Transport Flashcards
Contents of Sieve Tube
90% sucrose
-Also amino acids, minerals, and ions
What direction does sugar travel?
Source (Leaves and storage tissues in spring) to Sink (meristems, reproductive tissues, storage tissues in summer)
Pressure Flow Hypothesis
- Phloem loading at source creates high pressure
- Phloem unloading at sink creates low pressure
- Sugars flow down gradient
- Active transport to pump sugars and unload them
Transpiration
Loss of water out of stomata
-Plants open stomata for photosynthesis but lose water
Negative Pressure
Created by transpiration
-Negative pressure on water column inside plant pulls water up the plant
Tension
Pulling force on a string
Tensility
amount of force needed to break a substance
Physics of water in xylem
- water is under tension
- has high tensile strength
Tensile strength
Water forms a strong column in xylem
Adhesion
Water adheres to xylem creating tensility
Cohesion
Water molecules cohere to each other
Direction of water movement
-Passive
Roots->stems->out of leaves
-against gravity
Where do plants get their nutrients from?
atmosphere and soil solution
Nutrient functions
- synthesis of sugars, amino acids, etc
- regulate enzyme function
- create electrochem gradients
First 4 macronutrients
- Hydrogen (H2)
- Carbon (CO2)
- Oxygen (O2)
- Nitrogen (NH4+, NO3-)
Where 1) magnesium and 2) phosphorus are used
1) Chlorophyll
2) ATP
Where 1)Sulfur and 2) Manganese are used
1) 2 Amino Acids and protein folding
2) Oxygen Evolving Complex in PSII
Symptoms of nutrient deficiency
Stunting, wilting, chlorosis, necrosis
Nitrogen Paradox
78% of atmosphere has Nitrogen (N2) that can’t be used by most organisms
-Nitrogen (NO3-, NH4+) must be taken up from soil but there is lots of competition and it leaches away in water
Nitrogen FIxation
Reduction of N2 to Ammonium
- Via nitrogenase (must be kept away from O2)
- Requires a lot of ATP
Rhizobium
Nitrogen fixing bacteria
- Symbiotic w/ roots of legume family
- Live in root nodules
What percent of calories come from starch?
80%
6 crops for main sources of starch
Rice, wheat, corn, potatoes, sweet potatoes, cassava (yuca)
What crops came from Peru and where are they now a staple?
- Potato (all over)
- Sweet potato (Africa)
- Cassava (Latin Amer)
