Chapter 29 BiologyChlorophytes, Charophytes, and PlantaeMulticellularChloroplasts with same pigmentsCell wales with celluloseStorage molecules as starchCharophytes also share with Plantae: similar flagellated sperm, cellulose synthesis proteins, cytokinesis process.Sporopollenin- durable polymer that protects470 million years ago, multicellular green algae expanded from shallow seas into rivers and lakes.Green algae along lake shores: more resources; less competition. Subjected to periodic dehydration. Populations with land adaptations thrive. Advantages of Land: [CO_2] higher.Light intensity higherMore mineralsNo herbivoresNo competitionDisadvantages: risk of desiccationDivided resourcesNo support in air. First plants were similar to today’s liverworts. Derived Characteristics of Plants1. Alternation of generationsa. Plant sporophyte (2n) makes huge # unique diverse offspring per fertilization. Compare to charophyte life cycle; only multicellular is haploidZygote does meiosis to produce only 4 diverse offspring. 2. Walled haploid sporesa. Dispersal through air: sporopollenin protects the sporesEgg protected with in archegonium.Fertilization here: forming zygote.3. Sporophyte embryos grow protected within female gametophyte. 4. Apical Meristemsa. Continuously dividing cells. b. Roots and shoots grow toward resources.5. Waxy Cuticlea. Waxy Coat stops desiccationb. Pores needed to allow CO_2 /O_2 exchange. 6. Secondary Compoundsa. Chemicals that deter, repel or poison competitors, herbivores, and parasites7. Mycorrhizaea. Mutualism with fungi; helps water and mineral absorptionb. Dates back to first land plants (before true roots)Diversification of PlantsOne bryophyte-like ancestor of all plantsAbout 470 myaKey adaptations: major plants and algaeBryophytes-mosses.Liverworts-Phylum HepatophytaHornworts-Phylum NathocerophytaHaploid gametophyte is dominant formMakes eggs and flagellated sperm. Most are small and grow in dark damp areas.Lakes vascular and supportive tissuesVery thin body: depends on diffusion.With rhizoid for attachmentDiploid sporophyte depends on gametophyte for food and water. Grows within
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