Q. No.The improvement of microscopy techniques in the late 1800s set the stage for the emergence of modern genetics because:
1.
it revealed new and unanticipated features of Mendel’s pea plant varieties.
2.
it allowed biologists to study meiosis and mitosis, revealing the parallels between the behaviors of genes and chromosomes.
3.
it allowed scientists to see the DNA present within chromosomes.
4.
it led to the discovery of mitochondria.
Male pattern baldness is a ___________ trait.
| 1. | Sex-linked | 2. | Sex-limited |
| 3. | Sex-influenced | 4. | Y-linked |
A sex aneuploid Drosophila has 2 sets of autosomes and sex chromosome complement XXY. This fly would be:
| 1. | A normal fertile female | 2. | A normal fertile male |
| 3. | An intersex | 4. | A metamale |
In humans, the condition red-green color blindness is a sex-linked recessive trait. In a family pedigree analysis, you find that two people with normal color vision have a color-blind son. This is possible if the genotypes of the parents are:
| 1. | XcXc and XcY | 2. | XcXc and XCY |
| 3. | XCXC and XcY | 4. | XCXc and XCY |
A woman has four daughters. The chance that her next child will be a son is:
| 1. | 1 | 2. | 0 |
| 3. | \(1 \over 2\) | 4. | \(1 \over 4\) |
In Drosophila melanogaster cinnabar eye is a sex-linked recessive trait. A female fly having cinnabar eyes is crossed with a wild-type male. The percentage of the male progeny of this cross with cinnabar eyes is expected to be:
| 1. | 0% | 2. | 25% |
| 3. | 50% | 4. | 100% |
Nondisjunction of a pair of homologous chromosomes occurs during the anaphase of meiosis I. The four gametes produced as a result of this nondisjunction event will be:
| 1. | n + 1; n + 1; n - 1; n - 1 | 2. | n + 1; n - 1; n; n |
| 3. | n + 1; n - 1; n - 1; n - 1 | 4. | n + 1; n + 1; n; n |
Identify the chromosomal aberration:
| 1. | Inversion | 2. | Reciprocal translocation |
| 3. | Deletion | 4. | Duplication |
A couple comes to you for genetic counselling. Both have a sister affected with albinism but all other members are normal. Your advice regarding the risk of their child being affected with albinism would be:
| 1. | They must both be heterozygotes so their risk of having an affected child is ¼. |
| 2. | They might both be heterozygotes so they should get tested to see if they carry the disease allele or not. |
| 3. | Since neither one of them is affected, they are not at risk of having an affected child. |
| 4. | You can't give them any firm answers because you don't know their genotypes. |
Linkage maps:
| 1. | always have a total of 100 map units. |
| 2. | can be used to pinpoint the precise physical position of a gene on a chromosome. |
| 3. | are a genetic map based on recombination frequencies. |
| 4. | reflect the frequency of crossing over between X and Y chromosomes. |
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