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Flashcards in plant requirements / coordination Deck (15)
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1
Q

what are requirements for autotrophs

A
  • light: photosynthesis, produce sucrose / ATP, increase potential energy of e-
  • water: 80% water, central vacuole = turgid pressure, medium in which minerals / sugars dissolve, blood supply of plant, transport mechanism
  • carbon dioxide: carbon source that provides atoms to make up macromolecules
  • oxygen: cellular respiration
  • macro nutrients: large amounts (C, O, H, N, K, P, Mg, Ca, S), building tissue, photosynthesis
  • micro nutrients: needed in trace amounts (Mn, Mo, Cu, Zn, Fe, Cl, B, Ni), help with turgid pressure, movement
  • turgid pressure: cells coming together to form leaves, can change direction of leaves in order to gain largest amount of sunlight (petiole = flaccid, hangs low, petiole = turgid, sits high)
2
Q

how does transport of water occur in plants

A
  • xylem, circulatory system of plants, water movement

- water uptake through endodermis (root system, large cortex to regulate movement), vascular stele, casparian strip

3
Q

what are the two pathways that are possible in water transport

A
  • apoplastic: pink, least resistance, through cell walls and intracellular spaces, fibrous material, take in water / expand
  • symplastic: blue, across plasma membrane, cell to cell connections through cytoplasm, regulation, through plasmodesmata
4
Q

what is the casparian strip

A
  • suberin, waxy material, only laid down along 4 walls
  • connections between cells are water proof
  • regardless of pink or blue forced to cross symplastic (blue) due to cell wall being waterproof (casparian strip)
5
Q

how does water move upward in the plant

A
  • water moves down water potential gradient, high water to low water
  • psi (water potential symbol, devil stick)
  • in relation to pure water (0), presence of solutes (-ve)
  • measured in Mpa (megapascal)
  • Mpa becomes more -ve as you travel further upwards, hence upward movement of water through plant, soil (-0.1), root (-0.2), xylem (-1.1), leaf (-1.5) and atmosphere (-30)
6
Q

what is the water column

A
  • column of water in the xylem, h bonds (weak bond, easily formed / broken)
  • cohesion: allows water molecules to come together (fluid medium)
  • adhesion: water adheres to xylem wall / other polar substances
  • evaporation: of water from surface of leaf cells (transpiration), allows water column to be sucked upwards
  • transpirational pull: responsible for evaporation of water from the leafs surface, pulling water column up from roots to leaves
7
Q

how is prevention of too much water loss controlled

A
  • leaf boundary layer: under leaf, reduce large gradient of water potential, boundary of humid air (contains water)
  • hairs: trap water as it is being pulled out
  • stomata: open / shut, turgid pressure, pore, guard cells, cell loses water guard cells = flaccid (pores shut), guard cells take on water they bow outwards (open pore), also controlled by K levels
8
Q

describe the transport of photosynthetic products and the reason for sucrose production

A
  • circulatory system of plant, photosynthetic products down plant
  • create own sugar, formation of sucrose
  • easier to store, non reducing agent, transported throughout plant without impacting or reducing anything / affecting other molecules
  • leaves leaf to root system, or is stored in fruit, enzymes break it down easily
9
Q

describe the steps in movement of photosynthetic products

A
  1. loading of sugar: sugar into phloem cells (sieve tubes), actively accumulated (leaf = lots of chloroplasts, produce sugar)
  2. uptake of water: water enters phloem from xylem by osmosis, creates hydrostatic pressure (increases pressure, forces water down plant)
  3. unloading of sugar: root cells (sink), passive, phloem unload sugar / water at root, relieves pressure
  4. water recycling: water reabsorbed into xylem, moves up plant via water column
10
Q

what are plant hormones and growth responses

A
  • no evolution / growth without, low conc. to produce response, high conc. = herbicide (death)
  • control growth, division, development, elongation, differentiation
  • produced in one area and move to xylem / phloem
  • bind to receptor, cause change and activation of cellular responses
  • auxin, gibberellin, abscisic acid, cytokinin and ethylene
11
Q

what is auxin

A
  • produced by: shoot apical meristem, root meristem, young leaves
  • found in: seeds / fruit
  • function: primary growth
  • characteristic feature: phototropism (bend towards light) / gravitropism (against gravity), fruit development
  • stem elongation: acid growth hypothesis (breaks cell wall, acidifies = elongation / growth), increase central vacuole
  • lateral / adventitious root formation
  • prevents lateral growth (removal = shrub / bush)
  • achenes: fruit development, each cell = different time / conc., characteristic sizes
12
Q

what is gibberellin (GA)

A
  • produced by: young leaves. stem / root meristem, immature seeds, developing anthers
  • function: growth, elongation, germination, pollen development
  • characteristic feature: mobilisation of endosperm, production of amylase (breakdown endosperm to glucose)
  • rapid shoot / growth, internodes (stem in between leaves = longer, increased area for development of fruit / leaves)
13
Q

what is cytokinin

A
  • produced by: actively growing tissue (roots, cell division)
  • function: division / growth laterally, delay leaf senescence (anti-ageing, prevent breaking down, stay youthful)
  • characteristic feature: regulates cell division (stimulates cytokinesis, start dividing)
14
Q

what is ethylene

A
  • produced by: all structures
  • function: similar to auxin, seed germination, stem growth / shoot elongation, root hair formation, flowering, fruit ripening
  • characteristic feature: gas (all others diffuse via aqueous environment), ability to diffuse out of plant body, affect surroundings
  • thigmomorphogenesis: response to mechanical disturbance, touched = stunted growth
  • abscission / senescence: death, dead at functional maturity (xylem and sclerenchyma), opposite of cytokinin
  • stress response: hardier in structure, slowing of stem elongation, thickening, sturdier, move around an obstacle
15
Q

what is abscisic acid (ABA)

A
  • produced by: all structures
  • function: promotes stomatal closure during drought stress (controls osmotic balance of guard cells, opening (turgid) / closing (flaccid) of pores)
  • characteristic feature: inhibits growth, promotes seed dormancy (inhibits early germination
  • rain: washes ABA away, promotes growth after
  • seed remains dormant until soil conditions are favourable (water / sunlight)