopian tubes
14. Draw a diagram of fertilization. Be sure to label egg, sperm and zygote.
15. What is a zygote? How many cells are there in a zygote?
A zygote is a fertilized egg. A zygote consists of only one cell.
16. Explain the term cleavage.
Cleavage is a rapid series of mitotic (mitosis) divisions early on in the development of
an embryo.
17. What is differentiation? In what stage of development does differentiation occur?
Why is it important for cells in an embryo to differentiate during development?
Differentiation is when each cell gets its particular job. Differentiation takes place
during the gastrula stage of development. If differentiation did not occur, the embryo
would not develop into the complex organism it needs to be.
CPBiology
IntroductiontoGenetics
18. List the organ system(s) in each layer in a gastrula is responsible for creating:
a. Ectoderm
Skin, nervous system
b. Mesoderm
Skeleton, muscles, circulatory system, reproductive system
c. Endoderm
Digestive tract, respiratory system, liver, pancreas, bladder
MendelianGenetics
19. Know the vocabulary related to Mendelian genetics, as defined from the
textbook.
20. Be able to do each of the types of Punnett squares we did in class. These
include:
a. Complete/Simple dominance
b. Incomplete dominance
c. Codominance
d. Multiple alleles (blood type problems)
e. X-linked inheritance