Plants Flashcards
Seed coat
- hard outer layer that covers and protects the seed.
Endosperm
- storage material, provides the
embryo with nutrients.
Embryo: consists of 4 parts (plants)
1) Radicle
2) Hypocotyl
3) Plumule
4) Epicotyl
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)
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 ______.
1) meristems
Primary growth is _______ occurring at
_______ (located at tips of roots and
shoots). Occurs before secondary growth.
1) vertical growth
2) apical meristem
Root Growth: _____ covers roots protecting the apical meristem. The root tip has _____ zones:
1) root cap
2) 3
Zone of division
- where apical meristem cells
are located and divide.
Zone of elongation
- : above apical meristem,
cells absorb water and elongate.
Zone of maturation
- cells differentiate to
specific plant tissues.
_______ is _____ growth occurring at _____ meristems (vascular cambium and cork cambium). Only occurs in woody plants.
1) Secondary growth
2) horizontal
3) lateral
Vascular cambium
- is a ring of meristematic tissue (contains undifferentiated cells, which are the building blocks of the specialized plant structures. ) located between primary xylem (closer to center) and primary phloem (closer to outer edge).
Cells produced _____ the ring of vascular cambium become _______ (forms wood along with pith) and cells _____ become ______ (forms bark with cork and cork cambium). New ______ is produced every year (forming growth rings) whereas new _____ replaces old phloem.
1) inside
2) secondary xylem
3) outside
4) secondary phloem
5) xylem
6) phloem
Cork cambium
- is 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.
1) Parenchyma
2) Collenchyma
3) Schlerenchyma
Parenchyma
- filler tissue, makes up the
bulk of plant, thin cell walls.
Sclerenchyma
- provides main structural
support, thick cell walls.
Vascular tissue (plants)
- transports materials from a
source to a sink (source to sink theory).
The _____ is formed by xylem, phloem, and the _____ (made of parenchyma) in the ____ of the plant for transport.
1) Stele
2) pith
3) center
Phloem
- transports sugars from leaves
(source) to roots and other areas (sink).
Phloem is made of _____ (long cells, lacking
organelles, connected to form a tunnel for
transport) and _______ (connected to sieve cells, contain organelles for metabolic functions).
1) sieve cells
2) companion cells
Xylem
- transports water from roots
(source) to leaves (sink) and provides
structural support.
Xylem is made up of ______
(long and thin, water travels through pits in
their tapered ends) and ______
(short and stout, water travels via
perforations in cell walls).
1) tracheids
2) vessel elements
Plants are made up of 3 types of tissues:
1) Ground tissue
2) Vascular Tissue
3) Dermal Tissue
Dermal tissue
- outer layer of the plant.
Provides protection and regulation.
Epidermis
- covered by cuticle (waxy layer)
which limits water evaporation.
Root hairs
- increase surface area of roots
for greater nutrient and water uptake.
Water uptake in the roots occurs via the
______ (inside the cell’s cytoplasm) or the ________ (outside the cell through cell walls).
1) symplastic pathway
2) apoplastic pathway
The _______ (made of fat and wax) is an impenetrable substance in the cell walls of the roots. It forces water coming from the cell walls into the ______ for filtering before
entering the rest of the plant.
1) Casparian strip
2) cytoplasm
Leaves are covered by an ______,
covered by a waxy _____.
1) epidermal layer
2) cuticle
_______ in the lower epidermis open and close, allowing for _______. Water _____ to the guard cells makes them turgid, opening the stomata. Stomata are ____ when CO2 concentration is ____ (allows for CO2
intake and photosynthesis) and ____ when CO2 concentrations are _____ and when temperatures are ____ (prevents water loss via transpiration). A balance must exist between opening stomata for
food production via photosynthesis and closing stomata to prevent _____ (desiccation).
1) Stomata
2) gas exchange
3) influx
4) open
5) low
6) closed
7) high
8) high
9) water loss
(leaf) Between the upper and lower epidermis is the
_______.
1) mesophyll
2 types: 1) Palisade 2) Spongy
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
- surround and protect the
vascular bundle.
Movement of water in plant involve:
1) Cohesion-tension theory:
2) Capillary action:
3) Root pressure:
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.
Capillary action
- an adhesive force (between
dissimilar substances) due to attraction
between water and xylem vessels that causes
water to climb upwards.
Root pressure
- : builds up in roots to produce
an osmotic gradient which drives water from
soil into the roots.
Movement of food
1) Pressure flow hypothesis:
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.
Different plant hormones include:
1) Ethylene
2) Auxins
3) Cytokinins
4) Gibberellins
5) Abscisic Acid
Ethylene
- : gas that increases fruit ripening.
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.
Types of Tropisms due to Auxin
1) Phototropism
2) gravitropism
3) Thigmotropism:
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:(plant)
- functions during stress.
Promotes dormant seeds, closes stomata
(drought), inhibits growth.
Plants alternate between ____ and _____
1) diploid
2) haploid
Two haploid gametes fuse producing _____
zygote → zygote becomes sporophyte via _____ → in their _____, sporophyte undergoes _____ to produce haploid spores → spore becomes gametophyte via mitosis →
gametophyte produces gametes → cycle repeats.
1) diploid
2) mitosis
3) sporangia
4) meiosis
Homosporous plants:
- bisexual gametophyte,
produces one type of spore.
Heterosporous plants
- : produce two types of
spores; megaspores develop into the female
gametophyte, while microspores become the
male gametophyte.
Nonvascular plants (e.g. mosses, hornworts,
liverworts),
- 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. - Majority of their life cycle is spent in the
gametophyte stage ; they have a reduced
sporophyte which depends on and is attached to the gametophyte.
e.g.: Bryophytes
Tracheophytes
- are 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.
Includes: 1) Seedless tracheophytes and 2) seed-bearing tracheophytes
Seedless tracheophytes
- (lycophytes and
pterophytes, e.g. club moss, quillworts, fern,
horsetail). Mostly heterosporous with
flagellated sperm (can move on their own).
Additionally, seedless tracheophytes have
independent gametophyte and sporophyte
life-cycles.
Seed-bearing tracheophytes \
- (all heterosporous)
Includes: Gymnosperms and angiosperms
Gymnosperms
- The first seeded
plants. Seed not protected. E.g. conifers
such as firs, spruce, pine, redwood.
Most gymnosperms have
nonflagellated sperm that is
dispersed in seeds by wind.
Angiosperms:
- Most abundant plant.
Flower-bearing and fruit-producing
(plant ovary, protects seeds). Sperm is
nonflagellated and is dispersed by
wind or animals often as pollen. Can
exhibit double fertilization (female
gamete fertilized by two male sperm).
Flower Structures
1) Petals
2) Stamen
3)Pistil (Stigma, Style, Ovary)
Petals
- attract animals to achieve pollination.
Stamen
- male plant sex organ. Composed of
anther (site of microspore formation) and
filament (supports anther). - Microspore undergoes mitosis to form
generative cell (contains sperm) and tube
cell which combine to form pollen.
Pistil:
- female plant sex organ. Composed of
three parts: Stigma, Style, Ovary
Stigma (plant)
- The top of the pistil and
the site of where pollen lands for
germination.
Style
- Tube that leads to the
ovary.
Ovary
- Stores the ovule (egg).
Pollen lands on ______ → tube cell elongates down style forming ______ → generative cell travels down pollen tube to ______ → splits forming two sperm cells (______)
1) stigma
2) pollen tube
3) ovary
4) double fertilization
One sperm cell meets ovule to form the
seed or embryo. _____ develops into fruit,
which is eaten by animals and deposited in
a new location (______).
1) ovary
2) gene migration
The other sperm cell combines with ovule’s
polar nuclei to form the _____.
1) endosperm
The ________ (female gametophyte) is known as the ______ and develops within the ovule.
1) megagametophyte
2) embryo sac
Monocotyledons vs Dicotyledons
Monocotyledon:
- Single cotyledon
- Long narrow leaf, Parallel veins
- Vascular bundles scattered
- Floral parts in multiples of 3
- Fibrous fine root system near
surface
Dicotyledons:
- Two cotyledon
-Broad leaf, Network of veins
-Vascular bundles in a ring
-Floral parts in multiples of 4 or 5
-Single taproot with branching
Plants have a __________ with
_______ bacteria. Bacteria fix atmospheric ______ into a usable form for plants; in return, plants produce food for bacteria via ______.
1) symbiotic relationship
2) nitrogen-fixing
3) nitrogen
4) photosynthesis
Nitrogen fixing bacteria
- (in root nodules of legumes) fix atmospheric nitrogen (N2) to ammonia (NH3) and ammonium (NH4+).
Nitrifying bacteria
- convert ammonia and ammonium to nitrites (NO2-) and then to nitrates (NO3-).
______ are taken up by plants (assimilation of
nitrogen) and incorporated into _____
and ______. Animals (consumers) acquire
nitrogen by eating plants (producers).
1) nitrates
2) amino acids
3) chlorophyll
Detritus
- dead decaying plants and animals
provides soil with nitrates.
Denitrifying bacteria
- convert nitrates back to
atmospheric nitrogen.
