Chapter 29 Green Plants

Chapter 29 Green Plants - When Chapter 29: Green Plants...

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When Chapter 29: Green Plants --Green plants consist of green algae and land plants --Before the evolution of land plants, only bacteria, archaea, and single-celled protists lived. --Green algae, although traditionally considered protists, are studied with green plants bc (1) they are the closest living relative to land plants (monophyletc group with them) (2) the transition from aquatic to terrestrial life occurred when land plants evolved from green algae --Land plants were the first organisms that could grow with their tissues exposed to air instead of being partially submerged in water. (mutually beneficial relationships bw fungi and plants colonized land first) This enabled multicellular organisms to occupy dry land. I. Why do biologists study the Green Plants? a. Plants provide ecosystem services—they alter the landscape in a beneficial way. ( Ecosystem all the organisms in a particular area and physical traits of atmosphere, precipitation, sunlight, soil, nutrients etc.) i. Plants produce oxygen 1. Photosynthesis removes electrons from water and reduces carbon dioxide and makes sugars. Oxygen is a by-product. (oxygenic photosynthesis evolved in cyanobacteria and made an oxygen-rich atmosphere) ii. Plants build soil 1. Plant parts are decomposed (worms, fungi, bacteria, archaea, protists, etc) and these decomposers add organic matter to the soil. iii. Plants hold soil 1. Roots hold soil and its nutrients in place. (Wind and water erosion results in devegetated areas) iv. Plants hold water 1. Plant tissues take up and hold water. 2. Forests, prairies, wetlands prevent rain from quickly running off a landscape bc: leaves soften fall of rain, roots hold soil, plant organic matter builds the soil’s water-holding capacity. (In contrast, deforested areas have streams that flood, then dry up completely) v. Plants moderate the local climate 1. Shade lowers temperature and increases relative humidity. 2. Reduce the impact of winds that dry and cool the landscape. (in contrast, when plants are removed for people, habitats are dryer and have extreme temperature swings) vi. Plants provide food!! vii. Plants are the key to the carbon cycle on land (just like bacteria/protists are the key for ocean carbon cyces) 1. Plants fix more carbon dioxide than they produce. Deforestation results in higher carbon levels, which results in global warming. b. Plants provide humans with food, fuel, fiber, building material, and medicines i. Artificial selection —actively select individuals with the largest and most nutritious plant parts year after year for reproduction. ii. Wood and coal as fuel iii. Cotton and other fibers for clothes, towels, etc iv. Woody plants for lumber, papermaking. It is stronger than other materials v. Drugs made from plants. Plants make these compounds to repel insects and animals. II.
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Chapter 29 Green Plants - When Chapter 29: Green Plants...

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