Allergy shots require many injections over long periods of time to be effective. Why can't the body get over an allergy with just a couple of injections?
What will be an ideal response?
Allergens react inappropriately with mast cells, which then release histamine, a vasodilator. The inappropriate reaction cannot be undone, so the idea is to try to prevent the reaction from happening. Allergy shots are a form of vaccination against the allergen itself. Repeated low exposures to the allergen will stimulate the production of IgG antibodies. If the antibody levels can be repeatedly increased, any allergen that makes it into the body will be neutralized before it can interact with the mast cells and trigger an allergic response.
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Many patients who have a certain blood clotting disorder in which the blood clots too readily have a mutation in the promoter of a gene. This mutation most likely
A) deletes a gene for a clotting factor. B) blocks transcription of a clotting factor. C) increases susceptibility to a specific viral infection. D) increases the transcription rate of a particular clotting factor gene.
Four of the five answers listed below are characteristic of dicots. Select the exception
a. vascular bundles organized in a ring b. veins form a net-like array c. flower parts in fours or fives d. two cotyledons e. pollen grains with one pore or furrow
In presenting data that result from an experiment, a group of students show that most of their measurements fall on a straight diagonal line on their graph
However, two of their data points are "outliers" and fall far to one side of the expected relationship. What should they do? A) Do not show these points because clearly something went wrong in the experiment. B) Average several trials, rule out the improbable results, and do not show them in the final work. C) Show all results obtained and then try to explore the reason(s) for these outliers. D) Change the details of the experiment until they can obtain the expected results.
Edge effects are the result of which of the following?
A. Populations of flora and fauna have emigrated from the core of their population center to the edge of their habitat. B. Populations of particular species have decreased and are on the edge of extinction. C. Habitat fragmentation or habitat shrinkage has occurred, and thus the edge of the habitat has increased in relative proportion. D. Habitat fragmentation or habitat shrinkage has occurred, and thus the edge of the habitat has decreased in relative proportion. E. Metapopulations of some of the larger fauna have become more dominant on the landscape and as a result have increased the edge of their habitat.