Smooth muscle cells in the airways relax while those in the blood vessels contract in response to the hormone epinephrine. What would you expect to be different in these two types of cells exposed to epinephrine?
A. Types of proteins expressed.
B. Presence of epinephrine receptors.
C. Exposure to epinephrine released by neighboring cells.
D. Rate of metabolism.
E. Activation of protein kinases.
A. Types of proteins expressed.
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Consider two traits for an organism, determined by two genes, each of which is governed by at least two alleles. In the case of a dihybrid individual, the gametes formed will be of either the parental type or the recombinant type. Recombinant type gametes are formed because of
a. incomplete dominance. b. independent assortment. c. heterozyogosity. d. the principle of dihybrids. e. multiple alleles.
You are given a piece of connective tissue that you observe to be white, firm, and consists of a matrix of collagen. When chemically analyzed, it is found to contain high concentrations of minerals. What kind of connective tissue is this?
A. bone B. cartilage C. adipose D. dense connective E. blood
Which of the following best describes the tree of life as currently understood from analysis of DNA sequence data?
a. The tree of life consists of three domains: Bacteria, Archaea, and Eukarya. b. The base of the tree of life is still uncertain because the molecular clock is not accurate for evolutionary events that occurred that long ago. c. The tree of life consists of three domains—Bacteria, Archaea, and Eukarya—and there was substantial horizontal gene transfer between different organisms during the early history of life. d. The domain Archaea is known to be the first branch; domains Bacteria and Eukarya are more closely related to each other. e. There was substantial horizontal gene transfer between different organisms during the early history of life.
Microspores are indicated by the letter ____
a. A b. B c. C d. D e. E