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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 other plants

Seedless Seedbearing

-Bryophytes -Gymnosperms

-Lycophytes -Angiosperms

-Pteridophytes

Monocots Eudicots

-Having 1 Cotyledon -Having 2 Cotyledon

Angiosperms breakdown in to two groups the Monocots and the Eudicots

Cotyledon = embrionic seed lead in seed

Gymnosperms – Have “naked seeds”- seeds not covered by fruit…

-Cycads-Tropical-Gyngkos- grow anywhere

-Gnetphytes- Dessert plants-Conifers-Evergreen

Angiosperms– Have seeds covered by fruit

Nonvascular- Bryophytes, (hornworts,liverworts,mosses) – Have no true roots, stems, or leaves

Vascular- all other plants which have TRUE ROOTS, STEMS OR LEAVES.

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4 Categories of Tissues and Cell Types

1 .Dermal Tissue – Outer covering of plant body(a)Epiderm- One cell thick, most lack chloroplast -Location = above ground cells packed rightly & covered with cuticles (waxy, water proof material- prevents water loss) -Below ground cells it will be found but with no cuticle -Specializations – extensions “hairs”-increase surface area and slow air movement-Guard cells- pairs of “sausage shaped” cells around a “stoma” (small opening between guard cells) -Guart Cell function= let Co2+O2 diffuse and for release of H2O(b)Periderm- Woody stems only outer covering made of mostly of thick walled dead cork cells-because part of “bark”

2. Ground Tissue- Fills interior of plant(a)Parenchyma cells- thin walled, usually with large central vacuoles..in stems and leaves have chloroplast (just below epiderm -Function-Storage,metabolic functions, photosynthesis, hormone production, can reproduce -Location- pith, cortex, fruit flesh, leaf mesophyll(b)Collenchyma-Thick primary cell walls. -Function-Flexible support, cannot reproduce, occur in outer regions of stems & petioles and along larger beins of leaves. *many monocots do not have Collenchyma.(c )Sclerenchyma- Thick hardened secondary cell walls dead at maturity. -Function-Support, protection

3. Vascular Tissue - For transport(a) Xylem- Vascular tissue that carries H20 + minerals from roots toward leaves -dead 2 maturity, “wood of a plant” -no cell membrane or cytoplasm… just cell walls!

*Xylem has two types of conducting cells tracheids and vessel elements-Tracheids (found in all vascular plants) – long thin cells with tappered cells end with pits where no secondary cell wall forms-Vessel elements (only in angiosperms)- shofter, larger, diameter cells, blunt of slightly tappered ends with complete perforations (secondary and primary cell walls missing)

*both Tracheids + vessel elements= lateral pits-usually scherenchyma cells nearby for support

(b)Phloem- vascular tissue that carries products of photosynthesis from leaves toward roots -This tissie is living* contains sieve tube members and companion cells-Sieve Tuve members (CONDUCTION SYSTEM)- Membrace lines pores (sive plates) at junction-Companion Cells – nourishes and regulates functions of sieve tube members-nearby sclerenchyma cells for support

4.Meristem – Cells capable of cell division(a) Apical-located at tip of root, stems, and branches-result in “primary growth”- growth in length with accompanying differentiation(b)Lateral (cambium)- located in cylinders with roots and stems (vascular cambium & cork cambium)

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-result in “secondary growth”- growth in width with some stems becoming “woody”

Two types of Root Systems

Fibrous TapRoot-Primary root dies many -Primary root with many Secondary roots remain 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

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Cross Section Structure of a Root

Eudicot Monocot

Epidermis – “Soil water” enters here – root hairs increase surface areaHypodermis- Only in Monocots (1 layer)Cortex- Parenchyma cells- outer portion = converts sugar to starges and stores themEndodermis- 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

PhloemLocated in between arms of the star shaped xylem

Is the OUTER ring of smaller circular clumps of cells

Vascular CambiumBetween 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

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Stems

Node- Junction of leaf and stem

Axillary bud – or “lateral”- Meristem tissue located at node- branch stems grow from this

Internode- Region on stem between 2 nodes

Terminal Bud- Apical Meristem-and leaf primodia located at top of stem

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Internal Structures cross sections of Eudicots and Monocots

Epidermis – first dermal tissue layer, outside covering is the cuticle which prevents H2O loss, and has the stomaIn Eudicots the next layer is called the Cortex in Monocots the next layer is the ground tissueCortex/Ground tissue – is filled with PENCHYMA CELLS (convert sugar into starch) -Support from: turger pressure in young stems -Collenchyma & Sclerenchyma in older stems - Photosynthesis in outer layer (in herbasious dicots)

Vascular tissue (vascular bundles located in different patterns)

In Eudicots – Have vascular bundles in ringsFrom outer to inner order….. Phloem Vascular Cambium Xylem ……………Eudicots have PITH in middle for support

In Monocots - Vascular bundles are scattered all through ground tissueFrom outer to inner order……Phloem Vascular Cambium Xylem Air Space

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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

Blade – flat surface of the leaf

Petiole- -Stalk that connects blade to stem -Contains vascular tissue continuous between blade and stem

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1.Palisade- Closely packed column shaped cells 2.Spongy- Loose-arrangement of cells-many air spaces

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 cellsAnd/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 cells3. 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 StomataThe closing of the Stomata is triggered by one or both of two events.

1. The leaf loses H2O too fast- triggers release of abscisic acidAnd/Or

2. CO2 levels rise

-Active transport of K+ into guard cells is inhibited

The opening of guard cells is The STOMA

STOMA is surrounded by TWO GUARD CELLS

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-K+ leaks out, H20 follows, guard cells relax = Stomata Closing

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 from lateral 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

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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 winterEx.Onion = Bulb

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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 SUPPLY2. 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

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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 from going between cells

H2O enters cell by OSMOSIS - H2O DIFFUSES across cell H2O Leaves by OSMOSIS

Minerals enter by Active Transport1. Using energy from breakdown of ATP,

H+ are actively transported out of 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

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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 replace lost water

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Essay QuestionCompare 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 to inner order….. Phloem Vascular Cambium Xylem ……………Eudicots have PITH in middle for support

In Monocots - vascular bundles are scattered all through ground tissueFrom outer to inner order……Phloem Vascular Cambium Xylem Air Space

-Stem vascular bundles in a ring - Stem vacular bundles scattered - Has cortex (not ground tissue) -Has ground Tissue (not cortex) -HAS PITH -HAS NO PITH

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Essay question continued….

Roots Cross Sections Eudicot Monocot

Root Cross Section Eudicot Monocot

PhloemLocated in between arms of the star shaped xylem

Is the OUTER ring of smaller circular clumps of cells

Vascular CambiumBetween 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

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Definitions

Monocot- Having one cotyledon (embrionic seed leaf in seed)Eudicot- Having two cotyledonsEpiderm- One cell thick, most lack chloroplast, location is above ground cells…Cuticle- Waxy water proof material that prevents water lossStomata-Small opening between two guard cells, lets co2 and o2 diffuse and releases h2oGuard 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 mesophyllCollenchyma- 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 collenchymaSclerenchyma-Thick hardened secondary cell walls-Funtion-support,protectionSclerenchyma 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 juntionsCompanion 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

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Fibrous root system- Primary root dies, many secondary root remain-typical of monocots

Root Cap- Protective-thick cell wall, secretes slimy lubricant to help move through soilZone of Cell Division- Has Meristem Tissue 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 longerZone of Maturation- Overlaps top of zone of elongation, cells diffirentiate, secondary growth

begins…roots of cell start to widen as result of vascular camdiumEpidermis- ”Soil water”enters here, root hairs increase surface areaHypodermis- Only in monocots, 1 layerCortex- Parenchyma cells-outer portion…converts sugar to starches and stores themEndodermis- Ring at inner edge with specialized cellsCasparian Strip- Waxy-Causes h2o and minerals to go through endodermis cells (not between

them)..cytoplasm of those cells control how much h2o goes inVascular Cylinder- Pericycle (meristem)…Composed of phloem, vascular cambium, xylem..this is

where branch roots growNode- Junction of leaf and stemAxillary bud- Meristem tissue located at node-branch stems grow from thisTerminal bud- Apical meristem-and leaf primordia located at tip of stemInternode-Region on stem between 2 nodesBark- of a tree contains periderm (cork and cork cambium), and phloemBlade- Flat surface of leafPetiole- Stalk that connects blade to stem..contains vascular tissue continuous between blade

and stemVenetion- 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 spacesCohesion- H2O molecules stick to each other – creating a “rope” of h2oTension (force)- H2O transpired from stomata of leaves creates a tension pulling H2O up

through xylem to replace lost water

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