A lIthough most biology teachers are aware of the public's strong support for the teaching of creationism, we assume that our fellow biology teachers understand the overwhelming evidence supporting evolution, and therefore share our commitment to emphasizing evolution as the foundation of biology. We also assume that our colleagues do not include creationism in their biology classes because creationism-regardless of which of the hundreds of creationism stories one would promote-is not science. But how valid are these assumptions? To estimate the prevalence of creationism among biology teachers, we studied the evolution-related attitudes and actions of Minnesota high school biology teachers. We chose Minnesota for a variety of reasons: * Minnesota has strong state standards for evolution education. For example, the Minnesota K-12 Framework for Science (2003) requires that "the focus of instruction in life science for all students at the high school level is on developing an understanding of cell structure and function, the relationship of matter and energy in biological systems, heredity, biological evolution, [and] the behavior and interdependence of organisms" (p. 3-192). The Framework also includes the National Science Education Standards, which discuss evolutionary topics such as common descent, similarities among organisms, and natural selection.

Ten-d-old seedlings of Zea mays L. cv. Tx 5855 treated with 1-methyl-3-phenyl-5-(3-[trifluoromethyl]phenyl)-4-(1H)-pyridinone (Fluridone) were analyzed for abscisic acid (ABA) content using high-performance liquid chromatography with an analysis sensitivity of 2.5 ng ABA g-1 fresh weight (FW). Seedlings were divided into three portions: leaves, detipped roots, and root tips (terminal 1.5 mm). Control plants (water treatment only; no Fluridone) were characterized by the following amounts of ABA: leaves, 0.114 +/- 0.024 (standard deviation) microgram ABA g-1 FW; detipped roots, 0.260 +/- 0.039 +/- microgram ABA g-1 FW; root tips, no ABA detected. We did not detect any ABA in tissues of Fluridone-treated plants. Primary roots of treated and untreated seedlings were strongly graviresponsive, with no significant differences between the curvatures or the growth rates of primary roots of Fluridone-treated and control seedlings. These results indicate that 1) Fluridone completely inhibits ABA synthesis, and 2) ABA is not necessary for positive gravitropism by primary roots of Zea mays.

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Graviperception by plant roots is believed to occur via the sedimentation of amyloplasts in columella cells of the root cap. This physical stimulus results in an accumulation of calcium on the lower side of the cap, which in turn induces gravicurvature. In this paper we present a model for root gravitropism integrating gravity-induced changes in electrical potential, cytochemical localization of calcium in cells of gravistimulated roots, and the interdependence of calcium and auxin movement. Key features of the model are that 1) gravity-induced redistribution of calcium is an early event in the transduction mechanism, and 2) apoplastic movement of calcium through the root-cap mucilage may be an important component of the pathway for calcium movement.