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Biology Module 5 > Plant and animal responses 5.5 > Flashcards

Plant and animal responses 5.5 Flashcards

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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

allows the whole of the plant to receive light as if the lateral shoots were long it would cover the rest of the plant from getting light

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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
  • delay senescence in citrus
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18
Q

explain the experimental evidence that auxins maintain apical dominance

A
  • when auxins levels drop, causes ABA levels to drop
  • cytokinins diffuse evenly to promote lateral bud growth
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19
Q

explain the experimental evidence that gibberellins control stem elongation and germination

A

stem elongation: tall plants have higher gibberellin concentration than dwarf

germination: mutant seeds with non-functional gibberellin is applied externally

20
Q

how are cytokinins use commercially

A

prevent yellowing of lettuce leaves, promote shoot growth

21
Q

how are auxins used commercially

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

A

CNS
- brain
- spinal cord
- relay neurone

PNS
- receptors
- motor and sensory neurone

23
Q

what is the autonomic response

A

unconscious

e.g controls heart rate and breathing

24
Q

what is the somatic response

A

conscious

e.g moving hand up and down

25
Q

what is the sympathetic response

A

uses noradrenaline

fight or flight

increases heart rate

increases breathing rate

reduces digestion

dilates pupils

26
Q

what is the parasympathetic response

A

uses acetylcholine

rest and digest

decreases the heart rate

decreases breathing rate

increases digestion

constricts pupils

27
Q

what is the brain made up of and definitions

A
  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
Q

describe the knee jerk reflex

A
  • tap under kneecap - cause patellar tendon to stretch and extensor muscle too
  • sends reflex arc impulse through sensory neurone
  • reflex signal goes along one motor neurone causing the extensor muscle to contract
  • relay neurone inhibits the other motor neurone of flexor muscle and relaxes
  • leg kicks due to antagonistic muscle
29
Q

describe the blinking reflex

A
  • 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
Q

explain how coordinated responses work

A
  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
Q

describe what is the skeletal muscle

A
  • voluntary
  • multi-nucleate
  • cross-striated
  • contract quickly for speed
  • get fatigued
  • contract slowly for endurance
    -long muscle fibres
32
Q

describe what is the smooth muscle

A
  • 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
Q

describe what is the cardiac muscle

A
  • 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
Q

what is the neuromuscular junction

A

synapse between a motor neurone and muscle cell

uses AcH, binds to recpetors on post-synaptic membrane

work same as synapses between neurones

35
Q

what happens to the neuromuscular junction when a chemical is used

A

prevents the AcH from binding and being released

action potential not passed

muscle not contracted

36
Q

if chemical is used instead and action potential is not passed what effect does it have on the body

A

dangerous for muscles that control breathing e.g the intercostal muscles and diaphragm

cant respire aerobically

37
Q

what are myofibrils describe what the different structures are

A

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
Q

describe muscle contraction

A

myosin and actin slide over each other to make sarcomeres contract
(myofibrils DONT contract)

muscle relaxes and sarcomeres return to og length

39
Q

difference between relaxed and contracted sarcomeres

A

relaxed: A-band, I band and H band og length

contracted: A band same length, I band and H band shorten

40
Q

define sarcomere, sarcolemma, sarcoplasm, sarcoplasmic reticulum

A

sarcomere : basic functional unit of a fibre
sarcolemma: plasmic membrane around fibres
sarcoplasm: shared cytoplasm within fibres
sarcoplasmic reticulum: endoplasmic reticulum in sarcomere

41
Q

first step of the sliding filament model

A

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
Q

second stage of the sliding filament model

A

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
Q

third stage of the sliding filament model

A

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
Q

what happens when muscles stop being stimulated

A

Ca2+ leaves troponin mol. and returns to og shape

Tropomyosin blocks binding site

actin filaments slide back into relaxed position which lengthens sarcomere

45
Q

describe the ATP-creatine phosphate system

A

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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