Roots and soils Flashcards
embryonic root
radicle
what is the function of the root cap?
to protect the tissue
what is the endodermis?
innermost layer of the cortex
what is the function of the endodermis?
regulate what minerals come in and doesn’t let them escape
what is the root cap made up of?
parenchyma cells
what are the three zones on a root?
zone of maturation, zone of elongation, and meristematic zone
what does the procambium become?
xylem and phloem
what does a caspian strip do?
blocks water from moving toward the cell wall
what is the pericycle?
a single layer of cells in between the pith and endodermis
what does the pericycle generate?
lateral root and becomes meristematic
what is a passage cell?
cell that lets water/ certain minerals through
what is the cortex?
tissue composed of parenchyma cells lying between the epidermis and inner tissues
what is the function of the cortex?
store food
How to distinguish between monocot and eudicot roots?
eudicot roots have xylem arranged in a star formation
is there pith in a eudicot?
no
In a eudicot root, what cells fill the cortext (hint stores food)
parenchyma cells
what is the function of the vascular cylinder?
conduct water or food
what are the specialized food storage roots?
tubers
on tubers, what kind of bud develops?
adventitious
what do pneumatophores do for the roots beneath?
facilitate the exchange of oxygen and carbon dioxide
what are pneumatophores?
spongey outgrowths from the roots
which direction do pneumatophores grow and why?
grow up in order to aerate the roots
instead of photosynthesis, what do pneumatophores do?
cellular respiration
what is an example of a plant that would have pneumatophores?
mangroves
in an aerial roots, what does the velamen of the epidermis do?
slows down water loss because of how thick it is
what is a prop?
an adventitious root that keeps the plant upright
what is a contractile specialzed root?
the bulb moves lower as the roots grow and pull it down
what is a buttress root?
prop root that is woody
what is a dodder?
a weedy species that entangles around plants
parasitic plants have what?
specialized organs to pierce stems
what are peglike projection from a parasitic host?
haustoria
what are peglike projections that parasitize their host?
haustoria
what are epiphytes?
plants that grow on other plants and obtain moisture and nutrients from the air and rain
what is an epiparasite?
plant that obtains some or all of its carbon from fungus rather than photosynthesis
what is mycorrhizae
fungal interactions with root systems
what is the function of mycorrhizae?
increase ability to absorb phosphorous in the soil
ectomycorrhizae is where?
stays on the surface
endomycorrhizae is where?
inside
where do root nodules start at
the root hairs
what happens when a nodule is formed?
root hair becomes coiled and bacteria can pierce the cell wall
what does the bacteria do to the cortex when forming nodules
makes it larger so the nodule can be created
what is the solid portion of the soil
minerals and organic materials
what are pore spaces?
spaces between solid particles that contain water and air
soil is divided into what?
horizons
what are horizons?
layers in the soil at different stages of development
what are horizons?
layers in the soil at different stages of development
what is horizon A?
the top soil
what is horizon C?
the bottom layer that is broken down to create the other layers
what is weathering?
breaking soil down into smaller fragments
how does climate affect soil?
it affects weathering
low rainfall leads to
little weathering
temperature extremes lead to
breaking rocks
climate also affects what in soil?
mineral composition
bacteria and fungi are present in the soil to do what?
decompose organic matter from leaves and dead animals
what is humus?
partially decomposed organic matter
acidic humus yields…
better mineral solubility
steep feature leads to
erosion
flat areas leads to
poor drainage
what is loam?
good balance of all three particles
what are the three particles that make up soil?
sand, silt and clay
how does particle size affect soil characteristics?
surface area and packing capacity (porosity)
clay particles are
negatively charged
clay particles do what with cations?
exchange, attract and retain them
what is the best soil for agriculture?
loams; a balanced mix of all three particles
why is loam the ideal soil type for ag?
it creates the right combination of water – holding capacity against gravity and porosity
what are micelles?
sheet like, negatively charged held together by chemical bonds (in clay)
what is soil structure?
arrangement of particles into groups called aggregates
what is hygroscopic water?
water in the soil that plants can’t use
why can’t plants use hygroscopic water?
because it is physically bound to the soil particles
what is capillary water
water held in pores due to gravity
where is most of the water used by plants is found?
capillary water
the amount of water available in soil is determined by…
structure, organic matter, density/ type of vegetation, location of underground water tables
what is field capacity?
water remaining after draining by gravity
permanent wilting point?
the point at which if a plant does not get water, it will die
permanent wilting point?
the point at which if a plant does not get water, it will die
what does the pH affect?
mineral availability
what happens when the pH of the soil drops and vise versa?
some minerals become more accessible
to increase the pH of the soil what do you add?
calcium or magnesium
to decrease the pH of the soil what do you add?
sulfur or sulfur containing compounds
