Copyright Pearson Prentice Hall Biology Copyright Pearson Prentice Hall

Angiosperms—Flowering Plants Photo credit: ©Dorling Kindersley Copyright Pearson Prentice Hall

Diversity of Angiosperms What are monocots and dicots? Copyright Pearson Prentice Hall

Diversity of Angiosperms 1. Characteristics of Angiosperms—flowering plants Monocots and dicots are named for the number of seed leaves, or cotyledons, in the plant embryo. The table compares the characteristics of monocots and dicots. Copyright Pearson Prentice Hall

Diversity of Angiosperms Monocots and dicots are named for the number of seed leaves, or cotyledons, in the plant embryo. The table compares the characteristics of monocots and dicots. Copyright Pearson Prentice Hall

Diversity of Angiosperms Monocots include corn, wheat, lilies, orchids, and palms. Dicots include roses, clover, tomatoes, oaks, and daisies. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 23–2 Roots Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Types of Roots Types of Roots What are the two main types of roots? Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Types of Roots 1. 2 main types of roots are: A. taproots: primary root grows long -mainly in dicots - carrot is an example Plants have taproots, fibrous roots, or both. Taproots have a central primary root and generally grow deep into the soil. Fibrous roots are usually shallow and consist of many thin roots. Taproot Fibrous Roots Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Types of Roots b. fibrous roots: Branch, no single root grows larger than the rest. mainly in monocots *found in grasses. Plants have taproots, fibrous roots, or both. Fibrous roots are usually shallow and consist of many thin roots. Fibrous Roots Copyright Pearson Prentice Hall

Root Structure and Growth What are the main tissues in a mature root? Copyright Pearson Prentice Hall

Root Structure and Growth 1. the epidermis 2. central cylinder of vascular tissue 3. Ground tissue *The root system plays a key role in water and mineral transport. Copyright Pearson Prentice Hall

Root Structure and Growth 2. root hairs: * covers root’s surface *provide large surface area which water can enter the plant. Root hairs A root consists of a central vascular cylinder surrounded by ground tissue and the epidermis. Root hairs along the surface of the root aid in water absorption. Copyright Pearson Prentice Hall

Root Structure and Growth Epidermis 3. epidermis: protects the root and absorbs water. Copyright Pearson Prentice Hall

Root Structure and Growth 4. cortex: *Inside the epidermis * layer of ground tissue Ground tissue (cortex) A root consists of a central vascular cylinder surrounded by ground tissue and the epidermis. Copyright Pearson Prentice Hall

Root Structure and Growth 5. endodermis: encloses the vascular cylinder Endodermis Copyright Pearson Prentice Hall

Root Structure and Growth 6. vascular cylinder: central region of root that includes the xylem and phloem. Phloem Vascular cylinder Xylem Copyright Pearson Prentice Hall

Root Structure and Growth (Roots grow in length as their apical meristem produces new cells near the root tip.) Apical meristem Copyright Pearson Prentice Hall

Root Structure and Growth 7. root cap : *covers new cells * protects the root as it forces its way through the soil. Only the cells in the root tip divide. In the area just behind the root tip, the newly divided cells increase in length, pushing the root tip farther into the soil. The root cap, located just ahead of the root tip, protects the dividing cells as they are pushed forward. Apical meristem Root cap Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Root Functions Root Functions (What are the different functions of roots? Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Root Functions Roots anchor a plant in the ground and absorb water and dissolved nutrients from the soil. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Root Functions Uptake of Plant Nutrients To grow, flower, and produce seeds, plants need a variety of inorganic nutrients in addition to carbon dioxide and water.) Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Root Functions 8. most important nutrients plants need: nitrogen phosphorus potassium magnesium calcium Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Root Functions 9. Active Transport of Minerals: a. Osmosis and active transport move water and minerals from the root epidermis into the cortex. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Root Functions b. Transport proteins use ATP to pump mineral ions from the soil into the plant. Root hairs Roots absorb water and dissolved nutrients from the soil. Most water and minerals enter a plant through the tiny root hairs. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Root Functions c. high concentration of mineral ions in plant cells causes osmosis (water molecules to move into the plant by.) d. Root pressure is the starting point for movement of water through the vascular system of the entire plant Roots absorb water and dissolved nutrients from the soil. Most water and minerals enter a plant through the tiny root hairs. Water moves into the cortex, through the cells of the endodermis, and into the vascular cylinder. Finally, water reaches the xylem, where it is transported throughout the plant. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Root Functions The endodermis is composed of many individual cells. Endodermis Cells in the endodermis are made waterproof by the Casparian strip. The Casparian strip prevents the backflow of water out of the vascular cylinder into the root cortex. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Root Functions Each cell is surrounded on four sides by a waterproof strip called a Casparian strip. Casparian strip Casparian strip Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Root Functions The Casparian strip prevents the backflow of water out of the vascular cylinder into the root cortex. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Root Functions Water moves into the vascular cylinder by osmosis. Because water and minerals cannot pass through the Casparian strip, once they pass through the endodermis, they are trapped in the vascular cylinder. As a result, there is a one-way passage of materials into the vascular cylinder in plant roots. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Root Functions Root Pressure As minerals are pumped into the vascular cylinder, more and more water follows by osmosis, producing a strong pressure. This root pressure forces water through the vascular cylinder and into the xylem. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Root Functions As more water moves from the cortex into the vascular cylinder, more water in the xylem is forced upward through the root into the stem. Root pressure is the starting point for movement of water through the vascular system of the entire plant. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 23–2 Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 23–2 Taproots are more common than fibrous roots in monocots. dicots. neither monocots or dicots. both dicots and monocots. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 23–2 The cells in a root that divide are found in the apical meristem. epidermis. endodermis. vascular cylinder. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 23–2 The tough layer of cells that covers the root tip is called the vascular cylinder. root cap. ground tissue. apical meristem. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 23–2 Xylem and phloem are found in the epidermis. endodermis. apical meristem. vascular cylinder. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 23–2 Roots absorb minerals from the surrounding soil by diffusion. active transport. passive transport. root pressure. Copyright Pearson Prentice Hall

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