Plant Form and Function Flashcards
What is a tissue? Give an example.
A group of cells consisting of one or more cell types that together perform a specialized function.
ex. xylem
What is an organ? Give an example.
Several types of tissues that carry out particular functions.
ex. roots, stems and leaves
Where do plants sustain growth?
Apical meristems
Describe some characteristics of apical meristems.
- facilitate primary growth
- populations of pluripotent stem cells
- make the plant
- axial growth (growth in length)
true or false; the shoot apical meristem makes all of the cells below ground
false, that is the role of the root apical meristem
true or false; the root apical meristem makes all of the cells above ground
false, that is the role of the shoot apical meristem
What is the function of lateral meristems?
adding thickness to plants, in a process called secondary growth.
What are the 2 lateral meristems?
cork cambium and vascular cambium
what is the function of the vascular cambium?
adding layers of secondary xylem (wood) and secondary phloem (inner bark) in woody plants
what is the function of the cork cambium?
replaces epidermis with tougher and thicker periderm (outer bark).
where is the cork cambium located with respect to the vascular cambium
external to the vascular cambium
what comprises the dermal tissue system in non-woody plants. what is their function?
epidermis - protects plant
cuticle - prevents water loss from epidermis
what is the dermal tissue system comprised of in woody plants. what is its function?
epidermis in younger regions of plant
periderm in older regions of plant
both protect the plant
what is the function of the epidermis in roots?
allows for water to enter
what is the function of the epidermis in shoots?
guard cells - allow for gas exchange
trichomes - protect the plant from insects/water loss
what are trichomes?
outgrowths of the epidermis which protect the plants from insects/water loss/excess sun exposure
are living cells w/ a nucleus
what type of trichome has accumulated specialized metabolites for plant defence?
glandular trichomes (big ball on end)
what is the function of the dermal tissue system?
to protect the plant
what is the function of the vascular tissue system?
long distance transport between roots and shoots and provides mechanical support.
What is the function of the xylem?
Transports water and dissolved minerals upwards from roots to shoots.
What is the function of phloem?
Transports organic nutrients from where they are made to where they are needed.
The vascular tissue system of a shoot/root is collectively called the ____.
Stele
How is the stele organized in angiosperm roots?
Into one central vascular cylinder
How is the stele organized in angiosperm shoots?
In vascular bundles with the strands of xylem interior to the strands of phloem.
What is the function of ground tissue?
Not just filler, also includes cells specialized for storage, photosynthesis and support.
Ground tissue internal to vasculature is called ___
pith
ground tissue external to vasculature is called ___
cortex
describe the structure and function of parenchyma cells.
- thin, flexible primary cell walls made up of cellulose, other sugars and other proteins.
- lacking secondary cell walls
- large central vacuole
- least specialized, but perform metabolic functions
- retain ability to divide and differentiate into other cell types
-alive at maturity
describe the structure and function of collenchyma cells.
- thicker, more even cell walls
- grouped into strands to help support young shoot.
- flexible support without restraining growth
- alive at maturity
describe the structure and function of schlerenchyma cells.
- very thick cell walls made of lignin
- dead at maturity
- provides support
- either sclerid or fiber shaped
describe the shape of sclerid sclerenchyma cells
short, irregular w thick lignified cell wals
describe the shape of fiber sclerenchyma cells
long, slender and thread like
name some differences between monocot and dicot seeds.
monocot - lots of endosperm, embryo has one cotyledon, a coleoptile covers the embryo
dicot - embryo has 2 thick cotyledons, reduced endosperm
what is an embryonic root called?
radicle
what does seed germination depend on?
imbibition - uptake of water due to low water potential of dry seed.
what emerges first in seed germination?
the radicle
what is the function of roots?
anchoring plant into soil, absorbing minerals and water, storing carbs
what is the primary root?
the first root (and organ) to emerge from a germinating seed.
what are lateral roots?
roots branching from the primary root, which can also branch themselves.
what are root hairs?
tiny little hair-like extensions of root cells just behind the root tip that increase surface area of root, and therefore absorption.
describe mycorrhizal associations.
a plants symbiotic associations with soil fungi which increase the surface area of the plants roots, and allow for fungi to use carbs and carbon that plant produces.
What is the function of the root cap?
- protects the root as it moves through the soil
- cells are sloughed off,
- polysaccharide slime produced making it easier to push root through the ground
What are the three zones of cell growth in the root from nearest to the root tip up.
cell division (includes RAM), zone of elongation, zone of differentiation.
describe a typical dicot root cross section.
xylem arranged in central cross, with phloem in between each of the arms.
external to the vasculature is the pericycle, after which is the innermost layer of the cortex called the endodermis.
everything internal to endodermis comprises vascular cylinder.
between the endodermis and the epidermis is the cortex, filled with mostly parenchyma cells
what is the function of the endodermis?
regulating passage of substances from soil to vascular cylinder.
describe a typical monocot root cross section
same as eudicot but in the very center of vascular cylinder are core parenchyma cells, which are surrounded by little bundles of xylem and phloem.
what are lateral roots?
roots that come from pericycle of already established root. these roots are in line with xylem to facilitate transport.
describe the taproot system. in what type of plants is it likely to be found in?
- one main, long, vertical root developing from primary root
- allows for plants to be very tall
- found in eudicots and gymnosperms
describe the fibrous system. in what type of plants is it likely to be found in?
- small roots emerge from the stem, called adventitious roots.
- each root forms its own lateral roots which form their own lateral roots.
- found in monocots
name the root adaptations discussed in class and give an example.
prop roots - the roots of the hala trees prop up the top heavy tree
storage roots - beets store food and water in their roots
green roots - when the roots of plants without leaves perform photosynthesis
pneumatophores - roots of trees in swamps that project above the water so that the root is able to get oxygen
strangling roots - when seeds of one plant germinate in the branches of a host tree, and the roots are sent to the ground.
what organs is the shoot system made of ?
stems and leaves
what is the function of the shoot?
- photosynthesis
- transpiration (loss of water through open stomata)
- transport (via xylem and phloem)
- reproduction (via flowers, cones and leaves)
What are nodes?
Alternating system of points where leaves are attached to stem.
What are internodes?
the stem segments between nodes
what are axillary buds?
a bud that has the potential to produce a lateral shoot/stem. found at junctions between the stem and petiole (the stalk that attaches leaf to stem).
what are apical buds.
a bud that has the potential to elongate the shoot, found at the tip of the shoot.
what type of dominance causes plants to grow tall?
apical dominance, which also causes axial dormancy.
what is a rhizome?
a horizontal shoot that grows just below the soil.
what are stolons?
horizontal shoots that run across the surface, enabling a plant to produce asexually.
what are tubers?
enlarged ends of rhizomes/stolons specialized for storing food, like potatoes.
describe a eudicot stem cross section.
vascular bundles with phloem external to xylem arranged in a ring
what are the two types of water conducting cells in the xylem?
tracheids - tall, long, thin, short diameter
vessel elements - large, wide, short. perforated plates allow for water movement to go up and down.
what are the two sugar conducting cells of the phloem?
sieve tube elements - dead at maturity
companion cells - each sieve tube element has one that has nucleus and ribosomes that serve both itself and its sieve tube element.
what are sieve plates?
porous end walls of sieve tube elements that allow flow of fluid from cell to cell along sieve tube.
what is the shoot apical meristem physically shielded by?
leaf primordia
Which plant hormones stimulate primary growth?
auxin and giberellc acid
what is being elongated during primary growth?
internodes
describe the difference between simple and compound leaves.
simple: blade not divided into leaflets
compound: blade divided into leaflets
what are the two different types of compound leaves?
pinnate and palmate
what is the difference between pinnate and palmate leaves?
pinnate - leaflets attached along petiole
palmate - leaflets all attach to central location
what are stomata? what is their function?
holes interrupting the epidermis in leaves, allowing for;
- gas exchange
- water loss
- changes in potassium and calcium ions + plant hormones
what are guard cells? what are their function?
cells that flank each side of a stomata and regulate its opening and closing.
what time of day are stomata typically open? when are they closed?
open - day
closed - night
what is the ground tissue in a leaf called?
mesophyll
what are the two layers of mesophyll in eudicots? describe their structures.
palisade - long, tightly packed columns. on the upper portion.
spongy - like chunks idk on lower part with more space between them allowing for gas exchange.
how does the mesophyll look like in monocots?
uniform throughout leaf!
where does the majority of gas exchange occur in leaves?
mesophyll
what are a leaf’s vascular bundles also known as?
veins
each vein in a leaf are covered by a _____
protective sheath
describe the “stacking” of cells during primary growth.
undifferentiated cells from SAM will stack on top of older, differentiated cells.
what are some benefits of plants growing tall?
can get out of the shade, which allows for more photosynthesis
what are some disadvantages of plants growing tall?
- weight of shoot increases
- more support needed
- greater transport capacity needed
- not all problems can be solved by apical growth
what kind of growth does a lateral meristem facilitate
secondary
what tissues are derived by the vascular cambium?
secondary xylem + phloem
what tissue is derived by the cork cambium?
outer bark
where is secondary xylem found with respect to the vascular cambium
inside vascular cambium
where is secondary phloem found with respect to the vascular cambium
outside vascular cambium
what happens to pith after years of secondary growth?
gets crushed by secondary xylem
the vascular cambium is bifacial, meaning it ____
divides in both directions
the wood of a tree is also known as ___
secondary xylem
the inner bark of a tree is also known as _____
secondary phloem
the outer bark of the tree is also known as ____
periderm
the cork cambium replaces ______ with the thicker, tougher ______
epidermis, periderm
periderm includes all of the cell layers found in the outer bark, including:
cork, cork cambium, and phelloderm
do primary and secondary growth occur on the same part of the plant at the same time?
no!
while they both grow simultaneously on the same plant, they do not occur on the same part.
the younger parts of the plant are going to be undergoing primary growth, while the order parts are undergoing secondary growth, both at the same time.
in which parts of the plant does secondary growth occur?
stem and roots
in which plants does secondary growth occur?
gymnosperms and many eudicots
what are vascular rays?
rays of mostly parenchyma cells that move nutrients between secondary xylem + phloem, store carbs and aid wound repair.
are secondary phloem fibers dead or alive at maturity?
dead
describe the physical differences between late and early wood and the reasons for these differences
early - larger cell diameter and thinner cell walls as this wood grows in spring where is there is more moisture in the ground
late - smaller diameter and thicker walls because this wood grows in summer and autumn where there is less moisture in the ground
where is the vascular cambium located in in a typical woody stem?
before secondary growth - between primary xylem + phloem
where is the vascular cambium located in in a typical woody root?
also in between primary xylem + phloem
in secondary growth, is more secondary xylem or secondary phloem produced?
xylem
what is dendrochronology?
analysis of tree ring growth patterns used to study climate change.
what is sap wood?
the lighter coloured, actively conducting part of wood
what is heartwood?
darker, non-actively conducting part of wood
describe some softwood characteristics.
- uniform texture of secondary xylem
- coniferous
- predominantly tracheids
- some parenchyma
- resin canal
describe some hardwood characteristics.
- variable texture of secondary xylem
- colour variations
- eudicot
- fiber tracheids
where have we discussed that suberin can be found?
endodermis in root, and in cork oak
what are the 3 transport routes for water and solutes? describe them briefly
apoplastic - through cell wall
symplastic - through cytosol
transmembrane - across cell wall and plasma membrane
what is water potential?
property determining which direction water will flow in as a result of solute concentration and applied pressure.
water moves from ______ potential to _______ potential.
higher, lower
what is turgid? when is a plant cell turgid?
when a plant cell is swollen, bloated. it is turgid when the cell has lower water potential (higher solute concentration) than its surroundings.
what does turgor loss cause in plants? why?
wilting, due to the loss of water
changes in _______ open and close stomata
turgor pressure
describe the process by which a stomata will open.
guard cells accumulate K+ which gets pumped into vacuole, causing guard cells to become turgid, and the pore (stomata) between them opens.
efficient long distance transport of a fluid requires ___
bulk flow
what is bulk flow?
movement of fluid driven by pressure
where does most water and mineral absorption occur? why?
near root tips! bc there are root hairs and epidermis is permeable to water.
what is the last checkpoint for selective passage of minerals from cortex to vascular tissue?
endodermis
what is the casparian strip? what is its function?
waxy wall of endodermis made of suberin which blocks apoplastic transfer of minerals from cortex to vascular cylinder via cell walls?
water and minerals in apoplast must do what to get to the vascular cylinder?
cross plasma membrane of endodermal cell.
what regulates transport of minerals from soil to xylem?
endodermis
what is transpiration?
evaporation of water from a plant’s surface
describe the effect of the transpirational pull.
transpired water must be replaced by water travelling up from roots.
done by water vapour in leaves going down its water pressure gradient and exiting leaf via stomata.
as water evaporates, air-water interface retreats further into mesophyll cell walls
this surface tension pull water and minerals up from roots due to the negative pressure potential
what is the process of transporting products of photosynthesis through phloem called?
translocation
what is phloem sap? how does it travel?
sugar rich solution carried through phloem’s sieve tube elements.
goes from sugar source to sugar sink.
what is the difference between a sugar source and sink? what are some examples?
source - where sugars are made. ex. in chloroplasts of leaves
sink - where sugars end up. ex. roots, seeds, tubers
t/f; sugars can only move via symplastic ways.
false!
depending on the species, sugars can move in either symplastic or both symplastic and apoplastic ways.
