Structure of Plants Slide 1

A. Functions of Roots 1.Anchor & support plant in the ground 2.Absorb water & minerals 3.Hold soil in place Slide 2 Fibrous Roots Root Hairs

A. Functions of Stems 1.Support system for plant body 2.Transport system carries water & nutrients 3.Holds leaves & branches upright Slide 5 Each light and dark tree ring equals one year of annual growth. Light rings for fast spring growth, dark for slow summer growth. Smaller rings tell of past droughts that have occurred. Looking at the picture to the left: What years had the most rain? What years experienced the worst drought?

A. Functions of Leaves Slide # 6 1.Main photosynthetic organ 2.Broad, flat surface increases surface area for light absorption 3.Have systems to prevent water loss Stomata open in day but close at night or when hot to conserve water waxy cuticle on surface 4.System of gas exchange Allow CO 2 in and O 2 out of leaf Elephant Ear Plant

B. Leaf Structures 1.Cuticle: waxy layer; covers upper surface Protects leaf against water loss 2.Veins: transports water, nutrients and food Made of xylem and phloem 3.Mesophyll: contains cells that perform photosynthesis b/c they contain Chloroplasts. 2 Guard Cells Surround each Stoma M e s o p h y l l Slide # 7 (Opening) Leaf Cross-Section Veins Cuticle Stoma Stoma- singular Stomata-plural

Chapter 25 Plant Responses and Adaptations Slide # 18

Slide #19 Hormone- producing cells Target cells Movement of hormone Hormone Action on Plants A. Plant cells can produce hormones: which are chemical messengers that travel throughout the plant causing other cells called target cells to respond. B. In plants, hormones control: 1.Plant growth & development 2.Plant responses to environment Cells in one blooming flower signals other blooms using hormones to open.

C. Plant cells will send signals to one another to tell them: 1.When trees to drop their leaves. 2.When to start new growth. 3.When to cause fruit to ripen. 4.When to cause flowers to bloom. 5.When to cause seeds to sprout. Slide # 20 Leaf Drop Fruit Ripening Sprouting Corn Seeds Cactus Blooming Tree Budding

D. Ethylene causes Fruit to Ripen 1.Fruit tissues release a small amount of ethlyene 2.Causes fruits to ripen. 3.As fruit become ripe, they produce more and more ethlyene, accelerating the ripening process. Slide # 21 Ethylene released by apples and tomatoes causes fruit to age quickly.

Plant Tropisms 1. Tropism: the way a plant grows in response to stimuli in the environment. a.Phototropism: growth response to light - Plants bend towards light a.Geotrophism: growth response to gravity -plant roots grow down with gravity, shoots (stems) grow up against gravity and out of the soil. a.Thigmotropism: growth response to touch -vines grow up around trees, venus flytrap closes when leaves are touched Slide # 22

Slide # 23 Geotropism What type of tropism is shown in these pictures? Thigmotrophism Geotropism Phototropism