DAT bio Chapter 10 plants Flashcards
Endosperm:`
storage material, provides the
embryo with nutrients.
Embryo: consists of 4 parts:
Radicle: first to emerge, develops into root,
anchors the plant into soil.
● Hypocotyl : bottom region of young shoot.
● Plumule: develops into leaves.
● Epicotyl : top region (shoot tip).
What is Germination
the sprouting of a seedling from a
previously dormant state when environmental
conditions are favorable. Water is the most
important condition. The seed absorbs water
(imbibition) which breaks the seed coat and
initiates growth
Plant growth takes place via mitosis at ______
meristems
What is primary growth
s vertical growth occurring at
apical meristems (located at tips of roots and
shoots). Occurs before secondary growth
Primary growth (Root Growth: root cap covers roots protecting the apical meristem. The root tip has three zones: Name them
Zone of division: where apical meristem cells
are located and divide.
Zone of maturation: cells differentiate to
specific plant tissue
Zone of elongation: above apical meristem,
cells absorb water and elongate.
Secondary growth
is horizontal growth occurring
at lateral meristems (vascular cambium and
cork cambium). Only occurs in woody plants
Vascular cambium
a ring of meristematic tissue
located between primary xylem (closer to center)
and primary phloem (closer to outer edge). Cells
produced inside the ring of vascular cambium
become secondary xylem (forms wood along with
pith) and cells outside become secondary phloem
(forms bark with cork and cork cambium). New
xylem is produced every year (forming growth
rings) whereas new phloem replaces old phloem.
Cork cambium
a ring of meristematic tissue
located outside the phloem. Produces cork, the
outermost protective layer.
Ground tissue
provides structural support,
makes up most of the plant’s mass
Three parts of ground tissue
Parenchyma: filler tissue, makes up the bulk of plant, thin cell walls. Collenchyma: extra support (e.g. in areas of active growth), irregular cell walls. Sclerenchyma: provides main structural support, thick cell walls.
Vascular tissue:
transports materials from a
source to a sink (source to sink theory). The
stele is formed by xylem, phloem, and the
pith (made of parenchyma) in the center of the
plant for transport.
What does phloem transport?
: transports sugars from leaves
(source) to roots and other areas (sink).
Made of sieve cells (long cells, lacking
organelles, connected to form a tunnel for
transport) and companion cells which are connected to sieve cells, contain organelles
for metabolic functions).
What does xylem transport?
\: transports water from roots (source) to leaves (sink) and provides structural support. Made up of tracheids (long and thin, water travels through pits in their tapered ends) and vessel elements (short and stout, water travels via perforations in cell walls).
Dermal tissue
outer layer of the plant.
Provides protection and regulation.
expanding on dermal tissue:
what is epidermis
Epidermis: covered by cuticle (waxy layer)
which limits water evaporation.
expanding on dermal tissue:
what is root hairs
increase surface area of roots
for greater nutrient and water uptake.
Water uptake in the roots happens using what pathway?
symplastic pathway (inside the cell’s cytoplasm)
Water uptake in the roots occurs via the
symplastic pathway (water movement through the cell’s cytoplasm)
or the __________ pathway
apoplastic pathway ( water movement outside the cell, but within the cell wall.
What is the casparian strip
(made of
fat and wax) is an impenetrable substance in the
cell walls of the roots. It forces water coming from
the cell walls (outside) into the cytoplasm of the root cells for filtering before
entering the rest of the plant.
Stomata are
_____ when CO2 concentration is low (allows for CO2
intake and photosynthesis) and ______ when CO2
concentrations are high and when temperatures
are high (prevents water loss via transpiration).
Open, closed
Palisade mesophyll
closer to upper
epidermis, tightly packed cells that carry out
photosynthesis.
spongy mesophyll
closer to lower epidermis,
loosely-packed allowing for gas exchange.
Bundle sheath cells do what
surround and protect the
vascular bundle
(movement of water) Cohesion-tension theory:
: transpiration, the
driving force, causes water to evaporate from
the stomata and leads to a transpirational
pull . This cohesive force (between similar
substances, e.g. the water molecules) pulls the
water column upward.
(movement of water)
Capillary action:
an adhesive force (between
dissimilar substances) due to attraction
between water and xylem vessels that causes
water to climb upwards
(movement of water)
Root pressure:
builds up in roots to produce
an osmotic gradient which drives water from
soil into the roots
(movement of food)
Pressure flow hypothesis:
source cells produce
sugar and load it into phloem → increased sugar
concentration creates a gradient that pulls water
into phloem → turgor pressure in phloem increases,
resulting in bulk flow movement of sugar from
leaves down to roots`
Plant hormones:
ethylene
gas that increases fruit ripening.
Plant hormones:
auxins
cause cell growth. Work with
cytokinins. Responsible for plant tropisms
(growth in certain directions). Auxin
concentrated on one side of a stem leads to
asymmetric growth.
Phototropism
growth towards light.
Gravitropism
growth away from pull of
gravity.
Thigmotropism
growth in response to
contact (e.g. vine growing up a wall)
Cytokinins
regulate cell differentiation and
division with auxins. Can prevent aging.
Gibberellins
responsible for stem and shoot
elongation, elimination of dormancy of a seed,
flowering, fruit production, leaf and fruit death.
Abscisic Acid:
: functions during stress.
Promotes dormant seeds, closes stomata
(drought), inhibits growth.
Alternation between diploid and haploid.
Two haploid gametes fuse producing diploid
zygote → zygote becomes sporophyte via mitosis
→ in their sporangia, sporophyte undergoes
meiosis to produce haploid spores → spore
becomes gametophyte via mitosis →
gametophyte produces gametes → cycle repeats.
Homosporous plants:
bisexual gametophyte,
produces one type of spore
Heterosporous plants:
produce two types of
spores; microspores (male) and megaspores
(female).
(bryophytes)
Nonvascular plants
therefore are small and short. Found in
moist habitats, grow horizontally to remain close to
water and nutrients. Contain rhizoids (hair-like
projections) which aid in water absorption and
minor anchorage
nonvascular plants
mosses, hornworts,
liverworts
Majority of their life cycle is spent in what stage
; they have a reduced
sporophyte which depends on and is attached to
the gametophyte.
Tracheophytes
are what
vascular (contain xylem and
phloem), allowing them to grow vertically and tall
and have a root system for anchorage. Most of the
life cycle is spent in the sporophyte stage
Seedless tracheophytes:
(lycophytes and
pterophytes, e.g. club moss, quillworts, fern,
horsetail). Mostly heterosporous with
flagellated sperm (can move on their own).
Seed-bearing tracheophytes
all heterosporous
Gymnosperms:
The first seeded plants. Seed
not protected. E.g. conifers such as firs, spruce,
pine, redwood. Sperm is not-flagellated and is
dispersed in seeds by wind.
Angiosperms:
Most abundant plant.
Flower-bearing and fruit-producing (plant ovary,
protects seeds). Sperm is not-flagellated and
is dispersed by wind or animals often as
pollen. Can exhibit double fertilization
(female gamete fertilized by two male sperm).
Petals do what
attract animals to achieve pollination
stamen is what
male plant sex organ. Composed of
anther (site of microspore formation) and
filament (supports anther).
microspore undergoes what _______
mitosis to form
generative cell (contains sperm) and tube
cell which combine to form pollen
Pistil :
female plant sex organ. Composed of
stigma (top), style (tube leading to ovary), and
ovary (contains ovule or egg)
Steps for fertilization
Pollen lands on stigma → tube cell elongates down style forming pollen tube → generative cell travels down pollen tube to ovary → splits forming two sperm cells (double fertilization)
One sperm cell meets ovule to form the
_____. Ovary develops into _____,
which is eaten by animals and deposited in
a new location (gene migration)
seed or embryo,
fruit
the other sperm cell combines with ovule’s
______ to form the _____
polar nuclei
endosperm
Cotyledons
first leaves to appear on seedling.
Contain nutrients from seed to feed the growing
seedling
Monocotyledons (monocots)
single cotyledon long narrow leaf paralell veins vascular bundles scattered floral parts in multiples of 3
Dicotyledons
Two cotyledon broad leaf network of veins vascular bundles in a ring floral parts in multiples of 4 or 5
Plants have a symbiotic relationship with what
nitrogen fixing bacteria
Bacteria fixes atmospheric nitrogen into what
usable form for plants, in return, plants produce food for bacteria using photosynthesis
Nitrogen fixation
(nitrogen fixing bacteria)
step 1
(in root nodules of
legumes) fix atmospheric nitrogen (N2 ) to
ammonia (NH3 ) and ammonium (NH4
+ ).
Nitrogen fixation
(nitrifying bacteria)
step 2
convert ammonia and
ammonium to nitrites (NO2
- ) and then to nitrates
(NO3-
Nitrogen fixation
step 3
Nitrates are taken up by plants (assimilation of
nitrogen) and incorporated into amino acids
and chlorophyll. Animals (consumers) acquire
nitrogen by eating plants (producers)
Nitrogen fixation
step 4
Detritus
dead decaying plants and animals
provides soil with nitrates.
Nitrogen fixation
step 5
Denitrifying bacteria
convert nitrates back to
atmospheric nitrogen
