Plants: Structure and Function of Flowers, and Tissues Objectives: 1. Describe the parts of the shoot and root system on vascular plants 2. Describe the structure and function of the leaves, stem and roots of vascular plants. Homework: Explain the mechanisms by which materials are transported throughout the plant

What do you already know... Name the process that occurs within the mitochondria of living cells. What is the equation for this process? Name the process, that occurs within the leaves of green plants, by which plants make food. Why do plants carry out this process? What two substances do plants make, during photosynthesis, that animals need? What substance do animals make, during respiration, that plants need? Name two structures found in plant cells that are not found in animal cells. What else do you know about plants?

Characteristics All plants are multicellular, eukaryotic organisms. Almost all plants perform photosynthesis All have walls composed of cellulose They can’t move (sessile)

Classifying Plants Kingdom Plantae can be classified into two major divisions: Vascular Plants (ie: Ferns, Trees) Nonvascular Plants (ie: Mosses) In this unit we will be learning about vascular plants: their structure and how they function.

A Typical Vascular Plant

The "Typical" Plant Body The Shoot System (Leaves, Stem, Flowers) Above ground (usually) Elevates the plant above the soil Many functions including: photosynthesis reproduction & seed dispersal food and water transportation in leaves and stem The Root System (Roots) Underground (usually) Anchors the plant in the soil Absorb water and nutrients Transports water and nutrients to the shoot system Food Storage

ROOT SYSTEMS There are 2 main types of root systems: Fibrous Root Tap Root (monocots) (dicots) adapted to increase surface area for absorption shallow depth in soil grasses, lilies adapted to anchor (esp. huge plants like trees) and storage grow deeper into soil carrots, trees, dandelions

SHOOT SYSTEMS CO2 + H2O  C6H12O6 + O2 There are 3 parts to stem systems: 1. LEAF Main photosynthetic organ (light energy) CO2 + H2O  C6H12O6 + O2 (glucose) Organelles in the leaf called chloroplasts are responsible for this reaction

2. FLOWER Designed for sexual reproduction Can be male, female or, most often, both Pollination (male pollen landing on female stigma) can occur with the aid of wind (grass, maple trees), insects (bees, butterflies, flies), birds (humming birds) or even bats (Dracula)

The Flower

3. STEM Main function is support of leaves and flowers for maximum photosynthesis and pollination Transports sugars from the leaves to roots and roots to leaves in spring (think maple syrup) Transports and water, minerals and nutrients from the roots to the leaves and developing fruit

Major Plant Parts and Functions Explain what (general) function each of these plant parts carry out. Leaves: Roots: Stem: Flowers: (More on this later)

Plant Tissue Types There are 3 main types of plant tissue: Dermal Ground Vascular Each of these tissue systems includes a variety of specialized cells

Just like humans start off a unspecialized stem cells, plants start off as undifferentiated cells These meristem cells only grow in the meristematic regions of a plant After they appear, and depending on where they are, the meristem cells will differentiate into specialized cells

Dermal Tissue Forms outermost layer of a plant. Epidermis can be specialized: Epidermal root cells can form root ‘hairs’ to absorb water and minerals. cross section of a root

Dermal Tissue Epidermal leaf cells produce a waxy waterproof cuticle which stops intruders Glandular ‘trichomes’ on stems and leaves can produce toxins or even sticky stuff to prevent predators

Vascular Tissue – 2 types Xylem Transports water and dissolved minerals from the roots to the leaves. Elongated cells joined to make tubes Grow a thick cell wall then die – means there is great support and no cytoplasm in the way to impede transport Wood is actually old, non-transporting xylem cells

Vascular Tissue Phloem Transports products of photosynthesis, a sugar solution, around the plant. (up and down) Elongated cell like tubes remain alive at maturity Bark is old, non-transporting phloem cells

Xylem and Phloem

Ground Tissue “The Filler” Located between the dermal and vascular tissue. Perform a variety of functions: Photosynthesis Food and water storage Structural support

Your Task Read pp. 286-289 Copy table 1. from pp. 289 into your notes (This will be on the exam!!!!!!) Complete #1-7

Plants: Structure and Function of Leaves and Roots Objectives:

Leaves... All leaves are responsible for: Absorbing the sun's rays The majority of photosynthetic production (which can take place in any green part of a plant), Taking in carbon dioxide and releasing oxygen and water vapour (gas exchange) Removing waste products from the plant Using osmotic pressure to draw water up from the roots

Leaves are the major site for photosynthesis Chlorophyll is a green pigment that captures the light energy and uses it to make food (sugar). Chlorophyll is found in organelles called chloroplasts.

Photosynthesis is the process in which carbon dioxide (CO2) and water (H2O) are used to produce  carbohydrates and oxygen (O2) in the presence of light and chlorophyll. Equation:

Parts of the leaf Blade: Flattened area of leaf. Petiole: Stalk that attaches leaf blade to stem. Midrib and veins: Contains the vascular tissue.

Inside the Leaf

Epidermal Cells Tightly packed in a single layer covered by a waxy coating called the cuticle. Cuticle: Prevents water loss Provides a physical barrier against bacteria, mould and insects. Don’t contain chloroplasts. But are transparent so light can pass through.

Stomata Photosynthesis require a constant supply of carbon dioxide. The product of this process – oxygen – must be released. Gas exchange in plants occurs in the leaves and is regulated by small pores called stomata.

Guard Cells Stomata also regulates water loss. When stomata are open water is lost (transpiration) and plant can exchange oxygen for carbon dioxide. When stomata are closed the plant conserves water, but can not exchange gases. Guard cells located on either side of the stomata regulate the opening and closing of the stomata.

Carbon dioxide enters through these pores (stomata) and oxygen and water exits through them.

Mesophyll Located in the mid region of the leaf. Primary site of photosynthesis in the leaf. There are two types: 1. Palisade mesophyll (note how the cells are shaped): These cells contain many chloroplasts. Primary site for photosynthesis. 2. Spongy mesophyll (note the irregularly shaped and spaced cells): These cells have fewer chloroplasts. There are many air spaces which allows carbon dioxide to diffuse into cells and oxygen out of cells.

Leaf Specializations and Adaptations Aquatic Plants: (Water Lillies) have specialized aerenchyma tissue which consists of loosely packed containing large pores. This adaptation helps the plants float on the surface of the water. Many aquatic plants have stomata on their upper epidermis, instead of their lower, so that they are exposed to air. Some, underwater, aquatic plants don’t contain stomata at all.

Find out about other leaf adaptations… Read page 303 How do conifers are adapted to keeping their leaves all year round and reducing water loss? Describe leaves of plants that grow in the shade? Describe 3 plant features that help protect them from being eaten.

Your Turn Read pp. 301-304 Complete #1-4 on pp. 304

Roots Roots are responsible for: Anchoring the plant to the ground Extracting water and minerals from the soil Storage of food (carbohydrates or sugar) In a typical root we can distinguish the following parts: 1. Primary root – first root development from the seed 2. Secondary roots – smaller root branches growing sideways from the primary root 3. Root cap – a protective cap covering the growing region of the root tip. It is designed to drill the soil and it is able to guide the root growth by perceiving gravity. 4. Root hairs - are microscopic extension of the epidermal cells near the tip of a root. They absorb water and nutrients from the soil.

Vascular System in Roots Located at the centre of each root. Vascular cylinder called a stele contains xylem and phloem. A layer of cells called the endodermis surrounds the vascular tissue and regulates the movement of water and minerals

Root Adaptations and Specializations Specialized to help root efficiently absorb water and nutrients, anchor plant and store carbohydrates. Many plants have a relationship with other organisms to help them. Roots of some plants produce chemicals that harm other plants (allelopathy).

Epiphytes Grow on the stems and branches of other plants. Ie: Strangler Fig grows high up on a tree and develops aerial roots (grow from leaf nodes along stems). These roots grow down the tree to the ground. As the roots grow and thicken, they completely engulf and strangle the tree. The tree dies from lack of light and the Strangle Fig takes over the space continuing to grow to immense sizes.

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Find out about… Read page 296 Learn about and describe two other specialized roots/root adaptations and what environment they are suited for. Pp. 299 #1-2

Stems Stems are responsible for: supporting leaves and flowers physically Connect the vascular tissue in the leaves to the vascular tissue in the roots. using xylem and phloem to transport water and nutrients to and from leaves, roots, and reproductive parts like flowers, fruit and seeds. storing water and nutrients for future use (parenchyma)

Stem Structure Herbaceous plants: Stems don’t contain wood Vascular bundles (arrangements of vascular tissue) consists of xylem and phloem These bundles run from leaves to roots Woody plants: Stems contain wood Vascular cambium: a layer of tissue that separates xylem from phloem. Produces xylem and phloem Phloem is on the outside and xylem is on the inside ‘Wood’ is actually many layers of xylem cells.

Major Tissues in Stems Woody Stems (note: pith and cortex contain parenchyma tissue)

More Stem Structures Bark: Protective outer layer. Consists of phloem, cork cambium and cork Cork cambium: Layer between layers of bark Produces cork Every year the vascular cambium produces layers of xylem and phloem. (Growth rings)

Stem Adaptations… Read Page 298 Describe how the stems of Cacti are modified to survive desert environments. How are the stems of potatoes modified? What are some other stem adaptations?

Your Turn Read pp. 295 – 299 Complete #1-5 on pp. 299