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Biology Module 5 > Plant and animal responses 5.5 > Flashcards

Plant and animal responses 5.5 Flashcards

(45 cards)

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1
Q

describe what are auxins/IAA

A
  • found in apical meristems
  • cell elongation
  • maintains apical dominance
  • inhibits lateral shoot growth
  • inhibits fruit ripening
  • inhibits abscission
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2
Q

describe what are gibberellins

A
  • promotes seed germination
  • promotes stem elongation
  • stimulates pollen growth in fertilisation
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3
Q

describe what is ethene

A
  • promotes fruit ripening
  • promotes abscission
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4
Q

describe what is abscissic acid/ABA

A
  • maintains dormancy in leaves and seeds
  • stimulates protective measurements like antifreeze and stomatal closure
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5
Q

define tropisms

A

a directional growth response in plants

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6
Q

what is phototropism

A

shoots grow towards light (+ve tropism)

  • allows photosynthesis

roots away (-ve)

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7
Q

what is geotropism

A

roots grow towards pull of gravity (+ve)

  • helps intake lots of water for support
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8
Q

what are physical defences in plants

A

thorns, spikes or hairy leaves

folding leaves in response to touch

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9
Q

what are chemical defences in plants

A

Alkaloids : bitter taste and poisonous to animals

Phermones - affects the social behaviour of other members of the same species

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10
Q

describe abscission as a response to abiotic stress

A
  • phtochromes detect change is light levels or season
  • ethene produces hydrolytic enzymes
  • enzymes digest cell wall of separation zone
  • separation zone falls off
  • vascular bundles sealed off
  • leaf fall
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11
Q

what are the benefits of abscission

A
  • reduces energy needed to maintain leaves in the winter
  • fallen leaves insulate roots
  • rotten leaves provide minerals to plants
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12
Q

describe lack of water as a response to abiotic stress

A
  • roots detect lack of water and produce ABA
  • ABA travels to leaves and binds to receptors on guard cells
  • ions move out of guard cell and affects the water potential gradient
  • water leaves by osmosis
  • guard cells become flaccid and close stomata
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13
Q

describe the effect of auxin concentration on apical dominance

A
  • high auxin concentrations inhibit root growth and promote shoot growth
  • low auxin concentrations promote root growth and inhibit shoot growth
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14
Q

what are the benefits of apical dominance

A

inhibits lateral growth and promotes vertical growth so that whole plant can recieve light and photosynthesise

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15
Q

how does gibberellin concentration affect stem elongation

A

high gibberellin concentration means:

  • longer internodes

-therefore taller plants

  • and compete better for light

-so higher rate of photosynthesis

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16
Q

how is ethene used for commercial use

A

in fruits:
- speeds up ripening

  • promotes lateral growth

-promotes fruit drop

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17
Q

how are gibberellins used for commercial uses

A
  • farmers can prevent stem elongation to reduce waste and prevent crop damage in bad weather
  • breaking dormancy
  • flowering regardless of season
  • seedlless fruit
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18
Q

explain the experimental evidence that auxins maintain apical dominance

A
  • removing shoot of apex means removing the source of auxins, causes cytokinins to stimulate lateral bud growth
  • and causes ABA levels to drop
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19
Q

explain the experimental evidence that gibberellins control stem elongation and germination

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A

stem elongation: tall plants have higher gibberellin concentration than dwarf

farmers can apply gibberellin externally onto dwarf plants to make them grow taller

mutant seeds with non-functional gibberellin is need gibberellin applied externally to germinate

20
Q

how are cytokinins use commercially

Study These Flashcards
A

prevent yellowing of lettuce leaves, promote shoot growth

21
Q

how are auxins used commercially

Study These Flashcards
A

rooting powder

growing seedless fruit

herbicides

low concentrations prevent leaf and fruit drop

high concentrations promote fruit drop

22
Q

describe the difference between the CNS and PNS

Study These Flashcards
A

CNS
- brain
- spinal cord
- relay neurone

PNS
- receptors
- motor and sensory neurone

23
Q

what is the autonomic response

Study These Flashcards
A

unconscious

e.g controls heart rate and breathing

24
Q

what is the somatic response

Study These Flashcards
A

conscious

e.g moving hand up and down

25
what is the sympathetic response
uses noradrenaline fight or flight increases heart rate increases breathing rate reduces digestion dilates pupils
26
what is the parasympathetic response
uses acetylcholine rest and digest decreases the heart rate decreases breathing rate increases digestion constricts pupils
27
what is the brain made up of and definitions
1. cerebrum : main part of the brain that controls hearing,sight , thinking etc 2. cerebellum : movement, coordination and balance 3. medulla oblongata : autonomic, controls heart rate and breathing ] 4. hypothalamus : autonomic , controls homeostasis 5. pituitary gland : posterior (back) , controlled by hypothalamus and stores and releases ADH anterior (front), own glands and release own hormones
28
describe the knee jerk reflex
- tap under kneecap (patellar tendon) - stretch receptors detect signal - The impulses travel along a sensory neurone to the spinal cord - passed to a motor neurone, which takes it to a muscle in the leg - leg kicks due to antagonistic muscle fast bcs: - doesnt invlove the brain - only 1 synapse
29
describe the blinking reflex
- cornea is irritated -triggers impulse along sensory neurone - relay neurone in lower brain stem and passes impulse along - signal branches out in motor neurones to eyelid muscles - both eyes shut due to a consensus response
30
explain how coordinated responses work
1. nervous system detects threat stimuli 2. stimulates autonomic response 3. triggers hypothalamus - stimulates the sympathetic nervous system which signals the adrenal medulla to release adrenaline and noradrenaline AND - stimulates the pituitary gland to release ACTH, signals the adrenal cortex to release steroids hormones
31
describe what is the skeletal muscle
- voluntary - multi-nucleate - cross-striated - contract quickly for speed - get fatigued - contract slowly for endurance - long muscle fibres
32
describe what is the smooth muscle
- involuntary - found in walls of internal organs e.g small intestine - one nucleus - spindle shaped with pointed ends - very small and short - contract slowly - dont fatigue
33
describe what is the cardiac muscle
- heart muscle - myogenic - connected by intercalated discs - for low electrical resistance for fast impulses - branched - allow impulses to spread through the heart - contract rhythmically and don't fatigue - some striations
34
what is the neuromuscular junction
synapse between a motor neurone and muscle cell uses AcH, binds to recpetors on post-synaptic membrane work same as synapses between neurones
35
what happens to the neuromuscular junction when a chemical is used
prevents the AcH from binding and being released action potential not passed muscle not contracted
36
if chemical is used instead and action potential is not passed what effect does it have on the body
dangerous for muscles that control breathing e.g the intercostal muscles and diaphragm cant respire aerobically
37
what are myofibrils describe what the different structures are
made of sarcomeres thick myofibrils = myosin dark bands = A bands - myosin thin = actin Light bands = I bands - actin in the middle = M line around M line = H line and contains myosin only
38
describe muscle contraction
myosin and actin slide over each other to make sarcomeres contract (myofibrils DONT contract) muscle relaxes and sarcomeres return to og length
39
difference between relaxed and contracted sarcomeres
relaxed: A-band, I band and H band og length contracted: A band same length, I band and H band shorten
40
define sarcomere, sarcolemma, sarcoplasm, sarcoplasmic reticulum
sarcomere : basic functional unit of a fibre sarcolemma: plasmic membrane around fibres sarcoplasm: shared cytoplasm within fibres sarcoplasmic reticulum: endoplasmic reticulum in sarcomere
41
first step of the sliding filament model
stimulation and attachment action potential triggers influx of Ca2+ ions sarcoplasmic reticulum releases Ca2+ into the sarcoplasm Ca2+ binds to troponin and causes conformational change and pulls the tropomyosin out of A-M binding site myosin head binds to exposed site A-M cross bridge formed
42
second stage of the sliding filament model
movement of myosin head Ca2+ activate enzyme ATPase which breaks down ATP to ADP and Pi causes myosin head to bend releases ADP+Pi causes myosin head to move myosin filament along
43
third stage of the sliding filament model
detachment another mol. of ATP binds to myosin head, breaks cross-bridge, myosin head detaches M head reattaches to a diff binding site along actin filament new cross-bridge formed cycle repeated
44
what happens when muscles stop being stimulated
Ca2+ leaves troponin mol. and returns to og shape Tropomyosin blocks binding site actin filaments slide back into relaxed position which lengthens sarcomere
45
describe the ATP-creatine phosphate system
anaerobic and antlactic CP stored in ATP-CP system to generate ATP quickly used in short burst of vigorous exercise

Biology Module 5 (7 decks)

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