Ch. 29 Plant Structure and Function Flashcards
define desiccation
excessive water loss
what is the common ancestor to all land plants?
aquatic green algae
bryophytes
which organisms are in the “bryophytes”?
mosses
liverworts
hornworts
what are the 2 main groups that comprise all land plants?
vascular plants (monophyletic) bryophytes (paraphyletic)
what are the 4 subgroups of vascular plants?
- ferns and horsetails
- gymnosperms (pine trees, conifers)
- angiosperms (flowering plants, oak trees, grasses, sunflowers)
- lycophytes
what is desiccation tolerance?
bryophytes can tolerate being without water for extended amounts of time, they can resume photosynthesis once water is available
who can more easily adapt to varying environmental conditions: vascular plants or bryophytes?
vascular plants (bring water up from soil, and they don’t rely on surface moisture)
what forms the “shoot” of vascular plants?
leaves
stem
reproductive organs
what are the 4 main tissues in a leaf?
- upper epidermis
- palisade mesophyll
- spongy mesophyll
- lower epidermis
where does most of the plant’s need for water come from?
plants’ need for water arises as a consequence of CO2 uptake in air (transpiration)
how do guard cells of stomata open and close?
open = more H2O, more K+ and Cl- ions = swell close = less H20, less K+ and Cl- ions = shrink
what is the resting state of guard cells?
closed
closing doesn’t take any energy
how long does it take for angiosperm stomata to completely close/open?
about 10 minutes
what can cause stomata to open?
- light
2. increase in temperature
what can cause stomata to close?
- darkness
- increases in CO2
- water deficit
water loss and photosynthesis usually peak at the same time. what is one adaptation that allows plants to open their stomata and store CO2 during the nighttime?
CAM (crassulacean acid metabolism): CO2 fixed twice at two different times (temporal segregation)
opens stomata at night
greatly increases CO2 intake while minimizing water loss
-still go through C3 photosynthesis
where is CAM most often found?
- habitats such as deserts
- among epiphytes (plants that do not contact the soil because they grow high in a canopy of other plants)
all floral parts are modified leaves. true or false?
true!
what are some of the functions of leaves?
- capture insects (form of nitrogen)
- protection against herbivores
- protect juvenile leaves
- capture water
- store water/nutrients
- attract pollinators
what are C4 plants? what do they do?
C4: CO2 fixed twice in two different cell types
- spatial segregation
- these plants occur in dry environments
- still go through C3 photosynthesis
define “bundle sheath”
a cylinder of cells that surrounds each vein
what is xylem made up of? what is xylem’s main purpose?
to easily transport water throughout the plant
- tracheids (unicelular, narrow)
- vessel elements (multicellular, wider, unobstructed pipelines)
- water enters/exits through “pits”
how is water moved through the plant?
- pulled from above by an evaporative pipeline
- evaporation of water from leaves causes water to flow up form the soil
- hydrogen bonds between water molecules allow water to be pulled up the xylem
what are the two main threats to xylem?
- pipelines collapsing inward
- cavitation (caused by freezing, air leaks, or bubbles/ when water is abruptly replaced by water vapor)
what does phloem do? what is is made up of?
phloem transports nutrients and sugars throughout the body (phloem sap)
- sieve elements (each one is accompanied by a companion cell which is alive and fully functional)
- moves nutrients from source (leaves) to sinks (roots, fruits, young leaves, anything that needs carbs)
rhizosphere
phloem feeds this:
-the soil layer that surrounds actively growing
roots
• The rhizosphere is rich in microbial populations that aid in decomposition
what are casparian strips?
hydrophobic material that surrounds each cell at the endodermis
-roots can be very selective as to what material enters the xylem
how do plants benefit from fungi/fungal cells?
almost all plants do this! they form a symbiotic relationship with fungi
-mycorrhizae are fungi that form associations with plant roots, extend the surface area of the roots for plant, plant gives the fungi sugar in return
how do plants benefit from bacteria?
symbiotic relaitonship! this is how they get nitrogen
- Some free living soil bacteria are capable of nitrogen fixation
- bacteria enter the root through a root hair or a break in the epidermis
- bacteria reside in a root nodule
what are epiphytes?
- grow on trees
- absorb nutrients form rainwater that accumulates in leaves/on the bark of the host
carnivorous plants
venus fly traps, pitcher plants
get nutrients by trapping insects
