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Biology Exam Questions > Topic 7/8 > Flashcards

Topic 7/8 Flashcards

1
Q

Describe the differences in the structure of a myelinated sensory neuron and a myelinated motor neuron (3)

A

In sensory neuron, dendron is longer
in sensory neuron dendron is myelinated
In sensory neuron axon is shorter

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2
Q

explain the electrical changes in an axon when stimulated by a nerve impulse (4)

A

potential difference across axon changing
due to increased permeability to sodium ions (volt gates open)
sodium ions cause depolarisation
potassium channels then open
potassium ions cause repolarisation of the membrane

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3
Q 
Explain how conduction of nerve impulses will be affected if the following membrane proteins are damaged (6)
1 - Acetylcholine receptors
2 - Voltage-gated sodium ion channels
3 - Voltage-gated potassium ion channels
4 - Calcium ion channel
A

1 - if Acetylcholine receptors on post-synaptic neuron affected, post-synaptic neuron will not depolarise
2 - if Voltage-gated sodium ion channels affected, no depolarisation of axon
3 - if Voltage-gated potassium ion channels, no repolarisation of axon, no propagation of action potential
4 - if Calcium ion channels affected, vesicles in pre-synaptic neuron will not fuse with pre-synaptic membrane, neurotransmitter wont be released

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4
Q

Explain why there is a difference in the velocity of a myelinated neuron’s nerve impulse and an unmyelinated one (5)

A

Schwann cells cover axon of myelinated neuron
Schwann cells provide insulation
depolarisation occurs at nodes of Ranvier
Saltatory conduction depolarises part of a neuron not whole one
impulse jumps from node to node

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5
Q

describe and explain the sequence of events that occur at the synapse after a neurotransmitter has been released (5)

A

Diffuses across cleft
binds to receptors on post-synaptic membrane
causes it to depolarise
if depolarisation is sufficient enough, action potential is set up in post-synaptic membrane
neurotransmitters that are not taken up by the post-synaptic membrane are digested by enzymes in the cleft
Spatial summation allows multiple impulses from various neurons to meet at one neuron and continue to the next as one impulse

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6
Q

in which region is the hypothalamus found (1)

A

forebrain

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7
Q

State the functions of these regions of the brain (4)
1 - cerebral hemisphere
2 - cerebellum
3 - medulla oblongata

A

1 - cerebral hemisphere, initiating and controlling voluntary muscle movement
2 - cerebellum, coordinating skeletal muscle movement, balance and posture
3 - medulla oblongata, controlling heart and breathing rate

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8
Q

Describe the role of ATP in the contraction of a muscle fibre (5)

A

myosin slides along actin to contract muscle fibre
ATP binds to myosin head causing cross-bridge between actin and myosin to break
ATP hydrolyses to ADP and Pi releasing energy, causing myosin head to reset
myosin head binds to actin forming a cross-bridge
Pi is released from myosin head
ATP also transports Ca ions back into sarcoplasmic reticulum

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9
Q

Compare and contrast the properties of the slow and fast twitch cycle

A 
Property - Slow twitch - Fast twitch
Myoglobin - more - less
mitochondria - many - few
Glycogen - less - more
capillaries - many - few
Myosin ATPase activity - low - high
fibre diameter - small - large
Creatine phosphate - low high
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10
Q

explain changes when calcium ions bind to molecules in myofibrils (4)

A

myosin heads can bind to binding sites
myosin changes shape
actin filaments slide over the myosin, causing sarcomeres to shorten
ATP is hydrolysed releasing ADP and Pi

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11
Q

Explain how the blood pH of a sprint is returned to normal after a race (5)

A

Low pH due to acid in blood
lactate taken to liver
More oxygen has to be inhaled than normal
used to convert lactate back into pyruvate with production of reduced NAD
Pyruvate converted to glucose
chemoreceptors detect change in pH, increased rate

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12
Q

in genetic modification how does addition of chemical cause human gene to be switched on (3)

A

Chemical could be transcription factor
interaction at bacterial cell surface membrane
the transcription factor is activity

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13
Q

advantage of injecting chemicals into veins rather than arteries

A

Larger lumen
thinner wall so easier to penetrate
bp is low so less damage to vein

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14
Q

cell that links rod cell to sensory neuron (1)

A

Bipolar neuron

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15
Q

explain why only one restriction enzyme is used for genetic modification (3)

A

cuts a specific sequence of bases
generates complimentary sticky ends
easier to join together

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16
Q

suggest why FMRI is considered better than CT for studying brain function (2)

A

it views brain activity directly
safer as it does not use x rays
sees brain activity over a period of time

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17
Q

how is NAD formed in electron transport chain (3)

A

due to reduced NAD releasing electrons
electrons go to carriers
H+ moved into inner membrane space

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18
Q

explain link between ATP and H+ in electron transport chain (3)

A

H+ pass through ATP synthase
H+ pass down electrochemical gradient
Energy is released to join ADP and Pi

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19
Q

compare and contrast CT and MRI for studying brain structure (6)

A

Image resolution is higher in MRI and lower and CT
CT can only identify larger structures, MRI can identify small ones
MRI uses magnetic fields, CT uses xrays
MRI is safer than Xrays but is louder
both give 2D/3D images
MRI is more expensive than CT

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20
Q

Suggest why pupils appear black (1)

A

pigment at the back of the eye absorbs light

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21
Q

explain why panting generates heat (2)

A

panting involves muscle contractions

muscle contraction requires respiration which releases energy

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22
Q

explain the role of negative feedback in the panting response of dogs (5)

A

Blood temperature is kept in a state of homeostasis
thermoreceptors detect changes in temperature
thermoreceptors send nerve impulses to thermoregulatory centre
if blood temperature increases, TC sends nerve impulses to increase panting
panting causes blood temperature to fall
once normal blood temp is reached, impulse to TC stops and panting stops

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23
Q

Describe how FMRI can be used in an investigation (3)

A

conduct FMRI scan while someone is engaged in a cognitive activity
indicates areas with high blood flow
lit up areas indicate higher levels of brain activity

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24
Q

When a muscle fibre contracts what happens to the number of myosin heads (1)

A

stays the same

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25
What does the binding of calcium ions to troponin do (1)
expose myosin bindings sites
26
describe how the arrival of nerve impulse at synapse releases neurotransmitters (3)
Ca2+ enters synaptic knob vesicles contain neurotransmitters they fuse with presynaptic membrane and neurotransmitters are released by exocytosis
27
Explain the difference between the structure of a myelinated sensory neuron and myelinated motor neuron (3)
IN SENSORY NEURON dendron longer dendron myelinated axon shorter
28
explain how the sinoatrial node ensures that oxygenated blood enters the aorta (4)
initiates electrical activity over atria causes atria to contract forcing oxygenated blood into left ventricle electrical activity from SAN received by AVN travel through bundle of HIC causing left ventricle to contract forcing blood into aorta
29
explain how twin studies can be used to compare the effects of nature and nurture on human development (4)
monozygotic twins are genetically identical derived from one egg and sperm any phenotypic difference is due to nurture dizygotic twins are genetically different any phenotypic difference when the environment is the same is likely to be nature
30
suggest why mean concentration of L-dopa in blood plasma decreases after some time (4)
l-dopa leaves blood into tissues l-dopa crosses blood brain barrier converted to dopamine l-dopa is broken down
31
Explain how you would use traces from spirometer to compare tidal volume and breathing rates of male + female participants (6)
calibration for volume calibration for time one peak = one breath breathing rate is number of peaks per minute use the same age of participants for both males and females use non-smokers traces taken at test replicate the procedure 3 times with the same group to acquire mean results
32
suggest how habituation is beneficial to sea slugs (2)
avoids wasted effort to non-threatening stimulus, more energy for other purposes
33
explain what is meant by phase III trial (2)
randomised trial large sample of patients use of placebos
34
explain why radical and circular muscles need to be antagonistic (3)
to constrict pupils: Radical muscles relax, circular muscles contract To dilate pupils: Radical muscles contract, circular muscles relax allows changes to take into account varying light intensity muscles can only shorten antagonistic muscles have opposite effects
35
describe and explain the role of calcium ions and ATP in muscle contraction (5)
vesicles contain calcium ions which bind to troponin tropomyosin moves exposing binding sites for myosin ATP needed to remove calcium ions ATP provides shape for changing shape of myosin ATP required to break down cross-bridges
36
explain how high conc of H+ is maintained in intermembrane space (3)
``` H+ ions from reduced NAD pumped into intermembrane space energy needed for pump electrons move along electron transport chain ETC on cristae ```
37
describe how the cardiovascular centre in the medulla oblongata affects SAN during exercise (2)
increased impulses to SAN via sympathetic nervous system stimulates more frequent depolarisation in SAN increases heart rate
38
explain why muscles occur in antagonistic pairs (2)
muscles cannot extend themselves need opposing muscle to extend antagonistic muscles allows control of movement
39
two factors that determine how quickly an animal becomes habituated (2)
time between each stimulus | duration of the stimulus
40
describe how increased heart rate increases oxygen uptake by blood in the lungs (3)
more blood passing through lungs oxygen diffuses into blood oxygen diffuses faster
41
describe how epo production might be shut down when oxygen levels in blood are normal (3)
gene transcription stops transcription involves joining RNA bases on a template strand complimentary to the exposed DNA strand no MRNA produced no translation of MRNA
42
describe how fmri is used to investigate brain function (2)
detects levels of oxygenation of blood increased flow of oxygen suggests increased activity brain activity can be studied in relation to tasks
43
describe interaction of troponin and tropomyosin when skeletal muscle fibre contracts (2)
calcium ions bind to troponin troponin changes shape this displaces tropomyosin
44
Describe the role of the human nervous system in returning raised body temp to its normal level (4)
thermoreceptors in hypothalamus detects change in blood core temp heat loss centre activated Autonomous nervous system sends impulse down motor neuron to effector vasodilation of blood vessels, sweat released
45
suggest how the human genome project has helped develop drugs (3)
human genome project identified millions of alleles drug targets specific allele mutant allele can no longer express itself this type of drug is very effective
46
explain how plants can be genetically modified to be resistant to damage by insects (4)
Use gene that provides resistance to insects gene could code for insect enzyme inhibition gene would have to be isolated from rest of the insect resistant plan
47
suggest how heart decreases during hibernation (3)
Cardiovascular system sends nerve impulse down the presynaptic nerve to the SAN decreased frequency off signals from the SAN
48
describe how curate ligaments can be repaired with minimal damage to the joint (2)
keyhole surgery | doctor watched procedure through a screen
49
explain the role of acetylcholine in nerve impulse transmission (2)
to transmit nerve impulse across synapse | because action potential cant cross the gap
50
role of ligaments?
attach bones to other bones allows some movement which provides stability
51
explain how neurons enable pupils to increase in diameter in dim light (3)
Na+ ions are pumped out of inner segment causing membrane to depolarise glutamate is released which inhibits the bipolar cell bipolar cell does not depolarise and impulse is not produced down the optic nerve Radial cells contract causing pupils to dilate
52
describe the role of myelin sheath in the conduction of nerve impulses (4)
acts as an electrical insulator Depolarisation at nodes impulse jumps node to node known as saltatory conduction this provides faster conduction rather than depolarisation the entire axon
53
describe how structure of axon cell membrane is related to the conduction of nerve impulses (3)
phospholipids limit ion movement proteins span the membrane sodium potassium ion pump moves ions protein gates allow diffusion of ions
54
explain how electrocardiogram can be used to calculate someone's heart rate (3)
shows electrical activity of the heart peak is one heart beat count number of peaks within a minute
55
Explain how high CO2 concentration can change heart rate (5)
concentration of CO2 in alveoli is higher concentration of CO2 in blood is higher detected by chemoreceptors in the aorta, impulse sent to cardiovascular control centre in medulla more impulses are sent via the autonomic nervous system to SAN Noradrenaline is released into SAN heart rate increases
56
suggest how tendons and antagonistic muscles cause lower leg to kick a ball (4)
``` extensor muscles contract leg is straightened flexor muscles relax muscles work in opposite directions, one contracts the other relaxes tendons attach muscles to bone ```
57
explain what is meant by the term myogenic (2)
stimulation generated from within muscle | resulting in depolarisation
58
suggest suitable units for Y axis on an ECG (1)
Millivolts/MV
59
explain how electrocardiogram can be used to calculate person's heart rate (3)
shows electrical activity of the heart one heart beat is one peak on the ECG count number of peaks within 1 minute heart rate calculated by divided beats/minute
60
study scanning technique to study physical and emotional experiences of brain (3)
``` FMRI fmri operates in real time as experience will be short lived active areas light up on the image high resolution as areas may be small ```
61
what happens to rod cells in the dark (5)
Opsin uncouples from rod cell surface membrane rhodopsin formed from retinal and opsin results in dark adaptation permeability of cell surface membrane to Na+ increases hyperpolarisation of cell decreases more neurotransmitter is released
62
explain how heart rate of person is controlled when level of exercise increases during physical activity (6)
increased respiration rate rate in muscle cells more CO2 in blood more lactate in blood chemoreceptors in medulla stimulated impulses from cardiovascular centre in medulla sent to the SAN through autonomic nervous system SAN excitation rate increases, results in increased heart rate
63
ethical reason why drugs like EPO should be banned in sports (2)
it is not fair | poses a health risk to athletes
64
suggest why fast twitch muscle fibres are less red in colour than slow twitch muscle fibres (2)
some have less myoglobin present fewer red blood cells fewer capillaries present respiration is mainly anaerobic
65
describe how muscles in blood vessels in the skin help increase heat loss from the body (4)
muscles relax to increase diameter of arterioles redirects blood to surface of arterioles increase blood flow to capillaries more heat loss through radiation
66
state the location of rhodopsin within a rod cell (1)
outer segment
67
describe what happens to reduced NAD in aerobic respiration (4)
reduced NAD from glycolysis enters membrane moves to inner membrane of mitochondrion becomes oxidised as electrons are transferred to electron transport chain hydrogen ions are pumped into inter membrane space NAD returns to Krebs cycle
68
reasons why too little exercise is not good for health (2) reasons why too much exercise is not good for health (2)
increased risk of obesity coronary heart disease wear and tear of joints suppression of immune system
69
describe role of oxygen in aerobic respiration (4)
Oxygen is H+ acceptor at end of electron transport chain oxygen is used to form water plays a role in oxidative phosphorylation production of ATP
70
describes what happens to lactate in muscles (5)
lactate moves into the blood carried to the liver lactate is converted to pyruvate pyruvate is respired
71
why do older people see less clearly in low light (2)
pupil size is smaller in older people in low light conditions radical fibres in iris contract less in older people compared to younger people
72
explain role of IAA in a plant showing phototropism (4)
IAA moves away from light H bonds between cellulose molecules are broken cells elongate due to uptake of water IAA causes more cell elongation of dark side of the stem
73
how does panting enable dogs to maintain a stable body temp (4)
panting causes heat loss as water evaporates from mouth heat energy from blood is used panting increases air movement over tongue increased air movement increases rate of evaporation
74
relationship between day light and rhodopsin present (2)
linear relationship | increasing daylight length reduces rhodopsin

Biology Exam Questions (4 decks)

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