Final Unit: 5
Plants!!!
Vascular plants
 2 organ system
 Underground root system
 Anchors the plant by penetrating into the soil
 Root system absorbs water and nutrients
 Above-ground shoot system
 Made up of stems and leaves
 Leaves perform photosynthesis
 Stems bear the reproductive structures
Shoot
system
Root
system
Dermal Tissue
 Outer covering of a plant
 Epidermis: single layer of dermal tissue forms a
protective covering
 Guard cells: a specialized epidermal cells that
surrounds the stoma
 Stoma: small opening usually in the leaf, that allows
gas exchange to occur
Vascular Tissue
 Internal system of tubes that run lengthwise
throughout the stem, connecting roots and leaves
 Function: to transport water and dissolved substances
 2 types:
 Xylem: transports water and minerals from roots to
leaves
 Phloem: transports organic nutrients to areas needed
for growth and metabolism
Types of root systems
 2 types of root systems
 Taproot

Thick root with smaller lateral branching roots

Tap into sources of water far below ground level

Ex: Carrots
 Fibrous roots

Made up of many smaller branching roots

Grow from a central point

Do not grow as deeply

Ex: scallions
Stems
 Main function: to provide support for the plant’s leaves and
reproductive structures
 Tuber: enlarged part of an underground stem. Has buds
extending from it that will grow into new potato plants.
 Bulbs: shortened, compressed stems surrounded by fleshy leaves
(ie onions and tulips).
 Corms: composed almost entirely of stem tissue with some scaly
leaves on top.
 Stolons: horizontal stems that grow above ground along the
surface of the soil like strawberry plants.
 Rhizome: horizontal stems that grow underground.
Leaves
 Cuticle: a waxy layer on the epidermis that is secreted
by epidermal cells
 Mesophyll: the layer between the upper and lower
epidermis of a leaf that contains chloroplast
 Palisade mesophyll: the layer of cells where most
photosynthesis takes place, immediately below the
epidermis
 Spongy mesophyll: the layer of irregularly shaped,
loosely packed cells below the palisade mesophyll.
Allows oxygen, CO2 and H2O to move around easily
Identifying Leaves
 Venation: pattern of veins in a leaf
Leaf type
Leaf Venation
Leaf Arrangement
Monocot vs Dicot
 Organization of vascular tissue in roots and stems
 Monocot: Arranged in a ring
 Dicot: Roots arranged in star shape
 Venation
 Monocot: Veins parallel
 Dicot: Palmate or pinnate
 # of flowering plants
 Monocot: Multiples of threes
 Dicot: Multiples of four or five
 Root
 Monocot: Fibrous
 Dicot: Taproot
 Examples
 Monocot: Banana, onion, palm tree
 Dicot: Strawberry, cactus, rose tree
Homework
 P.559 #3, 4, 11, 12, 15, 16
Transport in Plants
Movement of water and
nutrients
 Diffusion: net movement of particles from an area of
high concentration to a low concentration
 Osmosis: diffusion with water
 These two occur naturally
 Active transport: to move sugar and nutrients cross
cell membranes, need energy
Transport in Xylem
 How can water move upward through trees
and other plants when common sense tells
us gravity should "pull" the water down
The answer is in the xylem of the
plants
 Water enters roots, rises through xylem, and exits
through stomata and leaves.
What helps water move through xylem?
• Water moves through the xylem these factors:
o
a small "pushing" pressure from water entering roots
o
a larger "pulling" pressure cause by water evaporating called
transpiration (process in which water evaporates from the
inside of a leaf to the outside through the stomata)
What about in tall trees?
 Negative pressure (pulling) from above is the strongest force for
long-distance transport in plants
 This is called the Cohesion-tension model
 3 main factors:
 1. transpiration: evaporation of water is responsible for the
movement of water and dissolved minerals upward in a plant. As
water evaporates, more comes up the plant.
 2. cohesion: water molecules sticking together
 3. adhesion: water molecules stick to the xylem walls
Nutrient transport in
Phloem
 Translocation: transport of sucrose and other organic
molecules
 Sink: any region in the plant where sugars are used or
stored
 Pressure-flow model: explains how organic molecules
from from source to sink
Pressure-flow model
 Bulbs are covered by selectively permeable membrane –
water can pass, not sucrose
 First bulb has high concentration
 Water flows into first bulb, and this creates a pressure
difference between the two bulbs
 Some contents of first bulb are forced up into tube
connecting both bulbs
 As pressure builds up in second bulb, water diffuses out
 When concentrations of sucrose are equal, flow stops
Homework
 P.566 #1, 2, 3, 7
Sexual Reproduction in
Angiosperms
 Angiosperm: A flowering plant
 Plants have 4 organs
 1. Sepals: protects the flower bud, can look like small leaves or
flower’s petals
 2. Petals: attract pollinating insects and provide a platform to land
 3. Stamens: male reproductive organs. Composed of a filament and
anther. Filament supports anther, which contains cells that undergo
meiosis and mitosis
 4. Pistil: female reproductive organs. Composed of a stigma, style,
ovary. Stigma and pistil is where pollination takes place.
Pollination
 Transfer of mature pollen grains from the anther to
the stigma
-wind
-insects
-birds & other animals
 When a pollen grain lands on the stigma, it germinates
and a pollen tube grows down through the style to an
ovule (egg)
Fertilization
 The sperm travels through the pollen tube to the
ovule. The sperm & egg fuse forming the zygote
(fertilized egg) –this grows into the plant embryo
(cells grow by mitosis)
*Self pollination –pollen from same flower
*Cross pollination – pollen from a different flower
- more variation
 The ovary and zygote (fertilized ovule) develop and
ripen.
*The ovule forms the seed and the ovary forms the fruit.
 A fruit is a ripened ovary
The plant embryo uses food stored in the
cotyledon of the seed until it develops
leaves for photosynthesis
Seed Germination
 When seeds disperse, they may begin to grow. As the seed
matures, it loses water and enters dormancy (metabolic
processes slow down)
 Germination: process of resuming growth after being
dormant
 Radicle: structure created by the division and lengthening
of embryonic root cells inside a germinating seed; it
develops into the primary root of the plant
 Hypocotyl: a hook shaped structure in dicots that
eventually emerges above the ground
Techniques of Artificial
Propagation
 The cloning of a plant from a portion of its stems, roots or leaves
Cutting
Cuttings are small pieces of stem with some
leaves attached, the new plant grows from this.
They can be placed in moist
soil or water (and sometimes
dipped in rooting
powder).
Grafting
A cut stem of one plant (with good flower or
fruit growth) (the graft) is taken and firmly
attached to the rootstock of another plant
(which has a strong, established root system)
(the stock).
Examples- roses, fruit trees
Division
A plant is split into 2, containing intact shoots and
roots. Planted in a new location
Homework: p.592 #3, 10, 13, 14a