End Show Slide 1 of 34 Copyright Pearson Prentice Hall 23–1 Specialized Tissues in Plants.

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End Show Slide 1 of 34 Copyright Pearson Prentice Hall 23–1 Specialized Tissues in Plants

Transcript of End Show Slide 1 of 34 Copyright Pearson Prentice Hall 23–1 Specialized Tissues in Plants.

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23–1 Specialized Tissues in Plants

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23–1 Specialized Tissues in Plants

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Seed Plant Structure

Seed Plant Structure

What are the three principal organs and tissues of seed plants?

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23–1 Specialized Tissues in Plants

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Seed Plant Structure

The three principal organs of seed plants are roots, stems, and leaves.

These organs perform functions such as the transport of nutrients, protection, and coordination of plant activities.

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23–1 Specialized Tissues in Plants

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Plant Tissue Systems

What are the three main tissue systems of plants?

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23–1 Specialized Tissues in Plants

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Plants consist of three main tissue systems:

• dermal tissue

• vascular tissue

• ground tissue

Plant Tissue Systems

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23–1 Specialized Tissues in Plants

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Seed Plant Structure

Leaf

Stem

Root

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23–1 Specialized Tissues in Plants

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Dermal Tissue

Dermal Tissue

The outer covering of a plant consists of epidermal cells.

Epidermal cells make up dermal tissue.

The outer surfaces of epidermal cells are covered with a thick waxy layer, known as the cuticle. The cuticle protects the plant against water loss and injury.

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23–1 Specialized Tissues in Plants

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Vascular Tissue

Vascular Tissue

Vascular tissue forms a transport system that moves water and nutrients throughout the plant.

Vascular tissue is made up of xylem, a water-conducting tissue, and phloem, a food-conducting tissue.

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23–1 Specialized Tissues in Plants

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Vascular Tissue

Xylem Phloem

Cross Section of a Stem

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23–1 Specialized Tissues in Plants

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Ground Tissue

Ground Tissue

Cells that lie between dermal and vascular tissues make up the ground tissues.

The three kinds of ground tissue are:

• parenchyma

• collenchyma

• sclerenchyma

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23–2 Roots

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23–1 Specialized Tissues in Plants

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Seed Plant Structure

Roots:

• absorb water and dissolved nutrients.

• anchor plants in the ground.

• protect the plant from harmful soil bacteria and fungi.

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23–2 Roots

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The two main types of roots are:

• taproots, which are found mainly in dicots, and

• fibrous roots, which are found mainly in monocots.

Types of Roots

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23–2 Roots

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Root Structure and Growth

The root’s surface is covered with cellular projections called root hairs. Root hairs provide a large surface area through which water can enter the plant.

Root hairs

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23–3 Stems

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23–3 Stems

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Stem Structure and Function

Stem Structure and Function

What are the three main functions of stems?

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23–3 Stems

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Stem Structure and Function

Stems have three important functions:

• they produce leaves, branches and flowers

• they hold leaves up to the sunlight

• they transport substances between roots and leaves

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23–3 Stems

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Monocot and Dicot Stems

Monocot and Dicot Stems

The arrangemnet of tissues in a stem differs among seed plants.

How do monocot and dicot stems differ?

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Monocot and Dicot Stems

Monocot Stems

Vascular bundles are scattered throughout the ground tissue.

Monocot

Vascular bundles

Epidermis

Ground tissue

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Monocot and Dicot Stems

Dicot Stems

Dicot stems have vascular bundles arranged in a ring-like pattern.

Dicot

Cortex

Pith

Vascular bundles Epidermis

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23–3 Stems

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23–4 Leaves

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23–1 Specialized Tissues in Plants

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Seed Plant Structure

Leaves:

• are a plant’s main photosynthetic systems.

• increase the amount of sunlight plants absorb.

Adjustable pores conserve water and let oxygen and carbon dioxide enter and exit the leaf.

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23–3 Stems

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Leaf Structure

Leaf Structure

How does the structure of a leaf enable it to carry out photosynthesis?

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23–3 Stems

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Leaf Functions

Leaf Functions

Most leaves consist of a specialized ground tissue known as mesophyll.

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Leaf Functions

The air spaces connect with the exterior through stomata.

Stomata are porelike openings in the underside of the leaf that allow carbon dioxide and oxygen to diffuse into and out of the leaf.

Stoma

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23–3 Stems

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Leaf Functions

Each stoma consists of two guard cells.

Guard cells are specialized cells that control the opening and closing of stomata by responding to changes in water pressure.

Guard cells

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Leaf Functions

When water pressure within guard cells is high, the stoma open.

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Leaf Functions

When water pressure within guard cells decreases, the stoma closes.

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Leaf Functions

Plants regulate the opening and closing of their stomata to balance water loss with rates of photosynthesis.

Stomata are open in daytime, when photosynthesis is active, and closed at night, to prevent water loss.

In hot, dry conditions stomata may close even in bright sunlight, to conserve water.