chapter 1 introduction to plants and botany. topics why knowledge in botany is crucial? what is a...
TRANSCRIPT
Chapter 1
Introduction to Plants and Botany
Topics
• Why knowledge in Botany is crucial?
• What is a plant?
• Kingdom Plantae
• Origin of photosynthesis
• Origin of plants
Why Botany? Me, others and abiotic environment
• Buildup of atmospheric CO2 - many sources - global climate change/warming
• CO2 removal and O2 release - only one way - Can plants reverse the CO2 accumulation? - plants have changed earth’s climate - impacted evolution and biodiversity
• Plants & People: Food - agriculture and human society today; Fiber - keep us unnaked; Lumber and paper - forestry and wood-based industries; Chemicals - Phytopharmacognosy, Dyes, Flavors, Perfumes, Pesticides, Preservatives, Texture-makers, Hormones; Biotechnology; Beauty and Spirituality
http://www.botanic.cam.ac.uk/Botanic/Trail.aspx?p=27&ix=11
Plants – Kingdom Plantae
Defining the term, plant, is difficult
– Inclusion or exclusion of some groups
– Green algae - similar biochemistry
– Archaeplastids – plants+green and red
algae
– phytoplanktons – CaCO3
tests – global CO2-O2
balance
• Brown algae: Is it a plant?
Plant Systematics - Natural selection
• Organisms make non-identical offspring whose features pass to its offspring
• Offspring with features that are well-adapted to the environment reproduce more
• New phenotypes arise periodically
by mutations - P=G X E• Natural selection - new features are
eliminated or continued/balanced• Evolution by natural selection is
consistent with:– observations on nature/life
– experimentation
– chemistry and physics
Origin of photosynthesis and plants
• Life on earth ~3.5 bybp with prokaryotes (bacteria and later archaeans)– Photosynthesis - 2.8 bybp in cyanobacteria mainly
• Organelles by endosymbiotic events (1.5 bybp) followed by division of labor and specialization– Eukaryotes nuclei and other organelles (plants, fungi, animals,
algae)
– DNA became stationary in its own organelles
– Those with mitochondria evolved to be protozoans, fungi, and animals
– Those with mitochondria + chloroplasts evolved into plants and algae – plants evolved from green algae ~475 mybp
Photosynthetic bacteria•Cyanobacteria – oxygenic - water is e donor - make O2
•Purple and purple sulfer bacteria, green sufer and green gliding bacteria etc. - nonoxygenic - H2S is a main e donor
Chl a + c/d + carotenoids
Chl a + b + carotenoids
Archaeplastid super group
Origin of plants
• Green algae to Bryophytes (~475 mybp) to Tracheophytes
• Flowering plants evolved 100-120 mybp– Many characteristics evolved with/following the flower
• Fruits• Simple, flat, broad leaves• Complex vascular syst.• Wood• Most dominant today
• Cladogram NEXT