Plants – Parts and Functions

• Plants are vital to our survival – the oxygen we breathe, the food we eat, most of our clothing, furniture, and our homes come from or are parts of plants

• Plants are multi-cellular eukaryotes (cells have a nucleus) with tissues and organs that have specialized structures and functions (just like ours)

• Ex. – photosynthetic tissue, organs like roots to help anchor them, etc.

The earth is about 4.6 billion years old, and plants are believed to have evolved about 400 million years ago

Fossil evidence from about 500 millions years ago shows that the shallow waters of ancient Earth were filled with organisms like archaea, bacteria, algae, and other protists that began the process of photosynthesis, and paved the way for other life

*they are looking for fossils like this on mars

You can tell a plant cell from an animal cell by the presence of:a cell wall (support

and protection) large vacuole (water

storage)Chloroplasts

(photosynthesis)

What are the levels of organization for living things? (how are our bodies put together?)

Remember that tissues are groups of cells that work together to do a specific job.

Depending on its function, a plant tissue can be composed of one or many types of cells

There are 4 different types of tissues – meristematic, dermal, vascular, and ground – *we’ll talk about each of

them in more detail

Meristimatic tissues make up meristems, which are areas of rapidly dividing cells

They can develop into many kinds of cells, and are located in different areas of the plant

They can increase the length and diameter of roots, stems, and leaves

The layer of cells that makes up the outer covering on a plant is dermal tissue (also called the epidermis, just like in humans and other animals)

Stomata are small openings on the epidermis, through which gases like carbon dioxide, water, and oxygen can pass. Two cells that form a stoma are

guard cells. These are usually found on the

underside of the leaf to prevent evaporation.

Trichomes – are hair-like projections on leaves and stems. They give leaves a fuzzy appearance and help protect the plant from insect and animal predators (some even release toxic substances when touched)

Root hairs - found on some roots, they increase the surface area and help the root to take in more material that it can without them

Responsible for the transport of water, food and dissolved substances

Two types: xylem and phloem Xylem – carries water and

dissolved materials up (made of vessel elements and/or tracheids)

Phloem – the main food-carrying tissue, it transports dissolved sugars down throughout the plant (made of sieve tube members and companion cells)

Cambium - a cylinder of unspecialized meristimatic cells that divide and specialize to form the xylem , and is located between these tissues .

*acts like the veins and arteries in your circulatory system, transporting material throughout the plant

They have a diverse function (and are made of all three types of cells) – responsible for photosynthesis, storage, and support

Most of a plant consists of ground tissue

In some stems, roots, and seeds, ground tissue cells have large vacuoles that store sugars, starch, oils, and other substances

They also provide support when they grow between other types of tissue

With your table partners, list the 4 different types of plant tissue, and draw an example of each

The root is usually the first structure to grow out of the seed when it sprouts (if you’ve ever eaten a carrot or potato, those are roots)

Roots take in water and dissolved minerals that are transported to the rest of the plant, they anchor a plant, and they support a plant against the effects of gravity, wind, and moving water

The tip of the root is covered by the root cap, that helps protect the root tissues as the root grows

the cells in the root cap produce a slimy substance that helps form a lubricant that reduces friction as the root grows through the soil

Some root epidermal cells produce root hairs to help absorb water

2 major types – taproots and fibrous roots

Taproots are a thick root with a few smaller branching roots (radishes, beets, carrots).

Fibrous roots have many branching roots that are all about the same size and grow from a central point (like spokes on a bicycle)

One other type, called adventitious roots, form where roots normally don’t grow and have specialized functions (see pictures of prop and adventitious roots)

With your table partners, draw and label the two different types of root systems

The main function of a stem is support of a plants leaves and reproductive structures

A stem grows when cells divide in the apical meristem (which provides additional support)

The main function of leaves is photosynthesis (natures solar panels)

The leaf blade is attached to the stem by a petiole (unless the leaf is attached directly to the stem, like in grasses)

The palisade mesophyll (or palisade layer) is a tissue filled with tightly packed cells directly below a leaf’s upper epidermis (this has the max. exposure to light, and so most photosynthesis takes place here)

The spongy mesophyll is below the palisade layer, and has loosely packed cells with spaces surrounding them, which allows gases (like O2, water vapor, and CO2) to move through them.

The epidermis covers the leaf, and contains stomata

Water travels from the roots up through the stems and into the leaves, replacing water used in photosynthesis and lost through evaporation.

When water evaporates from the inside of the leaf to the outside through a stomata it’s called transpiration, which helps pull the water column upward

You can identify plants by looking at their leaves; arrangement of leaves on the stem (opposite, alternate, or whorled), arrangement of veins in a leaf –called venation pattern (palmate, pinnate, or parallel), and leaf type (simple vs. compound) distinguish them

Although the primary function of leaves is photosynthesis, there are other chemical and structural leaf modifications related to other functions

Spines are modified leaves (found in succulent plants) that reduce water loss, store water, and protect the plant

Some leaves produce a sticky substance that traps insects (to get nitrogen missing from their soil)

Some release chemicals that irritate the skin to keep animals from touching them

Some have trichomes that help repel insects and other herbivores

With your table partners, draw and label the parts of a leaf

Flowers have four organs – sepals, petals, stamens, and pistils

Sepals protect the flower bud and look like small leaves

Petals are colorful structures that attract pollinators and give them a landing platform

Stamens are the male reproductive organs . Made of two parts: – the filament and the anther – the

filament supports the anther

The pistil is the female reproductive organ of a flower and has 3 parts : the stigma, the style and the ovary

(the stigma is the tip of the pistil and is where pollination occurs, the style connects the stigma to the ovary)

Draw a Venn Diagram showing AT LEAST 3 similarities and differences between plant parts and the circulatory and respiratory system in humans