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| 1 | |
How many genes are believed to constitute the human genome? |
| | A) | one million |
| | B) | ten million |
| | C) | 100,000 |
| | D) | 40,000 |
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| 2 | |
During which meiotic division is the number of chromosomes halved? |
| | A) | during meiosis I |
| | B) | during meiosis II |
| | C) | prior to meiosis I, during the S phase |
| | D) | after meiosis II |
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| 3 | |
Choose the recessive human trait from the list that follows. |
| | A) | widow's peak |
| | B) | cheek dimples |
| | C) | hairless forearms |
| | D) | freckles |
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| 4 | |
During which phase of meiosis does the phenomenon called crossing-over occur? |
| | A) | prophase I |
| | B) | metaphase I |
| | C) | telophase I |
| | D) | prophase II |
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| 5 | |
Homologous chromosomes are separated during _______________. |
| | A) | prophase I |
| | B) | metaphase I |
| | C) | anaphase I |
| | D) | telophase I |
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| 6 | |
Which of these does not contribute to genetic variability? |
| | A) | meiosis |
| | B) | crossing-over |
| | C) | having children with a close relative |
| | D) | having children with someone who is not a relative |
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| 7 | |
Several variant forms of a gene for a given trait are called ______________. |
| | A) | autosomes |
| | B) | alleles |
| | C) | sex chromosomes |
| | D) | histones |
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| 8 | |
A person who can pass either a widow's peak or straight hairline to the next generation is said to be _______________ for the hairline trait. |
| | A) | homozygous |
| | B) | heterozygous |
| | C) | incompletely dominant |
| | D) | recessive |
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| 9 | |
If a recessive trait, such as hemophilia, occurs more often in males than in females, it is because the gene for the trait is most likely carried on ________________. |
| | A) | the X chromosome |
| | B) | the Y chromosome |
| | C) | a mutant allele |
| | D) | an autosome |
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| 10 | |
If Chris, who carries the gene for cystic fibrosis but does not have the disease, fathers a child with Rhonda, who also carries the cystic fibrosis gene but does not have the disease, what is the likelihood that their first-born will have cystic fibrosis? |
| | A) | 75% chance |
| | B) | 50% chance |
| | C) | 25% chance |
| | D) | 0% chance |
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| 11 | |
What is an example of a codominant trait in humans? |
| | A) | sickle cell disease |
| | B) | Huntington disease |
| | C) | ABO blood groups |
| | D) | Tay-Sachs disease |
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| 12 | |
Traits that are controlled by one or more genes and influenced by the environment are said to be _________________. |
| | A) | incompletely dominant |
| | B) | multifactorial |
| | C) | polygenic |
| | D) | incompletely penetrant |
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| 13 | |
The fact that a woman cannot generally grow a beard is because beard growth is a(n) ________________ trait. |
| | A) | completely penetrant |
| | B) | pleiotropic |
| | C) | sex-limited |
| | D) | sex-influenced |
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| 14 | |
The normal chromosome number is referred to as _____________. |
| | A) | euploid |
| | B) | aneuploid |
| | C) | polyploid |
| | D) | tetraploid |
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| 15 | |
The last pair of 23 chromosomes is referred to as the _____. |
| | A) | karyotype |
| | B) | autosomes |
| | C) | nondisjunction chromosomes |
| | D) | sex chromosomes |
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| 16 | |
In Down's syndrome, there is an extra chromosome number _____. |
| | A) | 19 |
| | B) | 20 |
| | C) | 21 |
| | D) | 22 |
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| 17 | |
Which chromosomes indicate a normal male fetus? |
| | A) | XX |
| | B) | XXY |
| | C) | XY |
| | D) | XYY |
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