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28 Cards in this Set
- Front
- Back
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Describe Muller's Ratchet |
A model used to explain how mutations affect asexual organism. Like a ratchet can only move forward, asexual organisms can only move forward and any mutations obtained must be carried on to offspring. Without sexual reproduction, asexual organiss are at greater risk of extinction due to to deleterious mutations and disease. |
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What is the biggest benefit to sex? |
Sex allows for recombination providing a mechanism for genomic repair, eliminating deleterious mutations. Parents can produce offspring that have higher fitness genotypes than themselves.
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Which would result in offspring with higher fitness? A. Asexually reproducing organisms B. Sexually reproducing organisms |
B. Sexually reproducing organisms. |
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What idea, originally proposed by Weismann was used to explain the advantageous of sex? |
Sex allow natural selection to proceed more effectively because it increases genetic variation |
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During what situations would sexual reproduction be more advantageous than asexual reproduction? A. In changing environments B. In a highly predatory environment C. During times of disease D. All of the above |
D. All of the above |
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Define: Abiotic environment |
(Water, Temperatrue, etc) Don't usually change fast enough for sexual reproducers to win over asexual reproducers |
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Define: Biotic environment |
Co-evolutionary arms race. (ex. Resistance to disease and abiotic resistance) |
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Describe the Red queen hypothesis |
A hypothesis used to explain a biotic environment in which one organism is evolving in order to outpace another organism, however the other organism is also evolving at the same rate as the first organism keeping both essentially at a stand-still. Although both are moving forward, their relative distance does not change from each other (I.G. production of abiotics against bacteria and abiotic resistance) |
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Explain how sexual reproduction acts against parasites against snails |
Paraatic trematode worms castrate snails by eating their gonads. The more parasites the higher proportion of males produced by females. There is a sex ratio shift in the offspring causing more males to be born allowing sexual reproduction to continue. |
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Which of the following conditions accurately represent Muller's ratchet, in terms of the selective advantage of sexual reproduction A. Linkage disequilibrium increases in populations by genetic drift because no-mutation multilocus genotypes are lost by chance B. Sexual reproduction is selected because it reintroduces nomutation genotpes that have been lost fromt he population C. Deleterious mutations accumulate in asexual populations, resulting in a significant genetic load. D. all of the above accurately represent the conditions of Muller's Ratchet |
D. All of the above accurately represent the conditions of Muller's ratchet |
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Define: Qualitative traits |
Phenotypes in discrete categories that are often determined by a single gene (Ex. Color of pea, wrinkle, smooth) |
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Define: Quantitiative traits |
are continuously distributed phenotypes determined by many different loci (ex. Height) |
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T/F: Most traits are determined by single loci |
False. Most traits are determined by many different loci, and therefore vary continuously |
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T/F: Qualitative traits are influenced by environment |
False. Continuous characters, called Quantitative Traits, are also influenced by the environment to varying degrees. |
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What type of distribution do most guantitative traits display? |
A bell-shaped (binomial distribution) |
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T/F: Quantitative traits are more likely to produce greater combinations of phenotypes than qualitative traits |
True |
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Which of the following will result in a greater distribution? A. 2 Loci B. 4 Loci C. 6 Loci D. 8 Loci |
D. 8 Loci |
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What were East's Predictions in regards to quantitative traits |
1. The range of variations we see int he F2 generation do not extend to the original parental phenotypes. 2. Parental phenotypes are not lost, however. If we selectively breed for them, they will reappear in a few generations |
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East's predictions are directed towards: A. Quantitative Traits B. Qualitative Traits |
B. Qualitative Traits |
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Explain why East's predictions are not exactly true |
Extreme phenotypes will not return exactly as the parental phenotypes as expected in prediction two due to evnrionmental differences. This then results in phenotypic variations in isogenic plants |
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Define: Quantitative trait loci (QTL) |
Loci which have influence on quantitative traits (many genes) |
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Define: QTL Mapping |
Identification of chromosomal regions containing genes that contribute to quantitative trains. (i.e. where are the interesting genes) |
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Define: Marker Loci |
Known sites on chromosomes with easy identifiable allelic conditions |
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Explain how linked genes can be used to identify desired genes through quantitative traits |
If the quantitative traits are quantitatively associated with a given loci (Linkage Disequilibrium by physical closeness) the chromosomal regions for the interesting genes will be known (or at least approximated) |
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Describe the experiment which resulted in this image |
A QTL is used to determine the attractiveness of a certain type of flower to bees or hummingbirds. They found that when the F1 bread with F2 hybrids they displayed a number of variations of the same plant. To determine the QTL trait they used QTL mapping. If the marker is linked to a QTL then they will see the marker only in a specific phenotype, if the it isn't linked then the QTL will be seen in all phenotypes. While they were able to identify one of the QTL as YUP (which alters the attractiveness making it more pink and flat for bees to polinate), they found that there is more than just the one QTL responsible for attractiveness because there were so many genes acting at the same time. |
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You perform a QTL mapping and find that your results are similar to that of "A" what can you determine from this? |
There is close association between the marker and the QTL as a result of linkage disequilibrium |
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You perform a QTL mapping and find that your results are similar to that of "B" what can you determine from this? |
There is no association between the marker and the QTL and thus they are independent from one another. |
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What was the name of the QTL which was found to be one of many responsible for the attractiveness of flowers to Bees and Hummingbirds? |
YUP |
