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Biology OCR A level > 5.1.5 Plant and Animal Responses > Flashcards

5.1.5 Plant and Animal Responses Flashcards

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1
Q

How to plants respond to herbivores

A

Through chemical defences such as Tannins ,Alkaloids and pheromones which are are all toxic chemicals preventing themselves being eaten by plants

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2
Q

What are pheromones

A

Produce chemical which trigger a response from another - for example a plant will release a signal for parasites to eat caterpillars if they try eat plant

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3
Q

What are Tannins

A

Toxic to microorganism and herbivores , taste bad in upper epidermis in leaf and prevent infiltration of Pathan on in root

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4
Q

What are Alkaloids

A

Taste bitter and bind to proteins in gut to make digestion harder so less animals eat

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5
Q

Phototropism , geotropism , chemotropism ,thigmotropism

A
  • towards light or way (negative and positive )
  • roots grow towards pull of gravity
  • grow towards chemicals e.g pollen tubes towards chemical sin ovaries
  • roots wind around another plant
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6
Q

What is a nastic response

A

Non -directional response to external stimuli

- Mimosa pudica - fold when touched -thigmomnasty

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7
Q

Function of auxin

A

Promote cell elongation
Inhibit giro with of side shoots (lateral buds )
Prevent leaf abscission (LEAF FALL)

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8
Q

Role of Abscicic acid

A

Stop seed germination and growth

Cause stoma to close when plant under stress

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9
Q

Role of cytokines

A

Promote cell division
Overcome apical dominance (growth of lateral buds and side shoot)
Promote cell expansion

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10
Q

Role of gibberellins

A

Promote seed germination and growth of stems

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11
Q

Role of Ethan

A

Fruit ripening

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12
Q

Investigation for geotropism

A

3x Petri dish and moist cotton wool using same vol of water
Space 10 crest seeds
Tape lid and cover in foil preventing light from reaching
Leave where constant temp
Put each dish at different angles
All roots grow down and shoots up
Quantities results gained by measuring angle of cress root and amount of growth

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13
Q

Investigation for phototropism

A

Three plants -same soil same size and age
One covered tip in foil one base in foil and one covered in nothing
Same distance from light and same intensity
All grow to light other than the one with tip covered
Auxins produced in tip which allows cell elongation to bend and most sensitive to light

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14
Q

Role of auxin experiment

A

Plant 30 pea plants that similar age height and weight in pots
Count number of side shoots growing from each plant
For 10 remove tip and add paste containing auxin and for the other add a past not containing auxin
Leave 10 pea pants as control -comparison to see if its due to hormone and not her factor
Let plant grow keeping water availability oxygen and temp equal
Count number of side shoots now

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15
Q

Role of gibberellin

A 
Add plants to pots 
Control all variable 
Water in gibberellin
Leave for 40 days 
Measure length once a week
Gibberellin causes more growth
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16
Q

How does auxins work

A

They move to cell wall on shaded side

Encourage movement of H+ To cell wall which creates optimum condition for expansins to work

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17
Q

How does ABA cause stomata Closure

A

ABA binds to receptors in the guard cell wall
Ca ion channel open so calcium moves in
Causes other ion channel to open causing ions to leave guard cells increasing water potential
Cells become flaccid causing stoma to close

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18
Q

How are plant hormones used commercially

A

Auxins are in herbicides to kill weed as it causes root to grow so long weed canst support
Auxins are in rooting powder to help cell roots grow
Help promote ovule growth in seedless fruit that is unpollinated
Ethene helps ripen fruit as it stimulates enzymes that break starch to sugars
Gibberellin can extend the time fruit is left unpicked

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19
Q

The CNS

A

Brain and spinal cord

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20
Q

The PNS?

A

Neurones (sensory and motor ) connecting receptors and effectors to cns

21
Q

How is the PNS split

A

Autonomic -involuntary responses i.e peristalsis

Somatic -voluntary actions i.e running

22
Q

How is the autonomic nervous split

A

Sympathetic =fight or flight - release nor adrenaline as neurotransmitter -involves sensory neurones
Parasympathetic = rest and digest - nueoronetransimmter is acetylcholine-involves motor neurones and cranial nerves

23
Q

Differences between parasympathetic and sympathetic motor neurones

A

Para-long preganglionic motor neurones , short post ganglion in motor neurone -ganglion near visceral organ
Sympathetic -short pregangionic and long post ganglionic -ganglion near spinal cord

24
Q

Function of Hypothalamus

A

Maintains body temp

Produce hormones controlling pirturatary gland

25
Q

Function of cerebrum

A

Vision , hearing ,learning and thinking

26
Q

Cerebellum

A

Muscle co -ordination and balance

27
Q

Medulla oblongata

A

Controls breathing and heart rate

28
Q

Pirturitary gland

A

Release hormones or stimulate the release of hormones from other glands

29
Q

Blinking reflex

A
  • reflex arc don’t travel to conscious part of brain
  • sensory neurones in cornea respond to touch
  • sensory neurones travel to PONS in the brain
  • action potential to relay neurone - non myelinated cause shorts and then to ,motor neurone which passes back thru the face and triggers the facial muscles to close the eyelid
  • Consciously you can override the response if ap is passed to myelinated neurones which can carry the ap to the sensory region in the cerebral cortex quicker than non myelinated
30
Q

Knee-jerk reflex

A

Spinal reflex - passes thur spinal cords not the brain like the corneal reflex

Stretch receptors in quadriceps detect stretch (muscle spindles )
Nerve impulse travels along sensory neurone which triggers a response in the motor neurones directly without use of relay neurones
Motor travels to effector causing quads to contract
Can’t inhibit this response as brain is ware it happening but no relay neurone means u can’t trigger response

31
Q

What happens Physiologically as part of the flight or fight response

A

Pupils dilate
Heart increase and blood pressure
Erector pili muscles in skin contract - make hairs stand

32
Q

Mechanism of Adrenaline

A
  • sensory neurones arrive at hypothalamus
  • hypothalamus activate the sympathetic nervous system and hormonal system by causing the pirtuartairy gland to release ACTH which activates the sympathetic nervous system
  • this causes the adrenal medulla to release adrenaline
  • adrenaline is the first messenger which bind to specific receptors in plasma membrane
  • activates an enzyme callled adenyl cyclase by the G protein under receptor which converts ATP to cAMP ,
  • cAMP causes a cascade of reaction which create more glucose by catalysing the breakdown of glycogen to glucose
33
Q

Release of hormones from the context and medulla

A

Cortex Releases steroid hormones such as cortisol, these hormones have a long time and short-term response to stress, they stimulate the breakdown of proteins and fats into glucose providing more energy for the brain and muscles, the increased blood volume and pressure by increasing the uptake of sodium ions and water by the kidneys.
-Releases cortisol by ACTH released from pirturiatry gland

Medulla releases adrenaline and nor adrenaline

34
Q

Circulatory system function -

A
  • Deliver oxygen to the blood and co2 out the body
  • transport urea to he kidneys from liver
  • distribute heat around body
35
Q

Cardiac Output formula

A

Stroke volume x heart rate
M/beat , beats/m
Cardiac output = m/minute

36
Q

How can heart rate be modified

A
  • altering force of ventricular systole
  • altering stroke volume
  • raising or lowering heart rate
37
Q

Where is the cardiovascular centre

A

The cardio vascular centre is found in the medulla oblongata

  • these nerves supply the SAN
  • AP sent down accelerans nerve cause release of nor adrenaline to the SAN
  • AP sent down the vagus nerve release acetyl choline which slow down heart rate
38
Q

How Is Stimuli detected in the heart

A

From chemical receptors and pressure receptors
-chemical receptors (chemoreceptors ) - found in the aorta , caratoid artery , and medulla - they detect o2 levels and c02 and ph
-Pressure receptors (baroreceptors ) -aorta and vena cava
These send impulses to medulla via sensory neurones which send impulse to SAN via motor neurones

39
Q

What can control the heart rate artificially

A

Pacemaker

40
Q

What are the 3 types of muscle

A

Skeletal cardiac and involuntary (Smooth muscle )

41
Q

Involuntary smooth muscle cell

A

Circular layer of smooth muscle

Longitudinal layer of smooth muscle

42
Q

Cardiac Muscle

A

Forms muscular part of the heart
Individual cells of long fibres , branch to form cross bridges between the fibres -cross bridges help to ensure electrical stimulation split equally
Cells are joined by intercalated discs - produce gaps to allow diffusion of ions between cells so ap can travel easily
Appear striated under microscope

43
Q

Voluntary muscle (skeletal)

A

Occurs at joints in the skeleton
Muscle cell fibres are about 100 um in diameter , surround by a membrane called sarcolema
Muscle cell cytoplasm is known as sarcoplasm specialised with many mitochondria and sarcoplasmic reticulum
Contents of fibres are arranged into a number of myofibrils which are divided into sarcomeres

44
Q

Photo of each muscle tissue type and structure of skeletal muscle under microscope

A
45
Q

Stimulation of muscle contraction

A

AP arrive at end of axon and open calcium ion channels ,calcium ions flood into axon
Vesicles of acetyl choline move towards membrane and fuse
Acetyl choline molecules diffuse across the gap and fuse with receptors in the sarcolema
Opens sodium ion channels and allows sodium channels to enter muscle fibre ,causing depolarisation of the sarcolema
A wave of depolarisation spreads along the sarcolema and down transverse tubules into the muscle fibres

46
Q

Motor unit function

A

Motor neurone split across many muscle fibres and contract together to produce a stronger contraction

47
Q

structure of myofibril

A

Page 106 textbook

Sarcomere is about 2 um at rest .

48
Q

Thin filaments

A

Actin
Wound around each actin filament is a a molecule of tropomysin to which are attached globular molecules of troponin
Troponin complex bind to actin ,one to tropomysosin , and one attached to calcium when available
At rest tropomysoin and troponin block binding sites and stop them being exposed to stop muscular contraction

Biology OCR A level (1 decks)

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