Lecture: Primary Meristems Flashcards
meristems __ and __ cells
add; organize
meristems add cells by _-
mitosis
primary meristems are first formed in the_
embryo
embryonic meristems are _-
seeds
what is the function of the seed coat?
protection
function of endosperm
food supply for embryo
endosperms are found in what plant group(s)?
angiosperms only
endosperms are ___, they have 2 cells from __ and 1 cell from __
triploid; mom; dad
endosperm comes from __ fertilization
double
what are cotyledons?
seed leaves
initially, all cells in embryo can __
divide
suspensor breaks down once
embryo is large enough
once the embryo has reached it maximum size __ must occur for growth to continue
germination
what are the 2 apical meristems?
root, shoot
initial cells divide by
mitosis
what is the hypocotyl?
area between the radicle and cotyledons
which plant group has 2 cotyledons?
dicots
which plant group has one cotyledon?
monocots
is it more advanced to have one or two cotyledons?
1
initially, what cells in the embryo can divide?
all of them
when a cell divides, one daughter cell becomes __ and the other ___
the derivative and the other remains the initial
which daughter cell forms the 3 primary meristems?
derivative
what is another name for the cotyledon in monocots?
the scutellum
what is the function of the scutellum?
absorbs nutrients from the endosperm
what is the epicotyl?
area above cotyledon
what is the plumule?
epicotyl and leaves
some monocots have what 2 protective structures?
- coleoriza
2. coleoptile
what is the function of the coleoriza?
protect root
what is the function of the coleoptile?
protect plumule
what are the 3 requirements for seed germination?
- O2
- water
- temperature
(sometimes light)
why do seeds need water to germinate?
most are very dry, and water is needed for metabolic processes
why do seeds need O2 to germinate?
required for Rs
aside from the main 3, what other requiremnets might a seed have for germination?
- digestive enzymes of animal
- rainfall reaching inhibitors in seed coat
- crached mechanically
- heat from fire
- capopy opening
why is the root the first organ to emerge from the seed?
the plant needs to anchor in the soil and be able to absorb nutrients and water
what is contained in the quiescent centre of the root tip?
initials
what is the root cap made of?
parenchyma and slimy sheath (mucigel)
each cell in the root cap lives for __ days
4-9
what possible structures can break the soil first in epigeous plants?
- hypocotyl
2. cotyledon
what possible structures can break the soil first in hypogeous plants?
- epicotyl
2. coleoptile
what is the function of cotyledons on hypogeous plants?
nutrition
what is the function of cotyledons of epigeous plants?
photosynthesis
if the cotyledons emerge first, where does the plumule emerge?
from base of cotyledons
how does the plumule emerge from coleoptile?
through a hole
what are the 4 regions of stem?
- epidermis
- cortex
- vascular
- pith
the tunica divides to add __
surface area
the corpus divides to add__
girth
the tunica divides __
anticlinally
the corpus divides __
periclinally
the divisions of the tunica produce which meristem?
the protoderm
the divisions of the corpus produce which meristem?
the pith meristem
the divisions of both the tunica and corpus contribute to __ meristem
peripheral
what type of meristems exist at the nodes?
axillary
what are the 4 fates of axillary meristems at nodes?
- branch (default)
- develop partially
- inactive and waiting for signal
- convert to floral meristems
development of axillary meristems is controlled by __
apical meristem
what is the effect of apical meristem’s PGS’s on axillary meristems?
prevents branching, unless axillary meristems are below the effective difussion level
what type of climate is stable all year?
tropical
what climates are seasonal?
mediterranian and temperate
what are the 3 strategies for growth?
- growth (tough it out)
- hide and wait
- give up, start over
what is a lifeform?
form of plant growth
lifeforms are related to __ and controlled by ___
environment; position of meristems
what 2 things does Raunkiers lifeforms take into account?
- where is next year’s growth?
2. how is it protected from stresses?
what is an advantage of height?
access light
what are two disadvantages of height?
- takes time, perenial tissue is expensive
2. potential for damage to meristems
what is a perenating organ?
organ with a meristem in it
what are Raunkier’s 5 lifeforms?
- phanerophyte
- chamaephyte
- hemicryptophyte
- cryptophyte
- therophytes
where are the perenating buds of phanerophytes located?
far off the ground
phanerophytes are typically what types of plants?
trees, shrubs, epiphytes that grow on them
what type of plants are chamaephytes?
shrubs: short woody plants with multiple stems
where are the perenating buds located on chamaephytes?
30-100 cm off ground; below snow cover for insulation from winter winds
where are perenating buds located in hemicryptophytes?
just below soil surface, or under dead levaes (“half hidden”
what sort of climates have hemicryptophytes?
temperate
example of hemicryptophyes
carrots, daisies, dandelions
where are the perenating buds located in cryptophytes?
under soil, mud, or water
what sorts of climates have cryptophytes?
mediterranean
cryptophtes are often found where growinf season is __
long
examples of cryptophytes
bulbs, corms, deep rhizomes
what type of plants are therophytes?
annuals
therophytes are characteristic to what climate?
tropical
therophytes spend the unfavourable growing season as
seeds
example of therophytes
weeds
