Final Exam: Plants Flashcards

Question

Fungi as Mutualistic - micorrhizal (2) - endophytes - lichen (3)

Answer 1

Mycorrhizal Association: mutualism between fungi and plants → 450 million years ago, fungi invaded land, and nowadays the fungi incorporate themselves into plant roots for a MUTUALISTIC relationship (eg. fungi gather phosphorus for plants) 1. Ectomycorrhizal: found at temperate or boreal latitudes: fungal hyphae do not permeate cell walls, just spaces between cells (and outside of root) 2. Arbuscular: makes up 80 to 90% of all plant relationships with fungi; penetrate cell wall (but not membrane) and have extensive contact with the cell membrane Endophytes: aka microfungi inside plants that enter via plant pores that allow gas exchange; help repel herbivores by being unpalatable and therefore help improve plant tolerance in environmental conditions Lichen: association between a fungus (usually an ascomycete) and a unicellular photosynthetic green alga or cyanobacterium; play an important role in primary succession with the ability to colonize and breakdown barren surfaces and some nitrogen fixation (allow for better plant growth) → lichen reproduce asexually and disperse as a unit called soredia 1. Foliose: “leafy” 2. Fruticose: “shrubby” 3. Crustose: “crusting

Answer 2

process of incorporation of one organisms within the “cell” of another → multi-step process: early eukaryote (with cytoskeleton) engulfed by a prokaryote that become mitochondria

Answer 3

1. Size and structure of mitochondria / plastids similar to bacteria 2. Replication: reproduce by binary fission 3. Ribosomes: complexes of RNA and protein involved in genetic translation and protein synthesis 4. Antibiotics: target protein synthesis in bacteria 5. Genomes: mitochondria / plastids have genomes (usually circular, genetically similar to bacteria) separate from nuclear genome

Answer 4

some photosynthetic eukaryotes among “algae” have plastids surrounded by 3-4 membranes (more than expected for primary endosymbiosis) → additional membranes created from the engulfing of photosynthetic single-celled eukaryotes that have already acquired a plastid from an earlier engulfment) → explains the appearance of plastids in all eukaryotes No eukaryote evolved photosynthesis independently of cyanobacteria, which became incorporated into eukaryotic cells either primarily or secondarily to result in photosynthetic organisms in a wide diversity of clades. Red + 3 or more major secondary endosymbiosis = presence of chloroplasts

Answer 5

- primarily dominant haploid but also has fleeting, diploid generation - free-living - lack rigidity because does not have conducting tissue (lacking lignin), unlike vascular plants - sporophytes are typically visible to the naked eye - desiccation tolerance therefore great at hydrating and taking up resources quickly (trait not seen in vascular plants, especially seed) - No roots → possess unicellular or filamentous rhizoids as anchor - alternation of generations - dominance of gametophyte - development of archegonium and antheridium

Answer 6

MOSS: dominant “leafy” gametophyte generation; requires standing water for fertilization; peristome regulates spore dispersal; can reproduce aseuxually LIVERWORTS: name refers to shape of thing; unobvious sporophytes that don’t have stomata; earliest delineation from land plants; flattened, prostate gametophyte HORNWORTS: flattened, prostate gametophyte has association with cyanobacteria that allow for Nitrogen fixation and primary succession; horn shaped structures are sporophytes grown from archegonium; indefinite growth

Answer 7

PEAT MOSS EXAMPLE Acidity and chemistry (aka phenolics) of bogs are dominated by peat mosses, which inhibit decay via anaerobic, high altitude, and saturated soils → lack of decay leads to carbon build up, which are then harvested for fuel Good at preserving fossils via low pH, cool temperatures, and anaerobic conditions → allowing for reconstruction of past lifestyles Prevent microbial activity → used in WWII as sterile bandaging of wounds in highly dirty trenches, which saved a lot of lives Eg. “bog people” of Ancient N. Europe

Answer 8

1. Desiccation resistant spores and multicellular sporangia: sterile jacket cells to protect developing spores 2. Cuticle: waxy outer covering that helps reduce water loss 3. Stomata: found on sporophytes; pores allow gas exchange (CO2) in presence of cuticle; regulated by guard cells 4. Gametangia: haploid on gametophytes has sterile jacket; extends to protect embryo 5. Embryo: sheltered and nourished inside the female gametangia 6. Fungal Association: glomeromycetes x land plants; allowed them to colonize land 7. Production of rich secondary chemistry: refers to chemicals not involved in energy production; used to be considered waste but actually helps protect plants from UV light and then (later) herbivores

Answer 9

Used Rhyniophytes as a bridge: transitional species → important fossil link btwn gametophyte-dominant bryophyte to sporophyte-dominant vascular plants 1. Dominant sporophyte generation: diploid constitution allows for more complexity and protection from deleterious genes 2. Well developed cuticle: has lignin 3. Vascular tissue: allows for rigidity; made of xylem (water and inorganic nutrients) or phloem (sugar and other organic compounds) to conduct material throughout the plant body → tracheids 4. Branched sporophyte 5. Roots: nutrient / water intake ; anchorage

Answer 10

Seed plant; woody plants with seeds usually in cones and not enclosed in ovary (“naked seeds”), therefore exposed to environment CYCAD: the almost-palm (flower, coveted, rare, almost extinct); unbranched stem clothed by persistent leaf vase; huge cones; tough leaves; found in tropics via insect dispersion GINGKO: possibly related to cycads (?); highly branched woody stems with fan shaped, deciduous leaves; wind dispersed; seeds borne on stalks with no cone (fleshy, gross smelling); medicinal species; only one species left as a result of natural extinction GNETO: about 80 species; grow in different environments, don’t look alike BUT unified through fine scaled features; can be a shrub or platypus Eg. Mormon tea ephedra: shrub example; can be made into various stimulants (ephedrine, meth) Eg. Welwitschia: 2 foliage leaves that split indefinitely; non-elongated woody stems; grown in cultivation CONIFERO: oldest, biggest, tallest, most diverse surviving lineage (>600 species); decay and insect resistant bark and wood contributes to longevity / size, resulting in some of the oldest / largest well known non-clonal organisms; dominant in harsh environments worldwide (eg. higher latitudes / altitudes) BUT not well represented in lowland tropics

Answer 11

largest sperm in the world (flagellated); produce either pollen or seed but not both on the same tree (gendered trees) BUT cycad can change their sex within their lifetime

Answer 12

1. Increase in size of sporophyte and reduction of size of gametophyte 2. seed coat (originates from integument) 3. female gametophyte is the main content of pine seed, where the embryo embedded inside the gametophyte is the next sporophyte generation, meaning three generations of tissue protecting each other 4. pollination then (double) fertilization

Answer 13

Cone: made up of sterile / fertile appendages (= modified leaves, usually 3+ at a node) separated by very short stem segments (=internodes, usually so short as to be invisible) Sepals: protective, help to reduce grazing Petals: visually attractive to pollinators → understanding floral advertisement by petals requires considering the visual spectrum of the dominant pollinators (eg. bees see in lower wavelengths than we do) Stamen: aka sporophyll; have stalk with anther (enlarged tip) filled with sporangia; outer layer of pollen are v decay resistant; allow for study of history → modified leaf that bears microsporangia (typically differentiated into a filament and anther Carpal: MOST DISTINCTIVE FEATURE OF FLOWERING PLANTS; can be multiple or free / fused; individual units called pistil, made of stigma (at tip), style (tube), and ovary (bulbous bottom) → enrolled leaf with fused margins containing ovules

Answer 14

ancestral in flowering plants; requires an attractant or advertisement, such as showy parts or an odor → reward for pollinators often present (expensive to produce); often sticky, oily, clumped, sculptured; eg. nectar produced by nectaries; located variously in a flower with the floral timing synched with pollinator activity

Answer 15

Genetic incompatibility: aka “SI”; genetically based system that allows plants to recognize pollen that shares one or both alleles of the “S” gene and to prevent those male gametophytes from reaching the ovules Unisexual (imperfect) flowers: possessing either only functional stamen (male) or carpals (female) → promotes outcrossing and reduces inbreeding - MONOecious: both sexes on one individual - DIoecious: one sex on one individual; sex separation Spatial separation of anthers and stigmas in the same flower: differ in relative height placement → eg. anthers of one mating type at the same height as stigmas in a compatible mating type Temporal separation of pollen release and stigma receptivity in the same flower Co-evolution of pollinator x plant relationships: one of the most effective / efficient relationships

Answer 16

1. Loss of parts 2. Fusion of parts 3. Change in floral symmetry 4. Fusion about ovary

Answer 17

ovary at maturity becomes all or part of the fruit → 3 types of fruit: simple, aggregate, multiple Simple: typically fleshy; derive from one ovary; dispersed with the seed → eg. cherries Aggregate: derived from >1 separate carpels of 1 flower → eg. raspberries Multiple: derived from multiple flowers, aka compact inflorescence → eg. pineapples BONUS: accessory fruit: fruit with fleshy parts derived largely from tissues other than the ovary; includes all three types of fruit → apple (s), strawberry (a), dig (m)

Answer 18

Epicotyl: part of the embryonic shoot axis above the point of attachment of the cotyledon(s) Hypocotyl: The hypocotyl is the part of the embryonic shoot axis below the point of attachment of the cotyledons → pull cotyledons above ground Coleoptile: protective sheath; allows cotyledons to remain below ground Radicle: embryonic root. IN GENERAL: radicle emerges first (most advantageous as can obtain water), then embryonic shoot

Answer 19

outer protective covering of plant body; primary growth called epidermis; has cuticle to prevent dehydration and stomatal (pores); can also have hairy protrusions

Answer 20

incl. Cells that are specialized for photosynthesis, storage, and support (that is, the most metabolically active); lies between dermal and vascular tissues in stems / roots called cortex or (if internal to ring of vascular) in EUDICOTS then called pith PARENCHYMA: LIVING CELL (contain living protoplast); most metabolically active; undergo photosynthesis; different from embryonic cell types with thin primary walls that are flexible / can divide, therefore very responsive to damage; also contains chloroplasts that can be used in storage → makes up the majority of ground tissue in stems COLLENCHYMA: LIVING CELL; just below the epidermis; unevenly thick walls that serve as structural support for parts of the plant that are still lengthening, therefore still a little flexible → eg. celery strands SCLERENCHYMA: DEAD CELL at functional maturity; one of the most rigid, therefore provides the greatest structural strength; have both primary and secondary walls (second impregnated with lignin, a polymer that makes wood hard); not capable of expansion → eg. can be boxy (sclereids; used in seed coats) or elongated (fiber; used commercially)

Answer 21

aka conducting; xylem and phloem are discrete but adjacent components of vascular tissue (exact arrangement differs between different types of organs) XYLEM: conduction of water and inorganic nutrients from the soil 1. Tracheids: diagnostic feature of all plants; elongated with tapered ends; heavily lignified and hollow; essentially tubes for water to flow through; move from tracheid to tracheid via pits (naked primary walls that are permeable to water) 2. Vessel elements: usually present in tracheids / fibers; not a lot of structural strength; have perforation plates at the ends with large openings; better at conducting; allow for movement between tracheids PHLOEM: conduction of organic nutrients made by the plant (eg. sugar) 1. Sieve cells: connected to form sieve tubes (living!) that has a 1:1 peripheral of cytoplasm around the inner perimeter of the cell but not fully endowed with nucleus / ribosome therefore hollow for nutrient transport; sieve plate rapidly responds to damage via kalos that closes the wound to prevent sugar bleeding 2. Companion cells: sister to sieve; fully endowed, therefore helps to regulate functioning of sieve tubes since the latter doesn’t have a nucleus or anything

Answer 22

Shoot is considered to be the leaves and stem (above ground components); root is considered to be the roots (below ground components). Shoot is developmentally / morphologically / anatomically different from the root system. Shoot captures CO2 and light, performs photosynthesis to create sugar Root anchors plant, transports water and inorganic nutrients of soil

Answer 23

1. Node: point where the leaf connects to the stem → internode: between consecutive leaves 2. Leaves: made of blade and petiole (connection between stem and blade); blade as a platform for photosynthesis 3. Buds: opportunity for elongated growth - Auxiliary: located in upper angle between petiole and stem - Apical: aka terminal; located at the top of stem

Answer 24

Plants are modular (open development), meaning that multiple units can regenerate. Determinate Growth: growth up to a certain point than stopping → eg. human height Indeterminate Growth: potential for elongating growth all their life → eg. plants (but plant leaves can individually have determinate growth) Meristems: apical; sites of active cell division which can continue indefinitely in plants; indeterminate; located at shoot / root tips

Answer 25

EUDICOT: hypocotyl has (-) gravitropism, therefore pulls cotyledons above the ground (hook) and straightens once exposed to sunlight to promote growth of the shoot tip and foliage leaves MONOCOT: coleoptile (protective sheath) emerges first with (-) gravitropism, acting as a tunnel that the shoot tip can grow through (therefore having to damage from the soil); cotyledon remains underground to supply nutrients Germination: early establishment of the sporophyte → the weakest link because of high mortality rates at this stage; occurs only in optimal conditions that trigger different cues (long vs short term cues) Gravitropism: in relation to the pull of gravity → (+) if downward, (-) if upward

Answer 26

responsible for growth in length of stem (can also have root apical meristem) tissue systems developed from distinct cell lineages at the shoot apex → dermal from protoderm, ground from ground meristem, vascular from procambium

Answer 27

Eudicots: vascular bundles organized in a ring (xylem inside, phloem outside); pith at center; cortex between vascular and epidermis → this structure allows for secondary growth Monocots: scattered bundles with no differentiation between the pith and center

Answer 28

Leaf veins correspond to vascular tissue (xylem above, phylum below), surrounded by parenchyma (mesophyll) cells that make up a bundle sheath → Determinate with no secondary growth Stomata: sites of air exchange between inner lead and atmosphere → CO2 for photosynthesis with oxygen as product; results in water loss Guard cells: regulate pore opening of stomata and are typically on lower epidermis; important for controlling water loss Mesophyll: ground tissue in leaves that are specialized for photosynthesis; two types 1. Palisade: tightly packed along upper side of leaf; specialized in photosynthesis 2. Spongy: loosely organized along lower side of leaf, allowing for movement of gases

Answer 29

occurs only in woody plants; THICKENING rather than elongating growth; growth in width occurs from lateral, not apical, meristems (result in production of cells both to the inside and outside) → monocots do not undergo “true” secondary growth EUDICOT: cylindrical layer of cells btwn xylem and phloem and connecting the vascular bundles becomes meristematic (aka vascular cambium), producing xylem to inside and phloem to outside (as bundles are arranged within eudicot stems) → differentiates as primary vs secondary

Answer 30

Girdling a tree: process of removing a complete ring of bark on main stem below lowermost branches → “girdle” as ring that now lacks bark Effective way to kill a tree bc severs phloem completely → roots starve from lack of food (photosynthate, sugar produced in leave), which can no longer be transported from leaves to roots

Answer 31

alternates btwn divisions toward the inside of the stem and divisions toward the outside of the stem → growth enlarges stem diameter and vascular cambium + bark moves outward Wood: all tissues to the inside of vascular cambium; secondary xylem Bark: all tissues to the outside of vascular cambium; mix of tissues produced by vascular cambium (specifically, the secondary phloem) and cork cambium (specifically cork and parenchyma) ** More cell divisions to the inside than the outside, therefore diameter of WOOD increases faster than that of BARK → secondary xylem produced at a faster rate than secondary phloem **

Answer 32

forms to the outside of the vascular cambium but inside cortex of stem; important for continual production of secondary dermal tissue aka periderm (epidermis and cortex eventually destroyed by expansion) Periderm: made of cork cambium, cork cells (waxy suberin in cell walls), and parenchyma Vascular rays: parenchymal cells that are produced by the vascular cambium; living cell that helps transport / store nutrients; radial files of cell that connect secondary xylem and secondary phloem

Answer 33

small raised areas of more loosely arranged cells on the outside of bark; may have characteristic size and shape in different taxa; permit gas exchange within stems that have undergone secondary growth → basically replacement stomata

Answer 34

Secondary xylem = heartwood + sapwood 1. Heartwood: non-conducting wood that has become a depository of resin / other decay-resistant secondary compounds; make up majority of wood; typically older bc near heart of stem 2. Sapwood: conducting wood that transports xylem sap (water and minerals); width of growth rings dependent on water transport, allowing for dating / climate context; younger since Bark = secondary phloem + layers of periderm Vascular ray reaches from outermost edge of sapwood to pith of heartwood

Answer 35

no wood, mostly comprised of ground tissue w scattered vascular bundles lots of lignin for structural support (eg. palms, bamboo), which can result in thick stems without having undergone the process of secondary growth

Answer 36

Root apical meristem: primary source of growth; replenishes root cap Root cap: protects apical meristem as it moves thru soil; sloughed off but replaced by apical meristem Root tip: loosely organized cells that produce slime for lubrication; protected by root cap 3 MAJOR ZONES -- 1. Zone of Cell Division: closest to tip 2. Zone of Elongation: slightly older; cell divisions ceased, focus on enlargement 3. Zone of Cellular Differentiation: aka maturation; cells are differentiating; root hairs forming (extensions of epidermal cells to increase surface area and absorptive capacity of the root)

Answer 37

Endodermis: innermost layer of cortex; passive barrier of substances into the vascular cylinder Pericycle: outermost layer of vascular tissue; cell layer from which lateral roots or branching roots are formed Lateral roots: branch off from main root; formed within pericycle; must displace cells of the cortex (except endodermis) and cells of epidermis of the main root to emerge from that root → allows vascular tissue to remain continuous btwn main and lateral root Root hairs: extensions of epidermal cells that increase surface area for absorption of water and minerals

Answer 38

water and minerals can move into roots through 2 ways Apoplast: region outside of protoplast (therefore, outside membrane / not in cytoplasm); moves along cell walls and thru extracellular space Symplast: across a cell membrane and through the cytoplasm of cells which are connected by plasmodesmata Plasmodesmata: openings in cell walls of adjacent cells that allow for continuity of cytoplasm of those cells ** Selectivity of solutes allowed when moving through symplast (due to presence of cell membrane) but not through apoplast. Casparian strip: suberized strip outside endodermis cell; prevents apoplastic movement of water and solutes into the vascular cylinder → protects vascular cylinder from contamination and prevents diffusion of essential inorganic nutrients that have been actively concentrated by the xylem back out to soil

Answer 39

Passive transport: diffusion across a membrane; spontaneous movement of a substance down its concentration gradient from one cell to another; slow but effective at short distances Active transport: movement of a solute across a membrane AGAINST its concentration gradient; requires expenditure of cellular energy Bulk flow: main way; movement of fluid due to difference in PRESSURE btwn two locations; important for relatively long distance transport in plants

Answer 40

freedom of water to move; aka potential energy of water, denoted by greek symbol psi and measured in MegaPascals (MPa) → free water moves from regions of higher water potential to lower water potential (ie. if water potentials are negative then “higher” = less negative) The higher the solute concentration, the lower the water potential (water leaves cell) The higher the pressure on solution, the higher the water potential (water enters cell) Plasmolysis: condition where the cell membrane pulls away from the cell wall Turgor: important for structural support of organs → turgid: cell wall resisting further expansion funfact: An average size tree can transport over 200 gallons of water from its roots to its leaves in a single day, without a pumping mechanism.

Answer 41

Guttation: not dew; occurs due to increased solute concentration (thanks to active xylem) resulting in movement of water from cortex to xylem, increasing the pressure and exuding water from leaves Transpiration: evaporative water loss from plants; inner leaf cells increase surface tension of water in cell walls, thus creating negative pressure that is transmitted throughout the water column in xylem and results in the cohesion of water molecules

Answer 42

“Pull” from the negative pressure generated transpiration-cohesion-tension mechanism that moves water from the soil to roots to leaves

Answer 43

guard cells regulate pore cells when turgid (at maximum water holding capacity), they bow out (result of cellulose microfibril) open the pore and become thicker on the side facing the pore When flaccid, the pore closes

Answer 44

occurs when the negative pressure inside xylem becomes too great, resulting in an air bubble that breaks the cohesive unity of the water column Isolated / small scale cavitations are not an issue due to redirection via tracheids BUT Large scale cavitations disrupt the transpiration pull from the leaves, which can result in permanent wilting / death of the plant combatted with thinner vessels and irrigation systems (measure xylem sap flow to monitor drought stress)

Answer 45

Source: tissues that release sucrose to the phloem Sinks: tissues that take up sucrose from the phloem BUT, tissues can switch their roles → eg. a structure modified for storage can be source early in growth season (releasing nutrients) but sink later (accumulating starch) More concentrated at source = net movement of water into source rather than sink BUT buildup of water pressure results in bulk flow from source to sink. >> PUSH FROM ROOTS

Answer 46

both examples of bulk flow (aka fluid movement due to a difference in pressure at different ends of tubes) Phloem transport is due to positive pressure at source (resulting in push of sap to sink), whereas xylem transport is due to negative pressure / tension from transpiration (resulting from pull of leaves)

Answer 47

aka plant growth regulators that act to affect cell division, elongation, and / or differentiation (maturation) 1. Hormones can have a variety of effects. 2. Hormones may have contrasting effects; different plant parts may have different sensitivities to the hormone → aka “differential sensitivity” 3. Hormones often act together; the ratio of different hormones to one another may be an important determinant of their effect → aka “hormonal balance”

Answer 48

Regulates cell elongation (in coleoptiles, stems); apical dominance in shoot; fruit development; and lateral root formation

Answer 49

aptly named bc “cytokinesis” means cell division → promote cell division and differentiation; stimulate axillary bud growth

Answer 50

promote stem elongation via cell elongation and division; can be v important in promoting seed germination Seed germination: can easily break seeds out of dormancy period Used commercially to promote fruit enlargement / bunch length Eg. bolting response of herbs → bolting: rapid production of a flowering shoot, esp in an otherwise stem-less herb with only basal leaves

Answer 51

similar in function to auxin in that it stimulates plant growth; promote stem elongation; can also stimulate cell division and differentiation → has a chemical conformation (similar to that of animals)

Answer 52

Cytokinins promote development of branches from axillary buds, acting against (indirect) inhibition of buds by auxin. High C:A ratio is associated with activation of shoot branching Low C:A ratio is associated with activation of lateral roots Cytokinin largely produced in the roots and transported toward shoot tips whereas auxins are largely produced in shoot tips and transported toward roots. → creates gradient effect throughout the entire body of the plant that dictates overall architecture (regulate overall branching pattern)

Answer 53

Prevents damage to the plant’s physiology by playing a role in the dormancy of seeds, closing of the stomata, and overall inhibition of growth 1. inhibits plant growth; important in inducing seed dormancy and seed desiccation tolerance → Eg. mangrove seeds germinate while still on parent plant if lacking in ABA 2. Causes guard cells to lose potassium → ABA prevents drought stress from worsening by signaling closure of stomata upon or before onset of wilting (causes opening of potassium channels in guard cells, and consequent loss of potassium from those cells causing water to leave the guard cells, which become flaccid and close)

Answer 54

ABA and gibberellins are opposites in seed germination / stem growth, therefore the balance btwn the two is important for germination response.

Answer 55

functions in the gas phase (thereby can trigger nearby plants, creating a chain response) >> used for fruit ripening Produced in fruit signals ripening (enzymatic breakdown of cell walls, conversion of starch to sugar) → positive feedback loop: ripening triggers more ethylene production

Final Exam: Plants Flashcards

(79 cards)