plant biology

2 Systems3 Tissues2 MeristemsPhotosynthesisGrowthReproduction

Plant Biology

Plant Body Systems

Two types of systems:Root SystemShoot System: stem, leaf, flower

Plant organs: root, stem, leaf, flower referred to as plant parts

Root System Function Anchorage

Keeps plant in the soil

Prevents soil erosion Holds stem in place

Absorption water dissolved minerals

Storage Starch Other nutrients

Types of Rootshttp://www.bio.miami.edu/dana/pix/taproot_fibrousroot.jpg

http://tchefty.wikispaces.com/file/view/rootsystems1.jpg/260637884/rootsystems1.jpg

http://kentsimmons.uwinnipeg.ca/2153/rootsystems1.jpg

Taproot

Large long primary root Penetrate deep into the ground Small thin roots grow laterally off

main root Strong anchoring system Examples: evergreen trees

Taproot

Specialized to store water, food, nutrients

Better chance at drought survival

Examples: carrot, beet, turnip, radish

http://www.ontarioweeds.com/media/jpg/tropr_root.jpg

Fibrous Root

Many small roots that branch

Increases surface areaBetter absorption of water

and mineralsLess structural supportExamples: peas, beans,

lettuce

Root Hairs

Small fibrous objects that branch off roots

Absorbs water and minerals

Root Zones

Zone of maturation: cells differentiate into different types of cells

Zone of elongation: allows the root to get deeper within the soil

Meristematic region: rapid mitosis of undifferentiated meristematic cells

Root cap: protects the meristematic region

Shoot System

StemLeafFlower

Stem

Raises and supports branches, leaves and flowers

Transport of water and nutrients

In trees the main stem is the tree trunk

http://www.pxleyes.com/images/contests/bw%20tree%20trunks/fullsize/bw%20tree%20trunks_4b6283790291c.jpg

Stem

Young green stems can perform photosynthesis because they have chloroplast in their epidermal cells

Stem Some are specialized for food storage Examples: sugar cane, potatoes

http://upload.wikimedia.org/wikipedia/commons/9/96/Sugar_Cane.jpg

Leaf

Main function: Photosynthesis Parts of the Leaf:

Cuticle Epidermis Guard Cells & Stoma Palisade cells Spongy Layer Vascular Tissue

Epidermis

Outer layer of cells

Leaf epidermis produces cuticle

http://www.goldiesroom.org/Multimedia/Bio_Images/05%20Nutrition/15a%20Cross%20Section%20of%20a%20Leaf.jpg

Cuticle

Waxy substance that coats the exterior

Water proofing Protect interior

tissues Blocks passage

of gases

http://www.goldiesroom.org/Multimedia/Bio_Images/05%20Nutrition/15a%20Cross%20Section%20of%20a%20Leaf.jpg

Guard Cells & Stoma

Stoma (Greek for “mouth”)

Pore-like openings in the plant’s epidermis

Opening size controlled by two guard cells

permits gas exchange between the leaf’s interior and external environment.

larger opening, faster gas exchange

Guard Cells & Stoma

Spongy Layer

Where water is stored

Where the vascular tissues reside

Palisade Cells

Contains many chloroplast for photosynthesis

Cells stand tall and upright Top end

exposed to light

Bottom end exposed to the gases in the spongy layer

Chloroplast Structure

Thylakoids are flat disc-like structures where chlorophyll is embedded

Grana are thylakoids arranged in a stack

Chlorophyll is a pigment that captures light energy

Site for starch (a type of sugar) storage

Site for photosynthesis Reaction involves

trapping light energy to create food in the form of sugars

Starting substances are carbon dioxide and water

CO2 + H2O + energy O2 + glucose

Chloroplast Function

Leaf Cross Section Scanning electron microscope image

of a leaf from a Black Walnut tree. (Dartmouth Electron Microscope Facility/Dartmouth College)

http://cache.boston.com/universal/site_graphics/blogs/bigpicture/micro_11_14/m04_walnut_leaf.jpg

Modified Leaf: Cactus

Poinsettia Leaves

Flower

Specialized structures developed for sexual reproduction known as pollination

Can contain both male and female reproductive structures in the same flower

Flower Parts

Male reproductive organ: stamenFemale reproductive organ: pistil

http://www.exploringnature.org/graphics/teaching_aids/flower_parts_color72.jpg

Flower Parts

Male gametes: pollen grains found on anther Female gametes: ovule housed in ovary

Pollination

Act of sexual reproduction in plantsPollen reach stigma, travel down the

style into the ovary to fertilize the ovule

Pollen grains blown by wind

Plants are often small and drab but produce a large amount of pollen

Example: grass

Methods of Pollination: Wind

http://www.vcbio.science.ru.nl/images/pollen/pollen-grass-stigma.jpg

Methods of Pollination: Animals

Pollinators: Animals: birds,

bats, and on fur of land animals

Insects: bees Plants attract

pollinators with: Large, colourful

fragrant flowers nectar

http://4.bp.blogspot.com/_Xla0E3fwLto/S4CL_NstZuI/AAAAAAAABP4/PgoWyz-Mk2w/s400/4342259001_e10572466d_b.jpg

Methods of Pollination: Animals

Example: Dandelion plant attracting beeshttp://guelph.ca/uploads/Healthy%20Landscapes/Pollination_Bee_Dandelion_Zoom.jpg

After Pollination

Zygote (fertilized egg) becomes the seed

Ovary becomes the fruit

After Pollination

Zygote (fertilized egg) becomes the seed

Ovary becomes the fruit

http://www.biosci.ohio-state.edu/~plantbio/osu_pcmb/pcmb_lab_resources/images/pcmb101/flwrs_sds_frts/where_fruit.jpg

After Pollination

http://greatneck.k12.ny.us/gnps/shs/dept/science/krauz/bio_h/images/38_09FruitDevelopment_L.jpg

Plant Tissue

Dermal Tissue

Vascular Tissue

Ground Tissue

Dermal Tissue

Outermost layer of a plantEpidermis: thin layer of cells that

covers the surface of leaf, stem and root

Periderm tissue: bark on stem and large roots of woody plants (replaces the epidermis)

Dermal Tissue

Some dermal tissues have unique functions

Root cells: root hairs (long extensions)

Leaf cells: produce cuticle

Vascular Tissue

Plant circulatory systemVessels that connect roots to leavesTransports water, dissolved

minerals, and sugars throughout plant, providing cells with materials to carry out life functions

Two types: Xylem Phloem

Vascular Tissue: Xylem

made up of long hollow tubes formed by non-living cell walls (left over from plant cells that have died)

transports water and dissolved minerals upwards from roots

Vascular Tissue: Phloem

Made up of elongated cells that are living

Transports: solutions of sugars (food) Dissolved nutrients Hormones

Bi-directional movement of materials downward to roots upward to leaves

Vascular Bundle

Plant Sugars

Starch is NOT soluble in water Starch can be broken down into

sucrose Sucrose IS soluble in water Sucrose is transported through the

phloem to the plant parts that require it Sucrose can be broken down into

glucose Glucose is used in cellular respiration to

make cellular energy

Starch sucrose glucose

Spring

Trees need energy to grow leaves

Energy comes from cellular respiration of glucose:Glucose + oxygen carbon dioxide + water + energy

Glucose can be obtained by: Photosynthesis - but

spring trees don’t have any leaves to do photosynthesis

Converting it from starch

Spring

Starch Stored in the roots Insoluble in water so it cannot be transported

through phloem Convert to sucrose

Sucrose Soluble in water Transport from root to tree bud through phloem Convert to glucose in tree bud

Glucose Use in cellular respiration Converted to cellular energy needed to grow

leaves

Tree Sap

Starch Sucrose Glucose

Roots Stem Leaves

Storage TransportPhotosynthesi

s

Plant Sugars

SugarSolubilityin water

Location Function

Starch No Root Storage

Sucrose Yes Stem Transport

Glucose Yes Leaf Photosynthesis

Summer

Once leaves have grown, they can perform photosynthesis to produce their own glucose

Glucose is converted to sucrose and transported through the phloem to the roots

Sucrose is converted to starch in the roots for storage

Glucose

(leaves)

Sucrose

(stem)

Starch

(roots)

Winter storage

Summer and Fall

Summer and Fall

Spring

Spring

Sugar Movement through Phloem

http://www.nuscentscandle.com/blog/wp-content/uploads/tree-sap.jpg

Cells in the Root

Cells in the root have no chloroplasts and are not exposed to sunlight so they can not undergo photosynthesis to make their own food

Root cells must perform cellular respiration to obtain cellular energy

Glucose + oxygen carbon dioxide + water + energy

Glucose comes from the starch stored in the root

Oxygen is absorbed through the soil

Ground Tissue

Filler tissue in between the dermal and vascular tissue

Variety of processes depending on where it is in the plant

In leaf: palisade and spongy mesophyll cells