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Biology year 2 > Plant and animal responses > Flashcards

Plant and animal responses Flashcards

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1
Q

Plant chemical responses to herbivores

A

-tannins- toxic and make leaf taste bad
-alkaloids- growing tips and flowers, making them taste bitter
-pheromones- affect the behaviour or physiology of another organism

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2
Q

Types of plant response

A

Tropisms- directional growth responses:
-phototropism- shoots grow towards light= positively phototropic
-geotropism- roots grow towards the pull of gravity, anchoring them in the soil
-chemotropism- response to chemicals eg. pollen grows down style attracted by chemicals
-thigmotropism- shoots of climbing plants wind around other plants
Nastic response- non directional response to external stimuli eg. mimosa folding leaves when touched = thigmonasty

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3
Q

Effect cytokinins

A

-promote cell division
-delay leaf aging
-overcome apical dominance

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4
Q

Effect abscisic acid

A

-inhibits seed germination
-stomatal closure when low water availability

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5
Q

Effect auxins

A

-promote cell elongation
-inhibit growth side shoots
-inhibit leaf fall

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6
Q

Effect gibberellins

A

-promote seed germination
-promote growth of stems

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7
Q

Effect ethene

A

-promotes fruit ripening

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8
Q

Auxin when tip broken off and role abscisic acid, cytokinins

A

-auxin prevents growth lateral buds
-when tip broken, auxin levels drop and side shoots grow
-tested by applying auxin paste to broken tip and lateral buds didn’t grow
-high auxin keeps abscisic acid levels high, when tip removed, abscisic acid level drop causing growth lateral buds
-cytokinins promote lateral bud growth by overriding apical dominance effect. High auxin makes shoot apex a sink for cytokinins, when removed, they spread around plant

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9
Q

Gibberellic acid experiments

A

-compare GA1 levels of tall vs short pea plants
-Le gene responsible for producing enzyme that converts GA20 to GA1
-dominant Le allele= tall plant

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10
Q

Seed germination

A

-seed absorbs water and embryo releases gibberellins
-enables production amylase which breaks down starch to glucose
-glucose can be respired so seed grows

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11
Q

Location of meristems in plants

A

-apical meristems in tips of shoots or roots
-lateral bud meristems
-lateral meristems for widening of roots and shoots

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12
Q

Mechanism of auxin’s effect

A

-increases stretchiness of cell wall by promoting active transport of H+ by ATPase enzyme on membrane
-this decreased pH is optimum for wall-loosening enzymes to work
-enzymes break bonds between cellulose so become less rigid

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13
Q

Enzymes involved in redistribution of auxin

A

-phototropin 1 and phototropin 2- activity promoted by blue light

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14
Q

Commercial uses auxin

A

-take cuttings and dip in auxin to encourage root growth
-treat unpollinated flowers with auxin, it will grow seedless fruit
-used as herbicides as stems grow rapidly so the weed can’t support itself so buckles and dies

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15
Q

Commercial uses cytokinins

A

-prevent yellowing lettuce leaves after picked
-mass production of plants

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16
Q

Commercial uses gibberellins

A

-used in shops to keep fruit fresh for longer
-make apples elongate to improve shape
-elongate grape stalks, meaning grapes grow bigger
-brewing, as speed up process
-sugar productions, stems elongate, so more sugar available from each plant

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17
Q

Commercial uses ethene

A

-speed up fruit ripening in apple, tomatoes etc
-promote fruit drop in walnuts, cherries
-

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18
Q

Nervous system divisions

A

-divides CNS and PNS
-CNS divides spinal cord and brain
-PNS divides into motor and sensory
-motor divides autonomic and somatic
-autonomic divides into parasympathetic and sympathetic

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19
Q

CNS

A

-brain composed relay neurones, non-myelinated= grey matter
-spine has non-myelinated relay neurones making up grey matter, but also has myelinated which make outer region white matter

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20
Q

Motor nervous system

A

-conducts AP from CNS to effectors
-divided into somatic= voluntary control eg. muscles and autonomic= non-voluntary eg. glands

21
Q

Sympathetic system

A

-many nerves leading out CNS to effector
-ganglia outside CNS
-noradrenaline= neurotransmitter
-increase activity

22
Q

Parasympathetic system

A

-few nerves leading out CNS to effector
-ganglia in effector tissue
-acetylcholine= neurotransmitter
-decreases activity

23
Q

Cerebrum

A

-2 cerebral hemispheres
-higher brain functions eg. conscious thought, intelligence, decisions
-cerebral cortex- outermost layer for sensory, association and motor areas
Sensory areas-receive AP from sensory receptors
Motor areas- send AP to effectors
Association areas- compare sensory input with experience to come up with appropriate response

24
Q

Cerebellum

A

-balance and fine coordination
-receives info from sensory receptors eg. retina
-control requires learning and can then become 2nd nature
-cerebrum and cerebellum connected by pons

25
Q

Hypothalamus

A

-centre brain above pituitary gland
-controls homeostatic mechanisms using negative feedback eg. osmoregulation

26
Q

Pituitary

A

-posterior- links hypothalamus by neurosecretory cells to release hormones from hypothalamus
-anterior- produces hormones in response to releasing factor from hypothalamus

27
Q

Medulla oblongata

A

-control non skeletal muscles eg. cardiac by AP in ANS
-regulates heart rate, blood pressure, breathing rate
-coordinates by negative feedback

28
Q

Reflex actions

A

-don’t involve any processing in the brain to coordinate movement
-3 neurones - sensory, relay, motor
-for survival or to avoid danger

29
Q

Corneal reflex

A

-mediated sensory neurone in cornea that enters the pons
-3 neurones- sensory, relay, motor
-2 synapses
-rapid and causes both eyes to blink even if only 1 effected

30
Q

Optical reflex

A

-dilation of pupil
-can’t be overridden
-protects the retina from light damage
-slower than corneal reflex

31
Q

Knee jerk reflex

A

-spinal reflex
-2 neurones- sensory + motor
-one synapse

32
Q

Mechanism of adrenaline action

A

-binds receptor on plasma membrane
-activates g protein, which activates adenyl cyclase
-converts ATP to cAMP = 2nd messenger
-causing an effect inside cell by activating enzyme action

33
Q

Release of hormones from pituitary
molecules released

A

-CRH form hypothalamus causes release of ACTH which stimulates adrenal cortex to release cortisol, causing more glucose to be released from glycogen stores
-TRH causes release of TSH which causes more thyroxine to be released from thyroid gland, this increases metabolic rate of cells

34
Q

Roles of heart

A

-transport of oxygen and nutrients
-removal of waste eg CO2
-transport urea from liver to kidney
-distribute heat

35
Q

Myogenic

A

-the heart can initiate its own beat at regular intervals

36
Q

Change heart rate by cardiovascular centre

A

-in medulla oblongata
2 nerves alter frequency of contractions
-accelerans nerve- causes release noradrenaline which increases heart rate
-vagus nerve- releases acetylcholine which reduces heart rate

37
Q

Sensory input to cardiovascular centre

A

-stretch receptors in muscles, increased stretch= more Na+ released, so AP reached and sent to cardiovascular centre to increase heart rate
-chemoreceptors- monitor pH, high CO2 decreases pH, detected and send AP to cardiovascular centre
-Baroreceptors- monitor blood pressure, increase blood pressure causes stretching carotid artery, this prevents heart rate going too high

38
Q

Artificial control heart rate

A
  • artificial pacemaker which delivers electrical impulse to heart
    -implanted under skin or within chest cavity
    -connected to SAN or to ventricle muscle
39
Q

3 types muscle

A

Smooth (involuntary) muscle
-individual cells
-spindle shaped
-controlled autonomic NS
-arranged longitudinal and circular layers
Cardiac muscle
-individual cells form long fibres which branch forming cross bridges
-cells joined intercalated discs which allow free diffusion of ions between cells
Skeletal (striated) muscle
-cells form fibres which are multinucleate
-each fibre surrounded by the sarcolemma
-cytoplasm= sarcoplasm
-ER= sarcoplasmic reticulum
-arranged into myofibrils that divide into sarcomeres

40
Q

Structure of myofibril

A

-contain 2 types protein filament
-thin filaments= actin which make up light band held by z line
-thick filaments= myosin which make up dark band held by M line

41
Q

Sarcomere structure

A

-z line to z line
-gap where no overlap= H zone
-A band= length of thick filament
-I band= thin filament without overlapping thick filament

42
Q

Muscle contraction stimulation and control

A

-AP arrives at pre synaptic bulbs which opens Ca2+ channels
-Ca2+ diffuse in causing vesicles with acetylcholine to fuse with the membrane
-AC diffuses across cleft and binds receptors on Na+
-opens Na+, diffuse in, depolarising membrane
-depolarisation spreads along the sarcolemma and down the transverse tubules
-this causes Ca2+ to be released from the sarcoplasmic reticulum
-Ca2+ bind troponin, which alters the shape and pulls tropomyosin aside, exposing binding sites
-myosin heads bind to sites forming cross bridges
-heads move pulling the actin filament past the myosin filament
-myosin heads detach from actin and can bind again further up the actin filament
-acetylcholinesterase breaks down AC to stop another contraction

43
Q

Motor unit

A

-when all muscle fibres contract together providing a stronger contraction

44
Q

Thin filaments

A

-2 chains of actin wound around each other
-wound with tropomyosin and troponin
-at rest these proteins cover the binding sites so the thick filaments can’t bind

45
Q

Thick filaments

A

-bundle myosin fibres
-each myosin molecule has 2 protruding heads
-heads are mobile and bind to actin when site exposed

46
Q

Sliding filament hypothesis

A

-during contraction light band and H zone shorten
-z lines move closer, sarcomere gets shorter

47
Q

Roles of ATP in muscle contraction

A

-myosin head attaches to actin forming cross bridges
-head moves backwards, causing actin to slide past= power stroke which releases ADP + Pi form head
-after power stroke, ATP binds to head breaking cross bridge
-myosin head returns to normal position as ATP hydrolysed, releasing energy for this to occur

48
Q

Maintaining supply of ATP for muscle contractions

A

-aerobic respiration in mitochondria
-anaerobic respiration in the sarcoplasm
-creatine phosphate- in sarcoplasm and acts as a reserve of phosphate groups

Biology year 2 (14 decks)

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