Plant Structures and Plant Growth Flashcards
What do vascular plants for hydration and movement of products of photosynthesis?
hydration with water drawn from soil (xylem and roots)
bulk transport to move products of photosynthesis
What is the above ground and below ground anatomy of a vascular plant?
above ground: leaves, stems, and reproductive organs. collectively forming the shoot
below ground: roots
What is a leaf structure made up of?
blade, petiole (stalk), stipules
What are stipules?
scales or leaf-like appendages at the base of some leaves; protect the emerging leaf or bud
What are the 3 types of simple leaves?
undivided/entire, lobed, or toothed leaf blades
What are compound leaves?
blade divided into leaflets
each leaflet with own small ‘petiole’
What does it mean to be a palmately compound leaf?
leaflets attach at one point
What does it mean to be a pinnately compound leaf?
leaflets attach along a central axis = rachis
What is Phyllotaxy?
arrangement of leaves on stem
What are 3 types of phyllotaxy?
alternate arrangement
opposite arrangement
whorled arrangement
What is alternate arrangement of leaves?
one leaf per node, forming helical pattern around stem
what is opposite arrangement of leaves?
two leaves per node on opposite sides of stem
What is the function of leaves?
photosynthesis by chloroplasts - plants manufacture food (glucose) from carbon dioxide and water using energy from the sun
What are the 3 major tissues in a leaf?
the epidermis, mesophyll, and the veins
WHat is the epidermis?
sheets of cells that line the upper and lower surfaces
What is the mesophyll?
loosely packed or columnar photosynthetic cells
What is the veins?
system of vascular tubes or conduits that connects (transports water and glucose) the leaf to the rest of the plant
What do the upper and lower epidermal cells secrete on their surface?
a waxy cuticle
WHat does the waxy cuticle do?
limits water loss and CO2 diffusion into the cells
Where are stomata located? what is their function?
in the lower epidermis
allow CO2 and water to diffuse into and out of the leaf
What is the makeup of each stoma?
a pore on the lower surface of leaf formed by a pair of flanking guard cells
WHat do guard cells do?
allow stoma to function as valves that can open and close when they swell and shrink
what is the function of the lower spongy mesophyll?
when the air spaces surrounding are fiilled with CO2 they can use the CO2 for photosynthesis
What also occurs when stomata are open? (other than CO2 uptake)
transpiration - evaporative loss of water from leaves
What factors can contibute to opening anfd closing of stomata?
light, CO2 levels, and water loss
how do stomata cells open?
water moves into gurad cells by osmosis causing them to swell (dependent on K concentration in cells from active transport)
occuring when water is readily available and CO2 levels relatively low
how do stomata cells close?
potassium is actively transported out the cells, which causes water to move out by osmosis
causing guard cells to shrink closing off pores
occurs when water is limited and CO2 levels relatively high
What is the bundle sheath?
the photosynthetic cells arranged into a tightly packed sheath around the vascular tissue of a leaf; the sheath forms a protective layer around the vascular tissue
How do leaves begin to form?
as small bumps (leaf primordia), which from on the sides of the shoot apical meristem
what are the 4 types of tissue in plants?
meristematic tissue, dermal tissue, ground tissue, vascular tissue
What is meristematic tissue?
tissue regions or populations of cells which retain ability to divide throughout entire life of plant
What is the apical meristem?
are of primary growth - shoots and roots; increase plant length or height
what is the lateral meristem?
cambium - area of secondary growth : wood, bark; increases plant diameter
What is the shoot apical meristem?
tiny dome of cells at the very tip of each branch, totipotent cells that give rise to new tissues.
as new cells are added near the shoot tip, older cells stop to divide.
What does it mean to be a totipotent cell?
a cell capable of giving rise to any cell type
What did stem branching allow early plants to do?
to produce more sporangia (reproductive structures)
What did stem branching allow present-day plants to do?
support greater numbers of both reproductive structures (flowers and leaves)
In seed plants where do branches (stems) grow out from?
axillary buds
What are axillary buds?
meristems that from at the base of each leaf
What are the two layers of Dermal tissue?
Epidermis and Cuticle (functions earlier)
What makes up ground tissue?
bulk of non-woody plant tissue
parenchyma, collenchyma, sclerenchyma
What is the function of ground tissue?
structure/support. storage, photosynthesis
What is Parenchyma?
cortex (outer) and pith (inner) areas of stems and roots, mesophyll of leaves; sites of photosynthesis and storage
What is Collenchyma?
unevenly thickened primary cell walls; possess hemicellulose and cellulose; primary support tissue in young plants
What is sclerenchyma?
evenly thickened cell walls (lignin - stained red); mechanical support (strength) and protection, rigid support
What makes up a typical plant stem?
layer of epidermal cells
encloses parenchyma (cortex)
vascular tissues in a ring near outside of stem
sclerenchyma provides strength to vascular tissues area/stem
region inside ring of vascular bundles is the pith (parenchyma)
What is the arrangement of primary vascular bundles in a monocot stem?
scattered (randomly throughout)
What is the arrangement of primary vascular bundles in a dicot stem?
in a ring
What is the anatomy of the xylem?
water enters and exits xylem through pits, which allow the passage of water from one xylem conduit to another
what is a unicellular conduit called?
tracheids
what is a multicellular conduit called?
vessels
What re the three stages that allow water to be pulled from the soil?
evaporation of water from leaves causes water to flow from the soil
hydrogen bonds that form between water molecules allow water to be pulled through the xylem
the forces that develop in leaves must be large enough to overcome the capillary forces in the soil
What is the anatomy of the phloem?
mulitcellular sieve tubes which are connected end to end (transport of carbs)
companion cell is adjacent connected to sieve tubes by plasmodesmata
What does the companion cell do?
carries out cellular functions like protein synthesis
What is a source?
regions of the plant that produce or store carbohydrates (e.g. mature leaves, tubers)
What is a sink?
regions that need/use carbohydrates to fuel growth and respiration (e.g. roots, young leaves, developing fruits)
What is the anatomy of a root?
epidermis produce root hairs
inside is the cortex (parenchyma cells)
xylem and phloem center of root
surrounded by endodermal cells
root cap at end
WHat do root hairs do?
increase surface area
What do endodermal cells do?
controls the movement of substances into the xylem
WHat does the root cap do?
protect apical meristem
aid root penetration of soil
What is the root cap made out of?
a mass of parenchyma cells
What is the casparian strip?
band of lignin (hydrophobic material)
What does the Casparian strip do?
allows root system to control which substances enter the xylem. water and nutrient can gain access to the xylem only by pasing through the cytoplsm of the endodermal cells so are subject ot action of plasma membrane transport proteins
What are the 3 zones of the root tip?
zone of cell division
zone of elongation
zone of maturation
What is the zone of cell division?
made up of actively diving cells of the root meristem
what is the zone of elongation?
where newly fromed cells increase in length, thereby increasing the lenght of the root
What is the zone of maturation?
where the root cells begin to differentiate into special cell types
What happens to the root cap as it pushes through the soil?
gets damaged easily so is continuously replaced
how are the xylem and phloem organised in dicot roots?
in an X-shape in the center of the root
How are the xylem and phloem organised in ,monocot roots?
in a ring around the pith
What are the functions of roots?
anchor plant in soil
absorb water and dissolved nutrients
storage of carbs and water
conduct water and dissolved materials to aerial parts of plant
synthesis
What are the 2 types of root systems?>
taproot system
fibrous root system
What is the taproot system?
primary root grows downward, gives rise to lateral roots
primary root strongly developed, often enlarged
penetrate deeper into soil
what is the fibrous root system?
consists of groups of roots of similar size and length
do not penetrate as deeply into the soil
What are the advantages of a taproot system?
locate water and minerals deep in the soil; good at anchoring the plant ointo the soil
What are the advantages of a fibrous root system?
good at holding the soil together; allow the plant to absorb water and minerals over a large surface area closer to the surface of the soil
What happens to some carbohydrates trasnported to the roots?
spills out into the rhizosphere
what is the rhizosphere?
soil layer that surrounds growing roots
what do carbs supply in rhizosphere do?
stimulates the growth of soil microbes, important decomposers of soil organic matter
why is the decomposition of soil organic matter advantageous for plants?
provides essential nutrients from plants (eberythig enters plant by roots except CO2
what is a type of symbiosis between plant and fungi?
mycorrhizae
What do mycorrhizae do?
enhance nutrient uptake by the root system, by extending the range through fungal cells
fungi recieve carbs transported to roots by the phloem
What are ectomycorrhizae?
a sheath of fungal cells tha tsurroudn the root
what are endomycorhizae?
form highly branched structures, called arbuscules, that protrude into the interior of root (cortical) cells
what are nitrogen-fixing bacteria?
bacteria can convert nitrogen gas into biologically useful nitrogen compounds like ammonia
WHat are the 2 kinds of nitrogen-fixing bacteria?
nonsymbiotic bacteria (like cyanobacteria)
mutualistic bacteria (like Rhizobium)
How are lateral meristems different to apical meristems?
they surround the stem rather than occur at its tip
from after elongation is complete, increase diameter not length
become larger over time because as stem increases in diameter number of merisem cells needle to encircle stem increases
what are the 2 types of lateral meristems?
vascular cambium, cork cambium
what is teh vascualr cambium?
source of the new xylem and phloem (secondary)
What is the secondary xylem?
wood
what does a woody tree add each year in a ring?
earlywood xylem ring and latewood xylem ring
what is earlywood xylem?
porous and made up of thin-walled cells; they develop when rain and nutrients are abundant
what is latewood xylem?
densely-layered, strong, thick-walled cells; they develop toward the end of summer
what do the rings indicate? (clled waht?)_
growth rings - deteremine a trees age
where is functional xylem located?
in sapwood adjacent to vascular cambium
What is the heartwood?
center of the stem, does not conduct water, is often darker in colour due to added resins; more resistant to decay
what does the cork cambium do?
renews and maintains an outer layedr of cork that protects the stem that is actively increasing in diameter
what makes up the bark?
all material produced outside the vascular cambium (including the secondary phloem)
What makes up gymnosperm wood?
tracheids, rays and parenchyma. rekatively similar in proportion among gymnosperms
what makes up the angiosperm wood?
vessels, fibers, rays and parenchyma
