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Botany Exam 2
Lectures 9,10,11,12,13,14
| Term | Definition |
|---|---|
| Functions of Roots | Anchor plants into soil Absorption of water and minerals Store food or water |
| Function of Roots | Absorb oxygen, epiphytes mangrove Parasitize, dodder Habitat (symbiosis), Fungi (mycorrhizaie), Bacteria (rhizobium) on legumes- root nodules- nitrogen |
| Importance of Roots to Humans | Sources of food (carrots, sugar beets, turnips, cassava (tapioca), yams, sweet potatoes) Spices (licorice) Dyes (barberry) Drugs (ginseng) Insecticide (Rotenone from Derris sp) |
| The Radicle | First structure (organ) to emerge (root) |
| Taproot System | Many dicots Roots grow downwards Penetrate deeper in the soil Not easy to dislodge these plants e.g. soybean, cotton, trees |
| Fibrous Root System | Many monocots Hold soil very well Good for soul erosion Easy to dislodge plants e.g. corn, grasses |
| Growth | An irreversible increase in length |
| Differentiation | Region of maturation |
| The Root Cap | Parenchyma cells Protects apical meristem Helps, root to penetrate soul Perceive gravity, plants grow downward Positive geotropism |
| Region of Cell Division | Apical meristem Undergoes mitosis Parent cells that produces daughter cell with identical chromosome number (diploid-diploid) |
| Protoderm | Epidermis |
| Ground Meristem | Cortex |
| Procambium | Primary xylem and phloem |
| Region of Cell Elongation | Daughter cells elongate |
| Region of Cell Differentiation | Differentiate into tissues Root hairs Xylem and phloem |
| Cortex | Parenchyma |
| Endodermis | Innermost layer of cortex 1 cell thick Has suberin deposited along some of the cell wall (casparian strip) Water and minerals have to go through cell wall and cytoplasm |
| Casparian Strip | Water and minerals cannot pass through the casparian strip |
| Pericycle | Outer most layer of the vascualr tissue (cylinder-stele) Lateral roots arise from pericycle Vascular cambium for secondary root growth also arise from here |
| Movement of Water and Minerals Into Plant | Osmosis + Diffusion (in case of seeds through imbibition) Root hairs (radicle in seedlings) Epidermis Cortex Endodermis Pericycle Xylem Movement upwards or lateral depending on where it is needed |
| Functions of Stems | Support and growth Conduction of water + food to leaves/root |
| Hormones (stems) | e.g. auxins for root production |
| Other specialized functions (stems) | Store food Tubers (potato), bulbs (onion) |
| Propagation by horizontal stems | Rhizomes (ginger), stolons (strawberry) Tendrils (grape) |
| Photosynthesis (stem) | Cactus |
| Importance of Stems to Humans | Sources of food (Idaho potato, sugarcane, onions) Wood (pine, cedar) Latex and Syrup (rubber/maple) Fiver (hemp, kenaf) |
| The Plumule | 2nd organ (shoot) to elongate from a germinated seed Grows against gravity (negative geotropism) |
| Terminal | Apical bud Bud at the top of the plant |
| Node | Where leaves are attached |
| Axillary bud | Bud at the node Terminal bud is usually larger than the axillary bud |
| Internode | Stem region between nodes |
| Evergreen | Don't shed their leaves |
| Deciduous Trees | Shed their leaves during fall |
| Leaf Scar | Left after shedding |
| The bundle scar | Within the leaf scar, can see bundle scars (xylem + phloem) |
| Phyliotaxy | Defined as the arrangement of leaves along the stem Helps with taxonomy |
| Alternate leaves | Alternate on sides |
| Opposite Leaves | On same spot on each side of stem |
| Leaf Primordium | Immature leaves that protect the apical meristem (similar function as the root cap) |
| Apical Meristem Cells | Form three primary meristems |
| Protoderm | Gives rise to epidermis |
| Procambium | Produces primary xylem and phloem |
| Ground Meristem | Produces pith and cortex, both composed of parenchyma cells |
| Angiosperms | Flowering plants Classified into two groups |
| Eudicotyledon (dicot) | 2 seed cotyledon (seed leaves) Stores all food in cotyledon e.g. peanut, cotton, pea |
| Monocotyledon | 1 seed cotyledon Cannot separate into 2 Stores most food in endosperm e.g. corn, grass |
| Stem Morphology | Monocots and dicots can be differentiated based upon the arrangement of the vascular bundles (stele) in the stem |
| Dicot Stem | Vascular bundles in a circle Cambium (2nd growth) |
| Monocot | Vascular bundles are scattered No cambium |
| Herbaceous Plant | If dicot stems have little or no secondary growth e.g. sunflower, tobacco, tomato |
| Secondary Growth | Occurs in many angiosperms + gymnosperms Increase in thickness/girth of stem Results from vascular cambium |
| Cork Cambium | Cork (bark) + phelloderm (parenchym) |
| Vascular Cambium | Secondary xylem + phloem 1 years growth of xylem is called an annula ring Dendrochronology |
| Vascular Cambium | Older darker wood is heartwood Younger, functioning xylem (near the cambium) is sapwood |
| Heartwood | Does not conduct water Has oil, gum embedded which can make it aromatic (secondary compounds or waste) e.g. cedar |
| Sapwood | Conducts water |
| Functions of Leaves | Photosynthesis Gaseous exchange Transpiration |
| Transpiration | Evaporation of water |
| Other specialized functions (leaves) | Store food (succulents) Insect trapping (venus flytrap; pitcher plant) Reproduction and support (kalanchoe; tendrils (peas)) Spines (cactus (reduce water loss)) |
| Importance of leaves to humans | Oxygen (photosynthesis) Sources of food (cabbage, spinach) Spices (thyme, peppermint) Dyes and oils (henna; citronella) Fiber and tea (palm) Medicines (aloe; marijuana) |
| A Typical Leaf | Blade Vein Petiole Stipule |
| Blade | Lamina For photosynthesis |
| Vein | Has vascular tissue |
| Petiole | Stalk that attaches to stem |
| Stipule | Leaf-like appendages at base of petiole (taxonomy) |
| Sessile Leaf | If no petiole e.g. grasses, corn |
| Simple leaf | 1 blade |
| Compound leaf | Blade divided into leaflets |
| Pinnately | Leaflets in pairs along the petiole Auxillary bud @ very end |
| Palmately | Leaflets all attached at the same part of the petiole Hand (palm) |
| Venation | Defined as arrangement of veins in a leaf |
| Monocot Veins | Veins are parellel |
| Dicot Veins | 1 central vein with other veins arising from it (netted) (reticulate) |
| Guard Cells | Only epidermal cells with chloroplasts |
| Upper Epidermis | Covered with a cuticle + waxy substances Prevents water loss (transpiration) Reflects light Some plants have a lot of hairs (trichome: reduce water loss + trap insects) |
| Lower Epidermis | Usually have opening (stomata) If leaves are parallel to the earth, then stomata on both surfaces (monocot) If leaves are perpendicular to earth, stomata mainly on lower epidermis (dicot) |
| Stomata | Controlled by guard cells (specialized epidermal cells) Have chloroplasts Regulate gaseous exchange Oxygen, carbon dioxide + water vapor passes through |
| Stomata | Guard cells have a thicker inner cell wall Kidney shaped When they become turgid, stomatal opening When they become plasmolysed, stomata close |
| Stomata | Usually open during the day, close at night |
| Day | Photosynthesizing Increase of K+ ions into cells Decrease osmotic potential Water moves in by osmosis Increase in turgidity, become open |
| At night | K+ ions leaves Increase in osmotic potential Water moves out Cell becomes plasmolysed, close |
| Mesophyll | Majority of photosynthesis occurs here (parenchyma) Two layers in a typical leaf |
| Palisade (Mesophyll) | Upper region Cells are columnar More chloroplasts Very compact |
| Spongy (Mesophyll) | Below palisade Cells are irregular Less chloroplasts Larger intercellular airspaces |
| Mesophyll | Monocots do not have a differentiation of mesophyll |
| Bulliform Cells | Some may have specialized epidermal cells (bulliform) around the central vein |
| Why do some leaves fold | Reduce water loss |
| Vascular Bundles (Veins) | Scattered throughout mesophyll Contain xylem + phloem surrounded by thick wall parenchyma (cellenchyma) Some monocots (corn) have bundle sheath cells (C4 photosynthesis) |
| Leaf Abscission | Normal separation of leaf from the stem |
| Deciduous Trees | Usually more noticeable during fall when deciduous trees lose their leaves. Reusable compounds are sent to the stem e.g. sugars and amino acids Water soluble anthocyaninst carotenoids (gives leaves the color) accumulate in vacuole |
| Leaf Abscission | A protection layer near the stem is formed (cells become embedded in suberin) A separation layer is formed |
| Leaf Scar | Eventually only the xylem is left and will eventually break down (leaf scar + phloem) |
| Osmotic Potential | Pressure required to prevent osmosis (influenced by solute conc.) Osmotic potential by resistance of cell wall |
| Turgor Pressure (pressure potential) | Vacuole/cell wall exerts a pressure that stops too much water from entering the cell Turgid cell-firm cell due to water gained by osmosis |
| Water potential of the cell | Osmotic potential + turgor pressure (pressure potential) Water moves from cell with higher water potential to cell with lower water potential |
| Transpiration | Defined as water loss from leaves |
| Stomata (transpiration) | Also where gaseous exchange take place Regulate transpiration (stomatal opening and closing) Stomata of most plants open during the day and close at night |
| Light (Transpiration) | Increase light, increase transpiration |
| Temperature (Transpiration) | As temp increased, transpiration also increases, until 30-35 C when transpiration decreases |
| Humidity (Transpiration) | Amount of water vapor As humidity increases, transpiration decreases and vice versa |
| The Cohesion-Tension theory | Transpiration generates tension to pull water columns through plants from roots to leaves Water columns created when water molecules adhere to tracheids and vessels of xylem and cohere to each other |
| Water conservation in some plants | Stomata of most plants during the day and closed at night |
| Desert Plants | Plants' stomata open only at night Conserves water, but makes carbon dioxide inaccessible during day |
| CAM Photosynthesis | Crassulacean Acid Metabolism Carbon dioxide enters at night, converted to organic acids and stored in vacuoles |
| CAM Photosynthesis | Organic acids converted to carbon dioxide during day for photosynthesis (stomata closed during the day) May also have stomata recessed below surface of leaf or in chambers (e.g. desert plants, pines (higher humidity)) |
| Guttation | Loss of liquid water (some plants) If cool night follows war, humid day, water droplets are produced through hydathodes (pores) at tips of veins In absence of transpiration at night, pressure in xylem elements forces water out of hydathodes |
| Hydathodes | Pores |
| Transport of Organic Solutes in Solution | Important function of water is translocation of food substances in solution by phloem Xylem and phloem connected |
| Pressure-Flow Hypothesis | Organic solutes flow from source, where water enters by osmosis, to sinks, where food is utilized and water exits Organic solutes move along concentration gradients between sources and sinks |
| Specifics of Pressure-Flow Hypothesis | Phloem loading: sugar enters by active transport (need E) into sieve tubes Water potential of sieve tubes decreases and water enters by osmosis from the xylem |
| Phloem Loading | Turgor pressure develops and drives fluid through sieve tubes toward sinks Food actively removed at sink and water exits sieve tubes, lowering pressure in sieve tubes Process repeats |
| Mineral Requirements for Growth | Most essential elements Essential as building blocks for compounds made by plants |
| Macronutrients | Used by plants in greater amounts Nitrogen, potassium, phosphorus (NPK), calcium, magnesium and sulfur |
| Micronutrients | Needed by the plants in very small amounts Iron, sodium, chlorine, copper, manganese, cobalt, zinc, molybdenum and boron When any required element is deficient in soil, plants exhibit characteristic symptoms (soil tests) |
| Enzymes and Energy Transfer | Oxidation-reduction reaction |
| Oxidation | Loss of electron(s) |
| Reduction | Gain of electron(s) |
| Enzymes and Energy Transfer | Oxidation of one compound usually coupled with reduction of another compound with reduction of another compound is catalyzed by same enzyme or enzyme comples. Hydrogen atom is lost during oxidation and gained during reduction. |
| Enzymes and Energy Transfer | Oxygen is usually the final acceptor of electron in the cell |
| Photosynthesis | Production of food (sugars) Takes place in chloroplasts CH2O: building block of carbohydrate Produces most of the dry weight present in plant cells |
| A Chloroplast | Inner and outer membrane Granum Thylakoids Stroma |
| A Chloroplast | 75-125 chloroplast in the mesophyll in higher plants (dicots/monocots - larger organelles) |
| Inner and Outer membrane | Protection, movement in/out |
| Granum (stacks of coins) | Thylakoids |
| Thylakoids | Contain chlorophyll and other pigments |
| Stroma | Liquid matrix Enzymes, DNA, RNA, ribosomes |
| Important Factors in Photosynthesis | CO2 Water Light Chlorophyll |
| CO2 | Air has 78% N, 21% O, and 0.036% CO2 Diffuses through stomata into cells A steady increase in CO2 due to greenhouse gases Green plants remove carbon dioxide from atmosphere |
| Water | Plants get most from roots If reduction in water, photosynthesis decreases |
| Light | Visible light: Red to violet Plants absorb red-orange; violet-blue Reflect green Absorb about 80% of visible light |
| Light | Absorbed by pigments Chlorophyll II and carotenoids which help to capture light energy |
| Intensity | Increase intensity, increase photosynthesis Until: Photorespiration Photooxidation Stomatal closure |
| Photorespiration | Respire and use O2; release CO2 |
| Photooxidation | Bleaching of chloroplasts- inactivation |
| Stomatal closure | Reducing amount of CO2 |
| Chlorophyll | Mg atoms in center Similar to heme of blood hemoglobin Present in thylakoid of chloroplast |
| Main types of Chlorophyll | a (blue-green in color) b (yellow-green in color, wider spectrum) c,d,e (certain algae) Green plants have more a than b Chlorophyll b transfers light energy to a a=dominat |
| Photosynthesis | Divided into two steps: Light-dependent Light independent |
| Light-dependent (LD) | Occurs in thylakoid Light energy is used to form ATP and NADPH (energy providing molecules) |
| Light-dependent | Two photosystems are involved I and II (Z scheme- non-cyclic photophosphorylation) Consist of chlorophyll, other pigments (carotenoids) in thylakoid Reaction centers where light energy is utilized (p680 and p700) |
| Light - Dependent | Water is split into oxygen and hydrogen and electrons |
| Light-Dependent | Light energy (photon) from the sun hits PSII (P680) The energy boosts the electrons Chemiosmosis occurs- ATP formed (movement of ions across a selectively permeable membrane) Electrons pass along carrier molecules onto PSI (P700) |
| Light-Dependent | Light energy (photon) from the sun hits PSI Electron passes along carrier molecules (NADPH formed) End result? |
| End Result? LD | ATP, NADPH formed (stroma); oxygen given off |
| Light-Dependent (bacteria) | Cyclic photophorphorylation (in bacteria) Uses only PSI Water molecule not split (no oxygen is released) No oxygen is released |
| End Result LD Bacteria | Only ATP formed; no oxygen released |
| Light Independent | (LI: Carbon-fixation reactions) Occurs in stroma ATP and NADPH used to reduce carbon into sugars in the Calvin Cycle |
| Calvin Cycle | Needs RuBP-ribulose 1,5 bisphosphate And runisco (ribulose bisphosphate carboxylase/oxygenase Most abundant enzyme |
| First compound formed in C3 plants | e.g. cotton, soybean, rice 3C sugar (3 phosphogly cerate;PGA) Reduced to glyceraldehyde 3-phosphate (G3P)- used to make glucose Happens during the day |
| Photorespiration | Under hot, dry conditions, stomata close, no carbon dioxide enters, increases in oxygen If too much oxygen in cell, Rubisco binds to it (ribulose bisphophate Oxygenase) Formation of 2C (2-phosphoglycolate, PG) compound |
| Photorespiration | Helps to stop photooxidation Waste ATP on NADPH, less sugars formed Allows C3 plants to survive under hot dry conditions Less production of food under these conditions |
| 4-C Pathway | Happens in C4 plants Plants that grow in dry regions e.g. Sugarcane, corn (monocots) Have a special leaf histology |
| The Krantz Anatomy | Mesophyll cells Large bundle sheath cells LD-similar to C3 plants |
| Krantz Anatomy Mesophyll cells | Smaller chloroplasts with well-developed grana |
| Krantz Anatomy Large Bundle Sheath Cells | Large chloroplasts with numerous starch grains |
| LI and C4 Photosynthesis | CO2 converted to organic acids in mesophyll cells PEP (phospheoenolpyruvat) and CO2 combine, with aid of PEP carboxylase |
| First compound formed instead of PGA 4C | Form 4-carbon, oxaloacetic acid, instead of PGA |
| 4C Pathway | CO2 enters into Calvin cycle More efficient if climate gets hotter Less photorespiration PEP enzyme only binds to CO2, not )2 like Rubsico Rubisco more efficient if cooler temperatures |
| LI and CAM | Plants that have crassulacean acid metabolism Succulents (+ pineapples) Orchids (epiphytes) Similar 4-C compounds to C4 photosynthesis |
| LI and CAM | Fix CO2 in dark Live in areas of high temperature (limited water also), so stomata closes during day and only opens at night Organic acids accumulate @ night in vacuole (stomata open) Converted back to CO2 during day for use in calvin cycle (St closed) |
| Respiration | Complete breakdown of glucose to produce E in form of ATP ATP (most versatile form of E) Occurs in mitochondrion |
| Anaerobic | Fermentation- without oxygen- less E is produced |
| In plants and yeasts, what is produced? | Ethanol (2C) produced (+ CO2) Used to make beer wine |
| In bacteria and animals, what is produced? | Lactic acid (3C) Muscle fatigue Cramps |
| Aerobic | In presence of oxygen (many organisms) |
| Four Steps Aerobic Respiration | Glycolysis Krebs Cycle Electron Transport Chain Oxidative Phosphorylation |
| Glycolysis | Occurs in cytoplasm Glucose is broken down into 2 molecules of pyruvate No oxygen is used Formation of ATP and NADH (another source of energy) |
| What is net formation? Glycolysis | 2 molecules each of NADH and ATP 1 NADH make 2 molecules of ATP NADH has to be transported across the mictochondrial membrane Uses 1 ATP to transport NADH |
| Glycolysis | If O2 available, anaerobic respiration occurs after glycolysis |
| Krebs Cycle | Pyruvate enters in to mitochondrion Oxygen is necessary |
| Net formation? Krebs Cycle | (from x2 pyruvates) 1 ATP 4 NADH 1 FADH2- high E molecules |
| Electron Transport Chain | Electrons present in NADH and FADH2 pass along an electron gradient (in mitochondrion) Acceptance by several other molecules NADH and FADH2 oxidized to NAD+, FAD+, H+,e- |
| Oxidative Phosphorylation | Energy given off by electrons down chain produces ATP (ADP to ATP) [in mitochondrion] Electrons then accepted by oxygen and combine wit H+ ions to produce water 2H+ + 1/2 O2 ---> H2O NADH forms 3 ATP FADH2 forms 2 ATP |
| What is the overall net from 1 glucose molecule | 6 molecules of H20 and CO2 |
| Factors affecting respiration | Temperature Water Oxygen |
| Temperature (respiration) | Increase temperature, increases respiration Too much increase in temp Kill plants Due to loss of enzyme action |
| Water (respiration) | Decrease water, decreases respiration |
| Oxygen (respiration) | Decrease oxygen, decrease respiration Improve seed viability (store for a longer time) |
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