Chapter 30

Chapter 30 - Chapter 30: Green Plants Dominate terrestrial...

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Chapter 30: Green Plants Dominate terrestrial and freshwater habitats Green algae and land plants o Logical to study them together because (1) they are the closest living relative to land plants and form a monophyletic group with them, and (2) the transition from aquatic to terrestrial life occurred when land plants evolved from green algae Why study green plants? o Ecosystem: consists of all the organisms in a particular area, along with physical components of the environment such as the atmosphere, precipitation, surface water, sunlight, soil, and nutrients o *Plants are said to provide ecosystem services because they add to the quality of the atmosphere, surface water, soil, and other physical components of an ecosystem. Plants alter the landscape in ways that benefit other organisms. Plants produce oxygen--photosynthesis Plants build soil—decomposition Plants hold soil—roots Plants hold water—tissues take up and retain water Plants moderate the local climate—providing shade reduces temperatures beneath them and increase relative humidity o *The sugars and oils that land plants produce by photosynthesis provide the base of the food chain in the vast majority of terrestrial habitats. o *Just as photosynthetic protists and bacteria are the key to the carbon cycle in the oceans, green plants are the key to the carbon cycle on the continents. Plants take up CO2 from the atmosphere and reduce it to make sugars. Plants provide humans: o Artificial selection: actively selecting individuals with the largest and most nutritious seeds or leave or stalks year after year o Alternate energy sources—coal (forms from partially decayed plant material that is compacted over time by overlying sediments and hardened into rock) o Cotton and other plant fibers—clothes, rope, etc. o Wood—lumber, furniture, etc. o Drugs Morphological Traits o Phyla: a series of major lineages o Green algae and land plants are related on a basis of several morphological traits Contain chlorophyll a and b Similar arrangement of the internal, membrane-bound sacs called thylakoids Cell walls are similar in composition Synthesize starch as a storage product in their chloroplasts o Nonvascular plants Hepaticophyta (liverworts), Anthocerophyta (hornworts) and Bryophyta (mosses) Lack vascular tissue—specialized groups of cells that conduct water or dissolved nutrients from one part of the plant body to another Mosses have specialized tissue, but do not have reinforced cell walls that define true vascular tissue o Seedless vascular plants Have well-developed vascular tissue but do not make seeds
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Lycophyta (club mosses), Psilophyta (whisk ferns), Sphenophyta (horsetails), and Pteriodophyta (ferns) o Seed plants Seed: consists of an embryo and a store of nutritive tissue, surrounded by a tough protective layer Cycadophyta (cycads), Ginkgophyta (ginkgos), Gnetophyta (gnetophytes), Pinophyta (pines, spruces, firs), other conifers, and Anthophyta (angiosperms)
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This note was uploaded on 04/15/2008 for the course LS 1 taught by Professor Thomas during the Winter '05 term at UCLA.

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Chapter 30 - Chapter 30: Green Plants Dominate terrestrial...

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