Unit 9 - Gas Exchange/Transport in Plants

Name 4 properties of gas exchange in plants

permeability, large SA, thin tissue layers, moisture, concentration gradients

4 factors that affect transpiration- go! explain each as well

light intensity, wind intensity, temperature, humidity

high humidity - concentration gradient decreases, slowing rate of diffusion

temperature - high temp will make molecules move faster —> H20 will evaporate quickly

how does water get transported up the xylem?

• water loss by transpiration

• create negative pressure potential

• tension pulls water up through xylem (capillary action)

• cohesion ensures continuous water column

what does phloem do?

transports organic compounds such as sucrose and amino acid up and down stem of plant

When transpiration is insufficient for water transport in xylem, what kicks in?

root pressure (positive pressure potential) is generated to cause H20 movement in roots/plants

Symplastic Pathway (sym—>cyto)

water moves through cytoplasm of adjacent cells

Apoplastic Pathway (apo-apart)

water moves through cell walls of plant cells by capillary action

What are sieve tube adaptations? name 4

• reduced cytoplasm & organelles

• no nucleus for sieve tube elements

• protein pumps

• sieve plates

• plasmodesmata

Plasmodesmata

connect sieve tube elements to companion cells

What are reasons for locomotion?

FDMM!

Foraging for Food

Escaping from Danger

Searching for a mate

Migration