Plants Structure and Function Adaptations
The Plant Cell- review • Are plants autotrophic or heterotrophic? • Autotrophic (remember, plants are producers and they make their own food via photosynthesis) • Are plants prokaryotic or eukaryotic? • Eukaryotic (remember, eukaryotes have nuclei just like we do and YOU are EUkaryotes) • Are plants multicellular or unicellular? • Multicellular! • Plant cell walls are made of…. • Cellulose
Nonvascular vs. Vascular Nonvascular plants do not have a system for transporting water and other nutrients within their body • Nonvascular plants are small and lack vascular tissue (roots, stems and leaves). • Mosses, liverworts, and hornworts are nonvascular plants.
Nonvascular vs. Vascular Vascular plants are plants that contain structures with vascular tissue (roots, stems and leaves) • Seedless plants • Seed plants • Gymnosperms and Angiosperms • Vascular plants are composed of: • Tissue • Roots • Leaves • Stems • Each plant part – tissue, root, stem, leaf - has a specific role in keeping the plant alive through photosynthesis
Vascular Plants Seedless Vascular Plants: • Seedless vascular plants produce spores with thickened walls that prevent them from drying out. • Examples: Ferns, club mosses, horsetails, and whisk ferns are seedless vascular plants. Reproduce with spores - diagram shows spores growing in clusters called sori on the back of the fern http://en.wikipedia.org/wiki/Image:Lycopodium_plant.jpg
Structures of Vascular Plants Seed- adaptation to terrestrial life composed of a plant embryo, stores food and contains a protective coat Cone- reproductive structure of gymnosperms; contains pollen in males and ovules in females Ovulate cone- from a pinetree (female) Staminate cone- from a pinetree (male) Flower- reproductive structure of angisperms composed of 4 sets of modified leaves Fruit- mature ovary of a flower that protects dormant seeds and aids in their dispersal Cotyledons – nonphotosynthetic leaves of an immature plant; provide source of nutrients until plant can produce its own food
Vascular Plants • Vascular Plants that produce seeds: • Gymnosperms • Produce cones • Conifers, cycads, ginkgoes, and gnetophytes • Angiosperms • Fruits or flowers • The angiosperms are classified as either monocots or dicots.
Angiosperms Monocot vs. Dicot • Monocots: • One cotyledon • Veins parallel • Vascular bundles in complex arrangement • Fibrous root system • Floral parts in multiples of three • Ex. Iridaceae (irises), Liliaceae(lilies) and Poaceae (grass). • Dicots: • Two cotyledon • Veins netlike • Vascular bundles arranged in ring • Taproot usually present • Floral parts in four or five • Ex. Asteraceae (composite), Brassicaceae (mustard), Fabaceae (legume), and Rosaceae (rose),
Tissues, Roots, Leaves, Stems Tissue A vascular plant’s body contains three kinds of tissues—dermal tissue, ground tissue, and vascular tissue. • 1.Dermal Tissue Dermal tissue covers a plant. A thin layer of epidermis covers nonwoody parts. Several layers of cork cover woody parts. • 2.Ground Tissue Ground tissue is specialized for photosynthesis in leaves and for storage and support in stems and roots. • 3.Vascular Tissues Vascular tissue conducts water, minerals, and organic compounds throughout the plant. • Xylem (carries reactants) vs. phloem (carries products)
Vascular – refers to an internal system of tubes or vessels to transport materials throughout the plant - xylem – transports water and minerals up from the roots to the shoots - phloem – transports sugar (food) down from the leaves to the rest of the plant Translocation Organic compounds are pushed through the phloem from a source to a sink in a process called translocation. TranspirationTranspiration, the loss of water from a plant’s leaves, creates a pull that draws water up through xylem from roots to leaves.
Roots Function- absorption, storage and anchorage • Roots have a central core of vascular tissue that is surrounded by ground tissue and epidermal tissue. • Root hairs on root tips increase the surface area which increases absorption • Remember that Nitrogen Fixation happens in the roots! (Nitrogen fixation is when nitrogen in the atmosphere is converted by bacteria into nitrogen compounds like ammonia, nitrates and nitrites)
Stems Function: support and transfer • Contain the Xylem and Phloem • Help define plant types (shrubs, vines, trees, etc)
Compound leaf shapes Singly compound leaf Palmately compound leaf Doubly compound leaf Leaves • Site of photosynthesis • composed of blade, veins, petiole • simple or compound Simple leaf shapes Entire leaf Palmate (heart shaped) Palmately lobed Pinnately lobed
There are different layers of leaves • epidermis – adaptation for terrestrial life- covering of leaf • waxy cuticle - coats upper and lower epidermis • stomata – site of transpiration • Guard cells- control water loss by closing a plant’s stomata when water is scarce
Plant Adaptations • Absorbing Nutrients • To survive on land, plants evolved the ability to absorb mineral nutrients from the soil. • Preventing Water Loss • To survive on land, plants evolved a waxy outer covering called a cuticle, and stomata and guard cells for gas exchange, to prevent their bodies from drying out. • Reproducing on Land • To survive on land, plants use pollen to reproduce without water and transmit male gametes.
Vascular Plant Adaptations • Advantages of Conducting Tissue • Vascular plants have a system of well-developed tissues that transport water within a plant. • Advantages of Seeds • Seeds protect and nourish a plant’s embryo, disperse the offspring, and delay the growth of the embryo until conditions are favorable. • Advantages of Flowers • Flowers make reproduction more efficient by promoting pollination.
Plants in our Lives • Fruits and Vegetables • All types of plant parts—roots, stems, leaves, flowers, fruits, and seeds—provide food for humans. • Root Crops • Root crops, such as potatoes, grow underground. • Legumes • Legumes, such as peas, produce protein-rich seeds in long pods. • Wheat • For more than one-third of the world’s population, wheat is the primary source of food. • Corn • Corn is the most widely cultivated crop in the United States. • Rice • For more than half of the people in the world, rice is the main part of every meal.
Plants in Our Lives • Wood • Wood is a source of wood pulp used for making paper, lumber used for building materials, and fuel. • Medicines • Many important medicines are currently made from plants or were originally derived from plants. • Fibers • Plant fibers are used to make paper, cloth, and rope. The most important sources of plant fibers are wood and cotton.
Fruit or Veggie? • A fruit is the ripened ovary and contains seeds. • Therefore, tomatoes, peppers, squash, olives, and cucumbers are FRUITS, not vegetables.
Vascular Plants (Tracheophytes) Nonvascular Plants (Bryophytes) - spores Seed Plants Seedless Plants - spores Mosses Liverworts Hornworts 26,000 species Conifers (Gymnosperm) 600 species Flowering Plants (Angiosperm) 260,000 species Ferns 12,000 species Monocot 60,000 species Most grains Dicot 200,000 species Most flowering plants