Final Study Guide

Final Study Guide - Lecture 11: Invasion of Land Plants:...

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Lecture 11: Invasion of Land Plants: 450 (450-470)ma, Ordovician Invertebrates: 410 (430) ma, Silurian Vertebrates: 370 (360) ma, Devonian 427- 470 million year old fossil spores (simple, reproducing, 1-celled organisms) are 1st evidence for life on land. First life on land consisted of algae and fungi. Algae + fungi = lichens (like moss on rocks n stuff) Symbiosis : Fungus extracts nutrients from the rock that are used by the algae, and the algae returns energy to the fungus via photosynthesis. Problems to be overcome in making the transition to land include: 1) Lack of support (b/c of gravity) 2) Dessication: drying out 3) Near absence of dissolved nutrients and gases 4) No liquid medium for transport of gametes Plant Solutions: 1) Support: evolution of lignin (organic compound that strengthens plants) and cellulose (wood) 2) Dessication: evolution of waxy outer covering known as the cuticle 3) Respiration: Evolution of stomata , specialized cells on plant surface that can open and shut allowing gas exchange 4) Feeding/drinking: evolution of roots and internal transport system, xylem 5) Reproduction: spores that could be wind dispersed, and then seeds that did not require water for fertilization to occur. Potential problems faced by the 1 st land invertebrates (arthopods, worms): 1) Locomotion? No because it was the same as in water. 2) Dessication? Live in moist forest litter. 3) Feeding? Similar foods in water and on land. Early land animals were detritivores (feeds on dead organic material) or carnivores (feeds on flesh). 4) Respiration? May have been a problem. Solved by evolution of a trachea
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Final Study Guide - Lecture 11: Invasion of Land Plants:...

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