roots and stems & leaves interest grabber root words the word root is not used only by...

Roots and Stems & Leaves

Interest Grabber•Root Words

•The word root is not used only by biologists. Working with a partner, read over each of the following sentences. Try to determine the meaning of the boldfaced word(s) in each sentence. Then, explain how each use of the word root is related to the root of a plant.

1. The love of money is the root of all evil.

2. Tired of moving from place to place, he took root in our hometown.

3. The police were determined to root out the criminals.


Section OutlineSection 23-2

RootsA. Types of Roots

B. Root Structure and Growth

C. Root Functions

1. Uptake of Plant Nutrients

2. Active Transport of Minerals

3. Movement Into the Vascular Cylinder

4. Root Pressure


Role in Plant

Proper leaf growth and color; synthesis of amino acids, proteins, nucleic acids, and chlorophyll

Synthesis of DNA; development of roots, stems, flowers, and seeds

Synthesis of proteins and carbohydrates; development of roots, stems, and flowers; resistance to cold and disease

Synthesis of chlorophyll

Cell growth and division; cell wall structure; cellular transport; enzyme action

Result of Deficiency

Stunted plant growth; pale yellow leaves

Poor flowering; stunted growth

Weak stems and stunted roots; edges of leaves turn brown

Thin stems; mottled, pale leaves

Stunted growth; curled leaves

Nutrient

Nitrogen

Phosphorus

Potassium

Magnesium

Calcium

Section 23-2

Essential Plant Nutrients


Section 23-2

Epidermis

Ground tissue(cortex)

VascularCylinder

Cross Section of Plant Root(magnification: 40x)

Ground tissue (cortex)

Epidermis

Endodermis

Vascular cylinder

Root hairs

Phloem

Xylem

Apical meristem

Root cap

Zone of maturation

Zone of elongation

Endodermis

Figure 23–7 The Structure of a Root


Section 23-2

Endodermis

VascularCylinder

Cell membrane

Cell wall

Casparian strip

Phloem

Xylem

Cortex

Root hairs

Epidermis

Cortex

Active transportof minerals

Movement of water by osmosis

Figure 23–9 Water Transport in a Root


KEY CONCEPT Roots and stems form the support system of vascular plants.


Roots anchor plants and absorb mineral nutrients from soil.

• Roots provide many functions.– support the plant– absorb, transport,

and store nutrients – root hairs help

absorption


root cap

– root cap covers the tip

• There are several parts of a root.


apical meristem



– apical meristem is an area of growth


– vascular cylinder contains xylem and phloem

vascular cylinder



– apical meristem is an area of growth


– Fibrous root systems have fine branches.

Fibrous root Taproot

• There are two main types of roots.

– Taproot systems have one main root.


Stems support plants, transport materials, and provide storage.

• Stems have many functions. – support leaves and flowers – house most of the vascular system – store water

Baobab trees Cactus


– grow underground for storage

Ginger rhizomes Potato tubers




– grow underground for storage



– form new plants

Strawberry stolons


• Some stems are herbaceous and conduct photosynthesis.


• Some stems can be woody, and form protective bark.


• Secondary growth increases a plant’s width.

• Primary growth increases a plant’s length.


• Tree rings help determine the age of a tree.

heartwood

bands bark

one year of growth

sapwood


•Leaves—Up Close and Personal

•Leaves absorb light and carry on most of the photosynthesis that occurs in a plant. For this reason, leaves are important plant structures.Examine the drawings of the three types of leaves shown in the next slide.

Section 23-4

Interest Grabber


Section 23-4

Pin oak DandelionEastern

white pine

Interest Grabber continued

1. Describe the shape of each leaf.

2. Describe the features of each leaf.

3. How is the structure of a leaf related to its function?


Section Outline

LeavesA. Leaf Structure

B. Leaf Functions

1. Carrying Out Photosynthesis

2. Gas Exchange

Section 23-4


Section 23-4

Stoma Open Stoma Closed

Guard cells

Inner cell wall

Stoma

Guard cellsInner cell wall

Function of Guard Cells


Section 23-4

Veins

Xylem

PhloemVein

Cuticle

Epidermis

Palisademesophyll

Epidermis

Stoma

Guardcells

Spongymesophyll

Figure 23–18 The Internal Structure of a Leaf


Label the Leaf


KEY CONCEPT Leaves absorb light and carry out photosynthesis.


Most leaves share some similar structures.

• The blade is usually broad and flat. – collects sunlight for

photosynthesis– connects to the stem by a

petiole

blade

petiole


• Mesophyll is between the leaf’s dermal tissue layers.

cuticle

upperepidermis

palisademesophyll

spongymesophyll

lowerepidermis


– Stomata open and close when guard cells change shape.

– When stomata are open, water evaporates and gas exchanges.

– Stomata close at night and when plant loses too much water.

guard cells stoma

• Guard cells surround each stoma.


• Leaves may be simple, compound, or double compound.

Simple leaf Compound leaf Double compound leaf


• Leaf veins may be parallel or pinnate.

Pinnate veinsParallel veins


• Leaf margins may be toothed, entire, or lobed.

Toothed margin Entire margin Lobed margin


Most leaves are specialized systems for photosynthesis.

• There are two types of mesophyll cells. – both types contain chloroplasts – palisade mesophyll absorbs sunlight – spongy mesophyll connects to stomata

xylem

phloem

cuticle

upperepidermis

palisademesophyll

spongymesophyll

stomata

lowerepidermis


– for extreme temperatures, ex: pine needles

• Leaves have many adaptations.



– for water loss,ex: cactus spines


– for aquatic environments, ex: water lily



– for getting food,ex: Venus’ flytrap


roots and stems & leaves interest grabber root words the word root is not used only by...

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