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UNIT IX – KINGDOM PLANTAE

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1 UNIT IX – KINGDOM PLANTAE
Big Campbell Ch 29, 30, 35 – 39 Baby Campbell Ch 17, 31 – 33 Hillis Ch 21,

2 KINGDOM PLANTAE All Eukaryotic All Multicellular
All Autotrophic - photosyn Non-motile All have cell walls composed of cellulose Most contain organs and organ systems

3 KINGDOM PLANTAE, cont - Photosynthesis
Oxidation Reduction 3

4 KINGDOM PLANTAE, cont - Photosynthesis

5 CALVIN CYCLE OF PHOTOSYNTHESIS
Also known as Dark Reaction, Light-Independent Rxn Occurs in stroma of chloroplasts “Synthesis” part of photosynthesis; utilizes ATP, NADPH generated in Light Reaction + CO2 to produce organic molecules Anabolic; endergonic Requires enzyme Rubisco Three basic steps Carbon Fixation Reduction Regeneration of RuBP 5

6 KINGDOM PLANTAE, cont - Photosynthesis

7 I. EVOLUTION OF LAND PLANTS
Evolved from green algae known as charophytes Land Adaptations Obtaining Resources Organs Vascular tissue in plants xylem phloem Apical meristem (need for increased resources such as H2O, CO2, sunlight) Embryophytes (plants with embryos) Support Lignin – complex carb in cell walls; “wood”, strong, in trees Maintaining Moisture cuticle stomata/guard cells

8 I. EVOLUTION OF LAND PLANTS, cont
Reproduction Alternation of Generations Developing embryo protected, nourished by female parent plant Walled spores produced in sporangia Production of gametes within multicellular organs

9 II. PLANT CLASSIFICATION

10 II. PLANT CLASSIFICATION, cont Bryophytes
Mosses, liverworts, hornworts Non-vascular Dominant Stage = Gametophyte May have been helped by fungal mycorrhizae to aid in nutrient uptake from soil

11 II. PLANT CLASSIFICATION, cont Bryophyte Life Cycle

12 II. PLANT CLASSIFICATION, cont Pterophytes
Seedless vascular plants Ferns Dominant Stage = sporophyte Branched sporophytes not dependent on gametophytes for nutrition

13 II. PLANT CLASSIFICATION, cont Fern Life Cycle

14 II. PLANT CLASSIFICATION, cont Seed Plants

15 II. PLANT CLASSIFICATION, cont Seed Plants
Gymnosperms & Angiosperms Reduced Gametophyte Microscopic; can develop from spores inside sporangia; protects from environmental stresses & protects them from drying out. Advantages of Seeds Protection due to seed coat Contain a food source of starch for developing embryo Dormancy Easily dispersed Heterosporous (two kinds of spores) Megaspore → female gametophyte → egg Microspore → male gametophyte → sperm

16 II. PLANT CLASSIFICATION, cont Gymnosperms
Vascular Plants with seeds “Naked seed” Seed is not protected by a fruit Cone-bearing plants Ginkgo, cycads, and conifers “Evergreens” Most have needles Reproduction occurs in the cone

17 II. PLANT CLASSIFICATION, cont Gymnosperms

18 II. PLANT CLASSIFICATION, cont Angiosperms
Flowering plants Most successful of all plants primarily due to 2 important adaptations: Flower Fruit Angiosperms divided into 2 groups: Monocots - 1 embryonic seed leaf (lilies, palms, grasses, grain crops) Eudicots - 2 embryonic seed leaves (roses, peas, sunflowers, oaks, maples)

19 II. PLANT CLASSIFICATION, cont Classification of Angiosperms

20 II. PLANT CLASSIFICATION, cont Angiosperm Life Cycle

21 A CLOSER LOOK AT PLANT STRUCTURE & GROWTH

22 III. PLANT STRUCTURE Three Tissue Types
Dermal –Plant’s outer protective covering; helps reduce water loss and protect plant (cuticle, epidermis) Vascular – Long distance transport of materials between root and shoots Ground – includes cells specialized for storage, photosynthesis, and support.

23 III. PLANT STRUCTURE, cont - Tissues
Dermal Outer protective covering Epidermis Root hairs Trichomes (hairlike outgrowths of shoot epidermis that can secrete sticky fluids or toxic comp. for protection against insects) Cuticle Periderm in woody plants

24 III. PLANT STRUCTURE, cont - Tissues
Vascular Xylem Transports water, minerals Two types of “cells” Vessel Elements Tracheids Phloem Transports nutrients Composed of Sieve Tube Members Companion Cells

25 III. PLANT STRUCTURE, cont - Tissues
Ground Remaining plant tissue Location of photosynthesis, hormone production, storage, etc Made up of three cell types Parenchyma Most abundant cell type Living cells with thin, flexible primary cell walls Perform most of the metabolic functions Collenchyma Living cells with uneven, thickened primary cell walls Flexible support, storage Sclerenchyma Provide structural support Contain secondary cell walls, strengthened with lignin Dead at maturity 25

26 III. PLANT STRUCTURE, cont
Organs in Vascular Plants Roots Root hairs Stems Apical bud - tip Axillary bud – by stem Leaves Blade Petiole

27 III. PLANT STRUCTURE, cont - Roots
Function Root Hairs

28 III. PLANT STRUCTURE, cont - Roots

29 III. PLANT STRUCTURE, cont - Stems
Function – Support, transport, storage of some glucose

30 III. PLANT STRUCTURE, cont - Stems
Vascular bundles (xylem and phloem) Surrounded by ground tissue (xylem faces pith and phloem faces cortex) Mostly parenchyma; some collenchyma, sclerenchyma for support

31 III. PLANT STRUCTURE, cont - Leaves
Main organ of photosynthesis

32 III. PLANT STRUCTURE, cont - Leaves
Epidermis Cuticle Stomata & Guard Cells Mesophyll Ground tissue between upper & lower epidermis Parenchyma cells Made up of 2 regions Palisade Spongy

33 IV. PLANT GROWTH & DEVELOPMENT
Indeterminate Growth Growth carried out through increased cell numbers and increased cell size Meristem Embryonic tissue capable of unlimited growth; Two types Apical Meristem Found at tips Known as primary growth Lateral Meristem Cylinders of cells that extend the length of the plant Increases girth of plant Known as secondary growth

34 IV. PLANT GROWTH & DEVELOPMENT, cont Angiosperm Reproduction

35 IV. PLANT GROWTH & DEVELOPMENT, cont Angiosperm Reproduction

36 IV. PLANT GROWTH & DEVELOPMENT, cont Angiosperm Reproduction
Pollination Double Fertilization One sperm fertilizes egg contained in ovule; forms zygote Nucleus of second sperm fuses with diploid cell in embryo sac Triploid cell develops into food-storing tissue called endosperm

37 IV. PLANT GROWTH & DEVELOPMENT, cont Angiosperm Reproduction
Co-Evolution of Flowers and Pollinators

38 IV. PLANT GROWTH & DEVELOPMENT, cont Angiosperm Reproduction – Seed Development

39 Plant Nutrition

40 V. WATER TRANSPORT Water Transport
Osmosis Hyper, Hypo, Iso Water moves from high to low water potential Ψ = Ψs + Ψp Solute potential of pure water = 0 Solute present; solute potential is negative Pressure potential increased by cell wall Plasmolysis Cell in hypertonic environment Cell membrane pulls away Turgor pressure Cell in hypotonic environment Influx of water

41 V. WATER TRANSPORT, cont Uptake of Water & Minerals
Root hairs greatly increase surface area, absorptive capacity Water and solutes enter through epidermis and cortex of root Movement into xylem can happen in 2 ways: Symplastic – Water & solutes cross cell wall, cell membrane into epidermal cell. Plasmodesmata allow solution to move from cell to cell without crossing cell membranes all the way to xylem Apoplastic – Solution does not move into epidermal cells; stays in extracellular spaces. Crosses no cell membranes until it reaches Casparian strip – a continuous waxy barrier that forces solution through selectively permeable cell membrane of endodermal cell, then enters xylem.

42 V. WATER TRANSPORT, cont Uptake of Water & Minerals

43 V. WATER TRANSPORT, cont Transport of Xylem Sap From Roots to Shoots
Transpiration Loss of water vapor from leaves pulls water from roots (transpirational pull) Cohesion and adhesion of water Root pressure At night, low transpiration, roots cells continue to pump minerals into xylem Generates pressure, pushing sap upwards; guttation Not as great a force as transpiration

44 V. WATER TRANSPORT, cont Control of Transpiration
Photosynthesis-Transpiration compromise…. Guard cells control the size of the stomata Xerophytes - Plants adapted to arid environments; have thick cuticle, small spines for leaves CAM, C4 plants

45 VI. NUTRIENT TRANSPORT Essential Nutrients Required by Plants
Macro Carbon Oxygen Hydrogen Nitrogen Phosphorus Sulfur Potassium, calcium, magnesium Micro cofactors of enzymes chlorine, iron, boron, manganese, zinc, copper, molybdenum, nickel

46 VI. NUTRIENT TRANSPORT, cont Phloem Cells

47 VI. NUTRIENT TRANSPORT, cont Transport of Phloem Sap
Sugar Source – Plant organ that produces sugar; leaves Sugar Sink – Organ that consumes or stores sugar; growing roots, stems, fruit Translocation – Process of sugar transport Sugar is actively transported into phloem tube Raises solute concentration; lowers ψ Water moves into phloem tube; increases pressure at the source end Forces sap to move toward area of lower pressure Pressure gradient by movement of sugar out of phloem tube at sink end Xylem moves water from sink to source

48 VII. PLANT RELATIONSHIPS
Mutualism Rhizobium bacteria Nitrogen fixation Found in roots of legume (bean) plants Mycorrhizae fungi Increase plant root surface area Parasitism Mistletoe Epiphytes Live attached to plant but nutritionally self-supportive Orchids Carnivorous Venus Flytrap Pitcher Plants Insects provide needed minerals

49 Control Systems in Plants

50 VIII. PLANT RESPONSES Tropisms Movement toward or away from a stimulus
Phototropism Gravitropism Thigmatropism

51 IX. PLANT HORMONES Chemical signals that coordinate activities of an organism Produced in one part of the body and then transported to other parts of the body Bind to specific receptor; triggers a signal transduction pathway Low concentrations; have a profound effect

52 IX. PLANT HORMONES, cont Auxin
IAA (indoleacetic acid) Found in seed embryo, meristems of apical buds and young leaves Stimulates elongation of cells Functions include stem elongation, root growth, differentiation, branching, fruit development; apical dominance; tropisms Produced by developing seeds

53 IX. PLANT HORMONES, cont Cytokinins
Promote cell division, cytokinesis Found in roots, actively growing tissues Stimulate root growth and differentiation, germination Slow down aging of flowers, leaves Work with auxins to control apical dominance; that is, the ability of the terminal bud to suppress the growth of axillary buds

54 IX. PLANT HORMONES, cont Gibberellins
Isolated by Japanese farmers; originally thought it was due to a fungus Acts as growth regulator Stimulate cell division and elongation in stems and leaves Enhance effects of auxins Found in roots and young leaves

55 IX. PLANT HORMONES, cont Abscisic Acid
ABA Inhibits growth; maintains seed dormancy; causes stomata to close during dry conditions Found in leaves, stems, roots, unripe fruit

56 IX. PLANT HORMONES, cont Ethylene
Gaseous hormone Stimulates fruit ripening Breaks down cell walls, “softens” fruit Triggers breakdown of starch to glucose Separates leaf from stem; autumn leaf drop Stimulates formation of an abscission layer Works in opposition to auxins

57 X. PHOTOPERIODISM Internal plant clock
Based on relative lengths of day and night, especially night Allows plants to respond to seasonal changes Due to light receptors known as phytochromes

58 X. PHOTOPERIODISM, cont Critical night length controls flowering
Short-day Plant Light period shorter than a critical length to flower Flower in late summer, fall, winter Poinsettias, chrysanthemums Long-day Plant Light period longer than a critical period to flower Flower in late spring, early summer Spinach, iris, radish, lettuce Day-neutral Plant Unaffected by photoperiod Tomatoes, rice (is nice!), dandelions

59 X. PHOTOPERIODISM, cont


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