Plant Structure and Function

1)      Flowering Plants have three organs

a)      Root

i)        Anchors plant

ii)       Absorbs water and minerals

iii)     Stores the products of photosynthesis

b)      Stems

i)        Support leaves

ii)       Conduct materials to and from roots to leaves

iii)     Help store plant products

c)      Leaves

i)        Specialized for gas exchange

ii)       Carry on most of the photosynthesis in plants

2)      Plant Tissues

a)      Epidermal Tissue

i)        Forms the outer protective covering of a plant

b)      Ground Tissue

i)        Fills the interior of plant

c)      Vascular Tissue

i)        Transports water and nutrients in a plant and provides support

3)      Roots and Stems

a)      Parts of a Root

i)        Epidermis: outer most layer. 

(1)   The root hairs are derived from the epidermis

ii)       Cortex: next layer into plant. 

(1)   Water and food are stored here

iii)     Vascular Tissue: center of root

(1)   Made up of xylem and phloem

(a)    Xylem: carries water and dissolved minerals from the roots to the leaves

(b)   Phloem: carries food made in the leaves to the roots

b)      Types of Roots

i)        Taproot

(1)   One root grows much larger than the others.  This root stores food. Ex. Carrot

(2)   Grow deep into soil: absorbing water and minerals deep below surface. Ex. Tall Oak Tree may have a root that is 30m down into the soil

ii)       Fibrous Roots

(1)   Dense root network made up on many stringlike roots.

(2)   Do NOT grow deep into soil, but spread out absorbing water and minerals close to the surface

c)      Specialized Roots

i)        Some plants have different kinds of roots adapted for certain functions

(1)   Aerial plants: absorb water from the air

(2)   Prop roots: support the stems and leaves of the plant (ex. Corn)

d)      Root Growth

i)        Primary root: first root that grows from a seed

ii)       Secondary root: roots that grow from primary root

iii)     Root hairs: tiny, hairlike structures that grow from primary and secondary roots

(1)   Increase surface area of roots.  (Increasing absorption)

(2)    

4)      Stem Structure and Function

a)      General

i)        Four Tissue Types

(1)   Epidermis:  protects the plant from water loss

(2)   Cortex

(3)   Vascular Tissue

(4)   Pith: stores water in a stem

b)      herbaceous stems (nonwoody stems)

i)        soft, green, and filled with water

ii)       common for annual plants

iii)     usually do not grow very tall (not enough support)

c)      woody stems

i)        nongreen, thick, and hard

ii)       found on trees

iii)     Part of woody stem

(1)   bark: rough outer coating

(a)    made up of cork

(2)   cortex

(3)   cambium: very thin layer of meristem tissue.

(a)    As it grows the tree gets wider

d)      stem growth

i)        Springwood: large xylem cells are produced

ii)       Summerwood: smaller xylem cells are produced

iii)     This alteration in growth patterns provides the annual rings that we use to age trees

iv)     Terminal buds: meristem tissue at tip of stem that allows for growth in length

v)      Lateral buds: produce new branches, leaves, and flowers

5)      Leaf Structure and Function

a)      Blade: broad, flat part of leaf

i)        Simple Leaf: one blade and one petiole

ii)       Compound Leaf: blade is divided into smaller parts called leaflets

b)      Petiole: attached blade to stem

i)        Often becomes main vein of the leaf (carrying food and water)

c)      Leaf Layers

i)        Cuticle: nonliving waxy substance covering the upper epidermis

ii)       Epidermis: outermost layer of living tissue

(1)   Together with Cuticle: reduces water loss, and protects against bacteria, fungi, and insects

iii)     Palisade: below epidermis. Made up of parenchyma cells.

(1)   Most photosynthesis takes place in the palisade layer of leaves.

(2)   What substance needed for photosynthesis do you think is found in the parenchyma cells?

iv)     Vascular Tissue: from roots and stems and ends in the palisade layer of leaf

v)      Spongy Layer: below palisade layer. Contains air spaces.

(1)   Involved in gas exchange

d)      Gas Exchange

i)        Stomata: opening on lower surface of leaf

(1)   Allow for movement of carbon dioxide and oxygen into and out of the leaf

ii)       Guard cells: surround each stomata

(1)   Control size of stomata.

e)      Water Loss

i)        Water fills up the space in a leaf making it firm to the touch

ii)       Transpiration: loss of water through stomata

(1)   Guard cells shrink and close stomata on hot days to prevent excess water loss

f)        Specialized Leaves

i)        Cactus: spines to decrease transpiration

ii)       Vines: tendrils often allow for climbing

iii)     Venus Flytrap: carnivorous plants that have specialized leaves that trap insects

6)      Flowers

a)      Parts of a Flower

i)        Sepals: green  leaf like structures that surround and protect petals

ii)       Petals: surround the male and female reproductive organs

iii)     Stamen: male reproductive organ of a flower

iv)     Anther: on tip of stamen. 

(1)   Forms pollen

(a)    Sperm cells are formed inside pollen

v)      Pistil: female reproductive organ

(1)   Usually surrounded by several stamens

vi)     Ovary: bottom of pistil

(1)   Contains ovules

(a)    Eggs cells develop in ovules

b)      Pollination and Fertilization

i)        Pollination: transfer of a pollen grain from a stamen to a pistil

(1)   Self-pollination: in the same flower

(2)   Cross-pollination: by another flower (most common, why?)

ii)       Role of the Pollen Tube

(1)   Pollen grains develop pollen tubes after landing on the tip of the pistil

(2)   The tube grows down the entire length of the pistil

(3)   The sperm cells inside the pollen grain travel down the pollen tube to the ovary

iii)     Fertilization: A sperm cell (that has traveled down a pollen tube) unites with an egg cells

(1)   An emybro develops inside the ovule

7)      Seeds and Fruits

a)      General

i)        Seed: fertilized ovule.  Contains the embryo plant AND stored food for the embryo.

ii)       Fruit: a mature ovary containing seeds

b)      Seed Dispersal            

i)        Air Travel:

(1)   Maple tree fruit

ii)       Water

(1)   Seeds that float

(2)   Ex.milkweed

iii)     Animal

(1)   Sweet fleshy fruits.

(a)    Animals eat and eliminate seeds as waste products

(2)   Hooklike structures that stick to fur

c)      Seed Germination

i)        Germination: growth of an embryo plant from a seed

(1)   Requires moisture and warmth

8)      Growth and Response

a)      Basic growth requirements: light, water, minerals, and a proper temperature

b)      Growth Hormones: cause roots to grow deeper and stems to grow taller

i)        Located in the root tips, lateral buds, and terminal buds of plants

c)      Tropisms: response of a plant to a stimulus

i)        Phototropism: response to plant to light

ii)       Geotropism: response of a plant to gravity

iii)     Thigmotropism: response of plant to touch, or contact with a solid object.

9)      Monocots and Dicots

a)      Flowering plants are divided into two groups based on the number of cotyledons in the embryonic plant

i)        Cotyledons are embryonic seed leaves providing nutrition from the endosperm before the mature leaves begin photosynthesis.

b)      The distinction between monocots and dicots represents an important evolutionary division that relates to many structures

c)      monocots and dicots have the following traits: