Chapter Five: Roots Flashcards
underground part of a plant
roots
3 major functions of roots
- anchor plant to substrate
- absorb, transport, and store water and minerals
- absorb oxygen
two main types of roots
- taproots
- fibrous roots
taproots are primarily found in ___
monocots
in taproots, the radical becomes the ___
mature root system
fibrous roots are primarily found in ___
dicots
in fibrous roots, the radical ___ a few days after sprouting
dies
in fibrous roots, the mature root system develops from ____
adventitious roots from the meristem
four areas of the root tip
- root cap
- zone of cell division
- zone of elongation
- zone of maturation
the root cap is a cluster of ____ that function to ___
parenchymal cells
protect the growing tip of the root
a root will continue to grow until ____
its root cap is worn off
the root cap also secretes a ____ that functions to ___
slimy substance
lubricate the root’s passage through the soil
the zone of cell division consists of the ____; it is where most ____ takes place
apical meristem
cell division
the ___ merges with the apical meristem
zone of elongation
what do cells do in the zone of elongation
grow several times their original length and somewhat wider
which structure inside the cells forms in the zone of elongation
tiny vacuoles merge and grow together into one or two large vacuoles
cells in the zone of maturation ____ and ____ also form here
differentiate into cell types
root hairs
root hairs are extensions of the ____
epidermis
3 functions of root hairs
- absorb water and minerals
- adhere to the soil
- increase total absorptive surface for the root
refines and regulates water’s passage into and out of the vascular stele
endodermis
the endodermis is ___ thick
one cell layer
bands that surround endodermal cells that only allow water to pass through the face and rear
Casparian strips
wax that is in casparian strips
suberin
meristematic tissue in roots
pericycle
the pericycle surrounds ___ and sits just inside the ___
vascular tissue
endodermis
the pericycle is ___ thick
one cell layer
the pericycle gives rise to ___
lateral roots
lateral roots grow when ___ or ___
root cap wears off and root stops growing or in the zone of maturation while apical growth is still occurring
which tissues do lateral roots have to grow through
endodermis, cortex, and epidermis
roots that are modified to enlarge and store large quantities of starch and other carbs
storage roots
the starch and carbs help in storage roots can later be used for ___
extensive growth
some plants have ____, especially plants in arid environments or plants that live where precipitation is rare
water storage roots
spongy roots located on plants that live in water that extend above the water to enhance gas exchange
pneumatophores
why are pneumatophores necessary
plants that live in the water might not get enough gas exchange in their roots because oxygen concentration of water is low
roots that function to prevent loss of moisture
aerial roots
roots that function to pull the plant deeper into the soil
contractile root
huge roots toward the base of a tree trunk that give the tree great stability
buttress roots
when are parasitic roots beneficial
some plants do not produce chlorophyll, so they have to rely on chlorophyll producing plants for their nutrition; these roots can parasitize the chlorophyll producing plant to gain access to this
as association that most plants have with fungi
mycorrhizae
mycorrhizae greatly enhances the plants ability to ___, ___ and ___
eat, drink, and breathe from the soil
mycorrhizae can help get rid of ___ for the plant
nematodes or other harmful things
mycorrhizae can sometimes connect ____
all the plants in a community
why is it so difficult for a grassland to grow back after being tilled
the mycorrhizal connections are cut, which take thousands of years to form; therefore, the land will probably just grow back as a forest
nitrogen fixing bacteria
rhizobium
plants cannot convert nitrogen gas to ____
usable forms
rhizobium produce the ___ necessary to convert nitrogen gas into something that plants can use
enzymes
contain large amounts of rhizobium on a plant
root nodules
