Roots, Stems and Leaves Roots, Stems and Leaves

Chapter 23Chapter 23

Mr. BraggMr. Bragg

20142014

EQ: How are plant tissues organized?EQ: How are plant tissues organized?

Objectives:Objectives: Identify the main organs of vascular plantsIdentify the main organs of vascular plants Explain the functions of the main tissuesExplain the functions of the main tissues Contrast meristems with other plant tissuesContrast meristems with other plant tissues

A. Specialized Tissue in PlantsA. Specialized Tissue in Plants

1.1. Plants have 3 Plants have 3 main organsmain organs

a. Rootsa. Roots

b. stems b. stems

c. leavesc. leaves

2. Plants have three tissue systems:2. Plants have three tissue systems:

a. dermal tissuea. dermal tissue

b. vascular tissueb. vascular tissue

c. ground tissuec. ground tissue

3. A special type of tissue called 3. A special type of tissue called meristematicmeristematic tissue is the only plant tissue that can produce tissue is the only plant tissue that can produce new cells by mitosisnew cells by mitosis

a. Found in the tips of shoots and rootsa. Found in the tips of shoots and roots

4. Dermal Tissue4. Dermal Tissue

a. The outer covering a. The outer covering

b. single layer of epidermal cellsb. single layer of epidermal cellsCuticleCuticle – a waxy layer that often covers the epidermis – a waxy layer that often covers the epidermis

Provides protection against water loss & injuryProvides protection against water loss & injury

c. May include specialized structures such as root hairs c. May include specialized structures such as root hairs and guard cellsand guard cells

Stomata FunctionStomata Function

Allows for taking in of CO2 for Allows for taking in of CO2 for photosynthesisphotosynthesis

Drawback = loss of water vapor (transpiration)Drawback = loss of water vapor (transpiration) Larger leaf area = more water lossLarger leaf area = more water loss

5. Review - Vascular Tissue5. Review - Vascular Tissue

a. Transports water and a. Transports water and nutrients throughout the nutrients throughout the plantplantXylemXylem – transports – transports water; composed of dead water; composed of dead cellscellsPhloemPhloem – transports – transports nutrients; composed of nutrients; composed of living cells called sieve living cells called sieve tube elementstube elements

6. Ground Tissue6. Ground Tissue Lies between the dermal and vascular tissuesLies between the dermal and vascular tissues

Activity/labActivity/lab1.1. Work in pairsWork in pairs

2.2. No more than 4 people / lab tableNo more than 4 people / lab table

3.3. Follow handout procedureFollow handout procedure

4.4. Finish lab portion in classFinish lab portion in class

5.5. Take home the questions- due tomorrowTake home the questions- due tomorrow

Do Now - ReviewDo Now - Review

1. Compare and contrast gymnosperms and 1. Compare and contrast gymnosperms and angiosperms. angiosperms.

2. What are the 3 main tissues found in vascular 2. What are the 3 main tissues found in vascular plants?plants?

3. What are the 3 main organs of plants?3. What are the 3 main organs of plants?

EQ: How do the structure and function of the 3 EQ: How do the structure and function of the 3 main organs help a plant to carry out life main organs help a plant to carry out life processes?processes?

Objectives:Objectives: Describe the different functions of the 3 main Describe the different functions of the 3 main

organs in plants. organs in plants.

Root FunctionRoot Function

Anchor a plant in Anchor a plant in the groundthe ground

Absorb water and Absorb water and dissolved nutrients dissolved nutrients from the soilfrom the soil

Root Structure & GrowthRoot Structure & Growth

Root hairsRoot hairs – – tiny tiny projections projections from the from the epidermis that epidermis that increases the increases the surface area surface area for absorption for absorption of waterof water

1. Cortex1. Cortex – layer of ground tissue – layer of ground tissue

a. Cells in this layer may contain:a. Cells in this layer may contain:stored carbohydrates stored carbohydrates ResinsResinsLatexLatexEssential oilsEssential oilsTanninsTannins

EndodermisEndodermis – layer of tissue that encloses the – layer of tissue that encloses the vascular tissue; may be important for fluid vascular tissue; may be important for fluid transporttransport

Root Structure & FunctionRoot Structure & Function

Root cap – protects the root as it forces its way through the soilApical meristem – actively growing part of root; protected by cap

Modified RootsModified Roots

Why are they important?Food storage and/or increases fitness (adaptations)

Stem FunctionStem Function

Three important Three important functions:functions: Produce leaves, Produce leaves,

branches, and branches, and flowersflowers

Hold leaves up to Hold leaves up to the sunlightthe sunlight

Transport Transport substances between substances between roots and leavesroots and leaves

Stem types: Monocots and DicotsStem types: Monocots and Dicots

Two types:Monocot – has vascular bundles that contain the xylem & phloem scattered randomlyDicot – have vascular bundles organized in a ringlike pattern

Stem StructuresStem Structures

NodesNodes – where – where leaves are attachedleaves are attached

Internodes Internodes – regions – regions between the nodesbetween the nodes

BudsBuds – contain – contain undeveloped tissue undeveloped tissue that can produce new that can produce new stems and leavesstems and leaves

Specialized or Modified StemsSpecialized or Modified Stems

1.1. Includes:Includes:

a.a. StolonsStolons

b.b. TubersTubers

c.c. RhizomesRhizomes

d.d. BulbsBulbs

Why are they important?Food storage or exploiting new territory

Leaf FunctionsLeaf Functions

Photosynthesis – takes place in the mesophyll Photosynthesis – takes place in the mesophyll cells of the leafcells of the leaf

Transpiration – the loss of water from a plant Transpiration – the loss of water from a plant through its leaves (helps to pull water up from through its leaves (helps to pull water up from the roots)the roots)

Gas exchange – taking in carbon dioxide and Gas exchange – taking in carbon dioxide and releasing oxygenreleasing oxygen

Leaf StructureLeaf Structure

BladeBlade – thin, flattened section – thin, flattened section PetiolePetiole – thin stalk that attaches the leaf to the – thin stalk that attaches the leaf to the

stemstem VeinsVeins – contain the xylem and phloem – contain the xylem and phloem

Leaf StructureLeaf Structure

Palisade mesophyllPalisade mesophyll – tightly packed cells that – tightly packed cells that absorb lightabsorb light

Spongy mesophyllSpongy mesophyll – loosely packed cells with air – loosely packed cells with air spacesspaces

ReviewReview StomataStomata – pore-like openings for taking in CO – pore-like openings for taking in CO22

and releasing Oand releasing O22

Guard cellsGuard cells – cells that open and close the – cells that open and close the stomatastomata

Leaf StructureLeaf Structure

Modified LeavesModified Leaves

Why are they important?•Exploiting new territory, protection, nutrient acquisition

ClosingClosing

What are the 3 functions of stems? What are the 2 functions of roots? Give an example of a modified plant organ.

Why did some plants evolve these modifications?

HormonesHormones Defined: a chemical signal produced in one Defined: a chemical signal produced in one

part of the body and transported to other parts part of the body and transported to other parts of the body, where it can act on target cellsof the body, where it can act on target cells