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Biology year 2 > Plant and animal responses > Flashcards

Plant and animal responses Flashcards

(48 cards)

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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

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A

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

21
Q

Sympathetic system

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A

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

22
Q

Parasympathetic system

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A

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

23
Q

Cerebrum

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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

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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
Hypothalamus
-centre brain above pituitary gland -controls homeostatic mechanisms using negative feedback eg. osmoregulation
26
Pituitary
-posterior- links hypothalamus by neurosecretory cells to release hormones from hypothalamus -anterior- produces hormones in response to releasing factor from hypothalamus
27
Medulla oblongata
-control non skeletal muscles eg. cardiac by AP in ANS -regulates heart rate, blood pressure, breathing rate -coordinates by negative feedback
28
Reflex actions
-don't involve any processing in the brain to coordinate movement -3 neurones - sensory, relay, motor -for survival or to avoid danger
29
Corneal reflex
-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
Optical reflex
-dilation of pupil -can't be overridden -protects the retina from light damage -slower than corneal reflex
31
Knee jerk reflex
-spinal reflex -2 neurones- sensory + motor -one synapse
32
Mechanism of adrenaline action
-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
Release of hormones from pituitary molecules released
-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
Roles of heart
-transport of oxygen and nutrients -removal of waste eg CO2 -transport urea from liver to kidney -distribute heat
35
Myogenic
-the heart can initiate its own beat at regular intervals
36
Change heart rate by cardiovascular centre
-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
Sensory input to cardiovascular centre
-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
Artificial control heart rate
- artificial pacemaker which delivers electrical impulse to heart -implanted under skin or within chest cavity -connected to SAN or to ventricle muscle
39
3 types muscle
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
Structure of myofibril
-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
Sarcomere structure
-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
Muscle contraction stimulation and control
-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
Motor unit
-when all muscle fibres contract together providing a stronger contraction
44
Thin filaments
-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
Thick filaments
-bundle myosin fibres -each myosin molecule has 2 protruding heads -heads are mobile and bind to actin when site exposed
46
Sliding filament hypothesis
-during contraction light band and H zone shorten -z lines move closer, sarcomere gets shorter
47
Roles of ATP in muscle contraction
-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
Maintaining supply of ATP for muscle contractions
-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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