Slide1: Structure of Plants Slide 1 More free powerpoints at http://www.worldofteaching.com


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


B. Root Types: B. Root Types 2. Tap Roots –larger central root reaches deep water sources underground Ex. Trees, Carrots, & Dandelions 1. Fibrous Roots: branching roots hold soil in place to prevent soil erosion Ex. Grasses Slide 3 Tap Root


C. The Structure of a Root: Root Hairs: increase surface area for water & mineral absorption Meristem: region where new cells are produced Root Cap: protects tip of growing root C. The Structure of a Root Slide 4 Root Hairs Meristem Root Cap Xylem Phloem


A. Functions of Stems: A. Functions of Stems Support system for plant body Transport system carries water & nutrients 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: A. Functions of Leaves Slide # 6 Main photosynthetic organ Broad, flat surface increases surface area for light absorption Have systems to prevent water loss Stomata open in day but close at night or when hot to conserve water waxy cuticle on surface System of gas exchange Allow CO2 in and O2 out of leaf Elephant Ear Plant


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


Slide8: More Plant Parts… Guard Cells Guard cells: cells that open and close the stoma Stomata: openings in leaf’s surface; when open: GAS EXCHANGE: Allows CO2 in & O2 out of leaf TRANSPIRATION: Allows excess H2O out of leaf Slide # 8 Stoma


Function of Stomata: Slide # 9 Stoma Open Stoma Closed Guard Cells Stoma Function of Stomata Guard Cells What process involves using CO2 and H2O releasing O2 as a waste product? Photosynthesis What is the plant using this process to make? Carbohydrates-glucose If the plant needs water for photosynthesis, why is water coming out of the stoma?


Function of Guard Cells: Slide # 10 Stoma Open Stoma Closed Guard Cells Function of Guard Cells Guard Cells These stomata (leaf openings) naturally allow water to evaporate out. Why would the plant close stomata with guard cells? Prevent excess water loss through transpiration. (conserve water) So what is the point of having stomata? Allow gas exchange for photosynthesis


C. Plants find a use for Transpiration: Slide # 11 A average size maple tree can transpire 200 liters of water per hour during the summer. Transpiration is the #1 driving force for pulling water up stems from roots. C. Plants find a use for Transpiration Transpiration: loss of excess water from plant leaves 2. Significance: B A Transpiration causes enough pressure to help pull water (& required nutrients) up stem from roots. As part of the water cycle, trees transpire water back into the atmosphere. Transpiration provides much of the daily rain in rainforest.


Structure of a Flower: 1.Pistil:female reproductive structure Stigma: sticky tip; traps pollen Style: slender tube; transports pollen from stigma to ovary Ovary: contains ovules; ovary develops into fruit Ovule: contains egg cell which develops into a seed when fertilized Slide # 12 Structure of a Flower


Structure of a Flower: Stamen: male reproductive structure Filament: thin stalk; supports anther Anther: knob-like structure; produces pollen Pollen: contains microscopic cells that become sperm cells Structure of a Flower Slide # 13


 Structure of a Flower: Sepals: encloses & protects flower before it blooms Petals: usually colorful & scented; attracts pollinators  Structure of a Flower Slide # 14


Cross Pollination: Cross Pollination Slide # 15 How does pollination happen? Pollen from an anther is caught by the stigma, travels through style to the ovules in the ovary. What is the result of pollination? A Fruit: An ovary containing seeds.


Chapter 25: Chapter 25 Plant Responses and Adaptations Slide # 16


Hormone Action on Plants: Slide #17 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: Plant growth & development 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:: C. Plant cells will send signals to one another to tell them: When trees to drop their leaves. When to start new growth. When to cause fruit to ripen. When to cause flowers to bloom. When to cause seeds to sprout. Slide # 18 Leaf Drop Fruit Ripening Sprouting Corn Seeds Cactus Blooming Tree Budding


D. Ethylene causes Fruit to Ripen: D. Ethylene causes Fruit to Ripen Fruit tissues release a small amount of ethlyene Causes fruits to ripen. As fruit become ripe, they produce more and more ethlyene, accelerating the ripening process. Slide # 19 Ethylene released by apples and tomatoes causes fruit to age quickly.


Plant Tropisms: Plant Tropisms 1. Tropism: the way a plant grows in response to stimuli in the environment. Phototropism: growth response to light -Plants bend towards light Geotrophism: growth response to gravity -plant roots grow down with gravity, shoots (stems) grow up against gravity and out of the soil. Thigmotropism: growth response to touch -vines grow up around trees, venus flytrap closes when leaves are touched Slide # 20


Slide21: Slide # 21 Geotropism What type of tropism is shown in these pictures? Thigmotrophism Thigmotrophism Geotropism Phototropism Phototropism