Review questions, Nov 4

 

1. Why is crossing over important?
1. It holds tetrads together.
2. It ensures that homologous chromosomes pair.
3. It allows the exchange of genes between homologous chromosomes.
4. It prevents variation in gametes.
5. It is necessary for the attachment of chromosomes to the spindle.

 

2. Homologous chromosomes sometimes fail to separate properly. This phenomenon is known as _____, which ____________ zygote development.
1. gametic infertility ......... is often fatal to
2. cellular infertility .......... normally has no effects on
3. cellular intertility .......... is often fatal to
4. nondisjunction ..............normally has not effects on
5. nondisjunction ..............is often fatal to

 

3. Nondisjunction of chromosome 21 during meiosis results in ___________. 
1. Klinefelter syndrome
2. Turner syndrome
3. Down syndrome
4. myelogenous leukemia

 

4. A person with one X chromosome and two Y chromosomes is ________ .  This may be the result of nondisjunction of Y chromosome(s) during _________ .
1. normal female ................................. meiosis I
2. normal male .................................... meiosis I
3. male with abnormal development ... meiosis II
4. normal male .....................................meiosis II
5. female with abnormal development..mitosis

 

5. Chromosome abnormality resulted from the exchange of parts between nonhomologous chromosomes is called _____.
1. deletion          b. duplication             c. inversion                 d. translocation

e. frame shift mutation

 

6. If a fragment of a chromosome breaks off and then reattaches to the original chromosome at the same place but in the reverse direction, the resulting chromosomal abnormality is called _____.
1. deletion          b. duplication             c. inversion                 d. translocation

e. frame shift mutation

 

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