1. Morales 1
Biology 102
Exam 2 Study Guide Answers
Laura Morales
Presence/absence of seeds and Presence/absence of vascular tissue
Nonvascular Plants Vascular Plants
-Bryophytes -All otherplants
Seedless Seedbearing
-Bryophytes -Gymnosperms
-Lycophytes -Angiosperms
-Pteridophytes
Monocots Eudicots
-Having1 Cotyledon -Having2 Cotyledon
Angiospermsbreakdownintotwo
groups the Monocots and the Eudicots
Cotyledon=embrionicseedleadinseed
Gymnosperms– Have
“nakedseeds”- seedsnot
coveredbyfruit…
-Cycads-Tropical
-Gyngkos- grow anywhere
-Gnetphytes- Dessertplants
-Conifers-Evergreen
Angiosperms–Have seeds
coveredbyfruit
Nonvascular- Bryophytes,
(hornworts,liverworts,mosses) –Have
no true roots,stems,or leaves
Vascular- all otherplantswhichhave
TRUE ROOTS,STEMS OR LEAVES.
2. Morales 2
4 Categories of Tissues and Cell Types
1 .Dermal Tissue – Outercoveringof plantbody
(a)Epiderm- One cell thick,mostlackchloroplast
-Location= above groundcellspackedrightly&coveredwithcuticles
(waxy,waterproof material- preventswaterloss)
-Belowground cellsitwill be foundbutwithnocuticle
-Specializations –extensions“hairs”-increasesurface areaandslow airmovement
-Guardcells- pairsof “sausage shaped”cellsarounda“stoma” (small openingbetweenguardcells)
-Guart Cell function=letCo2+O2diffuse andforrelease of H2O
(b)Periderm- Woodystemsonlyoutercoveringmade of mostlyof thickwalleddeadcorkcells-because
part of “bark”
2. GroundTissue- Fillsinteriorof plant
(a)Parenchymacells- thinwalled,usuallywithlarge central vacuoles..instemsandleaveshave
chloroplast(justbelow epiderm
-Function-Storage,metabolicfunctions,photosynthesis,hormoneproduction,canreproduce
-Location- pith,cortex,fruitflesh,leaf mesophyll
(b)Collenchyma-Thickprimarycell walls.
-Function-Flexible support,cannotreproduce,occurinouterregionsof stems&petiolesand
alonglargerbeinsof leaves.*manymonocotsdonothave Collenchyma.
(c )Sclerenchyma- Thickhardenedsecondarycellwallsdeadatmaturity.
-Function-Support,protection
3. Vascular Tissue - For transport
(a) Xylem- Vasculartissue thatcarriesH20 + mineralsfromrootstowardleaves
-dead2 maturity,“woodof a plant”
-nocell membrane orcytoplasm…justcell walls!
*Xylem has two types of conducting cells tracheids and vessel elements
-Tracheids(foundinall vascularplants) –
longthincellswithtapperedcellsendwithpitswhere nosecondarycell wallforms
-Vessel elements(onlyinangiosperms)-
shofter,larger,diametercells,bluntof slightlytapperedendswithcompleteperforations
(secondaryandprimarycell wallsmissing)
*both Tracheids + vessel elements= lateral pits
-usually scherenchyma cells nearby for support
(b)Phloem- vasculartissuethatcarriesproductsof photosynthesisfromleavestowardroots
-Thistissie isliving
* containssieve tube membersand companioncells
-Sieve Tuve members (CONDUCTION SYSTEM)- Membrace linespores(siveplates) atjunction
-CompanionCells – nourishesandregulatesfunctionsof sieve tube members
-nearbysclerenchymacellsforsupport
4.Meristem– Cellscapable of cell division
(a) Apical-locatedattipof root,stems,andbranches
-resultin“primarygrowth”- growthinlengthwithaccompanyingdifferentiation
(b)Lateral (cambium)- locatedincylinderswithrootsandstems(vascularcambium&cork cambium)
-resultin“secondarygrowth”- growthinwidthwithsome stemsbecoming“woody”
3. Morales 3
Two types of Root Systems
Fibrous TapRoot
-Primaryrootdies many -Primaryroot withmany
Secondaryrootsremain lateral roots
-typical Monocots -typical Eudicot
Longitudinal structure of a root
Root Cap- Protectove-thick cell wall
-secrete slimy lubricant to help move through soil
Zone of Cell Division- Meristem tissue-rapid cell division
-reproduction
-cell at bottom move into root cap
- cells at top move into zone of elongation
Zone of Elongation- Cells grow in length causing root to
become longer
Zone of Maturation- Overlaps top of zone of elongation
-cells differentiate
-secondary growth begins…roots of cell start to
widen as result of vascular cambium
4. Morales 4
Cross Section Structure of a Root
Eudicot Monocot
Epidermis – “Soil water” enters here – root hairs increase surface area
Hypodermis- Only in Monocots (1 layer)
Cortex- Parenchyma cells- outer portion = converts sugar to starges and stores them
Endodermis- Ring at inner edge with specialized cells
-Casparian Strip Waxy causes H2O & minerals to go through
endodermis cells (not between them)
Vascular Cylinder Pericycle (meristem) – Branch roots grow here
Root Cross Section Eudicot Monocot
Phloem
Located in between
arms of the star shaped
xylem
Is the OUTER ring of
smaller circular clumps
of cells
Vascular Cambium
Between Phloem and
xylem
Between Phloem and
xylem
Xylem Star Shaped in the
middle
Inner ring of larger cells
Pith NO PITH PRESENT LOCATED AT CENTER
6. Morales 6
Internal Structures cross sections of Eudicots and Monocots
Epidermis– firstdermal tissue layer,outsidecoveringisthe cuticle whichpreventsH2Oloss,andhas
the stoma
In Eudicots the next layeris calledthe Cortex inMonocots the next layer isthe ground tissue
Cortex/Groundtissue – is filled withPENCHYMA CELLS (convertsugarintostarch)
-Supportfrom:turgerpressure inyoungstems
-Collenchyma&Sclerenchymainolderstems
- Photosynthesisinouterlayer(inherbasiousdicots)
Vascular tissue (vascular bundles located in different patterns)
In Eudicots – Have vascular bundles in rings
From outer toinner order…..
Phloem Vascular Cambium Xylem
……………Eudicotshave PITH in middle for support
In Monocots - Vascular bundles are scattered all through ground tissue
From outer toinner order……
Phloem Vascular Cambium Xylem Air Space
7. Morales 7
Leaves
-Where most photosynthesis occurs
-Leaves taken in CO2
- Leaves give off H2O (Transpiration)
-Leaves must balance between light and CO2 intake and H2O loss
Outer Structures of a leaf
Internal Structures of a leaf
Epidermis- Transparent layer on top and bottom of blade
Cuticule- Located on both upper and lower surfaces
of blade
Stomata- Most located on lower surfaces
Consist of – Stoma (opening)
-Guard cells- contain the stoma
When the stomato opens-
O2 moves into leaf, H2O is release
-Usually the stomata is open during day
unles leaf begins to dehydrate
Mesophyll – composed of parenchyma cells (most
photosynthesize)- THIS IS THE GROUND TISSUE IN LEAF
2 Types of Mesophyll
1.Palisade- Closely packed column shaped cells
2.Spongy- Loose-arrangement of cells-many air spaces
Blade – flat surface of the leaf
Petiole- -Stalk that connects blade to stem
-Contains vascular tissue continuous
between blade and stem
8. Morales 8
Opening of the Stomata
The opening of the Stomata (STOMA) is triggered by one or both of two events
1- Light is absorbed by pigments in guard cells
And/or
2- Guard cells photosynthesize because CO2 levels drop
This triggers a set of reactions….which open the stoMa
1. K+ Enters guard cell by active transport
2. H20 enters guard cells
3. Cellulose bands prevent guard cells from increasing diameter so they lenthen, since
they are attached at both ends, they must BOW OUT = opening of STOMA
Closing of the Stomata
The closing of the Stomata is triggered by one or both of two events.
1. The leaf loses H2O too fast- triggers release of abscisic acid
And/Or
2. CO2 levels rise
-Active transport of K+ into guard cells is inhibited
-K+ leaks out, H20 follows, guard cells relax = Stomata Closing
The openingof
guard cells is
The STOMA
STOMA is
surroundedby
TWO GUARD
CELLS
9. Morales 9
Secondary Growth in Woody Stems and and Roots
Secondary growth adds girth to stems and roots in woody plants
In vascular plants, secondary growth is the result of the activity of the two lateral meristems,
the cork cambium and vascular cambium. Arising fromlateral meristems, secondary growth
increases the girth of the plant root or stem, rather than its length. As long as the lateral
meristems continue to produce new cells, the stem or root will continue to grow in diameter.
In woody plants, this process produces wood.
• Secondary growth is characteristic of gymnosperms and many eudicots, but not monocots
10. Morales 10
Diversity of Structures in Stems
Stolons – Aboveground horizontal stems,
produce new plants where nodes touch ground.
Rhizomes- Underground horizontal Stems
-survives winters, helps with asexual
reproduction, because node bears bud
-Cacti have specialized succulent
stems for water storage
-Grape plants have tendrils (which
are stem branches) to allow them to
climb.
**Some Rhizomes have TUBERS-
function as food storage.
Ex.Potatoes are tubers
***Corms and Bulbous are
underground stems that lie dormant
during winter
Ex.Onion = Bulb
11. Morales 11
Plant Nutrients
Acquisition of Minerals & Water-
Nutrients and inorganic molecules come from soil, water and air
-ALL ENERGY COMES FROM THE SUN
Types of Minerals-
1. Macronutrients – Plant needs constant, LARGE SUPPLY
2. Micronutrients- Plant needs only trace amounts (too much can cause problems)
*Note N (Nitrogen) P (Phosphorus) and K (Potassium) are all MACROnutrients
needed for growth
12. Morales 12
Acquisition and Movement of H2O and Minerals
Think of this path in chronological order.
It must enter the EPIDERMIS to get to the ENDODERMIS.
Entrance into epidermis "soil water" depends on
concentration gradient- DIFFUSION
From “Soil Water” to Endodermis
***Path to Endodermis may be between
cells or through cells’ cytoplasm
“Soil Water” AT Endodermis
**Casparian Strip prevents H2O and Minerals
fromgoing between cells
H2O enterscell by OSMOSIS- H2O DIFFUSESacross cell H2O Leaves by OSMOSIS
Minerals enter by Active Transport
1. Usingenergyfrombreakdownof ATP,
H+ are activelytransportedoutof
endodermal cells
2. H+ outside endodermal cells
CREATE high concentration of positive
charges outside the cell
3. Other positively charged ions (K+,
Ca2+, Etc.) flow down this gradient
into cell through channel proteins
4. H+ diffuse back into cell
through carrier proteins carrying
negatively charged ions (I-,CL-,etc)
With them
From Endodermis into Xylem
H2O and Minerals DIFFUSE through or between cells into Xylem
13. Morales 13
Cohesion-Tension Theory Transporting
Water through the Plant
Pressure Flow Theory (sugars)
**Photosynthesis in leaf (source) mesophyll produces Sucrose
a. AT THE SOURCE (LEAF)
-There is a high concentration of sucrose in phloem cells (sometimes 25%)..sucrose
moves by ACTIVE TRANSPORT from source into sieve tube members of phloem
-Water follows by OSMOSIS from xylem into sieve tube members
b. Simultaneously, at sink (fruit,stem,cortex)
-Sucrose moves by active transport from sieve tube members into Sink
-Water follows by osmosis out of sieve tube members into sink then into xylem
c. Resul: Water leaving sieve tube members at sink, creates a difference in hydrostatic
preassure between top of phloem (near source) and bottom of phloem(near
sink)…substances in phloem move downward (fown their pressure gradient)
Cohesion- H2O molecules stick to each
other-creats a “rope” of H2O
Tension-(forces)- H2O transpired from
stomata of leaves creates a tension pulling
H2O up through xylem to replacelostwater
14. Morales 14
Essay Question
Compare and contrast the cross section (Root+ Stems)
structures of a Monocot group and a Eudicot group
EUDICOTS MONOCOTS
Stem Cross Section
Vascular tissue (vascular bundles located in different patterns)
In Eudicots – have vascular bundes in rings
From outer toinner order…..
Phloem Vascular Cambium Xylem
……………Eudicots have PITH in middle for support
In Monocots - vascular bundles are
scattered all through ground tissue
From outer toinner order……
Phloem Vascular Cambium Xylem Air Space
-Stemvascularbundlesinaring - Stemvacularbundlesscattered
- Has cortex (notgroundtissue) -Has groundTissue (notcortex)
-HASPITH -HAS NOPITH
15. Morales 15
Essay questioncontinued….
Roots Cross Sections
Eudicot Monocot
Root Cross Section Eudicot Monocot
Phloem
Located in between
arms of the star shaped
xylem
Is the OUTER ring of
smaller circular clumps
of cells
Vascular Cambium
Between Phloem and
xylem
Between Phloem and
xylem
Xylem Star Shaped in the
middle
Inner ring of larger cells
Pith NO PITH PRESENT LOCATED AT CENTER
16. Morales 16
Definitions
Monocot- Having one cotyledon (embrionic seed leaf in seed)
Eudicot- Having two cotyledons
Epiderm- One cell thick, most lack chloroplast, location is above ground cells…
Cuticle- Waxy water proof material that prevents water loss
Stomata-Small opening between two guard cells, lets co2 and o2 diffuse and releases h2o
Guard Cells- Pairs of Sausage shaped cells around “stoma”
Periderm-Woody Stems only outer covering made mostly of thick walled dead cork cells-
becomes part of “Bark”
Parenchyma cells- Thin walled, ussually with large central vacuole – in stems and leaves
-function- storage,metabolic funtions,photosynthesis,hormone production..can reproduce
-location is the pith,cortex,fruit flesh,leaf mesophyll
Collenchyma- Thickened primary cell walls.
-Function-flexible support
-occuses in outer regions of stems+petioles and a long larger veins of leaves
-Many monocots do not have collenchyma
Sclerenchyma-Thick hardened secondary cell walls
-Funtion-support,protection
Sclerenchyma fibers- Found in ground tissue, most are in vascular tissue. They are long slender
and may be grouped in bundles…fibers are used commersially to make rope.
Scherenchyma Sclereids- Shorter than fibers, vary in shape, found in seed coats and nutshells.
Xylem- Transports water and minerals from roots to leaves
Tracheids- (Found in all vascular plants) – are in the Xylem, are thin +long cells,
tappered cells end with pits where no secondary cell wall forms
Vessel Elements- (Only in angiosperms) – Shorter, larger, diatmeter cells, Blunt or
slightly tappered ends with complete perforations
(secondary and primary cell walls missing)
** Both Traicheids and Vessel Elements = lateral pits
- Usually Scherenchyma cells nearby for support
Phloem- Transports sucrose and other organic compounds
Sieve Tube Members – (CONDUCTION SYSTEM)
- Membrane lined pores (sieve plates) at juntions
Companion Cells (parenchyma)-Nourishes and regulares functions of Sieve Tube
members…Nearby sclerenchyma cells for support
Meristem- ells capable of cell division
Apical Meristem- Located at tip of roots, stems, and branches
-Results in “Primary Growth”- Growth in length with accompanying differentiations
Lateral Meristem- Located in cylinders with roots and stems (vascular cambium& cork
cambium) –Result in “Secondary Growth”-Growth in width with some stems becoming “woody”
Taproot root system- Primary root with many lateral roots – typical of eudicots
Fibrous root system- Primary root dies, many secondary root remain-typical of monocots
17. Morales 17
Root Cap- Protective-thick cell wall, secretes slimy lubricant to help move through soil
Zone of Cell Division- Has MeristemTissue which has rapid cell division, reproduction. Cells at
bottom move to root cap. Cells at top move into zone of elongation.
Zone of Elongation- Cells grow in length causing root to become longer
Zone of Maturation- Overlaps top of zone of elongation, cells diffirentiate, secondary growth
begins…roots of cell start to widen as result of vascular camdium
Epidermis- ”Soil water”enters here, root hairs increase surface area
Hypodermis- Only in monocots, 1 layer
Cortex- Parenchyma cells-outer portion…converts sugar to starches and stores them
Endodermis- Ring at inner edge with specialized cells
Casparian Strip- Waxy-Causes h2o and minerals to go through endodermis cells (not between
them)..cytoplasm of those cells control how much h2o goes in
Vascular Cylinder- Pericycle (meristem)…Composed of phloem, vascular cambium, xylem..this is
where branch roots grow
Node- Junction of leaf and stem
Axillary bud- Meristem tissue located at node-branch stems grow from this
Terminal bud- Apical meristem-and leaf primordia located at tip of stem
Internode-Region on stem between 2 nodes
Bark- of a tree contains periderm (cork and cork cambium), and phloem
Blade- Flat surface of leaf
Petiole- Stalk that connects blade to stem..contains vascular tissue continuous between blade
and stem
Venetion- Pattern of veings in leaf
Pinate (eudicots) Parallel (monocots) Palmate (eudicots)
Stolons – Aboveground horizontal stems, produce new plants where nodes touch ground.
Rhizomes- Underground horizontal Stems can have tubers which -survive winters, helps with
asexual reproduction, because node bears bud
Mesophyll- is the inside of a leaf…made of Parenchyma cells which photosynthesis.
2 types of mesophyll cells
Palisade closely packed column shaped cells
Spongy- Loose – arrangement of cells – many air spaces
Cohesion- H2O molecules stick to each other – creating a “rope” of h2o
Tension (force)- H2O transpired from stomata of leaves creates a tension pulling H2O up
through xylem to replace lost water
