1 2 3 4 5

		Bio 220 Lecture 4: Plant growth, structure and movement of water Campbell, pp.682-694 Review questions Today, we're going to discuss how plants grow, how that growth produces the internal structure of the roots, stems and leaves, and how that structure is used to transport water through the plant. On Friday, we are going to discuss how substances, including water, get into and out of cells across the plasma membrane. I. Plant growth A. Determinate vs Indeterminate Animals exhibit determinate growth:they stop growing at a specific point Plants exhibit indeterminate growth: they continue to grow as long as they live. Their size is environmentally determined. Both the largest and the oldest known living complex organisms are plants. However, the life spanof most plants appears to be genetically determined. B. Primary vs secondary Many plants grow in two ways: (1) All plants grow at the periphery- the roots go deeper, the stem grows higher, more leaves are added. This is primary growth. (2) Many plants also increase in girth- they get wider. This is secondary growthand it is accompanied by an accumulation of hardened xylem that makes the stem woody. All gymnosperms and most dicots exhibit 2º growth, but few monocots do. C. Patterns of growth 1. Modular35.21 Let's take another look at the basic structure of a plant to see what type of growth is required to create that structure. Remember, plant cells are fixed in position. They must be created and differentiate exactly where they are needed. The growth of the shoot is modular. It grows in segmentsthat contain one node(where a leaf or side branch forms), one internoderegion (the stem in between) and a bud that can form a new segment.