TAKS Objective 3 Plants: Structures and Adaptations

Structure of Plants Slide 1

Plants are... Multicellular Have cell walls Photosynthetic Growth occurs in modules or “pieces” Reproduction –Asexually –Sexual via spores or seeds

Plants are Primary source of food for people and animals Produce oxygen help to keep us cool renew the air

Photosynthesis Process by which CO 2 and H 2 O in the presence of light are converted into sugar and oxygen

Chemical formula 6CO 2 + 6H 2 O+sunlight ---->C 6 H 12 O 6 + 6O 2

Dermal tissue Vascular tissue Ground tissue Stem Root Leaf The basic structure of a plant: Root, Stem, and Leaf Tissues

THE LEAVES

A. Functions of Leaves 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 (Opening) Leaf Cross-Section Veins Cuticle Stoma Stoma- singular Stomata-plural

More Plant Parts… Guard Cells 4.Guard cells: cells that open and close the stoma 5.Stomata: openings in leaf’s surface; when open: GAS EXCHANGE: Allows CO 2 in & O 2 out of leaf TRANSPIRATION: Allows excess H 2 O out of leaf Stoma

Stoma Open Stoma Closed Guard Cells Stoma Function of Stomata Guard Cells CO 2 O2O2 H2OH2O What goes in? What goes out? What process involves using CO 2 and H 2 O releasing O 2 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?

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

THE REPRODUCTIVE ORGAN OF THE PLANT THE FLOWER

1.Pistil:female reproductive structure a.Stigma: sticky tip; traps pollen b.Style: slender tube; transports pollen from stigma to ovary c.Ovary: contains ovules; ovary develops into fruit d.Ovule: contains egg cell which develops into a seed when fertilized Filament Anther Stigma Style Ovary Pistil Petal Sepal Ovule Stamen Structure of a Flower

2.Stamen: male reproductive structure a.Filament: thin stalk; supports anther b.Anther: knob-like structure; produces pollen c.Pollen: contains microscopic cells that become sperm cells Structure of a Flower Filament Anther Stigma Style Ovary Pistil Petal Sepal Ovule Stamen

3.Sepals: encloses & protects flower before it blooms 4.Petals: usually colorful & scented; attracts pollinators Structure of a Flower Filament Anther Stigma Style Ovary Pistil Petal Sepal Ovule Stamen

Cross Pollination 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.

THE STEM

A. Functions of Stems 1.Support system for plant body 2.Transport system carries water & nutrients 3.Holds leaves & branches upright 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?

THE ROOTS

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

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 Tap Root

1.Root Hairs: increase surface area for water & mineral absorption 2.Meristem: region where new cells are produced 3.Root Cap: protects tip of growing root C. The Structure of a Root Root Hairs Meristem Root Cap Xylem Phloem

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. Plants find a use for Transpiration 1.Transpiration: loss of excess water from plant leaves 2. Significance: B A a.Transpiration causes enough pressure to help pull water (& required nutrients) up stem from roots. b.As part of the water cycle, trees transpire water back into the atmosphere. c.Transpiration provides much of the daily rain in rainforest.