Brainscape's Knowledge GenomeTM

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


See full index

N Biology A Level > Topic 9 Chemical Control in Animals > Flashcards

Topic 9 Chemical Control in Animals Flashcards

1
Q

The hormone adrenaline is unable to pass through cell membranes.
When liver and muscle cells are exposed to adrenaline, the enzyme glycogen phosphorylase breaks down glycogen.
Describe how adrenaline causes liver cells to increase the concentration of glucose in the blood. (3 marks)

A
  • adrenaline binds to receptors on membrane / cell surface
  • second messenger cAMP involved
  • activates glycogen phosphorylase
  • glucose diffuses out of cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Compare the mechanisms used in hormonal and nervous coordination in mammals. (3 marks)

A

Hormonal / nervous
- chemical / electrical impulses
- transported in blood / via neurones
- slow speed of transmission / fast speed
- long lasting response / short lived
- wide spread effect / localised

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

Given thyroxine is able to enter the cell,
How does thyroxine increase the secretion of adrenaline from adrenal glands? (4 marks)

A
  • can enter so it’s hydrophobic
    -thyroxine binds to receptors
  • enters the nucleus
  • activates transcription factor / stimulates transcription
  • increased protein synthesis
  • synthesise more adrenaline
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are endocrine glands?

A

Releases hormones

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

What are exocrine glands?

A

Secreting digestive juices like enzymes

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

What is the definition of hormones?

A

Chemical messengers released by glands travelling via blood towards target cell by binding complementary receptors

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

Which parts of the brain will help to coordinate endocrine functions?

A

Hypothalamus and pituitary gland

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the 2 types of hormones?

A

protein based and lipid based

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

What are examples of protein based hormones?

A

Adrenalin
melatonin
FSH
ADH
LH

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

What are examples of lipid based hormones?

A

steroid hormones like
oestrogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where are steroid (lipid) hormones derived from/made of?

A

cholesterol

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

Where are protein based lipids derived from/made of?

A

multiple amino acid chain
tyrosine and tryptophan

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

Describe the process of hydrophilic hormones

A
  • a cascade of reactions
  • binds to complementary receptor
  • changes shape of G protein
  • it becomes complementary to adenylyl cyclase
  • breaks down ATP to cAMP
  • cAMP is a second messenger, binds to kinase enzyme
  • catalyse reaction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Do cells have the same genes and how do they have different functions?

A

All have the same 46 chromosomes
but depends on what genes are switched on and off
hence gene expression

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

What do transcription factors do?

A

promote transcription and translation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe the process of hydrophobic hormones causing synthesis?

A

It can diffuse through the cell membrane
It binds to complementary steroid receptor
Forming hormone receptor complex
Enters nucleus - act as transcription factor
triggers more transcription

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

What are the 3 types of neurons?

A

Sensory
Relay/interneuron
Motor

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

Which 2 systems are the mammalian nervous system composed of?

A

central and peripheral

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

What is the central nervous system made up of?

A

brain and spinal cord

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

What are 2 systems in the peripheral nervous system?

A
  • autonomic
  • voluntary (under conscious control)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the structure of the spinal cord?

A
  • cylindrical bundle of nerve fibres from brain stem to lower back
  • consists of nerve tissues
  • 31 pairs of spinal nerves
  • grey matter: H shaped regions contained neurons
  • white matter: myelinated axons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the 2 main divisions of autonomic nervous system?

A
  • sympathetic (arousing)
  • parasympathetic (calming)
    act antagonistically
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Describe the sympathetic nervous system.

A
  • usually stimulates effectors (FIGHT OR FLIGHT) (s-s)
  • neurotransmitter nonadrenaline
  • ganglia located near CNS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Describe the parasympathetic nervous system

A
  • usually inhibits effectors
  • neurotransmitter acetylcholine
  • ganglia located far from CNS
    REST & DIGEST
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the location and main function of the medulla oblongata?

A

brain stem
control breathing and heart rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the location and main function of the cerebellum?

A

lower back, behind spinal cord
controls balance and coordination of movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what is the location and main function of the cerebrum?

A

front and top
initiates movement

28
Q

What is the location and main function of the hypothalamus?

A

above pituitary gland
temperature regulation and osmoregulation

29
Q

Compare the autonomic vs somatic nervous system

A

autonomic / somatic
both: part of peripheral nervous system
regulate function of internal organs / voluntary movements
we are not in control / in control

30
Q

What are the advantages having both autonomic and voluntary motor nerves?

A
  • leave conscious areas of brain free to make decisions
  • voluntary can override autonomic system if necessary
31
Q

what do sensory neurons do?

A

transmit impulses from receptors

32
Q

what do motor neurons do?

A

transmit electrical signals from CNS to glands of body

33
Q

what do relay neurons do?

A

transmit electrical impulses between motor and sensory neurons

34
Q

What is the resting potential of nerve cells?

A

-70mV

35
Q

What is potential difference?

A

When there’s a difference in charge

36
Q

What does it mean by polarised in sensory receptors?

A

When a neurone has resting potential

37
Q

What is the threshold value for sensory receptors?

A

When potential difference at -50mV
Sodium ion channels open

38
Q

What is the refractory period in sensory receptors?

A

Period of hyperpolarisation (lower than -70mV) in an action potential
To make the wave of depolarisation occur in one direction only

39
Q

How does the sodium/potassium pump used in resting potential ?

A

Pumps locate in neurone membrane
Pumps 3 Na+ out
Pumps 2 K+ in
->Resting potential achieved
More positive ions out

40
Q

Explain how the resting potential is maintained in a neurone. (4 marks)

A
  • sodium potassium pump
  • 3 Na+ ions out, 2 K+ ions in
  • K+ ions out via potassium channels (leaky)
  • sodium channels close, Na+ don’t move in
  • outside more positive than inside
41
Q

Can action potential increase in size?

A

NO! Only frequency.

42
Q

What happens in depolarisation?

A

Action potential has passed the threshold value
So voltage gated sodium channel open, sodium ions flood in neurones
Via facilitated diffusion
Then diffuse down the axon

43
Q

What happens in repolarisation?

A

Sodium ion channels shut
Potassium ion channels open, potassium ions facilitated diffuse out
+ hyperpolarise

44
Q

Why does hyperpolarisation happen?

A

Action potential can only travel in one direction
Prevent immediate stimulation again
Refractory period

45
Q

What produces myelin sheath?

A

Schwann cells

46
Q

What is between myelin sheath?

A

Nodes of Ranvier

47
Q

Why is conduction in myelinated neurones faster than normal neurones?

A

Action potentials jump between nodes of Ranvier aka saltatory conduction
(Less space for sodium ions to enter as they cannot travel through myelin sheath)

48
Q

What is the condition without myelin sheath or demyelination?

A

Multiple sclerosis

49
Q

What is the synapse called?

A

Synaptic cleft

50
Q

How does action potential travel between two neurones?

A
  1. Action pot travels down pre-synaptic knob
    • trigger voltage gated Calcium ion channels to open
  2. Calcium ions cause vesicles to exocytose (active)
    • release vesicles (that contain neurotransmitters [NT])
  3. NT diffuse down the conc grad across synaptic cleft
  4. Attaches to complementary receptors on post-synaptic membrane - that is attached to sodium channels
  5. Triggers CHEMICALLY gated sodium ion channels to open
    • sodium ions facilitated diffuse into post synaptic knob = depolarisation
  6. EPSP created
  7. Neurotransmitters broken down using enzymes into products
  8. Products reabsorbed and recycled at presynaptic knob
51
Q

What is EPSP

A

Excitatory post-synaptic potential

52
Q

Why is it important to digest neurotransmitters on receptors of post-synaptic knobs?

A

To close the sodium ion channels
So that new action potential can be triggered
If not, will cause paralysis
- make receptors available again, prevent prolonged action potential in post-synaptic membrane

53
Q

What enzyme is used to digest acetylcholine, and what are the products?

A

Acetylcholinesterase
Into Acetylcholine-CoA + choline

54
Q

Describe and explain the sequence of events that occurs at the synapse, AFTER a neurotransmitter has been released. (5 marks)

A
  • diffuses across synaptic cleft
  • binds to complementary receptor on post synaptic membrane
  • trigger opening of gated sodium ion channels
  • cause depolarisation
  • neurotransmitter broken down by enzyme
  • so don’t get prolonged action potential in post-synaptic membrane/make receptors available again
55
Q

Which region of the brain only controls breathing and heart rate?

A

medulla oblongata

56
Q

What type of neurone releases acetylcholine and what is the effect of it?

A
  • parasympathetic neurone
  • lowers HR
57
Q

Describe the events that lead to the release of acetylcholine at a synapse. (3 marks)

A
  • action potential arrives at pre-synaptic knob
  • calcium channel opens and influx of calcium ions
  • vesicles move to membrane
  • vesicles fuse w membrane, release acetylcholine by exocytosis
58
Q

Explain why a person with Alzheimer’s disease may show a change in behaviour. (2 marks)

A
  • reduced hippocampus
  • so loss of memory
    OR
  • reduced cerebral cortex
  • inability to perform everyday tasks
59
Q

What is the effect of inhibitory drugs? (3 marks)

A
  • Blocks voltage gated sodium ion channels
  • so no movement of sodium ions into neurone
  • so prevents depolarisation/action potential
60
Q

Describe the sequence of events that leads to an ESPS in the postsynaptic neurone. (4 marks)

A
  • arrival of action potential at presynaptic knob
  • calcium channels open, influx of calcium ions
  • vesicles fuse w presynaptic membrane
  • neurotransmitter diffuses across synaptic cleft
  • attaches to complementary receptor on postsynaptic membrane
61
Q

Is nicotine, Lidocaine and cobra venom excitatory or inhibitory respectively?

A

excitatory
inhibitory
inhibitory

62
Q

Explain why the speed of nerve impulses along axons is slower without myelination. (3 marks)

A
  • no saltatory transmission
  • as no nodes of Ranvier
  • so impulse does not jump between nodes
    (- sodium channels have to open in every part of membrane)
63
Q

What do IPSPs do?

A
  • open up K+ ions
  • lead to hyperpolarisation
  • K+ ions diffuse out of neurones
  • less likely to pass on action potential - since potential difference getting more -ve
64
Q

What is the effect of nicotine?

A
  • competitive inhibitor to acetylcholine (v similar effects)
  • triggers action potential
  • rest and digest effect
65
Q
A

N Biology A Level (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions