Name __________________________
Per. ___________
Grades Nine Through Twelve
Biology/Life Sciences
Science Content Standards
Standards that all students are expected to achieve in the course of their studies.
Genetics
2. Mutation and sexual reproduction lead to genetic variation in a population. As a basis for
understanding this concept:
a. Students know meiosis is an early step in sexual reproduction in which the pairs of chromosomes
separate and segregate randomly during cell division to produce gametes containing one chromosome
of each type.
b. Students know only certain cells in a multicellular organism undergo meiosis.
c. Students know how random chromosome segregation explains the probability that a particular allele
will be in a gamete.
d. Students know new combinations of alleles may be generated in a zygote through the fusion of male
and female gametes (fertilization).
e. Students know why approximately half of an individual's DNA sequence comes from each parent.
f. Students know the role of chromosomes in determining an individual's sex.
Section 7-1: Meiosis
Meiosis forms Haploid Cells
1. Sexual reproduction:
2. Gametes are _______________--they contain one set of chromosomes.
3. What would happen to the chromosome number in future generations if gametes were not haploid?
4. Meiosis:
5. Meiosis involves two divisions of the nucleus--___________________ and ____________________.
6. Although meiosis is a continuous process, biologists typically divide it into 8 major stages.
Stage-Draw the
Description of events
diagram
a. Prophase I
b. Metaphase I
c. Anaphase I
d. Telophase I and
cytokinesis
e. Prophase II
f. Metaphase II
g. Anaphase II
h. Telophase II
and cytokinesis
7. What is the diploid chromosomal number for the cell that is in prophase I in Figure 7-1 on pp.142-143?
2n = __________
8. What is the chromosomal content in the 4 daughter cells that result from meiosis?
Meiosis contributes to Genetic Variation.
9. Three mechanisms make key contributions to genetic variation. Describe each mechanism.
Mechanism
Description
Independent assortment
Crossing-over
Random fertilization
Crossing-over can occur
at one or more points
along adjacent
chromosomes, leading to
an exchange of DNA.
Such recombination may
cause alleles that
previously were on the
same chromosome to
become separated. For
example, genes 1, 2, and 3
each have two alleles
(variation of the gene) (a
and b, c and d, e and f),
and crossing-over occurs
between genes 2 and 3.
10. Explain the importance of generating variation.
11. How do independent assortment, crossing-over, and random fertilization affect the rate of evolution?
Gamete Formation in Male and Female Animals Involves
Meiosis
12. Describe the process by which sperm are produced,
spermatogenesis.
13. Describe the process by which sperm are produced,
oogenesis.
14. Explain what a polar body is and how it is created.
15. If a cell in a dog (2n = 78) undergoes meiosis, how many chromosomes will each resulting cell
contain?
Section 7-2: Sexual Reproduction
Similarity to Parents is determined by the Type of Reproduction.
Fission in
Paramecium
16. Describe asexual reproduction in prokaryotes.
17. Compare 2 types of asexual reproduction in eukaryotes.
a. Fission:
b. Budding:
Budding in
Hydra
18. Describe the advantages and disadvantages of each type of reproduction.
Advantages
Disadvantages
Asexual
Reproduction
Sexual
Reproduction
Eukaryotes have Three Kinds of Sexual Life Cycles
19. Life cycle:
20. Compare the haploid life cycle found in Chlamydomonas with a diploid life cycle.
21. Sporophyte:
22. Spore:
23. Gametophyte:
24. Summarize the process of alternation of generations.
25. Parthenogenesis:
26. Why does parthenogenesis occur?
Critical Thinking
27. A student state that organisms that reproduce asexually are at a disadvantage in a stable environment.
Do you agree or disagree? Explain.
28. Occasionally homologous chromosomes fail to separate during meiosis I. Using the hypothetical
example of an adult organism with two pairs of chromosomes, describe the chromosomal makeup of
the eggs that would result from this error in meiosis.
29. If the eggs described in question 28 were fertilized by normal sperm, what would the chromosomal
makeup of the resulting zygote be?