5.1.5 Plant and Animal Responses

Question 1

How to plants respond to herbivores

Answer 1

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

Question 2

What are pheromones

Answer 2

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

Question 3

What are Tannins

Answer 3

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

Question 4

What are Alkaloids

Answer 4

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

Question 5

Phototropism , geotropism , chemotropism ,thigmotropism

Answer 5

• 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

Question 6

What is a nastic response

Answer 6

Non -directional response to external stimuli

- Mimosa pudica - fold when touched -thigmomnasty

Question 7

Function of auxin

Answer 7

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

Question 8

Role of Abscicic acid

Answer 8

Stop seed germination and growth

Cause stoma to close when plant under stress

Question 9

Role of cytokines

Answer 9

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

Question 10

Role of gibberellins

Answer 10

Promote seed germination and growth of stems

Question 11

Role of Ethan

Answer 11

Fruit ripening

Question 12

Investigation for geotropism

Answer 12

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

Question 13

Investigation for phototropism

Answer 13

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

Question 14

Role of auxin experiment

Answer 14

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

Question 15

Role of gibberellin

Answer 15

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

Question 16

How does auxins work

Answer 16

They move to cell wall on shaded side

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

Question 17

How does ABA cause stomata Closure

Answer 17

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

Question 18

How are plant hormones used commercially

Answer 18

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

Question 19

The CNS

Answer 19

Brain and spinal cord

Question 20

The PNS?

Answer 20

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

Question 21

How is the PNS split

Answer 21

Autonomic -involuntary responses i.e peristalsis

Somatic -voluntary actions i.e running

Question 22

How is the autonomic nervous split

Answer 22

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

Question 23

Differences between parasympathetic and sympathetic motor neurones

Answer 23

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

Question 24

Function of Hypothalamus

Answer 24

Maintains body temp

Produce hormones controlling pirturatary gland

Question 25

Function of cerebrum

Answer 25

Vision , hearing ,learning and thinking

Question 26

Cerebellum

Answer 26

Muscle co -ordination and balance

Question 27

Medulla oblongata

Answer 27

Controls breathing and heart rate

Question 28

Pirturitary gland

Answer 28

Release hormones or stimulate the release of hormones from other glands

Question 29

Blinking reflex

Answer 29

- 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

Question 30

Knee-jerk reflex

Answer 30

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

Question 31

What happens Physiologically as part of the flight or fight response

Answer 31

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

Question 32

Mechanism of Adrenaline

Answer 32

- 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

Question 33

Release of hormones from the context and medulla

Answer 33

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

Question 34

Circulatory system function -

Answer 34

- Deliver oxygen to the blood and co2 out the body - transport urea to he kidneys from liver - distribute heat around body

Question 35

Cardiac Output formula

Answer 35

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

Question 36

How can heart rate be modified

Answer 36

- altering force of ventricular systole - altering stroke volume - raising or lowering heart rate

Question 37

Where is the cardiovascular centre

Answer 37

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

Question 38

How Is Stimuli detected in the heart

Answer 38

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

Question 39

What can control the heart rate artificially

Answer 39

Pacemaker

Question 40

What are the 3 types of muscle

Answer 40

Skeletal cardiac and involuntary (Smooth muscle )

Question 41

Involuntary smooth muscle cell

Answer 41

Circular layer of smooth muscle | Longitudinal layer of smooth muscle

Question 42

Cardiac Muscle

Answer 42

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

Question 43

Voluntary muscle (skeletal)

Answer 43

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

Question 44

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

Question 45

Stimulation of muscle contraction

Answer 45

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

Question 46

Motor unit function

Answer 46

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

Question 47

structure of myofibril

Answer 47

Page 106 textbook | Sarcomere is about 2 um at rest .

Question 48

Thin filaments

Answer 48

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