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Week 9
Reproduction intro + plant reproduction/development
| Question | Answer |
|---|---|
| Reproduction definition | the biological process by which new organisms/offspring are produced from their "parent" or parents |
| 2 types + subtypes of reproduction | Asexual (binary fission, budding, fragmentation, pathenogenesis) + sexual reproduction |
| Asexual reproduction defintion | creation of offspring without the fusion of an egg/sperm; only 1 parent is needed; offspring is genetically identical to parent (clone) |
| Sexual reproduction defintion | creation of offspring by fusion of male game (sperm) + female gamate (egg) to form a single cell called a zygote; 2 parents are needed (or one-hermaphrodites); offspring is genetically different from parents |
| Asexual vs. sexual # of offspring per time | asexual: many offspring in short period of time sexual: fewer offspring (reproduction takes longer period of time) |
| Asexual reproduction pros/cons | pros: well adapted clones good in stable enviroments; higher rate of reproduction; offspring mature at birth/soon after; dense clones keep out competition cons: change in enviromental conditions can lead to extinction |
| Sexual reproduction pros/cons | pros: genetic variability allows for better survival upon changes to the enviroment cons: it takes longer; its risky (finding mate, parenting); it is energetically expensive |
| Binary fission definition | an individual splits into 2 or more descendants ex. anemones |
| Budding definition | new individual arises from outgrowth/bud of a cell/body region leading to seperation from an original organism into two individuals ex. hydras + corals |
| Fragmentation definition | breaking of the body into pieces (some or all develop into adults); must be accompanied by regeneration ex. starfish + planaria !! |
| Parthenogenesis definition | eggs develop without being fertilized by a sperm, progeny can be either halpoid or diploid ex. bees + komodo dragons |
| What process in sexual reproduction accounts for genetic variation? | meiosis (crossing over + random assortment) + random fertilization |
| Sexual life cycle in animal vs. plants | animals are diploid dominant, haploid sex cells producing diploid offspring; plants have alteration of generations having a seperate diploid + haploid stage |
| Plant sexual life cycle general model | diploid stage = sporophyte, haploid stage =gametophyte, both stages are multicellular + meiosis produces spores |
| Moss overview | live in wet enviroments (needed for reproduction as they are non-vascular, therefore no seeds/flowers/fruits). gametophyte stage is dominant |
| Moss sexual life cycle | gametophytes develop reproductive structures (archegonia/anteridia) that produce gamates; flagellated sperm swim to archegonium to fertilize egg; which forms zygote; sporophyte produces haploid spores via meiosis to form new gametophytes |
| Fern overview | found in moist/wet enviroments; vascular; no seeds/flowers/fruit; sporophyte is dominant phase |
| Fern sexual life style | small gametophyte develop reproductive struc. (archegonia/anterida) produce gametes; sperm swim to archegonium to fertilize egg; which forms zygote which forms into large inde. sporophyte; which produces halpoid spores via meiosis to form new gametophytes |
| Gymnosperm overview | found in drier/cold enviroments; dominant sporophyte; vascular; seeds; no flowers/fruit |
| Gymnosperm sexual life cycle | most species have both ovulate + pollen cones; microsporocytes -> microspore -> pollen grain; pollination occurs when pollon grain reaches ovule, grain germinates forming pollen tube that eats its way through megasporangium/ovule; megasporocyte -> meiosis |
| Gymnosperm suexual life cycle pt. 2 | -> 4 haploid cells, surviving megaspore develops into female gemetophyte w/archgonia which form eggs; eggs mature, serm cells develop pollen tube + fertilization happens, usually only one zygote develops into embryo; ovule becomes seed |
| Seed structure + function + first organ to emerge from seed | seed coat; endosperm; embryo - have a supply of stored food, can by transported long distances by wind/animals, may remain dormant until conditions are favorable for germination (cued by changes in moisture/temp/light. radicle/primary root emerges first |
| Angiosperm overview | varied habits; dominant sporophyte; vascular, has seeds fruits + flowers |
| Flower anatomy | flower is the reproductive organ; most flowers possess male + female structures - can be bisexual (male parts (stamen/filament + female (stigma/style/ovary) on same flower) or unisexual (only 1 sex on flower) |
| Angiosperm sexual life style | female gametophyte produced in ovule; in stamen pollen is developed, gametopyte is divided producing 2 sperm + tube cell to pollen tube; pollen tube elongates though style discharges sperm in ovule; double fertilization occurs, 1 sperm forming zygote |
| Angiosperm sexual life style pt. 2 | 2nd sperm forning endosperm (3n); zygote develops into embryo;seed then germinates + embryo develops in to mature sporophyte |
| Pollination definition | transfer of pollen grains from the male stamen to the female stigma allowing fertilization to happen. happens by water, wind or pollinators ex. bees, butterflies, bats |
| Function of ovules + pollen grains | ovules (female) hold the zygote/embryo + become seeds; pollen grains carry the male gametes/sperm to the stigma so they can fertilize the ovule though a pollen tube |
| Sperm delivery in seedlesss vs. seed plants | seedless plants rely on water for sperm to be able to reach egg -> sperm goes from male game. (antheridium) to female game. (archegonium) seed plants have pollen, pollen goes through pollen tube to ovule to fertilize egg |
| Which components of flower develop into seed + fruit | ovules develop into fruit, ovary develops into fruit |
| Describe double fertilization | pollen tube grows down style to ovary; pollen tube discharges 2 sperm into female game. (embryo sac within ovule) 1 sperm fertilizes egg cell forming zygote, 2nd sperm combines w/ the 2 polar nuclei of the embryo sac to form 3n cell (endosperm) |
| Simple fruit | forms from 1 ovary of one flower ex. pea fruit |
| Aggregate fruit | forms from several ovaries of 1 flower ex. raspberry |
| Multiple fruit | forms from several ovaries of several flowers ex. pinapple |
| Accessory fruit | forms from ovaries and other floral parts ex. apple |
| Advantage of reduced gametophytes | spore + gametophyte are retained within the sporophyte (protected from UV radiation + drying out) gametophytes/spores are more sensitive to mutations then other stages bc they are haploid |
| What can plants sense + how to they gather/process/respond | can sense light/gravity/pressure/wounds. sensory cells recieve external signal + change it intracellular signal;sensory cells then send a signal to target cells in other parts of plant body;target cells recieve signal + change activity to produce response |
| How goes information from an activated sensory cell get to a target cell + processes affected by hormones (hormones are produced in very low amounts) | hormone is transported (via proteins, xylem/phloem, diffussion) to the target cells where it causes a physiological response. can be hydrophobic or philic. hormones effect cell division/elongation/differtiation/death |
| Tropism definition + 3 types | a growth response (any response resulting in the curvature of organs toward or away from a stimulus) positive = towards; negative = away. ex. phototropism, gravitropism + thigmotropism |
| Phototropism | response to light; usually positive |
| Gravitropism | repsonse to gravity; stem presents negative tropism + roots present postitve tropism |
| Thigmotropism | response to mechanical disturbance (can be postive or negative) |
| Dormancy + fruit maturation/ripening definition | Inhibition of plant growth including inhibiting seed germination; process of fruits becoming more palatable/sweeter and falling from plant |
| Germination + leaf abscission definition | development of plant from a seed or spore after a peroid of dormancy; process of leaf falling (in fall) |
| Senescense definition | programmed death of plant cells or organs or an entire plant |
| Darwin + Darwin experiment (phototropism) | detection of light occurs at tip (bends towards light); Boysen-jensen (phototropic response occurs with permeable but not impermeable barrier so tip + stem are connected) - Went (dark side has a higher concentration of auxin - growth promoting substance) |
| phototropism experiment continued | Auxin is transported to shaded side of seedling where it stimulates cell elongation (elongation of shaded side causes plant to bend towards light) |
| Auxin is involved in | root formation + branching, secondary growth by inducing cell division in the vascular cambium + influencing differentiation of secondary xylem; gravitropism + phototropism |
| Cytokinins definition | class of plant hormones that promote cell division, growth + differntiation - cytokinins stim. cytokinesis. produced in actively growing tissues; regulating growth by activating genes that keep the cell cycle going stimulating cell division. works w auxin |
| Control of apical domanince meaning | cytokinins auxin + other factors interact to control the terminal/apical buds ability to suppress the development of axillary/lateral buds so that the plant can grow vertically (if terminal bud removed plant grows more bushy) |
| Imbibition definition | first step of seed germination; a diffision where water is absorbed by solids causing rise in volume without forming a solution. ex. seed absorbing water |
| 6 main plant hormones | auxin, cytokinins, gibberellins, abscisic acid, ethylene + florigens |
| Auxin | class of plant hormones that promote cell elongation in stems and roots (stimulates proton pumps in the plasma membrane) plants grow cheaply/rapidly by intake of water in vacuoles, cells primarily expand along plants main axis |
| How does auxin contribute to the plant growth process | auxin stimulates proton pump, acidity increases;lower pH activates cellulose loosening emzymes (expansins) which break down H bonds between cellulose fibres which loosens cell wall; cell then absorbs water causing it to swell/elongate |
| What is the position based mechinsism used by root epidermal cells to differntiate into root hair cells and hairless epidermal cells | root epidermal cells border one cortical cell they will be hairless and if they are touching 2 they will become hair cells |
| Why does the name "abscisic acid" not suit auxin (explain role of acid) | because they have opp roles, auxin is a growth hormone + abscissic is a stress hormone |
| How does ethylene help plants respond to mechanical stress? | can reduce stem elongation + increase radial expansion |
| Megasporangium -> megasporocyte -> 4 megaspores via meiosis 1 survives becoming felmale gametophyte (female) | microsporaniguim contains microsporocytes via meiosis producing 4 microspores which develop into pollen grains |
| Anti aging effects of cytokinins | can deley the aging of some plant organs by inhibiting protein breakdown, stimulating RNA + protein synthesis + assemblong nuctrients from surrounding tissues. can slow deterioration of leaves on intact plants |
| Gibberellins | effect stem elongation, fruit growth + seed germination |
| Gibberellins (stem elongation) | stimualte the growth in leaves + stems (in stems they stimulate cell elongation + cell division) |
| Gibberellins (fruit growth) | both auxin + gibberellins must be present for fruit to set |
| Gibberellins (germination) | water taken up by seed; gibbs released by embryoto outer layer of seed coat (aleurone) to signal for seed germ; layer secretes alpha=amylaze to hydrolyze sugars in endosperm; sugars used by embryo/absorbed by the scutellum (cotyledon) for embryo to grow |
| Position based cell differentiation (GLABRA-2) | if an epidermal cell boders 1 cortical cell gene GLABRA-2 IS expressed + cell remains hairless; if epidermal cell borders 2 cortical cells gene GLABRA-2 is NOT expressed + cell develops root hair |
| Abscisic acid | slows growth (antagonistic to plant growth hormones like auxin) |
| Abscisic acid (seed dormancy) | ABA inhibits plant growth + seed germ; adding ABA to alerurone layer decreaes alpha amylaze levels; ABA can be removed by heavy rain, light or prelonged cold |
| Abscisic acid (drought tolerance) | ABA is the primary internal signal that enables plants to withstand drought; plant wilt -> ABA accumulate in leaves -> rapid closing of stomata -> reduces transpiration/water loss |
| Ethylene | form of gas released from plant tissues (antagonistic to plant growth hormones) produced in response in to drought/flooding/mechanical pressue/injury/infection (stresses) |
| Ethylene (fruit ripening) | burst of ethylene production trigger ripening process in fruit; ripening is the enzymatic breakdown of the cell wall, softning the fuit + conversion of starches/acids to sugars making it sweet |
| Ethylene (senescence) | = programmed death of plant cells/organs/plants; burst of ethylene is assoc. w apoptosis ^^ |
| Ethylene (leaf abscission) | a change in the balance of auxin + ethylene controls leaf absession (low auxin [] + high ethyl []) increased ethylene sensitivity activates enzymes that weaking the walls of cells in the abscission zone. cell wall degrades until leaf falls |
| Ethylene - triple response to dark + mechanical stress | (allowsa growing shoot to avoid obstacles) slowing of stem elongation, a thickening of the stem to make it stronger + horizontal growth |
| Florigens | floral response to seasons; flowering + photoperiodism |
| Short day vs. long day vs. neutral plants | short day bloom when days are shorter, longer when days are longer + nuetral one maturity/tempurature |
| How is night length to day length the critical factor in photoperiodism | act as a critical timer for flowering; short days can be effecting by a flash of light |
| Photoperiodism definition | Physiological response to the relative length of day + night |
| Look at summary table on page 206 of notes |
Created by:
every_august
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