PLANTS Unit 13 Quiz-March 27 Unit 13 plant project-April 4 Unit 13 (& unit 14) Test-April 7

Introduction (pg. 502 &604) Plants are placed into groups based on structural and functional similarities, but all plants share the following characteristics: Plants are eukaryotic, multicellular organisms with organs & organ systems All plant cells have cell walls composed of cellulose

C. Plants are autotrophic, which means they can use energy from the sun to make glucose in photosynthesis. Photosynthesis takes place in the chloroplasts of plant cells. The equation for photosynthesis is CO2+H2O C6H12O6 + O2 D. Plants are non-motile; therefore, special adaptations are required for reproduction

Plant Structure & Growth (pp. 579-597) Plant Transport Larger plants must have a way to transport water, food and minerals. This is carried out by two type of vessels. Together the vessels (cells working together) make up a tissue in plants known as vascular tissue. Plants are divided into two groups, based on whether or not they have vascular tissue.

Two types of vascular tissue Xylem transports water & minerals from the root to the rest of the plant. -Water always moves 1 direction-from the roots->stem->leaves -Water evaporates from the plant through opening on the underside of the leaves called stomata

Two types of vascular tissue 2.Phloem transports “food” (glucose) from the leaves to the rest of the plant. -It carries sugars in all directions -Sugar can be carried from where it is made (Usually the leaves) to where it is stored (usually stems and roots.)

Plant Growth 1. Primary Growth-Lifelong growth occurs at the tips of the stem and the end of the roots in tissue called the meristem *Apical meristem is located at the tips of stems and roots (groups of undifferentiated cells that divide to produce increased length of stems and roots)

2. Secondary Growth Trees and some other plants have a second type of meristem tissue; allow them to grow in width or girth. *Cambium is the meristem tissue that allows plants to get wider.

Plant Structure (639-647) C. Roots anchor the plant, absorb water and minerals from the soil, and transport these materials to the stem. Some plants also store food in their roots. Each root has root hairs, tiny extensions of epidermal cells that increase surface area for water absorption. *Water is absorbed into the plant by the process of osmosis

There are two kinds of roots Taproots- a large, main , primary root. Example = carrot Fibrous- branching, secondary roots. Example = grass

D. Stems Stems have 2 main functions Supporting leaves and flowers. Transporting water via xylem and food via phloem Some plant stems have the additional job of photosynthesis

E. Leaves * The actual leaf is the organ. It is attached to the stem by a thin structure called a petiole. *The vascular tissue enters the leaf through the petiole and forms the veins of the leaf. Leaves are the main organ for photosynthesis. They have a large surface area for maximum light absorption. The structures of a leaf include: Cuticle-Waxy covering to prevent water loss Epidermis-Outermost layer of cells; prevents injury, infection

Mesophyll-Photosynthetic layer of leaf 1. Palisade layer-Upper portion of mesophyll with closely packed cells; site of most photosynthesis 2. Spongy layer-Underside of leaf; loosely-packed cells to allow for exchange of CO2 and O2

D. Vein-xylem & phloem E. Stomata-Opening in underside of leaf that allow CO2 (carbon dioxide) to enter; O2 (oxygen) to exit

F. Guard Cells-Control size of stomata. Work to preserve balance between allowing for gas exchange without losing too much water. “Plant sweat” is known as transpiration.

Seeds: Bryophytes and pterophytes have spores. All other tracheophytes produce seeds. Seeds provide a tremendous reproductive advantage. A seed consists of an embryo surrounded by a tough protective coat. Advantages of Seeds Protection Nourishment-Starch is stored in the seed for developing embryo Dispersal-Easily spread by wind, animals, water; reduces competition for nutrients Dormancy-Seeds remain dormant or inactive until conditions are favorable

Seed Germination The first visible evidence that a seed is germinating is the emergence of the embryo’s root followed by the growth of an embryonic shoot that develops into the plant’s stem.

Angiosperms-Tracheophytes with Seeds & Fruit (pp. 569 -572) Angiosperms are the most complex and adaptable of all plant groups. They are also the most successful due to two important modifications: A. Fruit- A fruit is a mature ovary that contains one or more seeds. It provides the embryo with greater protection and nutrients than found in gymnosperm seeds. The fruit also increases seed dispersal because fruits are eaten by animals, seeds pass through the digestive tract and are eliminated. Some fruits are not intended to be edible.

B. Flower (668-669) The flower is the reproductive system of the angiosperm. It enhances pollination, which occurs as a first step to fertilization. The male reproductive organ is the stamen, which consists of the anther and filament. Pollen is produced by the anther and contains the sperm cells.

2. The female reproductive organ is the pistil, which consists of the sticky top called the stigma, the neck called the style, and the base called the ovary. The ovary contains the female gametes ovules or eggs. During pollination, pollen is transferred from the anther to the stigma. When a pollen grain lands on a stigma, it sends out a pollen tube that grows through the style to the ovary. Once the sperm reached the egg cell, fertilization take place.

3. The petals are usually colorful to attract pollinators. 4 3. The petals are usually colorful to attract pollinators. 4. The sepals are protective green modified leaves at the base of a flower. They protect the bud before the flower blooms.

V. PLANT HORMONES AND RESPONSE A hormone is a chemical substance that is produced in one part of an organism and affects another part of the same individual. Plant hormones are chemical substances that control a plant’s patterns of growth and development, and the plant’s responses to environmental conditions. Hormones 1. Auxins-Produced in the apical meristem; transported throughout the rest of the plant. Works by “stretching” cells to elongate shoot, stem, and/or root. 2.Cytokinins-Produced in growing roots and in developing fruits/seeds. Cytokinins stimulate cell division, growth of lateral buds, and dormant seeds to sprout. Cytokinins often produce effects opposite to those of auxin.

3. Gibberellins- produce dramatic increases in size, by stimulating growth and increasing size. 4. Ethylene-auxin controlled hormone that stimulates the ripening of fruit. 5. Abscisic Acid-prevents growth. Used to maintain seed dormancy and tolerate drought.

A. Tropism- response of a plant to an environmental stimulus. 1. Phototropism - is the tendency of a plant to grow toward a source of light. Auxin production increases in the shaded part of the stem; causes the dark side of the stem to elongatestem to bend toward the light.

2. Gravitropism - response to gravity due to action of auxin 2. Gravitropism - response to gravity due to action of auxin. This assures that roots grow down and stems grow up. 3. Thigmotropism-Response to touch. May be used for venus fly trap, to capture insects, or allow a plant to grow on a surface for support. Tendril