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– 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=J1PqUB7Tu3Y

The End

Unless otherwise specified, all images in this presentation came from:

Campbell, et al. 2008. Biology, 8th ed. Pearson Benjamin Cummings.