Exchange of chromosome segments between homologues at the beginning of meiosis
What will be an ideal response?
increases genetic variation in offspring
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Class Reptilia includes all reptiles, and Class Aves includes all birds. However, a cladistics approach would place birds in the same class with reptiles. Why would a cladistician classify birds and reptiles in a single class despite the behavioral and physical differences between the two?
What will be an ideal response?
In the late 1920s, a mutation occurred in many silver
fox farms around the world. The fox farms that sold expensive furs were proud of the quality of their furs, and each advertised that it had the best, purest breed of all the fox farms. The new mutations produced a “platinum” coat pattern that was commercially desirable, so the farms crossed them to get more. The results of their breeding experiments were as follows: (1) silver x silver >>> all silver offspring; (2) silver x platinum >>> equal numbers of silver and platinum; (3) platinum x platinum >>> two platinum for each silver offspring. Explain. What will be an ideal response?
Methylation and RNA interference are both involved in regulating mobile genetic elements. Which of the following statements is TRUE?
A) Methylation is a form of post-transcriptional silencing, whereas RNA interference is a form of pre-transcriptional silencing. B) Both are examples of post-transcriptional silencing. C) Both are examples of pre-transcriptional silencing. D) RNA interference is a form of post-transcriptional silencing, whereas methylation is a form of pre-transcriptional silencing.
An individual plant was discovered that could not grow towards light. After some research, it was determined that the reason was a defective gene that did not allow for the level of cell elongation necessary for a phototropic response. This mutation greatly reduces the fitness of the individual plant. Which reason best describes the reason for the loss of fitness?
A) The plant was too short to attract insects for pollination. B) The plant could not adjust to directional light, which reduced photosynthetic activity and therefore energy available for reproduction. C) Because the plant grew much taller and straighter, resources that could be used for reproduction were used for growth. D) The loss of a phototropic response meant that the plant's seeds could not germinate so reproduction would be unsuccessful.