Class Notes (810,512)
Canada (494,140)
BIOA02H3 (428)

2013BIOAO2 COMBINATION Lecture Notes06-12 .docx

14 Pages
Unlock Document

University of Toronto Scarborough
Biological Sciences
Ivana Stehlik

2013BIOAO2 S Module 1 th January 7 ~Feb1 2013 th Midterm date: Monday Febuary 4 2013th5-7pm Module 2: Begins on Tuesday Feb 5 . Total: 12 lectures Lecture outline: 1-2: Tree of life-plants 3-4 Plant cells and plant tissues 5-6. From seed to tree 7-8. Freom tree to seed 9. Transport in plants 10. Plant nutrition and soils 11. Plant defense 12. Plant life on the edge. Lecture 6 notes (From seed to tree) B) From primary to secondary plant body ii. Shoot and root primary growth. Primary meristem: Shoot apical meristem & Root apical meristem • Shoot apical meristem tissue from xylem (inside) to epidermis (outside): xylem> vascular cambium> phloem>collenchyma>cortex (made up of parenchyma)>epidermis o E.g sunflower (Helianthus) o From pith(inside) to epidermis: pith>primary xylem>vascular cambium>primary phloem>collenchyma>cortex(parenchyma with some collenchyma)>ground meristem>procambium>protoderm>epidermis. o X-section of shoot is circle and vascular bundles around. • Root apical meristem tissue o During mitotic cell division: procambium>ground meristem>root apical meristem>root cap>protoderm o During differentiation: primary xylem>vascular cambium(replace procambium)>primary phloem>endoderm>periccle>cortex>epidermis with root hair  Main difference between root and shoot: Root has no pith and the vascular cambium is at the centre. Root has endoderm and pericycle.  Endoderm acts as a filter for material from root hair to vascular tissue. o X-section of root is circle a star shaped. • Limited maximum size with primary growth: collenchyma has ligment that strengthen plant for structure. • Primary to secondary growth: the girth(middle) of root/stem is increased, Vascular cambium& cork cambium are secondary meristems that give rise to secondary tissues. Secondary meristem: Ground meristem & Vascular Cambium. Side-branches are axillary meristem iii. Shoot secondary growth Secondary growth in woody eudicots • Herbs have only primary phloem, primary xylem, vascular cambium in bundles • Trees& shrubs have ring of vascular cambium-interfascicular. • Cork cambium-another meristem- that grows with the phloem rays. As the vascular largens, the epidermis rips so the cork cambium fills in the rip holes. • Pith stays the same, vascular ring largens from year 1 to year 2. From bark (outside) to pith(inside): • Bark: cork>cork cambium>cortex>phloem ray> phloem • Vascular cambium -there are no rings in phloem • Wood: secondary xylem(includes the summer wood and spring wood=one annual ring)>primary xylem • Pith Diagram of primary and secondary growth of shoot / iv. Apical dominance and growth forms why are there so many growth forms? Because of apical dominance of Shoot apical meristem Shoot apical meristem produced hormone auxin. Apical dominance: suppression of axillary buds. Branching pattern depends on auxin conecntration and length of brank. Lower the branch, lower auxin that suppresses bud growth, so more buds at lower branh. / Figure 2. these plants low auxin level because there is a lot of branching and flowers so if there is a flower that buds=high auxin Breakdown of apical dominance: interior & exterior factor • If shoot apical meristem turns into a flower=end of merstem cell, no more auxin. • Cut off the bud by: wind, bug, sun clip, desiccation. And allow the side buds (axillary meristem to grow. Axillary meristem is used for backup once shoot apical meristem is gone) • Removal of Shoot apical meristem>auxillary meristem grows>develop into branches with own shoot pical meristem. Lecture 7 notes (From tree to seed);aka sex in plants 1) plant sex organs Generalized flower structure: 4=stamen,carpel,sepal,petal • Male: anther + filament=stamen • Female: stigma + style+ ovary = carpel • Sepal(sepal covers petal) • Petal Sepal • Protects inner flower organs before bud opens • Frequently green • Can be used to form tubes Petals • Typically colorful to attract pollinators • Can be fused to form tube. • E.g violet, walsteinia, bellflower Stamen • Anther: pollen produces. Has 4 pollen sacs Carpel • Stigma: sticky landing platform for pollen (e.g. kiwi, poppy, tulip) • Style: connects stigma with ovary (Azalea, primrose, lily,) • Ovary contains one to multiple ovules. Ovules contain egg cell. o Syncarpous ovary: many ovules (e.g cucumbers) Shoot apical meristem-generative to reproductive organs • Turns from leaf primordium into flower primordium • E.g arabidopsis thaliana. Is the evolution of flower originated from modified leaves? Different genes of rings: carpel>stamen>petal>petal Shoot apical meristem>flower primordium? ABC model of flower development A,B,C genes specify the four different flower organ types • Each of these genes is active in two adjacent rings of cells • A=sepal organ • A+B = petals organ • B+C=stamen organ • C=carpel organ 2) plant sex is not as boring as animal sex some plants can have missing sepals or petals • E.g sarcandra: no sepal, no petal • Chickweed: no petal • Golden saxifrage: no sepal • Meadow rue: no petal, no female organ. 6% of angiosperms are unisexual=dioecious flowers. (one male plant, and one female plant only just as how there is only one male, and one female) • E.g asparagus, hemp/dioecious 17% are monoecious=both genders (one male flower and female flower organ in the same plant) • E.g hazelnut, corn • /monoecious 75% complete flowers are hermaphroditism=perfect flower.= male & female on the same flower in the same plant • e.g trillium, rubus odoratus, blue cohosh, evening primose. • /Hermaphroditism. More varied plant reproduction • In dioecy: male plant 1 + female plant 2 (one plant, one sex) • In monoecy: -one plant 2 sex o male plant 1 + female plant 2 o male flower plant 1 + female flower plant 1 • In hermaphroditism:-one flower 2 sex o male plant 1 + female plant 2 o male flower plant 1 + female flower plant 1 o male flower 1 plant 1 + female flower 2 plant 1. Why Animals are mostly dioecious. 75% plants are hermaphroditism-one flower 2 sex.? This is because of self pollination=selfing=inbreeding. Selfing is generally detrimental. Same plant pollinating same plant.= inbreeding depression. Monoecious& hermaphroditic species has 94% of plants. Dioecious species-on female plant, one male plant- has no selfing possible. Because there is no femal and male organ in the same plant. 3) How to avoid doing it yourself inbreeding avoidance. a) temporal separation-several phases separated in time e.g Blood root: in the morning the stigma opens, anther closes. In the night, stigma closes, anther opens asynchrony: geitonogamous selfing:between flowers • pollination between flowers: fertilization of a flower by pollen from another flower on the same plant. • Monoecious, hermaphroditism. b) spatial separation of sexual organs within flower One plant with high anthers and short style. Other plant with low anther and high style. e.g sage, primrose in sage there is spatial and temporal separation. The stigma is sometimes not receptive. c) self incompatiblilty Lecture 8 notes (From tree to seed);aka sex in plants 3) How to avoid doing it yourself c) self incompatiblilty no fertilization with own pollen because there is biochemical self recognization. Stigma change biochemical surface, rejects its own pollen, if pollen gets into pollen tube, a plug is produced to prevent inbred offspring. e.g fruit trees such as apple trees, chrry, pear. 4) Sex slaves of the plant kingdom. Flowers: ingenious solution of angiosperms: non-directed or directed moblilty of pollen to seek egg. Triassic, Jurassic, Cretaceous, Cenozoic era. – angiosperms. Insects involved in angiosperms from smallest to largest influence: Diptera, Lepidoptera, hymenoptera, Coleoptera Forces behind the evolution of flowers; • Assurance of seed set: sheer mechanisms, bring female and male gametes together ot at least replace the two parents • Inbreeding avoidance: create high quaility offspring. Pollination syndromes: direct and indirect moblility of pollen to seek egg • Specialization of floral architecture, attraction, food requirements, rewards • Abiotic pollination- indirect. Water&wind. Most water plants produce above water o 10% of all plants are wind-pollinated o 18% of plants have wind-pollinated species in them o wind pollination found in high lattitdue/alititude, dry environments, open vegetation, island floras. o E.g orchard grass, awneless brome grass., willow, alder, manitoba maple o All grass are wind-pollinated o Wind pollinated plants are: small inconspicious flowers, no special flower, no nectar, long filaments, long styles. Produce a lot of pollen. o • Biotic pollination-direct. Animals, mammals. Can control which animals come. o Pollinator needs reward (pollen, nectar) o Specialized organ construction o Often only a restricted set of polinators can take rewards=adaptation to specialized pollinators  Specialist plants rely on more narrow group of polinators. Extreme co- evolution=one pollinator one plant. Exclusive relationship  Generalist flowering plants attract wide range of pollinators (e.g elderberry, goldenrod, Queen Anne’s lace, Coltsfoot). None-specialized food; pollen and nectar. Flowers make platform for insects of different size to roam. o BEE polination: most important pollinator group  Originate 80 million years=diversified along with the evolutionary radiation of flowering plants  Adult bees live on nectar (3-~35% sugar)  Larvae (juveniels) live on pollen-rich in protein  Bee strongest in color spectrium is yellow, blue, green, UV.  E.g hepatica, dog violet, trout lily, downy yellow violet, marsh marigold, blue- eyed grass  Bee are colorblind (relized by charlock)  Plants have nectar guides (leaf lines that points straight into to the plant into the nectar).  Hidden nectar: some plants only allow bee access (bee land on plant platform, bee open nectar). E.g dog violet, dwarf snapdragon, bird’s trefoil.  Bee do not see red  Subgroup plants that are built for bee but do not provide reward for bee. This limit cost of reproduction. Flower mimic female bee ot fool male bee into the plant. (e.g orchids-ophrys. Orchid pretend to be female bee in smell, touch, to have the male bee onto the flower)-coevolution!-one pollinator one plant o Fly pollination  Eastern skunk cabbage- attracts flies to thinking it is flesh  Largest angiosperm is the amorphophallus titanium for flies.  Flowers are: dull, white/red, putrid smell, flowers=trap o Butterfly pollination  Flower are red/orange  Narrow tubes for proboscis(beak?) of butterflies so that only butterfly gain access. o Moth pollination  E.g soapwort, dame’s rocket, white campion.  Since moths are only active at night. Flowers are white/dull color, small smell, long narrow floral tube.  Moth plants similar to butterfly plants o Humming birds:-attracted to red/yellow. Have bad sense of smell  Take in liquid nectar (less concentrated than bee nectar) because humming bird lap nectar with tonge(corolla tubular).  E.g Glaucous honeysuckle, red columbine. Lecture 9 notes Transport in plants Basic plant needs: sugar=carbon dioxide + light +water, water, oxygen, minerals A) Water transport through xylem i) Hypotheses on mechanisms of water transport. How does water move through xylem? Answer: 3 hypotheses: capillary action, root osmotic push, transpiration. 1] capillary action- travels 1 m up xylem water move upward xylem through adhesion (water & tube walls) and cohesion (water & water molecutes). Adhesion is stronger than cohesion. Capillary action is not strong enough for trees because it travels for 1 meter! 2) Root osmotic push- travels 3 m up xylem Osmosis (osmotic pressure) is where water diffusion through semipermeable membrane such as the cell wall from a low concentration to a high concentration until both concentration are equal. Plant actively pump ions into root cells with ATP . water moves into cells by osmosis when oot hair have greater osmotic pressure (high ion_ than surrounding soil. But his only pushes the xylem by 3meters! 3) Transpiration-travels 100 +m up xylem. Use of cohesion. Sun turns liquid water into gas > gas moves from parenchyma into intercellular leaf space> cohesion pulls water from veins into parenchyma>gas diffuse out of stomata. ii) Synthesis, total plant water transport soil to root hair; osmosis into xylem: osmosis & transpiration pull (from leaves) up xylem between root and stem: transpiration root to leaves: cohesion angiosperms have more efficient trachieds and vessel elements-have perforation holes entering of water into roots: • Apoplastic transport:water flows through cell walls, more rapid, faster, less resistant to water flow • Symplastic transport: water flows through cell and pits of parenchymas. • Casparian strip: waxy layer that makes apoplastic transport impassable. • So it’s: root hair> epidermis>cortex> endodermis> Casparian strip> stele.(middle/vascular cambium)>xylem parenchyma>xylem vessels o Endodermis: control layer to what substances can enter xylem. o So when apoplastic cannot pass, they active transport into symplastic transport to upload water. When symplastic-through cells transport passes endodermis, water active transport back into apoplast transport-thorugh cell wall.. iii) Control of water transport Stoma: two bordering guard cells (specialized epidermis cells). Photosynthesis-transpiration. • 90% water transported through xylem: lost to transpiration through stomata. • 200L of water/day transpiration • photosynthesis high=carbon dioxide high=transpiration high=cooling and nutrient flux=stomata open • photosynthesis low=carbon dioxide low=water saving mode=danger of overheating&low nutrient flux. =stomata open Factors affecting stomata to open: • water-open when a lot of water, • temperature-close when too hot/cold, • light-close when dark except CAM photosynthesis, • carbon dioxide concentration-open when low in carbon dioxide. How stoma opens & close • osmosis through active regulation of potassium concentration (ATP-driven pumps) • stoma opens when K pump into guard cell which cause water to flow into guard cell, dilating guard cell. • Increase K in cell, increase water intake. B) Sugar transport through phloem Xylem absorbs in roots: water, oxygen, minerals. Xylem releases water, oxygen in leaves. Phloem absorbs in leaves carbon dioxide, sugar. Phloem releases carbon dioxide in roots /figure 1. Xylem red arrow . Phloem blue arrow Sugars move from sources to sinks • Source of sugar: tissue or organs that make/store food. Seed endosperm, leaves, roots • Sink of sugar: tissue or organs that require metabolites for energy and for biosynthesis. Shoot/ root meristem, developing seed, flowers, roots. Xylem has no sugar. Xylem one direction route. • No end walls between cells • Water and minerals Phloems have a 2-way flow (not a the same time) • Have end walls between cells. • Water and food Phloem movement: pressure-flow model.
More Less

Related notes for BIOA02H3

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.