Chapter 12 Introduction to Plants
Section 1: Objectives • Identify 4 characteristics that all plants share. • Describe the 4 main groups of plants. • Explain the origin of plants.
Plant Characteristics • One plant may seem different than another, but all plants have certain things in common. • Plants come in a variety of shapes and sizes. • All plants have the following in common: • Photosynthesis • Cuticles • Cell walls
Plant Characteristics • All plant cells contain chlorophyll (green pigment). • Chlorophyll is found in chloroplasts. • Plants use energy from sunlight to make food from carbon dioxide and water. • This process is called photosynthesis. • This makes all plants producers.
Plant Characteristics • Most plants live on dry land and need sunlight to survive. • But why don’t plants dry out? • Plants are protected by a cuticle. • A cuticle is a waxy layer that coats the surfaces of plants. • This keeps the plant from drying out.
Plant Characteristics • How do plants stay upright? • They have no skeleton or muscles for support. • They have a rigid cell wall instead. • Carbohydrates and proteins form a hard material inside the cell wall. • Cell walls support and protect the plant cell.
Plant Characteristics • Plants have 2 stages in their life cycle: • Sporophyte stage: plants make spores • In suitable environments, the spores of these plants grow into new plants. • Gametophyte stage: plant produces sex cells • These cells cannot grow into new plants. • Instead the cells grow into spores and the cycle repeats.
Plant Characteristics • Plants can be divided into 2 main groups: • Nonvascular plants: lack roots, stems, and leaves • Example: mosses • Vascular plants: has roots, stems, or leaves • Example: Tomato plants • These are the 2 main groups that make up Kingdom Plantae.
Plant Characteristics • Vascular plants are divided into 3 groups: • Seedless plants • Gymnosperms • Angiosperms • Non-flowering seedless plants are called gymnosperms. • Flowering seedless plants are called angiosperms.
Plant Characteristics • What other organisms do plants share a common ancestor with? • What is a common ancestor? • Because plants and algae share many similarities, scientists believe that they share a common ancestor.
Section 2: Objectives • List 3 nonvascular plants and 3 seedless vascular plants. • Explain how seedless plants are important to the environment. • Describe the relationship between seedless vascular plants and coal.
Nonvascular Plants • These types of plants don’t have vascular tissue. • They grow in places that are damp and moist. • Each cell of the plant must get water from the environment. • Remember, these plants don’t have roots, stems, or leaves. • Examples: mosses, liverworts, & hornworts
Nonvascular Plants • Reasons these plants are important to the environment: • First to grow in a new environment • Reduce soil erosion • Food source for some animals
Mosses • Mosses often live together in large groups. • They cover soil or rocks with a mat of tiny green plants. • Mosses have leafy stalks and rhizoids. • A rhizoid is a root-like structure that holds the plants in place and helps plants get water and nutrients.
Liverworts and Hornworts • Like mosses, liverworts and hornworts are usually small, nonvascular plants that usually live in damp places. • Nonvascular plants are usually the first plants to live in a new environment, such as newly exposed rock. • When these nonvascular plants die, they form a thin layer of soil.
Seedless Vascular Plants • Examples include ferns, horsetails, and club mosses. • These plants once grew much taller than they actually do today. • In order to adapt to their environments, these plants change their shape and height over time.
Ferns • These grow in many places ranging from cold to warm climates. • Most ferns have a rhizome- an underground stem from which leaves and roots grow. • Ferns still go through the sporophyte and gametophyte stages in their life cycle.
Importance of Seedless Vascular Plants • These play many roles in the environment: • Help form soil • Prevent soil erosion • Popular houseplants • The remains of ancient ferns and club mosses form coal. • Coal is a fossil fuel and is used for energy.
Section 3: Objectives • Describe 3 ways that seed plants differ from seedless plants. • Describe the structure of seeds. • Compare angiosperms and gymnosperms.
Characteristics of Seed Plants • As with seedless plants, the life cycle of seed plants alternates between 2 cycles: • Sporophyte stage: plant produces spores to be distributed • Gametophyte stage: plant produces sex cells which mature into spores
Characteristics of Seed Plants • Seed plants produce seeds. • Unlike other plants, these plants produce tiny structures called seeds which help nourish and protect the sporophyte. • Pollen forms within these plants. • Pollen: tiny granules that contain the male gametophyte of seed plants.
Structure of Seeds • A seed forms after fertilization in plants. • Seeds have some advantages over seedless plants: • Have their own food supply • Seeds can be spread by animals • Animals spread seeds more efficiently than wind spreads spores.
Structure of Seeds • A seed is made up of 3 parts: • Young plant (sporophyte) • Stored food • Seed coat • The purpose of the seed coat is to surround and protect the sporophyte.
Gymnosperms • These are seed plants that do not have flowers or fruits. • These seeds are usually protected by a cone. • Any plant/tree that has cones would be an example of a gymnosperm. • Pine trees are probably the most popular example.
Gymnosperms • Conifers are probably the most familiar example. • The word conifer comes from 2 words: “cone-bearing.” • Pollination: the transfer of pollen from the male reproductive structure to the female reproductive structure of seed plants
Angiosperms • Vascular plants that produce flowers and fruits. • Most abundant group of plants. • Can be found in almost every ecosystem. • Flowers help angiosperms reproduce and some depend on wind to transfer pollen from plant to plant.
Angiosperms • Divided into 2 classes: • Monocots: have one seed coat • Grasses, onions, palm trees • Tips of flowers separate in parts of 3 • Leaves have parallel veins • Dicots: have 2 seed coats • Roses, cactuses, sunflowers • Tips of flowers are separated in parts of 4 or 5 • Leaves have branching veins
Angiosperms • Flowering plants provide many land animals with the food they need to survive. • People use flowering plants in many ways. • Major food crops, such as corn, wheat, and rice, are flowering plants. • Flowering plants are used to make cloth fibers, rope, medicines, rubber, perfume oil, and building materials.
Chapter 12 Sec. 3 Pop Quiz • 1)List 2 characteristics of seed plants. • 2) When does a seed form in plants? • 3) List the 3 parts of seeds. • 4) What is the difference between gymnosperms and angiosperms? • 5) What does “conifer” mean? • 6) List and describe the 2 groups of angiosperms.
Section 4: Objectives • Listthree functions of roots and three functions of stems. • Describe the structure of a leaf. • Identify the parts of a flower and their functions.
Transportation In Plants • There are two types of vascular tissue in plants: • Xylem is the type of tissue in vascular plants that provides support and conducts water and nutrients from the roots. • Phloemis the tissue that conducts food in vascular plants.
Transportation In Plants • Root Functions: The following are the main functions of roots: • Roots supply plants with water and dissolved minerals. • Roots hold plants securely in the soil. • Roots store surplus food made during photosynthesis
Transportation In Plants • The layers of cells that cover the surface of the roots is called the epidermis. • After water and minerals are absorbed by the epidermis, they diffuse into the center of the root where the vascular tissue is located. • A root cap can be found at the end of the root. • The root cap protects the tip and helps the root continue to grow.
Transportation In Plants • There are two kinds of root systems— taproot systems and fibrous root systems. • Taproot systems have a main root, or tap root, that grows downward.Dicots and gymnosperms usually have tap root systems. • Fibrous systems have several roots that spread out from the base of the stem. Monocots usually have fibrous root systems.
Transportation In Plants • A stem connects a plant’s roots to its leaves and flowers. A stem also has the following functions: • Stems support the plant body. • Stems transport materials between the root system and the shoot system. • Some stems store materials.
Transportation In Plants • Many plants have stems that are soft, thin, and flexible. • These stems are called herbaceous stems. • A cross section of an herbaceous stem is shown on the next slide.
Transportation In Plants • Trees and shrubs have rigid stems made of wood and bark. • This wood and bark provides for more support. • These stems are called woody stems.
Transportation In Plants • The main function of leaves is to make food for the plant. • The structure of leaves, shown on the next slide,is related to their main function— photosynthesis.
Transportation In Plants • Some leaves have functions other than photosynthesis. • The leaves of many cactuses are modified as spines. These spines keep animals from eating the cactuses. • The leaves of sundews are modified to catch insects, which the sundew digests.
Transportation In Plants • Flowers are adaptations for sexual reproduction. • Sepals and Petals The modified leaves that make up the outermost ring of flower parts and protect the bud are called sepals. • Petals arebroad, flat, thin leaflike parts of a flower.