An earthquake decimates a ground-squirrel population, killing 98% of the squirrels. The surviving population happens to have broader stripes, on average, than the initial population. If broadness of stripes is genetically determined,
what effect has the ground-squirrel population experienced during the earthquake?
A) directional selection
B) disruptive selection
C) a founder event
D) a genetic bottleneck
E) gene flow
Answer: D
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The various flower parts are attached to a modified branch called the:
a. style b. receptacle c. stigma d. filament e. sepal
Which of the following is not a chief function of inflammation?
A. Start tissue repair B. Block further invasion C. Destroy microbes D. Cause a fever E. Mobilize and attract immune components to injury site
Alterations in the ratio of CD4:CD8 lymphocytes are associated with risk of HIV infection progressing to AIDS, of autoimmune diseases, and of progression of some cancers
In searching for predictors of these effects in normal individuals, researchers have found two independent QTLs in the region of the genome known as the major histocompatibility complex (MHC), one in a region regulating CD8 and the other in a region regulating CD4. What does this indicate for the general population? A) Mutation in one or both of these genes causes HIV and AIDS. B) Autoimmune diseases such as type 1 diabetes are caused by one of these genes. C) Variation in linkage disequilibrium with one or both of these mutations may increase the risk of autoimmune disease. D) Only one mutation can be the cause of rheumatoid arthritis. E) The probability of an autoimmune disease demonstrates that additive genes are involved.
Which of the following plants is a biennial?
a. corn b. geranium c. sunflower d. marigold e. carrot