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Kingdom Plantae: Introduction, Structure, and Function Intro • Trees, grasses, flowers, ferns, and mosses • Primary producers on earth: -contribute oxygen, carbon fixation > 250,000 species • Botany: the study of plants • Classified by their structure • Structure: see figure 24.2.1 on page 508 • Organelles: see figure 24.2.2 on page 508 Characteristics: • Cell wall: -made of cellulose • Primary cell wall: -first cell wall made, surrounded by a layer of pectins -forms middle lamella • Secondary cell wall: -woody plants -adds more structural support -contains lignins • Plasmodesmata -small channels that connect plant cells to one another (share nutrients & water) Vascular and Nonvascular Plants • Vascular plants: -use a system on interconnected tubes to transport water and nutrition -examples: trees, flowers, grasses, bushes, etc. Xylem: transport water & minerals from roots to rest of the plant Phloem: transports glucose (nutrition) from photosynthesis to all parts of the plants • Nonvascular plants: -grow in moist environments, small in size -no tube network, use diffusion -examples: mosses, liverworts, and hornworts General Plant Reproduction • Reproduce by spores, seeds, both, or neither • Used to classify plants • Spore -small, one cell, no protective coating • Seed -larger, multicellular, protective coating -contain embryo + endosperm Monocots & Dicots Three General Plant Tissue Types • Parenchyma: unspecialized tissue, found throughout the plant • Collenchyma: thicker primary cell walls, provide structural support • Sclerenchyma: thick secondary cell walls, fill with lignin and become wood Vegetative organs: roots, stem, leaves Reproductive organs: flower, cone, etc. Meristem Tissue: • • • • Specialized tissue where growth takes place Tips of roots and stems Apical meristem = growth in length Lateral meristem = growth in girth Roots • Anchor plant; absorb water and minerals from the soil • Two types of root systems: taproot – one main root fibrous – many roots of equal size • Layers: Epidermis, cortex, endodermis, pericycle Vascular cambium: contains xylem & phloem Stem • Leaves or branches form at the nodes • Monocot vs. Dicot (page 518) Bark • Layers: inner bark, cork cambium, outer bark • Outermost protective layer of woody stems • Growth rings: rings of dead xylem cells; tell age, health, climate Leaves • • • • Primary photosynthetic organ of plant exchange gas, absorb sunlight Monocot: veins run parallel Dicot: veins are netted • cuticle: waxy covering, limits water loss • Guard cells close the stomata (openings) to limit water loss Importance of Water in Plants • Necessary for photosynthesis, turgor pressure, hydrolysis, and transport • Turgor pressure: keeps stems upright and leaves full – Water is drawn into the central vacuoles by osmosis Nastic movements: movement due to changes in plant’s environment as a result of changes in turgor pressure. Water and Transportation • Critical for transport of nutrients and food throughout the plant • Cohesion-tension theory: water molecules “stick” together • Translocation: movement of glucose from leaves to rest of plant