Plant Cells, Tissues, and OrgansSection 2.1

HomeworkPg. 62 #1-4

Chapter 2 Plants: From Cells to Systems

In this chapter you will investigate:• how plant cells specialize to form different tissues

• the link between cells, tissues, organs, and systems in plants

• the function of plant tissues and organs

• how organs work together to meet the needs of a plant

• diseases that threaten plant tissues and organs

Organization in a multi-cellular organismHierarchical levels of organization:

Organism

Organ systems

Organs

Tissues

Cells

Most complex

Least complex

Sp

ecia

lized

pla

nt

cells

simplest level of

organization

a collection of similar cells that perform a particular

function

a structure composed of two or more tissues

working together to perform a

complex body function

consists of one or more organs

and other structures that

work together to perform a vital body function

made up of many different organ systems

working together

Heart muscle cell

Epidermal cell Dermal tissue Leaf Shoot system

Maple tree

Heart muscle tissue

HeartCirculatory

system Zebra

•Plant stem cells are called meristematic cells.

•Meristematic cells have the potential to constantly divide and differentiate.▫photosynthesis▫gas exchange▫material transport▫support

Meristematic cells allow plants to constantly replace old organs.

All growth in the plant is due to the division of meristem.

▫Most occurs at the terminal bud.

BudsRegions containing meristematic cells

Apical meristems▫Found in buds at

tips of roots and shoots.

▫Responsible for increase in height.

Lateral meristems ▫Responsible for

increase in width.

Growth is controlled by chemicals called auxins.▫Produced by actively dividing cells.▫Signal neighbouring cells not to divide.

Plant tissue types

Meristematic tissue

Dermal tissuecovers outer surface

Vascular tissuemoves substances

through plant

Ground tissuesupportive tissue

Differentiates into...

Every plant organ contains tissue from all three systems.

Dermal tissue•Plant’s outermost

layer

•Two types:▫Epidermal tissue

thin layer of cells; covers non-woody surfaces of plant

▫Periderm tissue covering that forms

the woody surface on stems/large roots

Adaptations of dermal tissueAdaptation Function

Root hairs Maximize water uptake

Leaf hairs Contain chemical irritants

Waxy cuticle Makes surface waterproof

Vascular tissue•system of tubes•distributes absorbed water, minerals

and nutrients

Xylem

Dead, hollow tissue

Transports water and minerals

upwards from roots

Phloem

Living tissue

Transports sugars produced by leaves,

to the rest of the plant

Non-woody plantVascular tissue

arranged in bundles

Woody plantVascular tissue forms a

ring along trunk diameter

Ground tissue

•“Filler” tissue between dermal and vascular

•Variety of functions:

▫photosynthesis, in the green parts of plants

▫storage of carbohydrates in the roots

▫storage and support in the stems

Plants have two organ systems

SHOOT SYSTEMStem, leaves, flowers, fruit

(if present)

ROOT SYSTEMOne or more

separate roots

The Root SystemFunctions: • anchor the plant• absorb water and minerals

from soil• store food

Structure:• no leaves• usually grows below

ground• composed of dermal tissue• root hairs maximize

surface area

Spaces between cortex cells allow water to move from soil to the endodermis.

Endodermis controls transport of water and minerals between cortex and xylem.

Types of roots:Taproots vs. Fibrous roots

The Shoot System

Functions:• carry out photosynthesis (leaves)• structural support• transport substances throughout plant• produce flowers for sexual reproduction

Structure:• usually above

ground• components:

▫ leaves▫ stem▫ flowers/fruit

LeavesMain site of photosynthesis:

•chloroplasts contain chlorophyll; absorb sunlight’s energy

•glucose is used for cellular respiration, plant growth, and energy storage

CO2+ H2O + light energy ___________+ O2

Layers of the Leaf

Epidermis Transparent outer layer, made of dermal

tissue.▫The upper epidermis secretes waxy

cuticle.

▫The lower epidermis contains stomata (holes) for exchange of gases ((H2O, O2, CO2). opening/closing of stomata is controlled

by guard cells

Mesophyll Middle layers, sandwiched between upper

and lower epidermis▫Palisade cells – Perform most of the

photosynthesis in the leaf contain many chloroplasts tightly-packed together

▫Spongy parenchyma cells – Loosely-packed to allow the movement of gases within the leaf

Vascular bundles Composed of vascular tissue (xylem and

phloem)

▫arranged in bundles▫visible on the leaf as veins

Chloroplasts• membrane-

bound organelle

• contains more membrane-bound sacs (thylakoids)

• thylakoids are arranged in stacks (grana)

Leaves have structures that help the plant obtain and keep the reactants for photosynthesis:

CO2+ H2O + light energy glucose + O2

Cuticle is transparent to let light through. Palisade cells are tightly-packed to maximize the area exposed to the Sun.

Guard cells close the stomata on hot days to prevent evaporation of water.

Spongy parenchyma is loosely-packed to allow gases to circulate to all photosynthesizing cells.

The Stem

•Functions:▫Support for shoot system▫Transport of nutrients and water to leaves

•Specialized stems: Food storage, protection, photosynthesis, reproduction

•Uses: sugar cane, medicines, cork, wood and paper

Flowers•Contain reproductive structures

(male/female/both) Male Female

Organ Stamen Carpel/Pistil

Gamete Pollen grains Eggs

•Fertilization occurs by pollination, and produces seeds.▫contained in the fruit

•Pollination can be assisted by wind, animals, or insects.

Flowers: AdaptationsTo attract pollinators, plants will have attractive flowers or nectar.