BIOL 111 - Post Midterm 2 Flashcards
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.
What is climate?
A long term average weather pattern including mean annual temp, mean annual precipitation and seasonality.
Where would you find arid climates?
Dry air returns to the surface near 30 degrees latitude, creating arid climates.
Where does the most solar heating occur?
Around the equator.
Hot tropical air absorbs moisture and rises. Near the top of the troposphere water vapour condenses and falls back to the surface.
Where are “moist” climates found?
60 degrees latitude.
What are tropical air cells called?
Hadley cells
What creates alternating wet and dry climate zones?
Atmospheric cells.
Where do other air cells form?
Temperate and polar zones
What causes surface winds?
Earth’s rotation
What direction do tropical trade winds blow?
Easterly - east to west
What direction do temperate winds blow?
Westerly - west to east
Where are coastal temperate rainforests found in relation to winds?
Found where westerly winds bring high rainfall to the west coast of a continent.
What causes seasonal variation?
The tilt of the earths axis.
What is the effect of the June solstice versus the December solstice for the northern hemisphere?
During the June solstice the Northern Hemisphere tilts towards the sun and the opposite for the December solstice.
What is the rain shadow effect?
Cool air flows inland from the water, as the air encounters the mountains and flows upward it cools at higher altitudes and releases water as rain and snow. Less moisture is left in the air after the mountain creating a drier environment on the other side.
Coastal rain forest -> Subalpine meadow -> Grassland
What is the effect of altitude on temperature in the mountains?
Temp changes around 6 degrees for every 1000m of altitude.
Similar to moving poleward about 1400km
What drives the earths water cycle
Solar energy?
What drives surface currents in the oceans?
Trade winds and westerlies.
Which way do gyres rotate?
Clockwise in northern hemisphere and counter in the southern hemisphere.
Photic zone and Aphotic zone
Vertical zones
Photic zone is on the surface where there is enough light to support photosynthesis. Maximum depth of 150-200 metres.
Aphotic zone is dark zone below the photic zone.
Pelagic and benthic zones
Benthic is the sea floor
Pelagic zone is the water column above the sea floor.
Coastal and oceanic zone
Horizontal zones
Coastal zone is the area above the continental shelf.
Oceanic zone is everything is the ocean past the edge of the continental shelf.