BIOL 111 - Post Midterm 2 Flashcards
(114 cards)
Why can bryophytes only transport over short distances?
They do not have lignin or vascular tissues
What limits the size of bryophytes?
Due to the lack of specialized exchange surfaces or transport systems, body size is limited by diffusion.
What are the three transport routes in plants?
Apoplastic route - Continuum of cell walls and extracellular spaces.
Symplastic route - Continuum of cytoplasm connected to plasmodesmata
Transmembrane route - Goes through the cytoskeleton as well as cell wall.
What does the plasmodesmata allow?
Cell-to-cell transport without crossing a permeability barrier.
What type of barrier is the plasma membrane? (Permeability)
Selectively permeable
Symplast vs apoplast
The apoplast is the continuum of cell walls and extra cellular spaces
Symplast is the continuum of cytosine connected by plasmodesmata
What facilitates water movement across membranes (osmosis)?
Aquaporins
What is bulk flow? What is dependent on bulk flow?
Movement in response to pressure gradients.
Long distance transport depends on bulk flow.
What does the bulk flow in xylem depend on?
Depends on transpiration.
As water is lost from leaves the pressure gradient is lower higher in the tree causing water to move up the xylem.
Cohesion-Tension hypothesis steps
Evaporation at leaf surface produces negative pressure
Cohesion and adhesion in xylem pull water upward to replace water lost by transpiration
What regulates water loss and how?
Stomata regulate water loss by opening in response to light and CO2 and closing in response to drought stress.
Proton pumps in relation to stomata
Proton pumps are active when stomata are open - Passive ion diffusion ,inward osmosis, cell turgor increases.
Inactive when stomata are closed - Indirect active ion pumping, outward osmosis, cell turgor decreases.
What relative atmospheric CO2 would indicate high stomata density?
Low atmospheric CO2
What relative atmospheric CO2 would indicate low stomata density?
High atmospheric CO2
What can be used as an indicator of past CO2 concentrations?
Stomatal density in fossilized leaves.
Symplastic vs apoplastic loading
Symplastic loading is passive - Relatively low sucrose concentration in phloem sap
Apoplastic loading is active. - High sucrose concentration in phloem sap
What is meant by source to sink?
Refers to bulk flow in phloem - sucrose moves from source to sink
At source there is a high sucrose concentration in phloem which causes water to diffuse in from the xylem.
At sink there is low sucrose concentration resulting in water being pulled back into the xylem.
Biome
Ecosystems with similar structure structure in a large region
Ecosystem
All of the biotic and abiotic factors in a specific area. Total biotic community and its abiotic environment.
Includes all of the living organisms and the physical environmental factors in an area.
Community
Individuals of multiple species in a single area.
Population
Individuals of a single species in a specific area.
What are the five trophic levels?
Producers -> Primary consumers -> Secondary consumers -> Tertiary consumers -> Detritivores
What do autotrophs do generally?
Producers that convert solar energy and inorganic nutrients into organic matter.
What is the role of detritivores?
Consume dead organic matter and release inorganic nutrients back into the environment.