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KEY, 35.1 Plants homework assignment Dr. Herrera-Estrella’s views on genetically modified crops (specifically, corn): “Herrera-Estrella advocates for using genetic engineering to improve the lives of poor farmers in Mexico and other developing countries” (Campbell Biology, p.736) for several reasons including: GMO crops to date have been shown to be safe for consumption and safe for the environment, GM corn would increase agricultural productivity of poor farmers (example, from 1 T of corn to 3 T per acre), small scale, safe, experimental plantings are possible, if a transgene spreads into other corn varieties, that might not be a problem because the corn genome is “already a mess” due to its transposable elements, addition of a single transgene is actually a much less dramatic change than that brought by the breeding of teosinte into modern corn. Chart, 35.1 Neil 9e Organ Parts/key structures Usual function Unusual function ex. Root Taproot system or fibrous root system. Root epidermal cells put out thin root “hairs” for absorption. Anchors plant in soil, absorbs minerals and water, often stores carbs. Big storage roots of beets; prop roots of coastal trees; air roots of mangroves; buttress roots of big tropical trees in wet soil; aerial roots of strangler fig. Stem Nodes (where leaves are attached) and internodes; in the upper angle (axil) between stem and leaf is an axillary (lateral) bud; tip of stem is apical (terminal) bud. Usually cylindrical structure that raises and/or separates leaves to maximize photosynthesis; also raises flowers/fruits for dispersal Horizontal stems just below the surface (iris rhizome); vertical underground shoots consisting mostly of enlarged leaf bases for food storage (onion bulb); horizontal stolons for asexual reproduction (strawberry runners); enlarged ends of rhizomes or stolons specialized for food storage (potato tuber); photosynthesis (cactus stems). Leaf Blade, often joined to stem with a stalk called a petiole. Blade may be single, or divided into leaflets. Photosynthesis Climbing (tendrils of pea plant); discouraging herbivores (cactus spines); water storage (succulents); asexual reproduction (Kalanchoe plantlets); helping attract pollinators (“petals” of poinsettia).