5.1.5 Plant and Animal Responses Flashcards
How to plants respond to herbivores
Through chemical defences such as Tannins ,Alkaloids and pheromones which are are all toxic chemicals preventing themselves being eaten by plants
What are pheromones
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
What are Tannins
Toxic to microorganism and herbivores , taste bad in upper epidermis in leaf and prevent infiltration of Pathan on in root
What are Alkaloids
Taste bitter and bind to proteins in gut to make digestion harder so less animals eat
Phototropism , geotropism , chemotropism ,thigmotropism
- 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
What is a nastic response
Non -directional response to external stimuli
- Mimosa pudica - fold when touched -thigmomnasty
Function of auxin
Promote cell elongation
Inhibit giro with of side shoots (lateral buds )
Prevent leaf abscission (LEAF FALL)
Role of Abscicic acid
Stop seed germination and growth
Cause stoma to close when plant under stress
Role of cytokines
Promote cell division
Overcome apical dominance (growth of lateral buds and side shoot)
Promote cell expansion
Role of gibberellins
Promote seed germination and growth of stems
Role of Ethan
Fruit ripening
Investigation for geotropism
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
Investigation for phototropism
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
Role of auxin experiment
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
Role of gibberellin
Add plants to pots Control all variable Water in gibberellin Leave for 40 days Measure length once a week Gibberellin causes more growth
How does auxins work
They move to cell wall on shaded side
Encourage movement of H+ To cell wall which creates optimum condition for expansins to work
How does ABA cause stomata Closure
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
How are plant hormones used commercially
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
The CNS
Brain and spinal cord
The PNS?
Neurones (sensory and motor ) connecting receptors and effectors to cns
How is the PNS split
Autonomic -involuntary responses i.e peristalsis
Somatic -voluntary actions i.e running
How is the autonomic nervous split
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
Differences between parasympathetic and sympathetic motor neurones
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
Function of Hypothalamus
Maintains body temp
Produce hormones controlling pirturatary gland
Function of cerebrum
Vision , hearing ,learning and thinking
Cerebellum
Muscle co -ordination and balance
Medulla oblongata
Controls breathing and heart rate
Pirturitary gland
Release hormones or stimulate the release of hormones from other glands
Blinking reflex
- 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
Knee-jerk reflex
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
What happens Physiologically as part of the flight or fight response
Pupils dilate
Heart increase and blood pressure
Erector pili muscles in skin contract - make hairs stand
Mechanism of Adrenaline
- 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
Release of hormones from the context and medulla
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
Circulatory system function -
- Deliver oxygen to the blood and co2 out the body
- transport urea to he kidneys from liver
- distribute heat around body
Cardiac Output formula
Stroke volume x heart rate
M/beat , beats/m
Cardiac output = m/minute
How can heart rate be modified
- altering force of ventricular systole
- altering stroke volume
- raising or lowering heart rate
Where is the cardiovascular centre
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
How Is Stimuli detected in the heart
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
What can control the heart rate artificially
Pacemaker
What are the 3 types of muscle
Skeletal cardiac and involuntary (Smooth muscle )
Involuntary smooth muscle cell
Circular layer of smooth muscle
Longitudinal layer of smooth muscle
Cardiac Muscle
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
Voluntary muscle (skeletal)
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
Photo of each muscle tissue type and structure of skeletal muscle under microscope
Stimulation of muscle contraction
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
Motor unit function
Motor neurone split across many muscle fibres and contract together to produce a stronger contraction
structure of myofibril
Page 106 textbook
Sarcomere is about 2 um at rest .
Thin filaments
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
