Lesson 2.2

Plants have 3 distinct tissue types:1. Structural tissue• composes most of the plant• four types:

Lesson 2.2 Internal leaf structurePlants have three distinct tissue types:1. Structural tissueFour types

A. Epidermal•protects and covers •is covered by a cuticle (waxy layer) to prevent water loss and injury• Like plant’s skin• Is a single layer of cells

Epidermal layer

Cuticle causes water to bead on leaves.

Lesson 2.2 Internal leaf structure•Plants have three distinct tissue types:1. Structural tissue

• four types: A. Epidermal

B. Cork •replaces the epidermis as a plant grows• forms outer bark •protective layer •water proofs the stem•not found in herbaceous plants

http://en.wikipedia.org/wiki/Image:Japanese_Maple_Bark_by_David_Shankbone.jpg

Lesson 2.2 Internal leaf structure1. Structural tissue

• four types:A. Epidermal B. Cork

C. Parenchyma Found on the roots, stems

and leavesCarries out photosynthesisstores food

Lesson 2.2 Internal leaf structure1. Structural tissue

• four types:A. Epidermal B. Cork C. Parenchyma

D. Support/strengthening tissue • fibers run through stems, roots

and veins of leaves• thick walled • walls remain after dead for

support

Lesson 2.2 Internal leaf structure•Plants have three distinct tissue types:1. Structural tissue

2. Vascular tissue (transport)

•sap containing

•found in stems, roots and veins/petioles of leaves

Lesson 2.2 Internal leaf structure•Plants have three distinct tissue types:1. Structural tissue2. Vascular tissue (transport)

Two types of vascular tissue:

A.xylem – transports water and minerals upwardB.phloem – transports food from the

leaves to other parts of plant

Lesson 2.2 Internal leaf structure•Plants have three distinct tissue types:1. Structural tissue2. Vascular tissue

3. Meristem •function is for growth and repair•found in certain areas where growth

takes place•produces undifferentiated cells

Lesson 2.2 Internal leaf structure•Plants have three distinct tissue types:1. Structural tissue2. Vascular tissue3. Meristem

Two types of meristem:A. Apical meristem promotes growth in height Found in buds and growing roots

Lesson 2.2 Internal leaf structure•Plants have three distinct tissue types:1. Structural tissue2. Vascular tissue3. Meristem

Two types of meristem:A. Apical meristem

B. Lateral meristem Promotes growth in widthTwo types:• vascular cambium – produces new

vascular tissue• cork cambium – produces new

cork tissue (bark area on tree)

Transpiration – loss of water vapor from leaves and stems

Three things that reduce transpiration are:

1. Cuticle – waxy covering on some leaves

2. Guard cells – open and close leaf pores (stomata)

3. Leaf hairs – hair-like structures which form from the epidermis and reduce transpiration by reducing wind speed across the leaf

Electron microscopepicture of leaf hairs

Leaf structures – cross section:1.Upper and Lower

epidermis protects and reduces water loss Like skin of plant cuticle on top ofepidermis

Leaf structures:1. Upper and Lower epidermis

2. Mesophyll middle portion of leaf

Two layers of mesophyll:Palisade – where most of photosynthesis takes placeSpongy -where gases and water are stored

Leaf structures:1. Upper and Lower epidermis 2. Mesophyll

3. Stomata – Stoma (singular)

• Tiny openings for gas exchange

• Protected on each side by guard cells

• Where water exits during transpiration

Stomata

Leaf structures:1. Upper and Lower epidermis 2. Mesophyll 3. Stomata

4. Guard cells• Open and close the

stomata

Leaf structures:1. Upper and Lower epidermis 2. Mesophyll 3. Stomata4. Guard cells

5. Veins Contain the sap Run through mesophyll

Venation Patterns

1. Palmate – veins radiate from a central point at the base of the leaf; like the palm of the hand. Ex. maple

Venation Patterns 1. Palmate

2.Pinnate – has one main vein with smaller ones branching off; Ex. oak

Venation Patterns 1. Palmate2. Pinnate

3. Parallel - veins run parallel for the length of the leaf, from the base.

Ex. Lily leaf

PLANT CELLSoCell – basic unit of all living things

PLANT CELLS

oAll cells are made up of 4 main elements: carbon hydrogen oxygen and nitrogen

PLANT CELLS

These 4 main elements form major compounds of all living things:

carbohydrate lipids(fats/oils) proteins, and nucleic acid

The main parts of all cells:

1. Cell membrane

defines the cell and contains the cytoplasm and organelles within

Regulates what goes in and out of cell

The main parts of all cells:1. Cell membrane

2. Cytoplasm - Jelly-like fluid where organelles and nucleus are suspended

The main parts of all cells:1.Cell membrane 2. Cytoplasm

3. Nucleus Contains genetic

information (DNA) Controls cell activities Spherical shaped body near

center of the cell

The main parts of all cells:1.Cell membrane 2. Cytoplasm3. Nucleus

4. Organelles

Tiny organ-like structures of the cell

See Handout

Cell parts only in plants:

1. Cell wall Made of cellulose Only plant cells have them not

animal cells Humans are not able to digest

cellulose, but is good bulk for diet

Cell parts only in plants:1. Cell wall

Cellulose strengthens but allows for flexibility in plants•Cellulose is important to many industries such as the paper industry

Cell parts only in plants:

1. Cell wall

•Some cell walls also have lignin adding more stiffness to the cell wall of woody stems.

Cell parts only in plants:

1. Cell wall

2. Chloroplast and chlorophyll

Chloroplast•Organelle containing chlorophyll•Most numerous in palisade mesophyll•Site of photosynthesis

Cell parts only in plants:

1. Cell wall2. Chloroplast and chlorophyll

Chlorophyll•Green pigment found in the chloroplast•Traps energy from sunlight•Important to photosynthesis

Cell parts only in plants:

1. Cell wall2.Chloroplast and chlorophyll

3. VacuolesoStorage of food and wateroUsually 1 or 2 large ones

Differences between plant and animal cells:

Plant AnimalRectangular shape round shape1 large vacuole many small Larger than animal smaller thancell plant cell