Combined plant slides Ch 23, 24, 25, 26.

Combined plant slides Ch 23, 24, 25, 26

A review of: New?: Plants! Plant diversity Xylem and phloem
Evolution Adaptation Cladogram Diffusion Water potential Symbiotic relationships Nitrogen cycle Photosynthesis (stomata) Polyploidy Plant diversity Xylem and phloem Seed and flower adaptions Pressure flow model Transpiration Plant hormones

Plant Diversity (ch 23, 24) Plant phylogeny and classification
Basic plant life cycle Plant adaptations Basic plant structure

4. 3. 2. 1. plant phylogeny 1-4. Match the derived characters with the correct branch points: --flowers --embryos --seeds --vascular tissue 5. Draw a phylogenetic tree showing the evolution of land plants/. Include: Types: charophtyes, bryophytes, pteridophytes, gymnosperm, angiosperm Traits: cuticle, vascular, seeds, flowers

Fig. 23.1

Land plants evolved from green algae
Ch 23 Land plants evolved from green algae Green algae called charophyceans are the closest relatives of land plants

Charophytes v. Plants No alternation of generations No cuticle needed
Jacketed gametes No protection of embryos Alternation of generations Cuticle (prevents water loss/desiccation) Jacketed gametes (protects from desiccation) Protected embryo (protects from desiccation)

Evolution of Land Plants
500 mya land plants evolved special adaptations for life on dry land protection from drying = desiccation waxy cuticle gas exchange (through cuticle) stomates water & nutrient conducting systems from roots/soil to leaves xylem & phloem protection for embryo seeds

Alternation of Generations
Contains both a multicellular diploid (2n) form (sporophyte) and a multicellular haploid (n) form (gametophyte) 2:50

Evolutionary Trend Figure 23.4 Page 413 zygote SPOROPHYTE (2n)
GAMETOPHYTE (n) GREEN ALGA BRYOPHYTE FERN GYMNOSPERM ANGIOSPERM

zygophytes, related groups
Classifying Plants Plants can be divided into 2 major categories based on their characteristics: Nonvascular Plants Do NOT have specialized tissues to transport water and nutrients Instead, these plants transport water from cell-to-cell by osmosis Vascular Plants Have specialized tissues to transport water and nutrients in plants Xylem – carries water upward from roots Phloem – carries nutrients and carbohydrates produced by photosynthesis green algae zygophytes, related groups charophytes bryophytes lycophytes horsetails cycads conifers flowering plants seed plants euphyllophytes vascular plants embryophytes (land plants) (closely related groups) ferns ginkgos gnetophytes

Bryophytes: Mosses, liverworts, horworts
non-vascular= no water transport system motile (swimming) sperm (flagella) life cycle dominated by gametophyte stage fuzzy moss plant you are familiar with is haploid spores for reproduction, mostly gametophyte diploid haploid

Vascular Seedless Plants
sporophyte stage dominant; small gametophyte present; vascular tissue present; spores as a means of reproduction Whiskferns, club mosses, horsetails, ferns Contain: Xylem: transport water (and water soluble nutrients) up the plant Phloem: transport nutrients (2 way) Lycophytes Pteridophytes

Vascular Seed Plants - Seed Producers
– sporophyte stage dominant; vascular tissue, seeds as a means of reproduction heterospory: male vs. female gametophytes Reproduction: seeds naked seeds (no fruit) pollen contain male gametophyte Gymnosperms: evergreen, cone producing conifers, cycads, ginkgo, gnetae Angiosperm:, fruits and flowers

5 crucial adaptations that led the success of seed Plants?
Seeds Reduced gametophytes Heterospory Ovules Pollen

Seeds changed the course of plant evolution
sporophyte embryo, along with its food supply, packaged in a protective coat Can become dominant Can be transported

Reduced Gametophyte: protection of antheridia and archegonia
Fig. 30-2 PLANT GROUP Mosses and other nonvascular plants Ferns and other seedless vascular plants Seed plants (gymnosperms and angiosperms) Reduced, independent (photosynthetic and free-living) Reduced (usually microscopic), dependent on surrounding sporophyte tissue for nutrition Gametophyte Dominant Reduced, dependent on gametophyte for nutrition Sporophyte Dominant Dominant Gymnosperm Angiosperm Sporophyte (2n) Microscopic female gametophytes (n) inside ovulate cone Microscopic female gametophytes (n) inside these parts of flowers Sporophyte (2n) Gametophyte (n) Example Figure 30.2 Gametophyte/sporophyte relationships in different plant groups Microscopic male gametophytes (n) inside these parts of flowers Microscopic male gametophytes (n) inside pollen cone Sporophyte (2n) Sporophyte (2n) Reduced Gametophyte: protection of antheridia and archegonia Gametophyte (n)

Heterospory: genetic diversity
The ancestors of seed plants were likely homosporous, while seed plants are heterosporous Megasporangia produce megaspores that give rise to female gametophytes Microsporangia produce microspores that give rise to male gametophytes

Most seedless vascular
Most seedless vascular plants are homosporous, producing one type of spore that develops into a bisexual gametophyte All seed plants and some seedless vascular plants are heterosporous, having two types of spores that give rise to male and female gametophytes All seed vascular

Gymnosperms: Coniferophyta the conifers
Vascular plants Seed plants Seeds contain a food store for an embryo inside protective coat Seeds ensure dispersal Naked seeds born in cones Nonvascular plants (bryophytes) Seedless vascular plants Gymnosperms Angiosperms

Angiosperms Angiosperms are seed plants with reproductive structures called flowers and fruits They are the most widespread and diverse of all plants Nonvascular plants (bryophytes) Seedless vascular plants Gymnosperms Angiosperms

General Flower Structure - Angiosperms
Fig. 30-7 Stigma or pistil Carpel Stamen Anther Style Filament Ovary Figure 30.7 The structure of an idealized flower Petal Sepal Ovule Video: Flower Blooming (time lapse)

Fruits A fruit typically consists of a mature ovary but can also include other flower parts Fruits protect seeds and aid in their dispersal Mature fruits can be either fleshy or dry

Co-evolution: flowers & pollinators
How a bee sees a flower…insects see UV light = a bulls-eye to the nectar

Wings Seeds within berries Barbs Fig. 30-9
Figure 30.9 Fruit adaptations that enhance seed dispersal Barbs

Polyploidy: chromosome number above the normal 2n, common in plants!
Can cause sympatric speciation Autoploidy: diploid parent produced diploid offspring from nondisjunction. If diploid and haploid gametes fuse= 3n seedless plants! Alloploidy: hybridization with doubling of chromosomes

video Angiosperm are divide into 2 classes monocots 1 cotyledon
leaves with parallel veins grasses, palms, lilies dicots (eudicot) 2 cotyledons (seed leaves) leaves with network of veins woody plants, trees, shrubs, beans video

Dicots v Monocots – other differences
Dicotyledons Monocotyledons Tap roots and lateral branches Fibrous adventitious roots Net-veined leaves Parallel-veined leaves © 2008 Paul Billiet ODWS

Dicots v Monocots – other differences
Dicotyledons Monocotyledons Vascular tissue in a ring round the stem Vascular tissue scattered throughout stem Flowers with multiples of 4 or 5 organs of 3 organs Vascular tissue Pith Epidermis Cortex Vascular tissue © 2008 Paul Billiet ODWS video

Summary Feature Bryophyta Filicinophyta Coniferophyta Angiospermophyta
Common name Mosses Ferns Conifers Flowering plants Leaves Scales Yes Roots Rhizoids Vascular system No Woody tissue Small Waxy cuticle Damp habitats Water for fertilisation Seeds Cones Fruit © 2008 Paul Billiet ODWS

The Root System What do roots do? Types of root systems
Anchor the plant in the soil Absorb minerals and water Store food Types of root systems Fibrous root system Found mostly in monocots Taproot system Found mostly in dicots

How do roots grow? 3 distinct zones in a plant root
Zone of cell division apical meristem: Produces new cells by mitosis Zone of elongation Cells get longer Zone of maturation The cells differentiate and become specialized The root is protected by a root cap, which protects the apical meristem as the plant grows down into the soil

How do stems grow? Primary growth Secondary growth Increase in length
Occurs by cell divisions in apical meristem (at top of shoot) Secondary growth Increase in width Occurs by cell divisions in the lateral meristems

Tissue Systems in Plants
All 3 plant organs (root/stem/leaf) have dermal, vascular, and ground tissue systems Dermal Tissue System/ Epidermis Outer protective covering, similar to our skin  Protects the plant from water loss and disease The cuticle is a waxy coating that helps to prevent water loss

Review Videos Bozeman Plant Structure:
Bozeman Plant Nutrition and Transport:

Spore: n, haploid stage Sporophyte: 2n cell that produces spots to produce spores sporophyll: grows from spores, leaf that produces sporangia Sporangium: (sporangia) structure that produces sporophyte

Plant Nutrition and Transport
Chapter 25 Plant Nutrition and Transport Staple Transpiration Virtual Lab into QOD notebook. Date: 3/24 3/26 Plant Hormones

Most plants depend on bacteria to supply nitrogen
Soil bacteria convert nitrogen to forms plants can use Nitrogen-fixing bacteria convert atmospheric N2 to ammonia (NH3) Ammonifying bacteria decompose organic matter, producing ammonium (NH4+) Nitrifying bacteria convert NH4+ to nitrate NO3- ATMOSPHERE N2 Amino acids, etc. N2 Nitrogen-fixing bacteria NH4 H+ Soil NH3 NH4 NO3 (ammonium) (nitrate) Nitrifying bacteria Ammonifying bacteria Organic material Root

THE UPTAKE AND TRANSPORT OF PLANT NUTRIENTS
Plants acquire their nutrients from soil and air Roots absorb water, minerals, and some O2 from the soil Leaves absorb CO2 from the air Photosynthesis uses carbon, oxygen, and hydrogen to construct sugars and other organic materials the plant needs Cellular respiration breaks down sugars, producing O2 and energy Plants have adapted to transport nutrients from roots to leaves and sugars to specific areas CO2 O2 Minerals H2O

Root hairs take up certain inorganic particles by cation exchange
Ca2+, Mg2+, K+ adhere tightly to negative soil particles H+ released into soil solution by root hairs displaces them Can then be absorbed Anions less tightly bound to soil particles More readily available, but may leach from soil

LE 32-8c K+ K+ K+ Clay particle H+ K+ K+ K+ K+ K+ Root hair

The plasma membranes of root cells control solute uptake
A plant can absorb enough water and inorganic ions through its roots to survive and grow Root hairs greatly expand surface area for absorption Substances enter roots in solution Water and solutes can move through the root's epidermis Water and solutes must cross a plasma membrane to enter the xylem for transport upward

Water and mineral transport from roots to aerial parts of plant
LE 32-5b Phloem Xylem High sugar concentration Xylem: Water and mineral transport from roots to aerial parts of plant Unidirectional: move up stem Phloem: transport food and nutrients (sugar, amino acids) - bidirectional: move up and down stem High water pressure Sugar Sugar source Water Source cell Sieve plate Sugar sink Sink cell Sugar Water Low sugar concentration Low water pressure

Transpiration: Loss of water from plant's aerial parts
Aided by two properties of water: cohesion, adhesion= cohesion-tension model -no energy needed to pull water up Transpiration pulls water up xylem vessels Xylem sap Mesophyll cells Air space within leaf Stoma Outside air Transpiration Adhesion Cell wall Water molecule Flow of water Xylem cells Cohesion, by hydrogen bonding Cohesion and adhesion in the xylem Root hair Soil particle Water Water uptake from soil

Guard cells (Stomata) control transpiration
Opened and closed by flanking guard cells Controlled by movement of H2O and K+ Generally stay open during the day, allowing for entry of CO2 for photosynthesis Stay closed at night, conserving water Respond to cues from sunlight, CO2 level, biological clock

Pressure-flow model of phloem transport
- production of sugar causes water to enter plant, creating a positive pressure and water flows towards areas of less sugar The source-to sink transport model for phloem conductivity suggests that the production of sugar by photosynthesis in the leaves (source) produces a hypertonic situation that pulls water in and increases hydrostatic pressure. The phloem sap moves as much as 1 m per hour due to this high hydrostatic pressure which causes bulk (pressure) flow and pushes the phloem sap toward the organ (sink) that is using the sugar. There will always be a higher concentration of sugar at the source than the sink and,therefore, there will always be a higher hydrostatic pressure. Phloem consists of sieve tube cells that transport most of the sap and companion cells that support the sieve tube cells metabolically* Translocation involves the transport of sap (water with dissolved sugar) throughout the plant. The sucrose content of this sap may be 30%.

Factors that affect the rate of transpiration?
Temperature Wind Humidity Light What will increase evaporation, hence increase transpiration?

Factors that effect photosynthesis?
Light intensity Light wavelength CO2 (and O2) levels Availability of water

Ch 26 Plant Responses to Internal & External Signals

Plant Hormones Hormones are chemical signals that coordinate the various parts of an organism A hormone is a compound produced in one part of the body which is then transported to other parts of the body, where it triggers responses in target cells and tissues Examples of human hormones: Adrenaline, testosterone, estrogen, epinephrine…

Plant Hormones There are 5 major classes of plant hormones, each with specific functions: Auxin Cytokinins Gibberellins Abscisic acid Ethylene

Signal Transduction Pathway 1. reception 2. transduction 3. response

Auxin Stimulates stem elongation Stimulates development of fruit
Involved in phototropism and gravitropism

Cytokinins Stimulate cell division and growth
Stimulate cytokinesis Stimulate germination and flowering

Gibberellins Trigger seed and bud germination
Promote stem elongation and leaf growth Important in the growth of fruit

Ethylene Promotes fruit ripening
Senescence (aging) is a progression of irreversible change that eventually leads to death Caused, at least in part, by ethylene “One bad apple spoils the whole bunch”

Abscisic Acid Induces seed dormancy Inhibits cell growth
Anti-gibberellin Inhibits cell growth Anti-cytokinin Inhibits fruit ripening Anti-ethylene Closes stomata during water stress, allowing many plants to survive droughts

Tropisms Tropisms are growth responses that result in curvatures of whole plant organs toward or away from a stimuli There are three major stimuli that induce tropisms Light (Phototropism) Gravity (Gravitropism) Touch (Thigmotropism)

Phototropism is the growth of a shoot towards light
This is primarily due to the action of auxin Auxin elongates the cells on the non-light side Gravitropism: leaves grow up, roots grow down Due to cytokinins and auxins

Biological Clocks/Circadian Rhythms
A physiological cycle with a frequency of about 24 hours is called a circadian rhythm Even without external, environmental cues, circadian rhythms persist in humans and in all eukaryotes Example: jet lag in humans

Photoperiodism A physiological response to day length (differs in winter, summer, spring, and fall) is known as photoperiodism Short-day plants Require a shorter light period Flower in later summer/fall/winter Example: poinsettias Long-day plants Require a longer light period Flower in late spring/early summer Example: spinach Day-neutral plants Are unaffected by photoperiod Example: tomatoes But it’s actually the night that matters!!

Plant Defenses Plants defend themselves against herbivores in several ways Physical defenses, such as thorns Chemical defenses, such as producing distasteful/toxic compounds

CONNECTION Agricultural research is improving the yields and nutritional values of crops The majority of the world's people depend mainly on plants for protein Genetic modification holds great potential for creating more nutritious plants Example: golden rice Genetic engineering also has potential problems GM plants may overgrow native species

Combined plant slides Ch 23, 24, 25, 26.

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Combined plant slides Ch 23, 24, 25, 26.

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