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HL Bio > 9 plants (bioninja summary) > Flashcards

9 plants (bioninja summary) Flashcards

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Biology 101 flashcards
1
Q

the structure of a plant is related to…

A

its FUNCTIONS
eg Roots are highly branched, with a high SA:Vol ratio
(necessary for water and mineral uptake)

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2
Q

Leaf Tissue 2

A
  • Palisade mesophyll – upper layer of tightly packed
    cells that are rich in chloroplasts (⇧ light absorption)
  • Spongy mesophyll – lower layer of cells interspersed
    by space and located near the stomata (⇧ gas exchange)
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3
Q

Root systems adaptation

A

extensive branching in order to maximise the available surface area for material uptake

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4
Q

Fibrous (adventitious) root systems

A

many branching roots that are thin and very spread out

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5
Q
  • Tap root systems
A

deeply penetrating central root (for stability)
with many connected lateral branches

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6
Q

root hairs

A

small extentions on root epidermis (to further increase available surface area)

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7
Q

organisation of vascular bundles differ according to..

A

plant section (root vs stem) and plant type (monocot vs dicot)

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8
Q

vascular bundle distribution in roots

A

Vascular bundles are radially arranged within a big stele in monocots, but are centrally arranged within a small stele in dicots

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9
Q

vascular bundle distribution in stems

A

Vascular bundles are scattered haphazardly in monocots, but form a ring around a circular cambium in dicots

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10
Q

dicot root vs monocot root

A

dicot: ‘x’ in the middle (phloem), scattered xylem,
monocot: ring in the center, xylems outwards

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11
Q

dicot stem vs monocot stem

A

di: single ring lining inner wall
mono: scattered around, most around inner wall

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12
Q

what is transpiration + 3 basic steps

A

Transpiration is the loss of water vapor from a plant
* Active uptake of ions by roots promotes water uptake
* Water moves up the stem of a plant by mass flow
* Water is evaporated from leaves (via stomatal pores)

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13
Q

transpiration stream

A

flow of water from root to leaf

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14
Q

how and what do roots uptake 4

A
  1. Soil contains anionic clay particles to which minerals attach
  2. Roots pump H+ ions into the soil to displace the minerals
  3. Displaced minerals diffuse into root (indirect active transport)
  4. Water follows mineral ions into the root via osmosis
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15
Q

how does mass flow work

A

water moves up stem in xylem vessels

  • Pressure is high in root (water in) and low in leaf (water out)
  • The pressure differential results in the mass flow of water
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16
Q

what forces are part of capillary action?

A
  • Cohesion (water molecules stick together by H-bonding)
  • Adhesion (water molecules adhere to the xylem wall)
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17
Q

transpiration is a consequence of?

A

gas exchange in the leaf

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18
Q

how do guard cells manage transpiration rate

A

turgid – open (K+ ions pumped in, water moves in)
flaccid – closed (water moves out)

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19
Q

drawing of xylem structure

A

l spiral ll rings l l – l (sieve plates)
xylem has little gaps + little protrusions in the cell walls (pits)

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20
Q

water conservation adaptations Xerophytes (desert plants)

A
  • Reduced leaves (lowers evaporative SA)
  • Thick, waxy cuticles (reduces water loss from leaves)
  • Stomata in pits with hairs (traps vapor = ⇩ evaporation)
  • CAM physiology (only opens stomata at night)
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21
Q

water conservation adaptations Halophytes (salt water plants)

A
  • Cellular sequestration (salt is stored within the vacuoles)
  • Tissue partitioning (abscission of leaves containing salt)
  • Salt excretion (salt is actively removal from the plant)
  • Root level exclusion (roots avoid salt uptake)
22
Q

modelling of water transport in xyelm 3 ways

A
  • Capillary tubing (water moves along tubing via surface tension)
  • Filter paper (absorbs water due to adhesive properties)
  • Porous pots (semi-permeable containers can model osmosis)
23
Q

transpiration measurement

A

potometers
* measure movement of air bubble
* More movement= incr transpiration rate

24
Q

xylem vs phloem strcutre

A

Process
Transpiration // Translocation

Materials
Water, minerals // Organic nutrients

Transport
Unidirectional // Bidirectional

Composition
Vessel element and tracheid //
Sieve element and companion cell

Structure
Dead cells form a hollow tube //
Living cells form a tube with plates

Location
Inner or central region of bundle
// Outer region of vascular bundle

25
Q

measurement of translocation rate

A

aphids feed on sap in phloem
radioactive co2 = radioactively labelled sugars
time taken for radioisotopes to be detected = rate of t

26
Q

what are meristems

A

Meristems are undifferentiated cells in plants that are capable of indeterminate growth (analogous w totipotent stem cells)

  • They have specific regions of growth or development and allow for regrowth and vegetative propagation
27
Q

2 types of meristem tissue

A

Apical and Lateral

28
Q

apical meristem

A

Occurs in shoots and roots and is responsible for primary growth (i.e. lengthening) and leaf development

29
Q

lateral meristem

A

Occurs at the cambium and is responsible for secondary growth (i.e. widening) and the production of bark

30
Q

what are auxins

A

plant hormones control growth in auxins (stimulate/inhibit cell div)

31
Q

how are differentiated growth rates generated in plant tissue

A

Auxin efflux pumps can set up concentration gradients of auxin in plant tissues

32
Q

where does auxin come from and what does it coordinate

A

released by the shoot apical meristem

coordinates both apical growth and directional growth (tropism)

33
Q

how does auxin influence cell growth rates

A

by changing the pattern of gene expression within the plant tissue

34
Q

apical dominance

A

Auxins promote growth in apex but inhibit growth in buds

35
Q

how are axillary buds formed

A

growth occurs in sections (nodes), remaining meristem tissue forms inactive axillary buds – potential to form new shoots

36
Q

what is a tropism

A

the turning of an organism in response to a
directional external stimulus (e.g. light = phototropism)

37
Q

how do plant tropisms happen

A

the differential elongation of
plant cells (plant turns away from side with cell elongation)

38
Q

role of auxin in tropisms in shoots and roots

A
  • In plant shoots, auxin promotes cell elongation
  • In plant roots, auxin inhibits cell elongation
39
Q

what is micropropogation

A

technique used to produce large numbers of
identical plants (i.e. clones) from a selected stock plant

40
Q

uses of micropropogation 3

A
  • rapid bulking up of new plant varieties
  • production of virus-free strains of existing varieties
  • propagation of rare plant species
41
Q

3 stages of sexual repro in flwoering plants

A
  • Pollination – transfer of pollen from the anther to the stigma (usually between different plants)
  • Fertilisation – fusion of the male gamete nuclei (in pollen) with the female gamete nuclei (in ovule)
  • Seed Dispersal – fertilised ovule (seed) moves away from the parent plant to reduce the competition for growth
42
Q

components of pistil

A

female

stigma
style
ovule

43
Q

components of stamen

A

male

anther
filament

44
Q

seed strcutre 5

A

little leaf = epicotyl
little stem/bulb = radicle
seed indent = microphyle
main body = cotyledon
opposide side of indent = testa

45
Q

what is germination

A

the process by which a seed emerges from a
period of dormancy and sprouts (forming a new plant)

46
Q

what is needed for germination 3

A
  • Oxygen (to produce ATP via aerobic respiration)
  • Water (to metabolically activate the cells)
  • Suitable temperature and pH (for enzyme activity)
47
Q

what is photoperiodism

A

The response of a plant to the length of day or night

controls flowering

48
Q

2 forms of the phytochrome

A
  • sunlight – Pr –> Pfr (fast)
  • night – Pfr –> Pr (slow)
49
Q

flowering requires…

A

a set length of uninterrupted darkness

50
Q

long day plants

A
  • Pfr activates flowering
  • Flowering induced when night length is SHORT (⇧ Pfr)
51
Q

short day plants

A
  • Pfr inhibits flowering
  • Flowering INDUCED when night length is long (⇩ Pfr)

HL Bio (53 decks)

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