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Transcript
Plants II Chapter 30 What you need to know! Key adaptations to life on land unique to seed plants. The evolutionary significance of seeds and pollen. The role of flowers and fruits in angiosperm reproduction. The role of stamens and carpels in angiosperm reproduction Seeds Fertilized, embryo-containing female megaspore, surrounded by nutrients and covered by a seed coat (integument) Seeds contain high energy nutrients like fats, carbs, and proteins to help the new plant embryo grow until it has leaves and can do photosynthesis Remain dormant until favorable conditions Seeds and Reproduction Emerged 340 million years ago Miniaturization of the gametophyte Heterosporous Ovum (fruit): protection of delicate, large female megaspore (drought, UV light) Pollen: male microspores covered by tough membrane Pollination: pollen grain germinates and grows a pollen tube to let sperm reach the ovum Pollination fertilization seed development Tracheophyta – Seed Plants Class: Gymnosperms – naked seeds (no fruit), and flowerless Ginko and Conifers (pines and firs) Pollen cones (sperm) and ovule cones (eggs) Wind is primary pollinator Seeds grow in cones Tracheophyta – Seed Plants Class Angiosperm – flowering, fruit producing plants Subclass: monocot (single seed leaf) Subclass: dicots (double seedleaf) Leaves flattened blade Main photosynthetic organs Flowers Flowers Specialized Cells in Plants Parenchyma 1. No cell walls Carry out most of metabolism Few cellular divisions once mature Collenchyma 2. No cell wall Strength and support in young cells Sclerenchyma 3. Thick cell walls Carry lignin (wood forming substance) Lose protoplast (cellular innards) when mature Stems Xylem H2O and minerals Thick cell walls Lose protoplast when mature Transport of water up to 15 m/h or more Only one way direction root top Driven by water potential (vacuum) Phloem Transport of sugar, AA, ions Sieve tubes between cells with protoplast Transport in any direction Positive pressure flow mechanism (diffusion/osmosis) Sugars are transported from sugar source (leaves) to sugar sinks (starch stores) Uptake Minerals enter into root cells (active transport) Water enters into root cells (osmosis) Transpirational pull upward to tip of plant (water potential vacuum) Cohesion and adhesion of water to cell walls Photosynthesis & Transpiration Compromise Stomata surrounded by guard cells Regulate transpiration and gas exchange Open: + transpiration / + gas exchange Sufficient turgor = Influx of potassium followed by water Swelling of guard cells Opening of stomata Closed: - transpiration / - gas exchange Insufficient turgor = Outflux of potassium and water Shrinking of guard cells Closing of stomata Plant Anatomy Primary growth = UP Secondary Growth = OUT Monocots and Dicots (Eudicots) Monocots Cotyledons (seed leaves): 1 Leave veins: parallel Vascular tissue: scattered Roots: fibrous Photosynthesis: C4 Flower organs: X3 Dicots 2 netlike ring taproot C3 X5 Monocots and Dicots (Eudicot)