Transcript Introduction to Plants: Evolution, Characteristics and Life Cycle

Plant Functions
BIOL 1407
Essential Nutrients
• Chemicals that
organism cannot
produce
• Must be acquired
from environment
• Required to
complete life cycle
•
Photo Credit: BIOL 1407 Student, Austin
Nature Center, Fall 2006
Macronutrients
• Large quantities
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Carbon
Hydrogen
Oxygen
Nitrogen
Sulfur
Phosphorus
Potassium
Calcium
Magnesium
Zea mays Vascular Bundle (Orange
= Sclerenchyma)
Photo Credit: Barnading, 2002, Wikimedia Commons
Micronutrients
• Tiny quantities
• Cofactors or
components of
enzyme
systems
Source of Plant Nutrients
• Inorganic
Compounds
– Soil
– Air
Transport Systems
• Why are they
necessary?
Types of Transport
• Cell Transport
– Across membrane
• Short-distance
– Diffusion from cell to
cell
• Long-distance
– Bulk Flow
– Down pressure
gradients
Absorption of Water & Minerals
• From soil (most)
• Absorption
– Diffusion
– Osmosis
– Facilitated
Diffusion
– Active Transport
Mineral Uptake: Cation Exchange
• Cations firmly
bound to soil
particles
• Roots secrete H+
– Directly by H+
pump
– Indirectly by
cellular
respiration
Short-Distance Transport
• Lateral Transport
– Symplast
Pathway
– Apoplast
Pathway
– Transmembrane
Pathway
Short-Distance Transport in Roots
Long-Distance Transport
• Xylem
– Water
– Minerals
• Phloem
– Organic
compounds
Xylem
Xylem Transport
• Root Pressure
• Cohesion and
Adhesion of Water in
Xylem tubes
• Transpiration
Root Pressure
• Loading of water
and minerals into
xylem vessels 
hydrostatic
pressure in stele
Cohesion
&
Adhesion
Transpiration
• Evaporation of
water from plant
surfaces
• Mainly through
leaf stomata
Transpiration Pull
Shoot Gas Exchange
• Leaves
– Cuticle
– Stomata – Opening
– Guard Cells –
Regulate Gas
Exchange
• Stem
– Lenticels
•
Photo Credit of Lenticels: Sten Porse, 2007,
Wikimedia Commons
Root Gas Exchange
• No cuticle
• No stomata
Phloem Transport
• Sugar Sources
• Sugar Sinks
Phloem Cells
Lateral Transport of Sugars
Apoplast
Sieve tube element or companion cell
Phloem Transport
Plant Video
• http://www.youtube.com/watch?v=J1PqUB
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The End
Unless otherwise specified, all images in this presentation came from:
Campbell, et al. 2008. Biology, 8th ed. Pearson Benjamin Cummings.