Plant Science Exame 1

Determinate Growth

Maximum size genetically determined

-Growth stops after a time

-Usually cannot heal/regrow

Ex: Leaves, flowers, and fruits

Indeterminate Growth

No maxiumum size genetically

-Able to keep growing through life

-Can heal/regrow

-Only is limited by resource or environmnet

Ex: Roots and Stems

Cell Theory

-Robert Hook first spots cells under microscope

- Schleidern and Swann then say

1. All plants and animals are made of cells

2. Cell is basic unit of life

Virchow then added

3. Cells arise by reproduction from previous cells

General Features of All Cells

-Plasma

-Cytoplasm

-Dna

-Ribosomes

(Please Call Dr. Rob)

Eukaryotic Cells

Have unique components like:

-Mitochondria

-Golgi app

-ER

-Endomemrbane system

-Peroxisomes and Vesicles

Traits Unique to Plant Cells

-Cell wall

-Cell vacuole

-Chlorplast (plastid)

Central Vacuole

A large membrane-bound structure that stores water and can fill much of the cell.

Helps regulate water concentration through osmosis

-Surrounded by tonoplast and stores nutrients, ions, and waste products

Chloroplasts

Stores chlorophyll and other pigments for photosynthesis

-Pigments are stored in sacs called thylakoids, found in stacks called Grana

-Contains its own DNA and ribosomes

Cell Wall

Made up of the middle lamella_, Primary cell wall, and, secondary cell wall

-Middle lamella

Is a thin layer of pectin binding adjacent cells

-Primary Cell wall

-Surface of all plant cells

-Composed of cellulose microfibrils

-Thin and elastic to allow for cell enlargement

Microfibrils

The orientation of these determines the direction of cell enlargement. Expands longitudinally (ex:spring)

Secondary cell wallI

-Made of layers deposited on the inner primary wall

-Ligin+Cellulose deposited, adding rigidity

-Thicker than primary wall; can even push cell to death

Plasmosdesmata

Are pores which allow for communication btwn cell walls.

Meristems

Are regions of continuous cell divison and growth located in dif points of the plant

3 types: Apical, Lateral, and Intercalary

Apical Meristem

Located at the tips/ends of roots and stem, controls height

Produce 3 primary meristematic tissues:

-Protoderm,

-Ground Meristem

-Procambium

Protoderm

Gives rise to epidermis

Ground Meristem

Gives rise to ground

Procambium

Gives rise to vascular tissue (transport)

Lateral Meristem

Responsible for secondary growth, which is an increase in girth/width

Located in two regions:

-vascular cambium

-cork cambium

Vascular Cambium

Gives rise to vascular tissues

Cork Cambium

Produces periderm (secondary dermal tissues)

3 Types of Tissue Systems

-Ground Tissue (mesophyll, pith)

-Vasuclar tissue system (xylem and phloem)

-Dermal tissue system (epidermis and periderm)

Simple Tissues

-Composed mostly of a single cell type

3 main types:

-Parenchyma

-Collenchyma

-Sclerenchyma

-Perform essential functions like support, storage, regulation…

Parenchyma

-Spherical or elongated

-Thin primary cell walls but may develop secodnary walls

-Living cells perform many metabolic functions

-Only type of cell that when mature, can be reprogrammed to form other

- can aggregate(group) to form simple tissues like cortex,pith, and mesophy

Collenchyma

-Elongated, often containing chloroplasts, and alive at maturity

-Cell walls composed of alternating layers of pectin and cellulose, usually thicken at corners *strong and flexible

-Provides support to young stems and leaves, allowing for growth

-Outermost cells of cortex might aggregate into rights around the stem

Sclerenchyma

-Thick, lingified secondary cell walls. Dead at maturity

2 types of cells: Fibers and Sclerids

Fibers

Long narrow cells with thick, pitted walls tappered at ends

-Can aggregate into continuous cylinders around stems or form strands

Sclereids

Can have many shapes, from simple ones to highly branched

-Can form sheets or be in small clusters

Complex Tissues

Interconnected network of cells transversing the enitre plant. 3 types:

-Vasuclar

-Epidermis

-Periderm

V.E.P

Vascular System

Composed of:

-Vessel elements and tracheids

-Fibers

-Living parenchyma cells

Epidermis

Single layer of cells in the outer part of a plant, covered in cutin

Complex tissue composed of

-Epidermal cells

-Guard cells

-Trichomes: hairlike outgrowths

-Subsidiary cells

Periderm

-Protective layer that forms in older stems and roots and replaces the epidermis

A secondary tissue composed of:

-Phellem (Cork)

-Phellogen or cork cambium

-Phelloderm

Aboveground

Shoot system, which includes stems, leaves, and reproductive organs (flowers/Fruits)

Functions of Stem

-Support

-Conduction

-Photosynthesis

-Food storage

Stem Morphology

-Are characterized by their nodes, which are points of attachment of leaves

-Internode region, area between two nodes

-Axillary bud usually found in the region btwn leafe and stem

Primary Growth

Growth in length. Comes from apical meristems.

Secondary Growth

Increase in thickness or girth cause be the secondary meristem. Comes from lateral meristem

Vascular Cambium

Cork Cambium

Wood and Bark Formation

Stem Branching

Monopodial

Buds do NOT degrade, and all shoots continue to grow

Sympodial

Terminal buds degrade, and lateral buds closest to the apex become new terminal shoot

Leaf

-Organs for performing photosynthesis

-Arise from shoot apical meristem through leaf primordia

-Determinate growth

-True leaves have a bud located j above btwn leaf and stem

Leaf Morphology

Petiole

The stem-like part of the leaf, connecting the blade to the stem

Petiolate

Leaves containing a visible petiole

Peltate

A special type of petiolate where the petiole attaches underneath the blade instead

Sessile

Leaves without visible petiole

Perfoliate

Special type of sessile leaves in which the stem passed through the center of the blade

Phyllotaxy

Alternate

Opposite

Decussate

Distichous

Whorled

Simple vs. Compound Leaf

Simple Leaf

Compound Leaf

Palmate

Pinnate

Double

Venation

Midrib

Vein Arrangements

Parallel

Pinnate

Palmate

Tertiary Venation

Reticulate

Percurrent

Leaf Margins

Entire

Undulate

Lobate

Toothed

Leaf Shapes

Heterophylly

3 stages of te embryo proper in Eudicots

-Globular

-Heart

-Torpedo

Underground

Seeds

Allow populations to propagate

-Maintain genetically diversity

-survive harsh environments conditions

-Disperse into new ones

Function of Seeds

Seed Morphology

Contains a:

-embryo (new plant)

-Endosperm and/ or cotyledon (nutrient source)

-Seed coat (protection)

Seed Coat

Serves as protection and to maintain moisture

Testa

Tegmen

Hilum

Micropyle

Plumule

Responsible for shoot system

-shot apical meristem

-leaf primordia

Shoot Meristem

Leaf Primordia

Radicle

Very small before germination, its the embryonic root.

Hypocotyl

Region btwn cotyledon attachment point and radicle

Epicotyl

Region btwn cotyledon attachment point and shoot tip

Embryogenesis

Globular Stage

Heart Stage

The heart shape gives rise to cotyledons. The endosperm continues to divide

Torpedo Stage

The shoot apical meristem is btwn the cotyledons, and root apical meristem is anchored to the suspensore

Seed Dispersal