Plant Structure and Function

What’s the Difference?

What In This Unit

What makes plant cells work? What’s the difference between plant and

animal cells What’s inside of plants cells The breakdown of Stems, Roots, Leaves

and Flowers

For cells in a plant to multiply or enlarge a plant must have the following:

Carbon dioxide, water, oxygen, nitrogen, phosphorus, potassium and trace elements.

Plants & Animals

There are basically two differences between plants and animals.

Plant have the ability to make their own food.

The second difference is in their respiration.

Plants take in carbon dioxide and give off oxygen.

Plant Cells

Plant cells consist of the following:

Cell Wall: non-continuous structure surrounding the plasma membrane

Vacuole: cavity in the cytoplasm filled with cell water

Cytoplasm: total protoplasm in the cell except the cell nucleus

Mitochondrion: breaks down compounds for the cell

Nucleus: a small round body that contains the nucleolus and chromosomes.

Plant Tissue Systems

Meristematic Tissue: This is growth tissue where cell division and enlargement occur and is found near the tips of roots and stem buds.

Simple Tissues

Epidermal tissue: This tissue is one-cell thick and forms the outer layer of flowers, leaves, and many types of fruits.

Parenchyma tissue: This tissue comprises the fleshy part of fruits, roots, and tubers.

Its ,main function is to store food and water.

Complex Tissue

Xylem tissue: This tissue is called “wood” in vascular plants.

Its principal functions are to conduct water and support the plant

Phloem tissue: This tissue also conducts material in the plant and gives the plant support.

Its main function is to transfer food from the leaves to other parts of the plant

Parts of The Plant

The Plant Roots

The function of the plant’s roots are to absorb nutrients and water from the soil and to anchor the plant.

The root system can makeup 50% of a plants weight.

There are two types of root systems soilless roots which include aerial (ivy), and aquatic(water lily).

Soilborne roots are classified into tap and fibrous roots.

Tap roots are those roots which have a long main root such as a carrot or pine tree.

Fibrous roots spread out such as grass

Parts of the Root

At the tip is the roots cap, where cell division occurs and it pushes down into the soil.

Root hairs are used to help take in nutrients

The Plant Stem

The major function of the stem is to join the root and leaf systems.

Some photosynthesis also takes place in the stem.

Parts of the Stem

Node- jointed part of the stem on which leaf or flower buds develop

Internode- major part of the stem between the nodes.

Axillary Bud- bud found at the leaf axil from which flowers and branches arise.

Terminal Bud- tip or end of the shoot were growth takes place.

Petiole- is a stem-like leaf structure that attaches the leaf to the stem

Woody Stems

Outerbark- protects the interior of the plant from insects and diseases and excessive heat and cold.

Innerbark- carries food manufactured in leaves to the branches, trunk, and roots

Cambium- layer of cells between the bark and wood where growth is diameter occur and the formation of annual rings.

Sapwood(xylem)- carries sap from the roots to the leaves

Heartwood- is inactive sapwood which is darker in color and gives strength to the plant

Pith- is the dark center in the heartwood core.

Leaves

Leaves are the food factory of the plant producing all food that is used by the plant and stored for later use by the plant or by an animal.

Leaves vary in shape and size; with most of them being flat

The arrangement of the leaves differ alternate, opposite, whorled,

External Leaf Structures

The petiole is the stalk that attaches the leaf to the stem

The blade which is the flat part of the leaf The midrib which is the large center vein

from which all veins extend The margins which are the edges of the leaf

Internal Leaf Structures

The skin of the leaf is called the epidermis which is a single layer of cells. The epidermis provides protection from water loss.

The guard cells open and close a small space or pore on the underside of the leaf called the stoma

The stoma allows the plant to transpire. This gives off moisture and exchange of gases.

In the inner part of the leaf are the chloroplast. The chloroplast are filled with chlorophyll which give the leaf it’s green color.

With the use of chlorophyll , minerals, sugars sunlight and carbon dioxide the plant goes through photosynthesis

The formula for photosynthesis is the following:

6CO2 + 6 H2O + 672 Kcals (light energy) = C6H12O6 (Glucose) + O2

Flower

The purpose of the flower is the reproduction of the plant. This can be done through fruits and seed.

The reason flowers are colorful is to attract insects for pollination

Parts of the Flower

The sepals are the green leaflike part of the flower located at the base and are used to protect the flower bud.

The petals are actually leaves and are the most striking part of the flower

The stamen makes up the male reproductive part of the plant. This includes the anther which holds the pollen. The filament is the slender stalk that holds the anther

The pistil is the female reproductive part of the flower. This includes the stigma which is sticky and catches the pollen, the style which is a long tube that carries to the ovary, the ovary is where the egg is produced.

A complete flower has both male and female parts

An incomplete flower contains only one of the parts