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 withthe egg.

Fruits

Ovary fruit

Ovule seed

Seeds Cotyledon

– Dicot: two seed leaves

– Monocot: one seed leaf

Epicotyl: becomes the stem

Hypocotyl: becomes the roots