Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

OCR Biology A Level Module 5 Communication, homeostasis and energy > 5.5 Plant And Animal Responses > Flashcards

5.5 Plant And Animal Responses Flashcards

1
Q

What is a reflex action?

A

Response to stimulus that doesn’t involve the brain to coordinate movement, always with a survival value

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Explain the blinking reflex - what type of reflex is it? What occurs?

A
  • uses brain but without higher thought processes: CRANIAL
  • stimulus, then sensory neurone from cornea carries impulses to sensory centre in pons, which travels through non-myelinated relay neurone to motor centre in pons, and via motor neurone to facial muscles which usually causes both eyes to blink
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe how the knee jerk reflex works

A

Coordinated movement and balance

Stimulus - stretching of the quadriceps muscle caused by pressure on the ligament
Receptor - stretch receptors in the quadriceps muscle
Coordinator - the spinal cord
Effector - the quadriceps muscle
Response - contraction of the quadriceps muscle, causing the leg to straighten

Sensory -> motor ( bypasses relay)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What physiological changes occur when adrenaline is released?

A
  1. Pupils dilate so more light enters
  2. Heart rate and blood pressure increases so more oxygen and glucose reaches muscles
  3. Arterioles to digestive system constricted, to divert blood to muscles
  4. Blood glucose increases = more energy for muscle contraction
  5. Erector pills muscles contract = hairs stand up
  6. Ventilation rate increases to increase gaseous exchange
  7. Endorphins released = natural painkillers so wounds inflicted do not prevent activity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the pathway of nervous coordination of the fight or flight response

A

Inputs into cerebrum sensory centres -> signals to association centres -> hypothalamus stimulated -> activates sympathetic nervous system -> activate glands and smooth muscles or activates adrenal medulla to secrete adrenaline into bloodstream. Neuronal activity combines with hormones to constitute fight or flight response.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the pathway of endocrine communication in the fight or flight response

A

hypothalamus stimulated to secrete hormones into blood which pass down portal vessel to stimulate anterior pituitary gland to release tropic hormones

CRH -> ACTH released from pit -> adrenal cortex secretes corticoids e.g. cortisol to regulate metabolism of carb -> bloodstream
TRH -> TSH released from pit -> thyroid glands secretes thyroxine to increase metabolic rate and make cells more sensitive to adrenaline -> bloodstream

Neuronal activity and hormones combine to carry out response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe adrenaline action once it reaches a cell

A
  1. Binds to plasma membrane receptor, stimulating G protein to active adenyl cyclase
  2. Converts ATP to cAMP (second messenger)
  3. Activates enzyme action
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How is heart action modified?

A

Changing heart rate
Altering force of contractions
Altering stroke volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does myogenic mean?

A

Can initiate its own beat at regular intervals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What do sensory inputs to the cardiovascular centre include?

A
  • Stretch receptors in muscles that detect movement of limbs -> more oxygen needed -> inc heart rate
  • Chemoreceptors in carotid arteries, aorta and brain monitor blood pH. If too low, APS sent to centre and inc heart rate
  • Baroreceptors in carotid sinus monitor blood pressure. Pressure too high = send APs to centre = dec heart rate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the solution if the mechanism controlling the heart fails? E.g. fibrillation occurs

A

Artificial pacemaker delivered, connected to SAN or to ventricle muscle directly, delivering electrical impulse to heart muscle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are some features of smooth muscle?

A

one nucleus per cell
contracts slowly and regularly
tubular structures : blood vessels, digestive system

circular layer -> segmentation in intestine (spindle shaped)
longitudinal -> wave like contractions (circle cells)

involuntary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are some features of cardiac muscle?

A

cells -> long fibres -> branch to form cross bridges between fibres to ensure stimulation spreads evenly

intercalated discs - specialised cell surface membranes fused to produce gap junctions -> allow free ion diffusion

appears striated under microscope

involuntary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are some features of skeletal muscle?

A

joints in skeleton
antagonistic pairs
each fibre is multinucleate and surrounded by sarcolemma membrane, and with sarcoplasm and sarcoplasmic reticulum

myofibrils divided into functional subunits called sarcomeres (actin and myosin)

striated appearance

contracts quickly and powerfully

voluntary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the process that occurs at a neuromuscular junction

A
  1. APs at end of axon open calcium channels; they enter
  2. Acetylcholine vesicles move towards membrane and fuse
  3. Diffuse across gap and bind to receptors
  4. Sodium channels open and delopolarisation occurs
  5. Wave of depolarisation passes along sarcolemma and down transverse tubules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is a motor unit?

A

muscle fibres contract together (many motor neurones divide and connect to several muscle fibres)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the light and dark band?

A

light: thin filaments, actin
dark: thick filaments, myosin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe the structure of actin filaments

A

two chains of subunits wound around eachother

troponin complexes

tropomyosin wrapped around

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the structure of myosin filaments

A

thick filament, with heads. each molecule has 2 heads

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the A band, I band and H zone?

A

A band: between points they overlap
I band: only actin
H zone: only myosin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What happens to sarcomeres during contraction?

A
  • thick and thin filaments slide past one another. H zone gets smaller, Z lines more closer, sarcomere gets shorter. Filaments do NOT change in length. Little/no I band also
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How is contraction controlled?

A
  1. AP passes along sarcolemma and into muscle fibre
  2. AP carried to sarcoplasmic reticulum, and causes calcium ion release into sarcoplasm
  3. Calcium ions bind to troponin, altering shape and pulling it aside (exposes actin binding sites)
  4. Myosin heads bind to actin = cross bridges form
  5. Myosin heads move, pulling actin filament past
  6. Myosin heads detach and can bind again further up
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the role of ATP in muscle contraction?

A
  1. Myosin head attaches to actin
  2. Power stroke occurs, ADP and Pi are released (part of myosin head acts as ATPase)
  3. New ATP attaches to myosin head, breaking cross bridge
  4. Myosin head returns to position as ATP is hydrolysed, releasing energy.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How is ATP supply maintained?

A
  1. Aerobic respiration in many mitochondria. But, during intense activity it is less than demand
  2. Anaerobic respiration but toxic lactic acid is produced
  3. CREATINE PHOSPHATE: phosphate can be transferred to ADP molecules.
25
Q

What is the function and structure of the cerebrum?

A

2 cerebral hemispheres connected via corpus callosum

outermost layer consists of thin nerve cell body layer = cerebral cortex

higher thought processes, emotions, conscious actions, intelligence, decisions, memory

26
Q

What are the 3 different areas of the cerebral cortex?

A

sensory areas: receive APs from sensory receptors. The size of regions receiving inputs are related to the sensitivity of area that those inputs are recieved from.

association areas: compare sensory inputs with previous experience and interpret what it means

motor areas: send APs to various effectors. size of regions related to complexity of movements needed in their allocated effectors.

27
Q

What is the function and structure of the cerebellum?

A
  • balance and fine movements
  • connected to cerebrum by pons
  • info from sensory receptors
    -neurones conduct APs to motor areas

maintaining body position and balance, judging position of objects, tensing muscles, coordination of antagonistic skeletal muscles

  • requires learning and complex pathways are strengthened by practice
28
Q

What is the general function of hypothalamus? Whats special about it?

A

homeostatic mechanisms
own sensory receptors

29
Q

What is the general function and structure of the pituitary gland?

A

posterior: ADH made in the hypothalamus, passes down neurosecretory cells and released there.

anterior: produces its own hormones and released in response to releasing factors

control many processes/homeostatic mechanisms also

30
Q

What is the general function and structure of the medulla oblongata?What 3 different centres does it have?

A
  • controls non skeletal muscles via APs through autonomic nervous system
  • cardiac centre: heart rate
  • vasomotor centre: blood pressure
  • respiratory centre: breathing rate
31
Q

How is the CNS divided?

A

brain: relay neurones (non-myelinated), grey matter
spinal cord: grey and white (myelinated) matter. Protected by vertebral column. Between each vertebrae, peripheral nerves enter and leave to carry APs to and from rest of body.

32
Q

How is the PNS divided?

A

sensory and motor system

motor system divided into somatic and autonomic (autonomic has sensory elements too)

33
Q

Explain in more detail what the peripheral system involves - nerves doing what? What is the difference between motor and sensory?

A

sensory and motor nerves connecting sensory receptors and effectors to CNS

sensory: conduct APs from sensory receptors into CNS. Cell body in ganglia in DORSAL root leading into spinal cord, and short axon connecting to other neurones in CNS.

motor: conduct APs from CNS to effectors

34
Q

What is the difference between somatic and autonomic?

A

SOMATIC: conduct APs under voluntary control e.g. skeletal muscles. myelinated neurones. 1 SINGLE MOTOR NEURONE from CNS to effector

AUTONOMIC: conduct APs not under voluntary control e.g. glands, smooth and cardiac muscle, airways etc. Mostly non-myelinated. At least have TWO MOTOR NEURONES connected at ganglia ( and sensory too).

35
Q

How can autonomic further be divided?

A
  • sympathetic (prepares body for activity)
  • parasympathetic (conserves energy)

these are antagonistic and at rest APs travel at low freq in both.

36
Q

What are the differences between sympathetic and parasympathetic?

A

SYM: many nerves each leading to separate effectors
PARA: few nerves divide up and lead to diff effectors

SYM: ganglia outside CNS
PARA: ganglia in effector

SYM: short pre-ganglionic neurones
PARA: long pre-ganglionic neurones

SYM: noradrenaline
PARA: acetylcholine

SYM: increases heart rate, dilates pupils, decreases digestive activity
PARA: decreases heart rate, constricts pupils, increases digestive activity.

37
Q

what 3 ways do plants use to defend against herbivory?

A

tannins: toxic to insects and bitter tasting to deter large animals. prevent infiltration by pathogenic microorganisms in roots

alkaloids: bitter nitrogenous compounds, often poisonous

pheromones: chemicals released by an individual which can affect behaviour/ physiology of another

38
Q

How do plants defend against high temp, low temp, drought and wind?

A

high: thicker wax layer deposited

low: AFP’s produced to decrease crystal formation

windy: vascular tissue more heavily lignified

drought: close stomata to reduce transpiration and increase abscission

39
Q

What is tropism vs nastic responses?

A

tropism = directional growth
nastic = non directional response

positive is towards, negative is away

40
Q

What are the advantages/ purposes of:

  1. phototropism
  2. geotropism
  3. chemotropism
  4. thigmotropsim
  5. thigmonastic
A
  1. shoots positively phototropic, so more LDR occurs
  2. roots positively geotropic -> anchor in soil and increase uptake of mineral ions and water
  3. on a flower, pollen tubes grow down style towards ovary
  4. shoots of climbing plants wind around structures for support and greater light access
  5. mimosa pudica responses to touch with sudden leaf folding
41
Q

Whats the role of auxins?

A

cell elongation, inhibit growth of side shoots, inhibit leaf abscission

42
Q

Whats the role of cytokinins?

A

cell division, delay leaf senescence, overcome apical dominance, cell expansion

43
Q

What is the role of abscisic acid?

A

inhibits seed germination and growth, causes stomatal closure

44
Q

What is the role of gibberellins?

A

promote seed germination and stem elongation

45
Q

What is the role of ethene?

A

fruit ripening
Leaf drop

46
Q

How do hormones move in plants?

A

mass flow in vessels, diffusion or active transport

47
Q

What is the evidence for seed germination by gibberellins?

A
  • seed absorbs water, embryo releases gibberellin which travels to aleurone layer in endosperm region of seed
  • enables amylase production. starch -> glucose used in respiration of embryo
48
Q

If you break off the shoot tip (——-), the plant starts to grow from ———–

Suggested auxins in ———– —— lateral buds from growing ( tip removed = auxin —— and buds grow)

A

apical bud
lateral buds

apical bud prevents
decreases

49
Q

What are the 3 types of meristem?

A
  • apical meristem at tips
  • lateral meristems as cylinders around edge of shoots and roots responsible for width
  • intercalary meristems between nodes
50
Q

How would you investigate phototropism and what results would you expect?

A
  • experimental: light on one side
  • control: light on all sides
  • both shoots and roots marked every 2mm at the start
  • moist cotton wool plug used
  • would expect shady side of experimental plant to be elongated more and therefore that plant bends towards the light
51
Q

How would you investigate geotropism and what results would you expect?

A
  • experimental plant: no klinostat -> root bends downwards as upper side elongated more
  • control plant: klinostat so gravity applied equally to all sides -> roots and shoots grow horizontally
52
Q

What is the mechanism of auxins effect in shoots?

A

SHOOTS:
- produced at apex and travels to cells in zone of elongation = shoot grows
- light shining on one side causes auxins to be transported to shaded side = elongation there.
-extent to which cells elongate is proportional to auxin con

  • promotes active transport of H+ by ATPase enzyme on plasma membrane, into cell walls = low pH = expansins work
  • these enzymes break bonds within cellulose so walls become less rigid
53
Q

What do auxins do in roots?

A
  • accumulate on lower side of roots and inhibits cell elongation= bends downwards
54
Q

What are the commercial uses of auxins?

A
  • promote flowering
  • inhibit leaf/fruit drop
  • rooting powders
  • treating unpollinated flowers can promote seedless fruit growth
  • weed killers since they promote root growth too much
55
Q

What are the commercial uses of cytokinins?

A
  • prevent yellowing of lettuce leaves
  • tissue culture to help mass-produce plants
56
Q

What are the commercial uses of gibberellins?

A
  • delay senescence in citrus fruits
  • can make apples and grape stalks elongate
  • can speed up amylase production for brewing (turning starch into maltose)
  • stimulates internodal growth of sugar cane
  • induce seed formation in young trees to speed up breeding
57
Q

What are the commercial uses of ethene?

A
  • speed up fruit ripening in citrus, apples and tomatoes
  • promoting fruit drop in cotton and walnut
  • promoting female sex expression in cucumbers reducing chance of self pollination
  • promoting lateral growth in some plants
  • or can RESTRICT ethene so fruits can be stored for longer
58
Q

Suggest why a lack of ATP leads to muscle rigidity

A
  • ATP required to break cross bridges
  • actin and myosin filaments remain cross linked
  • muscle remains contracted
59
Q

Describe the different sources of ATP that is used in muscle during strenuous exercise

A

Sources:
- free in sarcoplasm
- creatine phosphate
- runs out in a few seconds/ quickly

Aerobic respiration:
- if oxygen available
- oxidative phosphorylation
- greater yield of ATP
- but O2 doesnt meet demand as it’s limited during strenuous exercise

Anaerobic respiration:
-needed during strenous exercise
- only involves glycolysis
- ATP formed by substrate level phosphorylation
- net yield of 2 ATP
- NAD regenerated so glycolysis can continue
- cannot continue forever due to lactic acid build up

OCR Biology A Level Module 5 Communication, homeostasis and energy (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions