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Wrong Past paper questions > Bio P2 > Flashcards

Bio P2 Flashcards

1
Q

) Describe how low serotonin levels in an individual can affect the transmission of
impulses in their brain.
(2)

A
  • Serotonin is a neurotransmitter
  • So less of it means that there is less chance of action potential being fired.
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2
Q

) Describe how the sinoatrial node (SAN) is involved in bringing about a change in
heart rate as the level of activity increases.
(2)

A
  • this causes more frequent waves of depolarisation
  • causing more frequent contraction of the atria
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3
Q

Explain how pressure differences in the heart ensure efficient pumping of the
blood into the arteries.

A
  • pressure in the ventricles is higher than in the atria
  • during ventricular systole, pressure in the ventricles increases
  • forcing the SV valves to open, and AV valves too close
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4
Q

Explain why cystic fibrosis affects the rate of oxygen uptake in the lungs. (3)

A
  • Mucus becomes sticky
  • this reduces SA needed for gas exchange
  • which reduces air flow through bronchi
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5
Q

State what is meant by the term Q10 temperature coefficient

A

The ratio of the rate of an enzyme reaction taking place at temps differing by 10 degrees celcius.

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6
Q

Devise an investigation to determine Q10 for an extract of lipoprotein lipase enzyme.
(5)

A
  • control temperatures using water bath
  • set up test tube with controlled conc of lipoprotein lipase enzyme solutions
  • provide an excess of triglyceride
  • measure rate of production of fatty acids by measuring change in pH in certain intervals of time (eg every 10 secs)
  • plot graph and determine initial rate of reaction.
  • calculate Q10 by doing rate at T+10 sec/T
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7
Q

Give reasons why blood lactate concentration remains constant between
5 and 15 minutes.
(3)

A
  • there is sufficient supply of oxygen for aerobic respiration
  • so rate of lactate production is balanced by breakdown of lactate in the liver
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8
Q

Describe the changes caused when calcium ions bind to the molecules shown
in the diagram.
(2)

A
  • Ca2+ ions bind to troponin
  • troponin moves tropomyosin
  • myosin binding sites are exposed.
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9
Q

Explain how these changes cause muscles to contract.
(4)

A
  • myosin can now bind to the binding sites
  • myosin heads change shape
  • causing actin filaments to slide over
  • causing sarcomeres to shorten
  • ATP is then hydrolysed by ATPase in the myosin head, forming ADP and Pi.
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10
Q

Describe how the concentration of calcium ions around the myofibrils is controlled.
(3)

A
  • released from the sarcoplasmic reticulum
  • in response to an action potential
  • they are then re up taken by the sarcoplasmic reticulum by active transport
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11
Q

Explain how the unfolding of the enzymes in E. coli makes them ‘become ineffective
at 60 °C’ (paragraph 12).

A
  • unfolding due to breaking of bonds
  • this denatures the enzyme
  • so enzyme’s active site is no longer complimentary to substrate.
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12
Q

Explain how the extensor and flexor muscles bring about movement of the
lower leg.
(2)

A
  • extensor pulls on the tibia to move the leg
  • they both act as an antagonistic pair
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13
Q

Deduce how athletes with transtibial amputations are able to move their
prosthetic limbs during a race.
(1)

A
  • the muscles in the lower leg are still attached to the tibia, and prosthetic limbs attached to lower leg
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14
Q

Describe how dopamine acts as a neurotransmitter.
(4)

A
  • released from the pre-synaptic neuron into the synaptic cleft
  • diffuses across the pre-synaptic cleft
  • binds to receptors on the post-synaptic neuron
  • causes Na+ channels to open.
  • triggers another action potential in the post-synaptic neuron
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15
Q

Serotonin is found in the brain and is important in health and wellbeing.
An imbalance of serotonin can lead to problems such as depression. An individual with
symptoms of depression may have low serotonin levels in the brain.
The use of drugs such as MDMA (ecstasy) can cause an imbalance of chemicals in the
brain.
(i) Describe how the use of MDMA could affect the transmission of impulses in the brain.
(2)

A
  • could bind to post-synaptic neuron
  • thus causing less action potentials
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16
Q

Individuals who use MDMA may develop the symptoms of depression.
Explain how the use of MDMA could result in the development of these symptoms.
(2)

A
  • MDMA could cause depletion of serotonin levels
  • thus leading to depressive symptoms like a negative sense of self
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17
Q

Explain how nicotine causes an action potential in the post-synaptic neurone that
releases noradrenaline. (3)

A
  • voltage gated Na+ open
  • causing the Na+ ions to diffuse into the cell
  • this causes the depolarisation to reach the threshold level, allowing noradrenaline to be released.
18
Q

Describe how these ions and neurotransmitter molecules are involved in the transmission
of an impulse.
(4)

A
  • Ca2+ channels open
  • causes neurotransmitter particles to diffuse across the synaptic cleft
  • neurotransmitter binds to receptors on the post synaptic neuron
  • triggers the Na+ channels to open in the post-synaptic neuron, causing an action potential.
19
Q

) The data for calculating metabolic rate are collected using a respirometer.
The rate of respiration for small mammals can be measured using a
continuous flow respirometer. A continuous flow respirometer circulates
air through a chamber containing the animal. The rate of air flow can be
measured using flowmeters on the inlet and outlet tubes.

Devise a procedure using a continuous flow respirometer to collect the data
required to calculate the metabolic rate of an arctic ground squirrel.
(4)

A
  • add soda lime to outlet to absorb CO2.
  • measure volume of air being used up in the chamber which represents respiration
  • control temperature of the chamber
  • divide volume used up over time that animal was kept in chamber eg - 5 mins, and then times it by the mass of the animal.
20
Q

Describe the role of the dendrites in a neurone. (3)

A
  • form connections with other neurons
  • receive impulses from other neurons
  • involved in summation
21
Q

The electron transport chain occurs in the cristae of mitochondria. The electron
transport chain involves a number of carrier molecules.
Explain the role of these carrier molecules in the electron transport chain.
(3)

A
  • NADH and FADH2 are oxidised to NAD and FAD
  • electrons are passed throught ETC by series of redox reactions
  • which releases energy
  • this energy is used to pump H+ ions across to the intermembrane space
22
Q

Acetylcholinesterase is an enzyme involved in regulating the transmission of nerve impulses
across some synapses.
Alzheimer’s disease is associated with the loss of neurones that produce acetylcholine.
It has been suggested that inhibitors of acetylcholinesterase may be useful in the treatment
of Alzheimer’s disease.
(i) Explain why inhibitors of acetylcholinesterase could be useful in the treatment of
Alzheimer’s disease.
(3)

A
  • Acetylcholinesterase breaks down acetylcholine
  • which means that it inhibitors of it will prevent breakdown of acetyl choline
  • As a result, more acetyl choline will be available to bind to post synaptic neurons and
23
Q

The effect of being shown a cheeseburger on saliva production in a child was studied.
The mass of saliva produced by this child was measured.
The child was then shown a cheeseburger and the new mass of saliva produced
was measured. The change in the mass of saliva produced was recorded.
This was repeated with the child being shown a cheeseburger on eight occasions,
at five minute intervals.
Explain what happens at the synapse to cause a decrease in saliva production
when the child was shown a cheeseburger on more than six occasions.
(4)

A
  • membrane becomes less permeable to Ca2+ ions
  • so less vesicles move towards presynaptic knob
  • so less neurotransmitter can bind to receptors on the post synaptic neuron
  • so less chance of an action potential being reached.
24
Q

Compare and contrast the structure of a sensory neurone and a motor neurone

A
  • both have an axon
  • both have dendrites and terminal branches at the end
  • both have cell body containing a nucleus.
  • cell body of the sensory neuron is on one side of the axon, but at the end of an axon for a motor neuron
25
Q

Explain how the structure of a muscle fibre is related to its specialised function. (3)

A
  • myosin and actin filaments
  • myosin binds to actin to help muscle contractions
  • lots of ATP to provide energy for the contraction
26
Q

Explain what is meant by no significant difference at the 0.05 probability level for the rate
of breakdown of protein.
(2)

A
  • there is less than a 95% likelihood.
  • so the rate of protein breakdown will be the same for both conditions
  • and the calculated value will be less than the critical value at p=0.05.
27
Q

Some of the myosin in the muscle cells was broken down.
Describe how the tertiary structure of myosin is related to its function.
(3)

A
  • has specific shape that is complimentary to its binding sites on actin
  • allows it to bind to actin to slide it along during muscle contraction.
  • has site to bind with ATP.
28
Q

Deduce how adrenaline can cause a change in heart rate.
(4)

A
  • adrenaline carried in blood
  • acts on the sinoatrial node
  • increases frequency of the waves of depolarisation in the SAN
  • which increases HR.
29
Q

Explain the effect of exercise on the changes in oxygen consumption (4)

A
  • more of a demand for oxygen
  • because there is a higher rate of aerobic respiration
  • thus more energy needed for muscle contraction
  • As a result, more oxygen is needed to convert lactate to glucose again.
30
Q

he norovirus causes a type of food poisoning, commonly called stomach flu. Norovirus is a non-enveloped RNA virus.​
The virus stays in the small intestine and causes symptoms approximately 24 hours after eating the contaminated food.​
Stomach flu can be caused by eating food containing as few as 20 viral particles.​

​
(i) Suggest how new viral particles are formed inside the host cells.(4)​

A
  • Viral mRNA is made
  • using host enzymes
  • this produces polypeptide chain
  • host cell’s tRNA used to form polypeptide
  • this is folded to produce viral proteins
31
Q

Suggest why so few viral particles are enough to cause symptoms after 24 hours.(2)​

A
  • because it replicates very quickly
  • which infects even more host cells
32
Q

​
(iii) The risk of transmitting food poisoning microorganisms can often be reduced by using alcohol-based handwashes.​

Suggest why alcohol-based handwashes do not reduce transmission of the norovirus. (2)​

A
  • the virus is non enveloped
  • so alcohol doesn’t damage the protein coat/capsid.
33
Q

Explain why the amplified DNA fragments for the G20210A allele and the wild type allele
are different.

A
  • they have different base sequences
  • meaning that the restriction enzymes cut at different points on each allele
  • this produces a shorter fragment for G20210A allele, as it has a shorter base sequence.
34
Q

Devise an investigation to determine the optimum number of cycles for the
polymerase chain reaction used to amplify the DNA for this test. (4)

A
  • control duration of each cycle
  • change the number of cycles for DNA strand being amplified
  • use gel electrophoresis to observe bands
  • determine the smallest number of cycles it takes t see the most observable band.
35
Q

The extent of decomposition is important in helping to determine the time of death
of a mammal.
Body farms are outdoor laboratories where experiments take place to investigate
the changes that take place after death in a range of conditions. Body farms use the
bodies of pigs or donated human bodies.
The effects of factors such as temperature, moisture and position of the body on the
rate of decomposition can be studied.
Explain the effect of ambient temperature on the rate of decomposition.
(3)

A
  • increased temp increases rate of growth of decomposers
  • higher temp means higher rate of decomposition
  • due to higher enzyme activity
36
Q

when do we accept the null hypothesis

A
  • when the calculated value is less than critical value
  • so no significant relationship between the variables.
37
Q

It was observed that all the living larvae in the rhinoceros belonged to species F.
The metabolic activity of the larvae of species F increases the temperature within the
dead rhinoceros.
Explain the advantages for this species of blowfly of increasing the temperature within
the dead rhinoceros.
(3)

A
  • higher enzymes activity
  • might denature other species’ enzymes
  • may outcompete other larvae for food etc.
38
Q

Hospitals have developed practices in response to the increase in hospital acquired
infections.
Describe the infection control practices hospitals have introduced.
(3)

A
  • regular sanitation of surfaces.
  • Handwashing and sanitiser stations
  • isolation of infected patients
39
Q

These new antibiotics attach to a site on the ribosome not affected by any known
antibiotics.
Deduce why these new antibiotics might be used to treat bacteria that are resistant to
other antibiotics.

A
  • bacteria have not been exposed to the new antibiotics
  • so they have not had time to develop resistance through a mutation.
40
Q

The poison also caused the pupils of this person to dilate.
Describe the interaction of the muscles in the eye that led to this dilation of
the pupils.
(3)

A
  • muscles interact antagonistically
  • in the iris
  • radial muscles contract, circular muscles relax
41
Q

) Explain one way in which cartilage at the ends of the bones in the knee joint
reduces wear and tear.
(2)

A
  • acts as cushioning between joints
  • to act as a shock absorber
42
Q

Explain why cyanide does not affect the production of ATP from
anaerobic respiration.
(2)

A
  • anaerobic respiration involves just glycolysis
  • anaerobic respiration also takes place in the cytoplasm, doesn’t involve mitochondira

Wrong Past paper questions (6 decks)

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