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.
Conifers
Cone bearing trees, most with needle-like leaves.
What type of trees produce flowers and fruits?
Broad-leaf trees are typically flowering
What differences can be seen between broadleaf trees in the tropics versus more season climates?
Broadleaf trees in the tropics are typically evergreen as opposed to deciduous.
Are most conifers evergreen or deciduous?
Evergreen with a few exceptions
What do forests require?
High precipitation and warm temps during growing season.
What limits tree growth?
Water availability and length of the growing season.
Fire also suppresses tree growth and promotes the spread of grasses.
Attributes of tropical forests
Tropical rain forest - High temp and precipitation all year. Broad-leaved evergreens.
Tropical dry forest - High temp, wet and dry seasons. Broad-leaved deciduous trees.
Attributes of tropical savannas
High temp, wet/dry seasons, frequent fires.
Mixed trees and grasses.
Attributes of deserts
Low precipitation year round, hot or cold, sparse vegetation.
Xerophytes (cactus)
Temperate shrubland
Warm temperate/subtropical climate.
Winter rain/summer drought
Frequent fires
Hard-leaved shrubs
Cold winters/warm summers
Temperate grasslands
Large temp range
Semi-arid
Frequent fires
Grasses
Cold winters/warm summers
Temperate broadleaf forests
Cool temperate
High precipitation
Broad-leaved evergreen or deciduous trees.
North American temperate rainforests
Cool temperate climate
Very high precipitation
Needle-leaved evergreen trees
Boreal forests
Cold winter
Low precipitation
Needle-leaved evergreen trees.
Polar ecosystems
Tundra - Cold and dry all year, shrubs and grasses.
Polar ice - Very cold and dry, no vascular plants.
What accounts for most of the photosynthesis in aquatic ecosystems?
Single-celled phytoplankton.
Large seaweed and aquatic plants have high productivity in some local environments.
What are the three clades of unicellular eukaryotic algae that are the most important ocean producers?
Dinoflagellate, Diatom, Haptophyte.
What clade of algae would you expect to find in high nutrient vs. low nutrient areas?
Mostly large diatoms in high nutrient areas. Cyanobacteria and small flagellates in low nutrient areas
What characterizes freshwater ecosystems?
Flow regimes - flowing water characterizes rivers and still water characterizes lakes and ponds.
What is included in freshwater wetlands?
Swamps, marshes, and seasonally flooded grasslands.
What are estuaries?
Environments where rivers flow into the sea.
Where are kelp forests found?
Temperate oceans
Where are some of the most productive and diverse marine ecosystems found?
Shallow coastal waters
Where are coral reefs found?
Tropical oceans
Are corals animals?
Yes! They have symbiotic algae living in their tissues.
Where does life in the aphotic zone get its nutrients?
Organic material that is transported down from the photic zone
Deep sea hydrothermal vent producers?
Chemosynthetic bacteria
What is an ecological niche?
The range of environmental resources and conditions a species requires
Describes the role an organism plays in a community.
Example: The range of water temp a species of salmon can tolerate.
Habitat
The place where a species is found
There is a population of 10 lizards, 2 lizards are born and 1 dies, what is the populations growth rate
r = b - d
b = 2/10 = 0.2
d = 1/10 = 0.1
r = 0.2 - 0.1 = 0.1
r = 10%
When might a population grow exponentially?
When it first colonizes a new area or a change in environmental factors.
Example: Elephant population grew exponentially after protection from hunting.
What is a carrying capacity?
The maximum number that a population can be sustained at.
Depends on the habitats resources.
What are some examples of density dependent population limiters?
Limited resources, predators, disease.
What are some examples of density independent population limiters?
Fires, floods, extreme weather.
Which factors; independent or dependent regulate a population?
Dependent factors.
What is an example of a density dependent population cycle?
Large numbers of moose leads to large number of wolves. Large amount of wolves leads to a decrease in moose population leading to a decrease in wolf population.
Effect of competition between species?
Negative effect on both species - typically species on the same trophic level.
Example of competition between two different trophic levels occur?
Two animals competing for a water hole.
What are the two main outcomes of competition between species?
Coexistence through resource partitioning - each species specializes on using a part of the resource.
Competitive exclusion - One species excludes the other species from a community.
What is an example of coexistence?
Savanna herbivores migrate at different times of the year.
Effect of predation, parasitism, and herbivory?
One species benefits the other is negatively effected.
One species uses the the other as a resource.
Predation
Predators kill and eat prey.
Herbivory
Herbivores consume all or part of a plant or alga.
Not usually immediately lethal but causes strong selection for defensive adaptations.
Parasitism
Feed on host without killing normally.
Mutualism
Interaction that increases the fitness of both species.
What are some examples of mutualism in plants?
Mycorrhizae - fungi colonize the root system of a host plant, providing increased water and nutrient absorption capabilities due to high SA. Plant provides the fungus with carbohydrates formed from photosynthesis.
Angiosperms and pollinators
Reef corals have symbiotic algae in their tissues.
What is a dominant species?
Species with the most biomass in a community.
Often primary producers
Keystone species
Species with large effects on other species.
Often predators that regulate prey populations.
Example of bottom-up control
More grass introduced = more deer = more wolves
Example of top-down control
Wolves introduced = less deer = more grass
What are disturbances?
Removal of living producer biomass
What are examples of disturbances?
Fire, wind-throw, natural disasters.
Primary succesion
No soil - lichen - soil - grasses
Secondary succesion
Soil - grasses - herbs
What is ecological succesion
A process of community development
Pioneer vs mature communities post-fire succession.
Pioneer community is fast growing herbaceous plants with high dispersal ability that require a lot of light.
Mature community are slow growing conifers with lower seed dispersal ability and can grow in shade.
Shades out the pioneer community.
Stem exclusion stage
Phase in forest development where intense competition among trees for light, space, and resources results in the suppression and eventual death of less competitive individuals, leading to a thinning of the forest and dominance by a few species or individuals.
Flow of energy
Flows in one direction - enters as light from the sun and leaves in the form of heat.
Can not be recycled.
Net primary production (NPP)
= Gross primary production - respiration by autotrophs
The rate at which energy and fixed carbon become available to other trophic levels.
What limits terrestrial NPP? Aquatic?
Water and temperature.
Nutrients
How much of the organic matter that plants produce do they respire?
About 50%
Where is a large amount of carbon stored?
Living plants store a large amount of carbon as biomass
What is the difference between the actual living biomass and the potential?
450 GtC vs 900 GtC
Largely reduced due to forestry and agriculture.
Where is the most carbon stored?
Stored in soil.
Most soil carbon is in northern forests and tundras.
What is trophic efficiency?
The percentage of energy fixed at one trophic level that is passed to the next trophic level.
Typically about 10%
Why does soil hold so much carbon?
In forests herbivore consumption is low and most plant biomass goes into the soil.
Chemical cycle
CO2 available to producers is converted into CH20 which is consumed and then decomposers eventually return the CO2 back into the soil.
Preindustrial carbon cycle
Same amount of carbon enters and leaves the atmosphere each year.
Photosynthesis = -100
Plant respiration + soil respiration = +100
Carbon cycle today
The amount of carbon in atmosphere has increased by 50%.
Increased from 280ppm to 420.
Combustion of fossil fuels and land use increasing carbon.
Ocean is up-taking more carbon
