Chapter 1 Botany: An Introduction

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Chapter 1Botany An Introduction
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Outline

• Intro
• Evolution of plants
• Evolution of communities
• Human influences

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Intro to Botany

• Plants/algae/bacteria essential for life b/c
  photosynthesis (Ps)
• means of S input into biosphere
• basis of food chains/webs
• 1 producer
• provide other resources
• fiber for clothing, wood for shelter/fuel/paper,
  spices, pharmaceuticals, shade, aesthetic value,
  most importantly O2
• Botany study of plants
• derived from boskein to feed
• sometimes includes prokaryotes/fungi/algae
• botany as part of a biology curriculum

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Intro to Botany

• Branches of botany
• physiology how plants func. (Ps/growth/developme
  nt)
• morphology plant form
• anatomy internal structures
• economic botany uses of plants by people
• paleobotany evolution of fossils
• taxonomy/systematics naming/classification/relat
  ionships
• cytology cell structure and func.
• genetics heredity and variation
• genomics manipulation of genes to improve
  characteristics
• molecular biology structure and func. of
  biological molecules
• ecology relationships btwn organism and
  environment
• ethnobotany use of plants by indigenous people

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Evolution of Plants

• Formation of Earth 4.6 BYA
• Oldest fossils 3.5 BYA (Australia)
• bacteria-like
• prokaryote-only for 1.4 B years
• 1st photosynthetic organisms 3.4 BYA
• Eukaryotes 2.1 BYA
• Multicellular organisms 700 MYA
• Invasion of land by plants 510 MYA
• gymnosperms 290 MYA
• angiosperms 145 MYA
• Birds 208 MYA
• Mammals 245 MYA (humans 1.6 MYA)

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Evolution of Plants

• First life forms are aggregations of molecules
• microspheres of proteinaceous material
• membrane separates external from internal
  environment
• Characteristics of life
• ability to grow, reproduce, pass on traits,
  organization
• Origin of life
• hydrothermal vents
• shallow, warm water
• interstallar dust (evidence of water on Mars)

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Evolution of Plants

• Animals/fungi are heterotrophic
• heterotrophic other feeder
• S derived from organic molecules
• now organic molecules produced by other organisms
• S used up thus need to be able to use inorganic
  cmpds and obtain S elsewhere
• heterotrophs evolved prior autotrophs
• Plants are autotrophic (also some bacteria/algae)
• autotrophic self feeder
• S derived from sun (Ps), other S sources
• allow life on Earth to continue
• increasingly complex organisms

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Evolution of Plants

• As photosynthetic organisms proliferate, Earths
  atmosphere altered
• O2 in atmosphere ?
• O3 layer develops, absorbs UV rays
• thus, life on land
• aerobic respiration
• more efficient than anaerobic respiration (R)
• corresponds to appearance of eukaryotes

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Evolution of Plants

• Early photosynthetic organisms
• near surface in water
• shortage of nutrients/CO2/light favors mvmt to
  land
• land environment is drier and unpredictable,
  gravity an issue
• organisms become more complex, multicellular
• cell walls to withstand pressure
• anchors for support
• vascular tissue for water transport to tissue in
  dry air

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Evolution of Plants

• Structures evolve to ? water loss while obtaining
  CO2
• roots for anchorage/water absorption, stems for
  water transport, and leaves for Ps
• Ps in green stems
• tissues differentiate (tissue group of cells w/
  distinct func./structure)
• vascular, ground and meristematic tissues
• vascular system of xylem (X) and phloem (P)
• X conducts water/minerals, P conducts
  photosynthates
• vascular vs. nonvascular plants
• meristematic tissue cells that produce new
  cells (growth)
• apical meristem and 1 growth, lateral meristem
  and 2 growth
• vascular and cork cambiums

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Evolution of Plants

• cuticle covers epidermis to prevent dehydration
• stomata allow gas exchange through
  epidermis/cuticle
• guard cells
• drought resistant spores and later seeds
• seed embryo w/ specialized covering (seed coat)
  that protects from dehydration/predation, also
  has food stores

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Evolution of Communities

• Plants adapt to diversity of landscapes
• rise of biomes (savannas, wet forests, temperate
  forests, deserts)
• biome complex of terrestrial communities,
  characterized by climate and soil
• ecosystem stability depend on plants
• S enters ecosystem via Ps
• 1 producers
• base of trophic system
• O2 needs

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The Human Factor

• Humans appear 1.6 MYA (30 sec. before midnight)
• agriculture 8500 YA, Industrial Revolution
• huge environmental impact
• pollution, climate change, etc.
• s???

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The Human Factor

• Hopes for the future
• phytoremediation
• genetic engineering
• ? nutrition
• herbicide resistance
• quicker time to reproduction
• pharmaceuticals
• biodegradable plastics