Plant Unit Notes

Plants vs. Animals  Plants are very different from animals. They can’t move, they don’t have hearts or brains, can’t seek shelter. So, how do plants live without moving?

 How do plants eat?  How do plants breath?  How do plants circulate materials?  How do plants regulate?  How do plants reproduce?  How do plants protect themselves?

Animal eating

Plant eating

 Before a plant can eat, it has to make its own food by photosynthesis.

Light and color  When light strikes matter, some of the matter’s atoms may absorb photons.  Electrons are excited and absorbed light changes into heat.  In photosynthesis, the light is used for energy to make chemical bonds.

Color  The color you see is reflected off the object and into your eyes. All other colors are absorbed by the object.

Photosynthetic Pigments  Chlorophyll: –Two varieties…  Chlorophyll a  Chlorophyll b  They are green. They absorb mainly blue and red light.

Other pigments  Carotenes: orange pigment  Xanthophylls: yellow pigment

Chloroplasts

Plant Structures  Outside coverings –Epidermis: skin on leaf –Cork: bark- not living

Growing Tissue  Meristems: –At top of plant –Actively dividing cells –Makes plant grow taller  Cambium: –Below bark –New xylem and phloem tissue –Makes plant grow out/wider

Animal circulation

How do plants transport materials?

Vascular Tissue  Xylem: –carries water from roots to leaves  Phloem: –Carries sugar from leaves to plant

 The blue cells are phloem cells.  The large open vessels are xylem

Roots  Primary roots  Secondary roots  Root hairs

Stem structure  Herbaceous stems: soft  Woody stems: hard

Leaves  Simple leaf

Complex leaves

Leaf structure  Cuticle: waxy covering  Upper epidermis: top layer of cells  Palisade mesophyll: tall cells, photosynthesis occurs here  Spongy mesophyll: many air spaces for gas exchange  Veins: contain xylem and phloem

How do plants breath?

 Guard cells: open and close the stomate  Stomate: an opening in the bottom of the leaf that allows gasses to enter or leave.

How do plants get water from roots to leaves?  Capillary action: water sticks to walls of xylem.  Root pressure: water can only go up.  Transpiration pull: water evaporating out of leaf pulls up more water.

How do plants regulate?  They have no brain…. So how do they communicate with the rest of the plant?

Plant hormones  Auxins tell plants to grow towards the light.

 Gibberellins tell the plants to grow taller and produce fruit.  The grapes on the right were treated with more gibberellins

 Cytokinins: stimulate cell division and seed germination  Ethylene: ripens fruit (C2H4 … a gas)  Abscisic acid: causes leaves to fall off tree.

Tropisms:  Phototropism: grow towards light  Geotropism: tells roots to grow down.  Thigmotropism: responds to touch… wrap around things.  Hydrotropism: growing toward water.

How do plants reproduce?

Flower parts  Petals: colorful part (usually)  Sepals: green (usually) parts under petals  Corolla: all petals together  Receptacle: attachment point of flower parts.

 Stamen: male reproductive parts –Anther: contains pollen –Filament: holds up anther

 Pistil: Female reproductive parts –Stigma: sticky end that catches pollen –Style: tube that pollen grows down –Ovary : contains eggs –Ovule: eggs

Pollination  Wind, water, or animals carry pollen from one plant to another.

Fertilization Pollen grain grows down the style to the ovary and fuses with the egg.

Fruits Ovary  fruit Ovule  seed

Seeds  Cotyledon –Dicot: two seed leaves –Monocot: one seed leaf

 Epicotyl: becomes the stem  Hypocotyl: becomes the roots