PLANTS What are plants Eukaryotic have a nucleus

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PLANTS

PLANTS

What are plants? Eukaryotic (have a nucleus) Have cell walls made of cellulose Carry

What are plants? Eukaryotic (have a nucleus) Have cell walls made of cellulose Carry out photosynthesis using the pigment chlorophyll a and chlorophyll b Belong to the kingdom Plantae

What do plants need to survive Sunlight – make food through photosynthesis Gas Exchange

What do plants need to survive Sunlight – make food through photosynthesis Gas Exchange (CO 2 and O 2) Water and Minerals PHOTOSYNTHESIS 6 CO 2 + 6 H 2 O → C 6 H 12 O 6 + 6 O 2 Carbon dioxide + Water + Light energy → Glucose + Oxygen

Plant evolution The ancestor to today’s plants were similar to green algae Plants are

Plant evolution The ancestor to today’s plants were similar to green algae Plants are divided into 4 major groups

Alternation of generations The lifecycle of plants has 2 phases � Gametophyte (haploid –

Alternation of generations The lifecycle of plants has 2 phases � Gametophyte (haploid – N) � Sporophyte (diploid – 2 N) During evolution – the size of the gametophyte decreased and sporophyte increased

Types of plants 1) Bryophytes (Mosses and others) 2) Ferns 3) Gymnosperms ------- 4)

Types of plants 1) Bryophytes (Mosses and others) 2) Ferns 3) Gymnosperms ------- 4) Angiosperms

Bryophytes Found in damp places Have specialized reproductive cells that require water for reproduction.

Bryophytes Found in damp places Have specialized reproductive cells that require water for reproduction. Lack vascular tissue – water/nutrient carrying tissue supported by lignin � Lack support to grow tall

Moss life cycle

Moss life cycle

Seedless vascular plants - Ferns and relatives Have vascular tissue which makes it possible

Seedless vascular plants - Ferns and relatives Have vascular tissue which makes it possible to move fluids through the plant (against gravity) � Phloem = carries nutrients � Xylem = carries water Do not have seeds – reproduce through spores Reproductive cells need water for fertilization

Gymnosperms – cone bearing plants First seed plants – allows the plant to �

Gymnosperms – cone bearing plants First seed plants – allows the plant to � Reproduce without water � Protect the embryo in a seed � Provide nutrients to the embryo Reproduction occurs through pollination � Pollen (the male gametophyte) is transferred to the female cone

Gymnospserm lifecycle

Gymnospserm lifecycle

Angiosperms – flowering plants Reproduce sexually through flowers � Ovaries in flowers develop into

Angiosperms – flowering plants Reproduce sexually through flowers � Ovaries in flowers develop into fruits to help disperse seeds � Flowers attract pollinators and reproduction is more efficient than the wind pollination of gymnosperms

Monocot vs. dicot

Monocot vs. dicot

Chapter 28 Plant Structure and Function Plants have tissues and organs too!!!!! � TISSUES

Chapter 28 Plant Structure and Function Plants have tissues and organs too!!!!! � TISSUES = dermal, vascular and ground � ORGANS = Roots, stems and leaves

Plant growth Where do plants grow? ? Meristems = regions of cells in which

Plant growth Where do plants grow? ? Meristems = regions of cells in which mitosis produces new cells that are ready for differentiation � Apical meristem = rapidly growing regions at the tip of the stem and roots

Meristems All plants tissues arise at meristems (regions of rapidly dividing, undifferentiated cells) Growth

Meristems All plants tissues arise at meristems (regions of rapidly dividing, undifferentiated cells) Growth in apical meristems at tips of shoots and roots (primary growth) increases length In some plants, growth in lateral meristems (secondary growth)

Apical and Lateral Meristems

Apical and Lateral Meristems

Apical Meristem and Primary Growth

Apical Meristem and Primary Growth

Simple Tissue (Ground) Tissue Ground tissue = produces and stores sugars and contributes to

Simple Tissue (Ground) Tissue Ground tissue = produces and stores sugars and contributes to the support of the plant � Parenchyma = thin cell walls, contain a large vacuole, in leaves have chloroplasts (mesophyll) � Collenchyma = thicker cell walls Supports rapidly growing plant parts (make up “strings” of celery) � Sclerenchyma = thickest cell walls – resist stretching, cloth, rope, nutshells, seed coats

Types of tissue – Dermal Tissue Dermal tissue = the protective outer covering in

Types of tissue – Dermal Tissue Dermal tissue = the protective outer covering in a plant Epidermis - Usually a single outer layer of cells that secrete a waxy, protective cuticle � May contain specialized cells that form stomata for gas exchange Periderm - Replaces epidermis in woody stems and roots

Vascular Tissue Vascular tissue = supports the body and transports water and nutrients Xylem-

Vascular Tissue Vascular tissue = supports the body and transports water and nutrients Xylem- carries water and ions through the plant � Consists of two types of cells that are dead at maturity: tracheids and vessel members � Lignin-filled secondary walls Phloem conducts sugars, other organic solutes � Sieve tubes connect end to end at sieve plates � Companion cells load sugars

Flowering Plant Tissues

Flowering Plant Tissues

Studying Plant Parts: Tissue Specimens Tissue specimens are cut along standard planes

Studying Plant Parts: Tissue Specimens Tissue specimens are cut along standard planes

Roots Root Function � Support a plant � Anchor it to the ground �

Roots Root Function � Support a plant � Anchor it to the ground � Store food � Absorb water from the soil � Absorb nutrients from the soil

28. 5 Primary Structure of Roots mainly function to provide plants with a large

28. 5 Primary Structure of Roots mainly function to provide plants with a large surface area for absorbing water and dissolved mineral ions � Support a plant � Anchor it � Store food Root hairs � Fine extensions of root epidermis that increase the

Roots cont. Types of roots � Taproot – carrots, beets, dandelions � Fibrous root

Roots cont. Types of roots � Taproot – carrots, beets, dandelions � Fibrous root - grasses Root pressure – roots actively pump nutrients into the root. Water moves in by osmosis. This causes a pressure that causes water to move up the plant into the stem

Eudicot and Monocot Root Structures Taproot system (eudicots) � � A primary root and

Eudicot and Monocot Root Structures Taproot system (eudicots) � � A primary root and lateral branchings Central vascular cylinder Fibrous root system (monocots) � � Adventitious and lateral roots Vascular cylinder divides root into cortex and pith

Stems Functions of stems � Produce leaves, branches and flowers � Hold up the

Stems Functions of stems � Produce leaves, branches and flowers � Hold up the leaves to the sun � Transport substances throughout the plant

Inside the Stem Vascular bundles � Multistranded cords of vascular tissues threaded lengthwise through

Inside the Stem Vascular bundles � Multistranded cords of vascular tissues threaded lengthwise through ground tissues of all shoots Two distinct patterns of vascular bundles

Tissues in a Buttercup Stem

Tissues in a Buttercup Stem

Structure of Wood

Structure of Wood

Seasonal Growth Vascular cambium is inactive in cool winters or long dry spells, and

Seasonal Growth Vascular cambium is inactive in cool winters or long dry spells, and active when warmth or moisture returns In regions where seasonal change is pronounced, alternating bands of early and late wood form “tree rings”

Seasonal Growth

Seasonal Growth

28. 7 Tree Rings and Old Secrets The number and relative thickness of a

28. 7 Tree Rings and Old Secrets The number and relative thickness of a tree’s rings hold clues to environmental conditions – such as annual rainfall – during its lifetime Tree rings are used to date archaeological ruins, study ecology, and provide evidence about wildfires, floods, landslides and glaciers

Historical Evidence Settlements in North Carolina (1587) and in Virginia (1610) experienced severe drought

Historical Evidence Settlements in North Carolina (1587) and in Virginia (1610) experienced severe drought

Leaves Anatomy of a Leaf � Stomata (next slide) � Mesophyll – where photosynthesis

Leaves Anatomy of a Leaf � Stomata (next slide) � Mesophyll – where photosynthesis occurs � Cuticle – waxy cover to protect/prevent water loss All leaves are metabolic factories where photosynthetic cells produce sugars – but they vary in size, shape, surface specializations, and internal structure

Mesophyll – Photosynthetic Ground Tissue Mesophyll=Photosynthetic parenchyma with air between cells � CO 2

Mesophyll – Photosynthetic Ground Tissue Mesophyll=Photosynthetic parenchyma with air between cells � CO 2 diffuses in and oxygen diffuses out through stomata � Plasmodesmata connect adjacent cells � Single layer or double layer (palisade and spongy mesophyll)

Veins – The Leaf’s Vascular Bundles Veins � Vascular bundles in leaves, strengthened with

Veins – The Leaf’s Vascular Bundles Veins � Vascular bundles in leaves, strengthened with fibers, containing xylem and phloem Two distinct patterns � Eudicots: Large veins branch into networks of smaller veins � Monocots: Veins of similar size run parallel to the leaf axis

Leaves – stomata Stomata – openings in the leaf that allow CO 2, water,

Leaves – stomata Stomata – openings in the leaf that allow CO 2, water, and O 2 to diffuse in and out of the leaf Guard cells = cells that surround the stomata and regulate their opening and closing

Homeostasis and stomata Plants keep stomata open just enough so that gas exchange can

Homeostasis and stomata Plants keep stomata open just enough so that gas exchange can occur for photosynthesis but not so much that they lose too much water When water is abundant water flows into the leaf. This increases water pressure in the guard cells and opens them. When water is scarce, pressure decreases and the stomata close

Water transport in plants Transpiration = water loss from a plant through its leaves

Water transport in plants Transpiration = water loss from a plant through its leaves � Water leaves through open stomata � Dry cell walls pull water from deeper in the leaf and pulls water from the roots, stem and leaf through xylem � Water “sticks” to water (cohesion) and other molecules (adhesion) � Even small trees can lose 100 L of water/day What conditions increase transpiration? ? ? � Hot � Dry � Wind

How does water move up the plant? Capillary action – the tendency of water

How does water move up the plant? Capillary action – the tendency of water to rise in a thin tube

29 Reproduction in flowering plants Parts of a flower � Sepals = enclose the

29 Reproduction in flowering plants Parts of a flower � Sepals = enclose the flower before the bud opens and protects the flower � Petals = attract pollinators to the flower often brightly colored inside the sepals

Parts of a flower (cont. ) Parts of a flower � Stamen = male

Parts of a flower (cont. ) Parts of a flower � Stamen = male parts of the flower Anther – produce pollen Filament – a stalk that holds up the anther � Carpels Stigma (pistil) = female parts of the flower – sticky structure designed to capture pollen Style – a stalk that holds up the stigma

Angiosperm gamete production

Angiosperm gamete production

Angiosperm lifecycle

Angiosperm lifecycle

Fruit and seed development Fruit = a thickened ovary wall that encloses seeds Seed

Fruit and seed development Fruit = a thickened ovary wall that encloses seeds Seed Dispersal = � Animals = seeds with tough coats are encased in a sweet fleshy fruit Apples, grapes � Wind = lightweight fruits that allow them to be carried in the air Dandelions � Water = buoyant fruits that allow them to float coconuts

Seed Dormancy and Germination Dormancy = the embryo is alive but not growing Germination

Seed Dormancy and Germination Dormancy = the embryo is alive but not growing Germination = growth of the plant embryo following dormancy

Advantages of Dormancy Allows for long distance dispersal Allows seeds to germinate in ideal

Advantages of Dormancy Allows for long distance dispersal Allows seeds to germinate in ideal growth conditions Some seeds only germinate under extreme conditions � Some pine cones remain sealed until the high temps generated by forest fires cause the cones to open

Plant Hormones = chemical signals produced by an organism that affect the growth, activity,

Plant Hormones = chemical signals produced by an organism that affect the growth, activity, and development of cells and tissues � Auxin – stimulate cell elongation and growth of roots Produced in the shoot apical meristem and transported When light hits a part of a plant, auxins build up in the shaded region, causing the plant to bend toward the light Growth of lateral buds is inhibited by auxin (if you cut off the top of a plant, the lateral buds grow more quickly.

Cytokinins = hormones produced in the growing roots and developing fruits and seeds. �

Cytokinins = hormones produced in the growing roots and developing fruits and seeds. � Often produce effects opposite of auxins � Stimulate cell division � Interact with auxins to balance root and shoot growth � Stimulate regeneration of tissues damaged by injury

Giberellin, abscisic acid, ethylene Giberellins � Found in meristems of shoot, root, and seed

Giberellin, abscisic acid, ethylene Giberellins � Found in meristems of shoot, root, and seed embryo � Stimulate growth, promote germination Abscisic Acid � Found in terminal buds and seeds � Inhibits cell division � Promotes seed dormancy Ethylene � Found in fruit tissues and aging leaves and flowers � Stimulates fruits to ripen � Causes plants to seal off and drop leaves

Tropisms Tropism = plants response to environmental stimuli � Phototropism – tendency of a

Tropisms Tropism = plants response to environmental stimuli � Phototropism – tendency of a plant to grow toward light � Gravitropism – response of a plant to gravity � Thigmotropism – response of a plant to touch

Rapid responses Some plants can also adjust quickly to their environment � Venus fly

Rapid responses Some plants can also adjust quickly to their environment � Venus fly trap � Mimosa (folds leaflets in a few seconds when touched)

Response to seasons How do plants know when to flower, drop leaves, etc? Photoperiod

Response to seasons How do plants know when to flower, drop leaves, etc? Photoperiod = the number of hours of light/dark a plant receives (pigment phytochrome) Winter Dormancy Deciduous plants turn off photosynthetic pathways Transport materials from leaves to roots Seal off leaves Chlorophyll breaks down allowing other pigments to be seen (brown, yellow, etc. )