The valves of bivalves are closed by the action of:
a. siphons.
b. adductor muscles.
c. longitudinal muscles.
d. myomeres.
e. mantle contractions.
B
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Diabetes mellitus translates roughly as "copious urination" + "honey." This disease results from disorders of glucose uptake by systemic cells and can cause, among other symptoms, high levels of glucose in the blood and glucose appearing in the urine (this is what diastix measure). Which of the following is a reasonable explanation of this observation?
A. The reabsorption capacity of the kidney for glucose is exceeded. B. A lack of sodium in the filtrate blocks the function of the Na+/glucose symport protein. C. High levels of glucose interfere with ADH function. D. The high levels of glucose induce a "dehydrated" state that promotes production of a large amount of dilute urine. E. None of the choices given are a logical explanation for this observation.
Which of the following human populations likely evolved lactase persistence?
a. populations living on islands b. populations in which milk is a component of the diet throughout an individual’s life c. populations in which milk-derived products are essential for young individuals d. Lactase persistence will evolve in any population that has a strong need for digesting milk.
Which form of selection is most likely to contribute to speciation over time?
a. stabilizing selection b. directional selection c. diversifying selection d. sexual selection
Which cyclin(s) is/are required to pass the G1 restriction point in animal cells?
a. Cyclin A b. Cyclin A and Cyclin B c. Cyclin D d. Cyclin D and Cyclin E