HUMAN BIOLOGY

CeLL reprOduCtIOn 371

section 18.8 Meiosis contributes

to genetic variation. Crossing over during

prophase I creates new combinations of genes

in chromosomes. Random alignment of pairs

of homologues at metaphase I results in new

combinations of maternal and paternal traits.

revieW Questions

1. Define somatic cell and germ cell.


2. What is a chromosome? What is the difference between a
   diploid cell and a haploid cell?


3. What are homologous chromosomes?


4. Name the four main stages of mitosis, and describe what
   happens in each stage.


5. In the diagram above, summarize the main events
   in meiosis.


6. In a paragraph, summarize the similarities and differences
   between mitosis and meiosis.

seLF-Quiz Answers in Appendix VI

1. DNA, packaged in chromosomes, is distributed to daughter
   cells by or.


2. Each kind of organism contains a characteristic number
   of in each cell; each of those structures is composed
   of a molecule and proteins.


3. A pair of chromosomes that are similar in length and the
   traits they govern are called.
   a. diploid chromosomes
   b. mitotic chromosomes
   c. homologous chromosomes
   d. germ chromosomes


4. Somatic cells have a number of chromosomes.
   5. Interphase is the stage when.
   a. a cell ceases to function
   b. a germ cell forms its spindle
   c. a cell grows and duplicates its DNA
   d. mitosis takes place
   6. After mitosis, each daughter cell contains genetic
   instructions that are and chromosome
   number of the parent cell.
   a. identical to the parent cell’s; the same
   b. identical to the parent cell’s; one-half the
   c. rearranged; the same
   d. rearranged; one-half the
   7. All of the following are stages of mitosis except.
   a. prophase
   b. interphase
   c. metaphase
   d. anaphase
   8. A duplicated chromosome has chromatids.
   a. one c. three
   b. two d. four
   9. Crossing over in meiosis.
   a. occurs between sperm DNA and egg DNA at
   fertilization
   b. leads to genetic recombination
   c. occurs only rarely
   10. Because of the alignment of homologous
   chromosomes during meiosis, gametes can end up with
   mixes of maternal and paternal chromosomes.
   a. unvarying; different c. random; duplicate
   b. unvarying; duplicate d. random; different
   11. Match the stage of mitosis with the following key events.
   metaphase a. sister chromatids separate
   prophase and move to opposite poles
   telophase b. chromosomes condense and
   anaphase a microtubular spindle forms
   c. chromosomes decondense,
   daughter nuclei re-form
   d. chromosomes line up at a
   spindle equator

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