Biology (Holt)

PARTB: Test Hypotheses

Answer each of the following questions by
writing a hypothesis. Use your model to test
each hypothesis, and describe your results.

5.In humans, gametes (eggs and sperm)

result from meiosis. Will all gametes pro-

duced by one parent be identical?

6.When an egg and a sperm fuse during sex-

ual reproduction, the resulting cell (the

first cell of a new organism) is called a

zygote. How many copies of each chro-

mosome and each gene will be found in a

zygote?

7.Crossing-over frequently occurs between

the chromatids of homologous chromo-

somes during meiosis. Under what cir-

cumstances does crossing-over result in

new combinations of genes in gametes?

8.Synapsis (the pairing of homologous

chromosomes) must occur before cross-

ing-over can take place. How would the

outcome of meiosis be different if synap-

sis did not occur?

PARTC: Cleanup and Disposal

9. Dispose of paper and yarn scraps in
   the designated waste container.


10. Clean up your work area and all lab
    equipment. Return lab equipment to
    its proper place. Wash your hands thor-
    oughly before you leave the lab and after
    finishing all work.

Analyze and Conclude

1. Analyzing ResultsHow do the nuclei
   you made by modeling meiosis compare
   with the nucleus of the cell you started
   with? Explain your result.


2. Recognizing RelationshipsHow are
   homologous chromosomes different from
   chromatids?


3. Forming Reasoned Opinions How is
   synapsis important to the outcome of
   meiosis? Explain.


4. Evaluating Methods How could you
   modify your model to better illustrate the
   process of meiosis?


5. Drawing Conclusions How are the
   processes of meiosis similar to those of
   mitosis? How are they different?


6. Predicting OutcomesWhat would hap-
   pen to the chromosome number of an
   organism’s offspring if the gametes for sex-
   ual reproduction were made by mitosis
   instead of by meiosis?


7. Further InquiryWrite a new question
   about meiosis or sexual reproduction that
   could be explored with your model.

CHAPTER 7Meiosis and Sexual Reproduction 159

http://www.scilinks.org

Topic:Meiosis

Keyword:HX4120

Do You Know?

Do research in the library or media center

to answer these questions:

1.What types of human abnormalities

arise when chromosomes do not sepa-

rate properly during meiosis?

2.How do chemicals such as nicotine

affect meiosis?

Use the following Internet resources to

explore your own questions about meiosis

and gamete formation.