Plants with Seeds Structure – Leaves stem stem roots roots

Leaves

Function of leaves  Trap light energy for photosynthesis  Producing sugar from photosynthesis  Take in water  Exchange of gases – oxygen and carbon dioxide

Parts of Leaves  Compound  Simple  Stalk: connects leaves to the stem  Blades: thin flat part that is the site of photosynthesis  Simple leaf: 1 single leaf  Ex. Maple, Oak, Apple  Compound: divided into a # of separate parts  Ex. Roses, clovers, and palms

Structure Wide Helps to catch more light energy Thin Help get carbon dioxide from bottom to top of leaf for photosynthesis

Internal Parts of Leaves  Epidermis: outside layer of leaf covered in cuticle  Stomata: pores where CO 2 and H 2 O enter the leaf and O 2 leaves  Guard Cells: cells on both sides of stomata that open and close

Internal Parts of Leaves  Mesophyll: inner layer of leaf  Pallisade: upper mesophyll where photosynthesis happens  Spongy Layer: filled with air spaces for CO 2,H 2 O and O 2

Leaf structure Greener on top CO 2 gets in here Most chlorophyll

Leaf diagram – palisade layer CO 2 Most chlorophyll

Leaf cell - palisade Position? Upper surface of leaf Features? Box shape ChloroplastsFunction?Photosynthesis

Gas exchange  Leaves are designed to allow carbon dioxide to get to the main chlorophyll layer at the top of the leaf  They have small holes called stomata on the under surface  Each hole is open & closed by 2 guard cells

Leaf diagram – stoma and guard cells

Stoma position

Stoma is a small hole Its size is controlled by 2 guard cells closed open

Stoma function is for gas exchange in the leaf Carbon dioxide oxygen Guard cell Provided plant is photosynthesising

Stomata open and close at different times of the day When it is light the plant needs CO 2 for photosynthesis so the stoma open At night (darkness) they close

Gas exchange

PHOTOSYNTHESIS  The process of photosynthesis is a chemical reaction.  It is the most important chemical reaction on our planet. chemical reaction on our planet.

PHOTOSYNTHESIS EQUATION

Six molecules of carbon dioxide react with six molecules of water to form 1 molecule of glucose and six molecules of oxygen.

Describe Photosynthesis  The process of changing light energy to chemical energy  Energy stored as sugar  Plants need light energy, CO 2, and H 2 O  Takes place in the chloroplasts, using chlorophyll, the green pigment in plants chloroplasts chlorophyllchloroplasts chlorophyll

What happens during photosynthesis?  Carbon dioxide enters the leaf through holes called stomata stomata  CO 2 combines with the stored energy in the chloroplasts through a chemical reaction to make glucose  The sugar is moved through tubes in the leaf to the roots, stems and fruits of the plants  Some of the sugar is used right away by the plant for energy; some is stored as starch; and some is built into plant tissue

ROOTS

ROOTS – function and structure  Anchor plant in position  Absorb water and minerals from the soil  Specialized cells to increase surface area for water intake  Store food

Types of Roots  Fibrous: several thin roots that branch to form a tangle mass  Ex. Grass, corn, most trees

Types of Roots  Taproots: long thick main root and thin branching roots  Ex. Carrots, cacti,dandelions

Parts of a root  Epidermis: outermost layer of the root that has hairs on it

Root hair cells (x150)

Root ‘B’ has had the hairs damaged -

Parts of a root  Cortex: layer just inside the epidermis  Stores food  Carries water and minerals into vascular tissue

Parts of a root  Root Cap: protects the root as it grows through the soil

Parts of a root  Growth tissue: just behind the root cap, where new cells form

Human uses for roots  Food:  Carrots, beets, yams  Licorice, horseradish,and sassafras used as spices  Medicine  Dyes  Insecticides

Parts of Root Root hairs Fragile parts of cells that grow from the main root They massively increase the surface area for absorption

STEM: Structure and Function  Gets water and nutrients from the roots to the leaves  Holds the leaves up in the air so it can get sunlight to make food

STEM: Structure and Function  Vary greatly in size  Trunk  Branches  Twigs

Types of Stems  Herbaceous: have stems that are green and soft  Ex. Sunflowers, pea, tomatoes, grass, abd dandekions

Types of Stems  Woody: have stems that are hard and made of wood  Ex. Roses, Firs, and Maples

Structure of Woody stem

 Bark: outermost layer of stem  Tough  Waterproof  Helps protect the fragile tissue inside  Inner part of the bark is the phloem

Phloem  Transports glucose and starch made during photosynthesis.

Structure of Woody Stem  Vascular Cambium: growth region of the stem  This is where xylem and phloem are produced  Pith: Center of the stem  Stores water and food food

Stem Rings  Each ring represents a year’s growth of xylem  1 ring = 1 year  If a tree had 12 rings how old would it be?  12 years old