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2. Monocots and Eudicots = Phylum ANTHOPHYTA 2 Both are MONOPHYLETIC = ONE common ancestor

3. - Plants need resources from both the air and soil, so the ROOT system (ground) needs to work with the SHOOT system (air)…they depend on each other 3 Tissue  a group of cells, consisting of one or more types, which perform a specific function (ex. ground tissue, vascular tissue, etc) Organ  several types of tissues that work together to carry out particular functions (3 main organs in plants = roots, stems, leaves) Tissue  a group of cells, consisting of one or more types, which perform a specific function (ex. ground tissue, vascular tissue, etc) Organ  several types of tissues that work together to carry out particular functions (3 main organs in plants = roots, stems, leaves)

4. Roots - Function → anchor, absorb water, store food -Monocots = fibrous roots -Dicots = taproots - Roots may have root hairs to increase the surface area and take up water - Adventitious roots are above ground roots -Have epidermal tissue but no waxy cuticle Roots - Function → anchor, absorb water, store food -Monocots = fibrous roots -Dicots = taproots - Roots may have root hairs to increase the surface area and take up water - Adventitious roots are above ground roots -Have epidermal tissue but no waxy cuticle Taproot – Ex. Carrot Fibrous Root – Ex. Onion Taproot – Ex. Carrot Fibrous Root – Ex. Onion Root Hairs Adventitious Roots of Ficus 4

5. Shoots -Stems and Leaves - Can be: -Vegetative (leaves) - Reproductive (flowers) Shoots -Stems and Leaves - Can be: -Vegetative (leaves) - Reproductive (flowers) 5

6. Stems -Alternating system of nodes (leaf attachments) and internodes (between leaves) - Axillary bud (angle at leaf/stem) have potential to bud -Terminal bud → concentrated growth; this inhibits the axillary buds = APICAL DOMINANCE Stems -Alternating system of nodes (leaf attachments) and internodes (between leaves) - Axillary bud (angle at leaf/stem) have potential to bud -Terminal bud → concentrated growth; this inhibits the axillary buds = APICAL DOMINANCE The presence of a terminal bud is responsible for inhibiting the growth of axillary buds. If the terminal bud gets removed (pruning), then the axillary bud will start to grow. Sometimes gardeners cut the terminal bud off so that the axillary buds will grow and the plant will become fuller. 6

7. Leaves -Main photosynthetic organ in plants - Flattened blade and petiole (stalk) -Waxy cuticle (helps prevent water loss) - Some have special functions Leaves -Main photosynthetic organ in plants - Flattened blade and petiole (stalk) -Waxy cuticle (helps prevent water loss) - Some have special functions 7 COPY THIS INTO YOUR NOTES!!! Mesophyll Tissue  -VERY photosynthetic -Divided into spongy and palisades mesophyll COPY THIS INTO YOUR NOTES!!! Mesophyll Tissue  -VERY photosynthetic -Divided into spongy and palisades mesophyll

8. 3 Types of Plant Tissues: - Dermal → outer layer; “epidermis” - Vascular → transport; xylem and phloem - Ground → photosynthetic; storage; support 3 Types of Plant Tissues: - Dermal → outer layer; “epidermis” - Vascular → transport; xylem and phloem - Ground → photosynthetic; storage; support 8

9. Dermal Tissue -The dermal tissue is the epidermis of the plant; it is called the “skin of the plant” - It is the outside layer of the plant - It is a single layer of cells that are tightly packed together - It can secrete a waxy cuticle (prevent dehydration) Dermal Tissue -The dermal tissue is the epidermis of the plant; it is called the “skin of the plant” - It is the outside layer of the plant - It is a single layer of cells that are tightly packed together - It can secrete a waxy cuticle (prevent dehydration) Note the upper and lower epidermis 9

10. Vascular Tissue -Organized into veins - Transports materials between the roots and the shoots -The vascular tissue of the root or stem is called the stele - 2 main parts: - Xylem → transports water “up” - Phloem → transports food to roots and non- photosynthetic parts of the plant; from “source to sink”; transports up and down Vascular Tissue -Organized into veins - Transports materials between the roots and the shoots -The vascular tissue of the root or stem is called the stele - 2 main parts: - Xylem → transports water “up” - Phloem → transports food to roots and non- photosynthetic parts of the plant; from “source to sink”; transports up and down In this picture, the “S” stands for phloem (sieve tube elements) 10

11. Ground Tissue -Neither dermal nor vascular -Functions in photosynthesis, storage, and structural support -In eudicots (where the vascular bundles are arranged in a ring) it is divided into: -Pith (internal to the vascular tissue) - Cortex (external to the vascular tissue) Ground Tissue -Neither dermal nor vascular -Functions in photosynthesis, storage, and structural support -In eudicots (where the vascular bundles are arranged in a ring) it is divided into: -Pith (internal to the vascular tissue) - Cortex (external to the vascular tissue) 11

12. There are 3 basic types of plant cells : 1. Parenchyma 2. Collenchyma 3. Sclerenchyma Each cell type has structural adaptations in the cell contents (protoplast) and in the cell wall. Terms to know: - Plasmodesmata → channels connecting cells - Middle lamella → cements adjacent cell walls - Primary wall → made as the cell grows - Secondary wall → made after the growth stops There are 3 basic types of plant cells : 1. Parenchyma 2. Collenchyma 3. Sclerenchyma Each cell type has structural adaptations in the cell contents (protoplast) and in the cell wall. Terms to know: - Plasmodesmata → channels connecting cells - Middle lamella → cements adjacent cell walls - Primary wall → made as the cell grows - Secondary wall → made after the growth stops 12

13. Parenchyma -Thin, flexible primary walls - Most lack secondary walls - “Typical cell” → generally the LEAST specialized (all cells start out as parenchyma) -Can dedifferentiate for plant tissue cultures -Photosynthetic!! - Perform most metabolic functions -Do not usually do cell division (unless in meristems), but retain the ability to divide and differentiate Parenchyma -Thin, flexible primary walls - Most lack secondary walls - “Typical cell” → generally the LEAST specialized (all cells start out as parenchyma) -Can dedifferentiate for plant tissue cultures -Photosynthetic!! - Perform most metabolic functions -Do not usually do cell division (unless in meristems), but retain the ability to divide and differentiate 13

14. Collenchyma -Thicker, but uneven primary cell walls - Grouped together to support young parts of shoots -LACK secondary walls Collenchyma -Thicker, but uneven primary cell walls - Grouped together to support young parts of shoots -LACK secondary walls 14

15. Sclerenchyma -Function as SUPPORT ELEMENTS in plants - They have thick secondary walls strengthened with lignin -More rigid than collenchyma -Mature cells cannot elongate (b/c of rigid cell walls), so they are present in cells that have stopped growing Sclerenchyma -Function as SUPPORT ELEMENTS in plants - They have thick secondary walls strengthened with lignin -More rigid than collenchyma -Mature cells cannot elongate (b/c of rigid cell walls), so they are present in cells that have stopped growing 15

16. Xylem -Transports water and dissolved materials “up” from the roots - There are two types of water conducting elements: -Tracheids → long and thin; their secondary cell walls have hardened with lignin; they have pits where water flows through -Vessel Elements → wider and shorter; thinner walls and linked together forming long tubes (called xylem vessels) -The cells that make up xylem are DEAD at maturity Xylem -Transports water and dissolved materials “up” from the roots - There are two types of water conducting elements: -Tracheids → long and thin; their secondary cell walls have hardened with lignin; they have pits where water flows through -Vessel Elements → wider and shorter; thinner walls and linked together forming long tubes (called xylem vessels) -The cells that make up xylem are DEAD at maturity Xylem 16

17. Phloem -Transports food to roots and other non-photosynthetic parts of the plant - Moves sucrose and other organic molecules through tubes formed by chains of cells called sieve tube elements → -These sieve tube elements are ALIVE at maturity - The end of each element has a sieve plate, which has pores to allow substances through - They are associated with non-conducting companion cells that help them move the materials (via plasmodesmata) -Used in TRANSLOCATION (Bulk Flow Movement) Phloem -Transports food to roots and other non-photosynthetic parts of the plant - Moves sucrose and other organic molecules through tubes formed by chains of cells called sieve tube elements → -These sieve tube elements are ALIVE at maturity - The end of each element has a sieve plate, which has pores to allow substances through - They are associated with non-conducting companion cells that help them move the materials (via plasmodesmata) -Used in TRANSLOCATION (Bulk Flow Movement) Phloem = Blue (in this picture) 17

18. Meristems -Perpetual embryonic tissue in growth areas (makes more cells!) - Pattern of growth depends on the locations of the meristems - There are 2 main types of meristems: -Apical Meristems -Lateral Meristems Meristems -Perpetual embryonic tissue in growth areas (makes more cells!) - Pattern of growth depends on the locations of the meristems - There are 2 main types of meristems: -Apical Meristems -Lateral Meristems Meristems allow for LIFELONG GROWTH!!! 18

19. Apical meristems are found at the tips of roots and at the buds of shoots. These are for PRIMARY growth (LENGTH). They give rise to the primary plant body. They allow roots to extend through the soil and the shoots to increase their exposure to light and carbon dioxide. 19

20. Lateral meristems are cylinders that run along the root/ shoot. They provide SECONDARY growth (THICKNESS). They add girth to the plant by making secondary vascular tissue and periderm. These meristems are very important in woody plants (trees, etc). 20 -There are two types of lateral meristems: the vascular cambium and the cork cambium. -The vascular cambium adds layers of vascular tissue called secondary xylem ( wood ) and secondary phloem. - Plants with vascular cambium with lignified cell walls are called woody plants (not herbaceous) - The cork cambium replaces the epidermis with thicker, tougher periderm. -There are two types of lateral meristems: the vascular cambium and the cork cambium. -The vascular cambium adds layers of vascular tissue called secondary xylem ( wood ) and secondary phloem. - Plants with vascular cambium with lignified cell walls are called woody plants (not herbaceous) - The cork cambium replaces the epidermis with thicker, tougher periderm.

21. 21 - Annuals  complete their life cycle—from germination to flowering to seed production to death—in a single year or less. - Biennials  s pan two years, with flowering and fruiting in the second year - Perennials  plants such as trees, shrubs, and some grasses that live many years - Annuals  complete their life cycle—from germination to flowering to seed production to death—in a single year or less. - Biennials  s pan two years, with flowering and fruiting in the second year - Perennials  plants such as trees, shrubs, and some grasses that live many years

22. Root Cap → protects meristem Zone of cell division → apical meristem and its derivatives Quiescent Center → Cells that divide more slowly than meristem cells; resistant to damage Zone of elongation → cells elongate; responsible for pushing the root tip Zone of differentiation (aka zone of maturation) → specialization; complete differentiation and become distinct cell types Root Cap → protects meristem Zone of cell division → apical meristem and its derivatives Quiescent Center → Cells that divide more slowly than meristem cells; resistant to damage Zone of elongation → cells elongate; responsible for pushing the root tip Zone of differentiation (aka zone of maturation) → specialization; complete differentiation and become distinct cell types 22 - Roots show mostly PRIMARY GROWTH and produce the epidermis, ground tissue, and vascular tissue. - Water and minerals absorbed from the soil must enter the plant through the epidermis, a single layer of cells covering the root. - Root hairs greatly increase the surface area of the epidermis. - In angiosperm roots, the stele is a vascular cylinder with a solid core of xylem and phloem. - The ground tissue of roots consists of parenchyma cells. - When plant stems are cut, roots will develop at the cut end which is opposite the apical bud. - Roots show mostly PRIMARY GROWTH and produce the epidermis, ground tissue, and vascular tissue. - Water and minerals absorbed from the soil must enter the plant through the epidermis, a single layer of cells covering the root. - Root hairs greatly increase the surface area of the epidermis. - In angiosperm roots, the stele is a vascular cylinder with a solid core of xylem and phloem. - The ground tissue of roots consists of parenchyma cells. - When plant stems are cut, roots will develop at the cut end which is opposite the apical bud.

23. There are 3 Primary Meristems: Protoderm – forms the dermal tissue (epidermis) Procambium – forms the stele (vascular tissue in the center of roots – primary xylem/phloem) Ground – forms ground tissue There are 3 Primary Meristems: Protoderm – forms the dermal tissue (epidermis) Procambium – forms the stele (vascular tissue in the center of roots – primary xylem/phloem) Ground – forms ground tissue Stele – vascular bundle in the center of roots; produced by the procambium 23

24. Secondary Growth – Thickness - Occurs in stems and sometimes in roots, but rarely in leaves - TWO LATERAL MERISTEMS: -Vascular Cambium → makes secondary xylem (WOOD) and secondary phloem -Cork Cambium → Makes the tough covering for roots and stems which replaces the epidermis -Periderm → layers of cork and cork cambium - Bark → refers to all tissue external to vascular cambium (secondary phloem, cork, cork cambium) Secondary Growth – Thickness - Occurs in stems and sometimes in roots, but rarely in leaves - TWO LATERAL MERISTEMS: -Vascular Cambium → makes secondary xylem (WOOD) and secondary phloem -Cork Cambium → Makes the tough covering for roots and stems which replaces the epidermis -Periderm → layers of cork and cork cambium - Bark → refers to all tissue external to vascular cambium (secondary phloem, cork, cork cambium) KNOW THIS PICTURE AND THESE DEFINITIONS!! IF there is secondary growth, the plant is considered to be “woody” not “herbaceous” 24

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26. One of the major differences between plants and animals is TOTIPOTENCY! For plants growth and development is NOT restricted to the embryonic/ juvenile period but occurs throughout the life of the plant; can develop into any part of the plant; to get features from the juvenile form, must take cuttings from areas formed in that period One of the major differences between plants and animals is TOTIPOTENCY! For plants growth and development is NOT restricted to the embryonic/ juvenile period but occurs throughout the life of the plant; can develop into any part of the plant; to get features from the juvenile form, must take cuttings from areas formed in that period Growth = increase in size Development = changes that elaborate an organisms body Growth = increase in size Development = changes that elaborate an organisms body Plant Life Cycle: Germ → Flower →Seed → Death RECALL: Annual = 1 year or less Biennial = 2 years Perennial = Lives many years Plant Life Cycle: Germ → Flower →Seed → Death RECALL: Annual = 1 year or less Biennial = 2 years Perennial = Lives many years 26

27. Processes that are important to the development of plants: 1. Morphogenesis → development of body form and organization; depends on pattern formation (specific structure in specific location) 2. Differentiation → specialization of cells; depends on control of gene expression (regulating transcription and translation) 3. Growth → includes both: - Cell Division (can be symmetrical or asymmetrical) - Cell Expansion (water accounts for 90% of expansion – fills vacuoles) Both of these contribute to plant form Processes that are important to the development of plants: 1. Morphogenesis → development of body form and organization; depends on pattern formation (specific structure in specific location) 2. Differentiation → specialization of cells; depends on control of gene expression (regulating transcription and translation) 3. Growth → includes both: - Cell Division (can be symmetrical or asymmetrical) - Cell Expansion (water accounts for 90% of expansion – fills vacuoles) Both of these contribute to plant form 27

28. Terms to Know: - Stomata - Guard Cells - Palisades Mesophyll - Spongy Mesophyll -Mycorrhizae (symbiotic fungus on roots to help get water) Terms to Know: - Stomata - Guard Cells - Palisades Mesophyll - Spongy Mesophyll -Mycorrhizae (symbiotic fungus on roots to help get water) 28

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30. 30 Mycorrhizae is a fungus that grows in association with the roots of a plant in a symbiotic or mildly pathogenic relationship. It helps the plant absorb water from the surrounding soil and in turn has access to the carbohydrates (sugars) of the plant.

31. Symplastic → Continuum of cytosolic compartments; requires only one crossing of the membrane; once it is in the cell, it moves from cell to cell via plasmodesmata; (therefore the PM can regulate what can and cannot be shared through the plant) Apoplastic → Continuum of cell walls and extracellular spaces without actually entering the cell (when it wants to cross into the cellular compartment, it also has to pass through the PM to be “checked”) Transmembrane - water and solutes move out of one cell, across the cell wall, and into the neighboring cell, and keep moving following this pattern; this route requires repeated crossings of plasma membranes Symplastic → Continuum of cytosolic compartments; requires only one crossing of the membrane; once it is in the cell, it moves from cell to cell via plasmodesmata; (therefore the PM can regulate what can and cannot be shared through the plant) Apoplastic → Continuum of cell walls and extracellular spaces without actually entering the cell (when it wants to cross into the cellular compartment, it also has to pass through the PM to be “checked”) Transmembrane - water and solutes move out of one cell, across the cell wall, and into the neighboring cell, and keep moving following this pattern; this route requires repeated crossings of plasma membranes It is important to pass through the PM so that the materials can get checked and the vascular system does not spread harmful things to the rest of the plant 31

32. 32 Hydrogen ions (H + ) play the primary role in basic transport processes in plant cells. The membrane potential is established mainly through the pumping of H + by proton pumps. During cotransport, plant cells use the energy in the H + gradient and membrane potential to drive the active transport of many different solutes. For instance, cotransport with H + is responsible for absorption of neutral solutes, such as sucrose, by phloem cells and other plant cells. An H + /sucrose cotransporter couples movement of sucrose against its concentration gradient with movement of H + down its electrochemical gradient. Hydrogen ions (H + ) play the primary role in basic transport processes in plant cells. The membrane potential is established mainly through the pumping of H + by proton pumps. During cotransport, plant cells use the energy in the H + gradient and membrane potential to drive the active transport of many different solutes. For instance, cotransport with H + is responsible for absorption of neutral solutes, such as sucrose, by phloem cells and other plant cells. An H + /sucrose cotransporter couples movement of sucrose against its concentration gradient with movement of H + down its electrochemical gradient.

33. WATER POTENTIAL   =  S +  P -Water potential depends on two things: -1. Solute concentration -Adding SOLUTES LOWERS ψ -2. Physical pressure - adding PRESSURE INCREASES ψ - Water moves from HIGH ψ to LOW ψ - Pure water → ψ = 0 WATER POTENTIAL   =  S +  P -Water potential depends on two things: -1. Solute concentration -Adding SOLUTES LOWERS ψ -2. Physical pressure - adding PRESSURE INCREASES ψ - Water moves from HIGH ψ to LOW ψ - Pure water → ψ = 0 Determines the direction and movement of water in plants! 33

34.  Bulk flow functions in long-distance transport.  Diffusion is efficient for transport within a cell or between cells.  However, diffusion is much too slow for long-distance transport within a plant, such as the movement of water and minerals from roots to leaves.  Water and solutes move through xylem vessels and sieve tubes by bulk flow, the movement of a fluid driven by a pressure gradient.  Phloem transport moves by bulk flow.  Bulk flow functions in long-distance transport.  Diffusion is efficient for transport within a cell or between cells.  However, diffusion is much too slow for long-distance transport within a plant, such as the movement of water and minerals from roots to leaves.  Water and solutes move through xylem vessels and sieve tubes by bulk flow, the movement of a fluid driven by a pressure gradient.  Phloem transport moves by bulk flow. 34

35. Bulk Flow → movement of water and solutes by pressure Root Hairs → increase SA to increase absorption Mycorrhizae → RECALL: a fungus that has a symbiotic relationship with plant roots; absorbs water Endodermis → surrounds the stele (center where the vascular tissue is); contains the casparian strip Casparian Strip → waxy layer made of suberin that is impervious to water; ensures that materials from the apoplastic pathway have to cross a PM to get “checked”; everything must pass through a cell before entering the stele Bulk Flow → movement of water and solutes by pressure Root Hairs → increase SA to increase absorption Mycorrhizae → RECALL: a fungus that has a symbiotic relationship with plant roots; absorbs water Endodermis → surrounds the stele (center where the vascular tissue is); contains the casparian strip Casparian Strip → waxy layer made of suberin that is impervious to water; ensures that materials from the apoplastic pathway have to cross a PM to get “checked”; everything must pass through a cell before entering the stele 35 See Next Slide…

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37. Sap = water and dissolved minerals The sap moves through the plant by 2 forces: 1. Root Pressure → “PUSH” 2. Transpiration/ Cohesion/ Adhesion → “PULL” Sap = water and dissolved minerals The sap moves through the plant by 2 forces: 1. Root Pressure → “PUSH” 2. Transpiration/ Cohesion/ Adhesion → “PULL” 37

38. Root Pressure = PUSH -Minerals accumulate in the stele; this DECREASES Ψ …therefore water flows INTO the root cortex which creates a pressure that forces the fluid up the xylem -Guttation → if more water is “pushed up” than is transpired (lost/evaporated), water is forced out of the leaves (occurs at night and when there is high humidity) - This is NOT the major mechanism Root Pressure = PUSH -Minerals accumulate in the stele; this DECREASES Ψ …therefore water flows INTO the root cortex which creates a pressure that forces the fluid up the xylem -Guttation → if more water is “pushed up” than is transpired (lost/evaporated), water is forced out of the leaves (occurs at night and when there is high humidity) - This is NOT the major mechanism 38

39. Transpiration/ Cohesion/ Adhesion = PULL -Water is lost by transpiration (loss of water vapor from leaves); therefore water is drawn from other cells by osmosis -Cohesion – water sticking to water -Adhesion – water sticking to cell walls ***Both of these factors are due to H- bonding*** -This is the MAJOR MECHANISM of xylem sap Transpiration/ Cohesion/ Adhesion = PULL -Water is lost by transpiration (loss of water vapor from leaves); therefore water is drawn from other cells by osmosis -Cohesion – water sticking to water -Adhesion – water sticking to cell walls ***Both of these factors are due to H- bonding*** -This is the MAJOR MECHANISM of xylem sap Xylem sap transport is SOLAR POWERED! Most of the movement of xylem is due to the evaporation of water through stomata!! 39

40.  The transpiration-cohesion- tension mechanism transports xylem sap against gravity.  Long-distance transport of water from roots to leaves occurs by bulk flow, with the movement of fluid driven by a water potential difference at opposite ends of xylem tissue.  The transpiration-cohesion- tension mechanism transports xylem sap against gravity.  Long-distance transport of water from roots to leaves occurs by bulk flow, with the movement of fluid driven by a water potential difference at opposite ends of xylem tissue. 40

41. The BENEFIT of transpiration is evaporative cooling. If the temperature of the plant stays down, the enzymes for photosynthesis and respiration will not denature. Stomata open and close (via guard cells) by changing shape. If the plant has enough water, the vacuoles will be full and the guard cells will be turgid/ swollen and therefore OPEN. If there is little water available, the guard cells are flaccid and the stomata will be CLOSED…which means no gas exchange for PS! 41 Guard cells control stomatal opening on a moment-to-moment basis, reacting to a cloud or transient shaft of sunlight. In general, transpiration is greatest on sunny, warm, dry, and windy days because these environmental factors increase evaporation Guard cells control stomatal opening on a moment-to-moment basis, reacting to a cloud or transient shaft of sunlight. In general, transpiration is greatest on sunny, warm, dry, and windy days because these environmental factors increase evaporation

42. Lots of K+ = ↓Ψ (adding solutes decreases water potential) = Osmosis (H 2 O IN) = turgid = stomata open Little K+ = ↑Ψ = Osmosis (H 2 O OUT) = flaccid = stomata closed Lots of K+ = ↓Ψ (adding solutes decreases water potential) = Osmosis (H 2 O IN) = turgid = stomata open Little K+ = ↑Ψ = Osmosis (H 2 O OUT) = flaccid = stomata closed Stomata are usually open at night to decrease transpiration. CAM plants have the stomata open at night. Then the CO 2 is converted into an organic acid, which releases CO 2 for Calvin Cycle during the day. 42

43. - Translocation = movement of food via phloem; utilizes sieve tube cells -Usually the “food” is the disaccharide sucrose (SUGAR!!) - Sugar “source” = WHERE the sugar is MADE (usually leaves) - Sugar “sink” = consumer/ storer of sugar (growing roots, shoots, fruits, apical meristems) - Movement is always: SOURCE to SINK -The sugar may go up or down depending on where the source and sink are in relation to one another - Requires active transport (moves by bulk flow which is driven by pressure)…needs ENERGY!! - Translocation = movement of food via phloem; utilizes sieve tube cells -Usually the “food” is the disaccharide sucrose (SUGAR!!) - Sugar “source” = WHERE the sugar is MADE (usually leaves) - Sugar “sink” = consumer/ storer of sugar (growing roots, shoots, fruits, apical meristems) - Movement is always: SOURCE to SINK -The sugar may go up or down depending on where the source and sink are in relation to one another - Requires active transport (moves by bulk flow which is driven by pressure)…needs ENERGY!! 43

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45. A plant goes through 2 different generations: - Gametophyte = produces gametes by mitosis; haploid - Sporophyte = produces haploid spores by meiosis; diploid; usually the dominant phase A plant goes through 2 different generations: - Gametophyte = produces gametes by mitosis; haploid - Sporophyte = produces haploid spores by meiosis; diploid; usually the dominant phase 45 The diploid plant, the sporophyte, makes haploid spores by meiosis. These spores divide by mitosis to form gametophytes, multicellular male and female haploid plants that produce gametes (eggs and sperm). Fertilization results in diploid zygotes, which divide by mitosis to form new sporophytes.

46. -Non-reproductive parts = sepal and petals - Reproductive parts: - Male = Stamen (anther makes pollen) - Female = Carpel (stigma, style, ovary) - Complete flower = have all 4 organs; all bisexual (have both male and female) - Incomplete flower = lacking one or more floral parts; unisexual -Non-reproductive parts = sepal and petals - Reproductive parts: - Male = Stamen (anther makes pollen) - Female = Carpel (stigma, style, ovary) - Complete flower = have all 4 organs; all bisexual (have both male and female) - Incomplete flower = lacking one or more floral parts; unisexual 46

47. -In sporangia (pollen sacs) are diploid cells (called microsporocytes) that do meiosis to form haploid microspores, which gives rise to pollen (male gametophyte) - Two cells: - Generative cell = produces sperm - Tube cell = produces pollen tube -Pollen = 2 sperm cells -In sporangia (pollen sacs) are diploid cells (called microsporocytes) that do meiosis to form haploid microspores, which gives rise to pollen (male gametophyte) - Two cells: - Generative cell = produces sperm - Tube cell = produces pollen tube -Pollen = 2 sperm cells Microsporocyte 47

48. Ovary → Ovule → Megasporocyte → Megaspores - The megasporocyte goes through MEIOSIS to form the megaspores -Only 1 of the 4 megaspores survive -The surviving megaspore divides 3 times without cytokinesis to give one cell with 8 haploid nuclei - 3 antipodal cells  unknown function - 2 polar nuclei  combines with a sperm to form the 3n endosperm (food source for the seed) - 1 egg  combines with a sperm cell to form the 2n zygote - 2 synergids  helps attract the pollen tube Ovary → Ovule → Megasporocyte → Megaspores - The megasporocyte goes through MEIOSIS to form the megaspores -Only 1 of the 4 megaspores survive -The surviving megaspore divides 3 times without cytokinesis to give one cell with 8 haploid nuclei - 3 antipodal cells  unknown function - 2 polar nuclei  combines with a sperm to form the 3n endosperm (food source for the seed) - 1 egg  combines with a sperm cell to form the 2n zygote - 2 synergids  helps attract the pollen tube 48

49. Development of Gametophytes 49

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51. Brings male and female gametes together to that fertilization can occur. Fertilization = fusion of gametes 51

52. Double fertilization synchronizes embryo development with food supply. Remember each pollen grain contains 2 sperm: - 1 sperm + egg = 2n zygote - 1 sperm + 2 polar nuclei = 3n endosperm (food) Double fertilization synchronizes embryo development with food supply. Remember each pollen grain contains 2 sperm: - 1 sperm + egg = 2n zygote - 1 sperm + 2 polar nuclei = 3n endosperm (food) BOTH sperm fertilize nuclei of the female gametophyte 52

53. -After double fertilization, ovule develops into a seed and the ovary develops into a fruit -Enclosed in a protective seed coat - Mature seed = dehydrated (dormant!); when it gets rehydrated, it forms an embryonic root (radicle) -After double fertilization, ovule develops into a seed and the ovary develops into a fruit -Enclosed in a protective seed coat - Mature seed = dehydrated (dormant!); when it gets rehydrated, it forms an embryonic root (radicle) 53

54. Germination of seeds depends on imbibition (the uptake of water due to the low water potential of the seed). Imbibition causes metabolic changes that resume growth in the seed. The radicle (root) emerges first (so it can supply water to the rest of the plant). Germination of seeds depends on imbibition (the uptake of water due to the low water potential of the seed). Imbibition causes metabolic changes that resume growth in the seed. The radicle (root) emerges first (so it can supply water to the rest of the plant). 54

55. Definition of Fruit: - Angiosperm structure that protects dormant seeds and aids in dispersal Definition of Fruit: - Angiosperm structure that protects dormant seeds and aids in dispersal Mature Ovary = FRUIT -Pollination → hormonal changes → Ovarian growth into the fruit - The ovary wall becomes a pericarp (thickened wall of the fruit) -Helps in dispersal by wind and animals Mature Ovary = FRUIT -Pollination → hormonal changes → Ovarian growth into the fruit - The ovary wall becomes a pericarp (thickened wall of the fruit) -Helps in dispersal by wind and animals 55

56. Simple Fruit -Develop from a single ovary (Ex. cherry, soybean) Simple Fruit -Develop from a single ovary (Ex. cherry, soybean) Aggregate Fruit - Single flower, several carpals (Ex. blackberry) Aggregate Fruit - Single flower, several carpals (Ex. blackberry) Multiple Fruit - Tightly clustered group of flowers (Ex. pineapple) Multiple Fruit - Tightly clustered group of flowers (Ex. pineapple) 56

57. -Asexual reproduction is also called Vegetative Reproduction - Results in CLONES (also called CLONAL reproduction)  no genetic variation! - Can grow from one parenchyma cell! -Fragmentation → separation of parent plant into pieces that reform the whole plant; done to make cuttings; this can also occur naturally - Apomixis → flowers (ex. dandelions) that can produce seeds without flowers being fertilized -Test-tube cloning; can cross genes -Asexual reproduction is also called Vegetative Reproduction - Results in CLONES (also called CLONAL reproduction)  no genetic variation! - Can grow from one parenchyma cell! -Fragmentation → separation of parent plant into pieces that reform the whole plant; done to make cuttings; this can also occur naturally - Apomixis → flowers (ex. dandelions) that can produce seeds without flowers being fertilized -Test-tube cloning; can cross genes 57

58.  Asexual Reproduction   Advantages = can clone itself rapidly; seedlings are sturdy  Disadvantage = no genetic variation  Sexual Reproduction   Advantages = genetic diversity  Disadvantages = sometimes seedlings can be more frail  Seed dormancy suspends growth until hostile environmental conditions are reversed.  Asexual Reproduction   Advantages = can clone itself rapidly; seedlings are sturdy  Disadvantage = no genetic variation  Sexual Reproduction   Advantages = genetic diversity  Disadvantages = sometimes seedlings can be more frail  Seed dormancy suspends growth until hostile environmental conditions are reversed. 58

59. -Prevention of self- fertilization ensures that the egg and sperm are from different parents - There are several possibilities to prevent this: - Stamens/ carpals mature at different times - Structural arrangement (see below) - Self-incompatibility → plant rejects its own pollen and that of closely related individuals (biochemical blocker) -Prevention of self- fertilization ensures that the egg and sperm are from different parents - There are several possibilities to prevent this: - Stamens/ carpals mature at different times - Structural arrangement (see below) - Self-incompatibility → plant rejects its own pollen and that of closely related individuals (biochemical blocker) 59

60. Humans do selective breeding for our own benefit. Plants are totipotent and have the ability to go from one cell to a clone of the original organism. Transgenic Plants → plants that have genes from 2 or more species; they have been genetically modified (GM) OR they can occur in nature naturally Much debate surrounds plant biotechnology with respect to politics, the economy, and ethical concerns. Humans do selective breeding for our own benefit. Plants are totipotent and have the ability to go from one cell to a clone of the original organism. Transgenic Plants → plants that have genes from 2 or more species; they have been genetically modified (GM) OR they can occur in nature naturally Much debate surrounds plant biotechnology with respect to politics, the economy, and ethical concerns. 60

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62. 3 Stages in the Cell Signaling Process  *Reception (signal detected by receptors) * Transduction (signal amplified by second messengers and carried) * Response (enzymes activated) Greening (De-Etiolation)  * involves changes in levels of growth hormones and activation of enzymes related to photosynthesis: * shoot reaches sunlight * stem elongation slows * leaves expand * root system elongates * chlorophyll production begins 3 Stages in the Cell Signaling Process  *Reception (signal detected by receptors) * Transduction (signal amplified by second messengers and carried) * Response (enzymes activated) Greening (De-Etiolation)  * involves changes in levels of growth hormones and activation of enzymes related to photosynthesis: * shoot reaches sunlight * stem elongation slows * leaves expand * root system elongates * chlorophyll production begins 62

63. 63  Plants do not have a circulatory system like animals do; some hormones can only act locally  Plant hormones are produced at very low concentrations, so signal transduction pathways amplify the signals  Plant hormones control plant growth and development by affecting the division, elongation, and differentiation of cells  Each hormone has multiple effects, depending on its site of action, its concentration, and the developmental stage of the plant.  Response to a hormone usually depends not so much on its absolute concentration as on its relative concentration compared to other hormones.  It is hormonal balance, rather than hormones acting in isolation, that controls growth and development of plants.  Plants do not have a circulatory system like animals do; some hormones can only act locally  Plant hormones are produced at very low concentrations, so signal transduction pathways amplify the signals  Plant hormones control plant growth and development by affecting the division, elongation, and differentiation of cells  Each hormone has multiple effects, depending on its site of action, its concentration, and the developmental stage of the plant.  Response to a hormone usually depends not so much on its absolute concentration as on its relative concentration compared to other hormones.  It is hormonal balance, rather than hormones acting in isolation, that controls growth and development of plants.

64.  Tropism  growth response toward OR away from a stimulus  Example: phototropism  (bending toward light is a positive tropism)  Bending away from light is a negative tropism)  Research  Darwin & son: plant does NOT grow toward light if tip covered or removed  Went : extracted the chemical messenger for phototropism – auxin!  He realized that there was more produced on the DARKER side of the plant, so those cells elongated more …and grew TOWARDS the light  Tropism  growth response toward OR away from a stimulus  Example: phototropism  (bending toward light is a positive tropism)  Bending away from light is a negative tropism)  Research  Darwin & son: plant does NOT grow toward light if tip covered or removed  Went : extracted the chemical messenger for phototropism – auxin!  He realized that there was more produced on the DARKER side of the plant, so those cells elongated more …and grew TOWARDS the light 64

65. Went’s experiment represents the first time anyone had isolated a hormone from plants. 65

66.  Auxin  made mostly in apical meristem of the shoot; stimulates cell elongation in different target tissues, enhances apical dominance, promotes fruit growth (this is what was discovered in the Went experiment!); role in pattern formation  Cytokinins  produced in actively growing tissues (ex. Roots, embryos, fruits); stimulate cytokinesis, can stimulate germination and delay senesence (aging)  Gibberellins  made in roots and young leaves; stimulates growth in leaves and stems, causes flower and fruit development, bolting (elongation of stalk)  Abscisic acid  maintains dormancy in seeds by inhibiting germination and therefore SLOWS GROWTH, reduces drought stress by closing stomata  Ethylene  (gas) controls fruit ripening by positive feedback (more gas, more ripening), promotes leaf abscission (leaf loss by deciduous in winter); a chain reaction occurs during ripening: Ethylene triggers ripening, and ripening triggers more ethylene production – hence the expression – “one bad apple spoils the whole bunch”  Brassionsteroids  similar to animal sex hormones; induces cell elongation and cell division, slows abscission (dropping leaves) MAKE SURE YOU KNOW THESE!! 66

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68. Photomorphogenesis  effect of light on plant growth/development; red and blue light most important BLUE light – initiates several responses: bending toward/away from light, hypocotyl elongation and opening of stomata PHYTOCHROMES (reds) - red light (660nm) – increases germination - far red light (730 nm) – inhibits germination - the response depends on the LAST flash of light - effects of red and far red light are reversible Photomorphogenesis  effect of light on plant growth/development; red and blue light most important BLUE light – initiates several responses: bending toward/away from light, hypocotyl elongation and opening of stomata PHYTOCHROMES (reds) - red light (660nm) – increases germination - far red light (730 nm) – inhibits germination - the response depends on the LAST flash of light - effects of red and far red light are reversible 68

69.  Circadian rhythm   Many plant processes, such as transpiration and synthesis of certain enzymes, undergo a daily oscillation.  Physiological cycles with a frequency of about 24 hours that are not directly paced by any known environmental variable are called circadian rhythms.  If an organism is kept in a constant environment, its circadian rhythms deviate from a 24-hour period to free-running periods ranging from 21 to 27 hours.  Photoperiodism   Relative length of night and day and the resulting physiological response  Critical Night Length – length of NIGHT (not day) controls flowering and other photoperiod responses  Circadian rhythm   Many plant processes, such as transpiration and synthesis of certain enzymes, undergo a daily oscillation.  Physiological cycles with a frequency of about 24 hours that are not directly paced by any known environmental variable are called circadian rhythms.  If an organism is kept in a constant environment, its circadian rhythms deviate from a 24-hour period to free-running periods ranging from 21 to 27 hours.  Photoperiodism   Relative length of night and day and the resulting physiological response  Critical Night Length – length of NIGHT (not day) controls flowering and other photoperiod responses 69

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71.  Gravity –  Roots show POSITIVE gravitropism and shoots show NEGATIVE gravitropism; this ensure that the roots reach soil and the shoots reach the sunlight regardless of how the seed lands  Stress -  Drought – mechanisms to reduce transpiration include guard cells closing stomata and slowing shallow root growth help plants deal with drought  Heat – heat shock proteins aid to scaffold protein folding (can function as chaperonin proteins)  Cold – increase unsaturated fatty acids for fluidity, when freezing – ability to resist dehydration from water loss affects survival  Gravity –  Roots show POSITIVE gravitropism and shoots show NEGATIVE gravitropism; this ensure that the roots reach soil and the shoots reach the sunlight regardless of how the seed lands  Stress -  Drought – mechanisms to reduce transpiration include guard cells closing stomata and slowing shallow root growth help plants deal with drought  Heat – heat shock proteins aid to scaffold protein folding (can function as chaperonin proteins)  Cold – increase unsaturated fatty acids for fluidity, when freezing – ability to resist dehydration from water loss affects survival 71

72.  Physical – first line of defense is the epidermis and periderm; also plants have thorns to deter predators  Chemical – chemical attacks are the second line of defense; this helps to destroy pathogens to prevent spread of infection; production of distasteful/toxic compounds;  Recruitment of predators of herbivores  Wasp (predator)  caterpillars (herbivore)  plants  Physical – first line of defense is the epidermis and periderm; also plants have thorns to deter predators  Chemical – chemical attacks are the second line of defense; this helps to destroy pathogens to prevent spread of infection; production of distasteful/toxic compounds;  Recruitment of predators of herbivores  Wasp (predator)  caterpillars (herbivore)  plants 72

73.  Hypersensitive Response  Complex early defense response that causes cell and tissue death near the infection site and restricts the spread of a pathogen.  Systematic Acquired Resistance (SAR)  Provoked by chemicals that “sound the alarm”  Non-specific, and provides protection against diverse pathogens  SAR = alarm hormones!  One hormone example is salicylic acid (ingredient in aspirin)  Hypersensitive Response  Complex early defense response that causes cell and tissue death near the infection site and restricts the spread of a pathogen.  Systematic Acquired Resistance (SAR)  Provoked by chemicals that “sound the alarm”  Non-specific, and provides protection against diverse pathogens  SAR = alarm hormones!  One hormone example is salicylic acid (ingredient in aspirin) 73