independent study questions part 1 Flashcards by Taylor Brennan

A flatworm is a simple soft bodied animal. The diagram shows the movement of aquatic flatworm in light and in shade. The path followed by the flatworm over a period of 3 minutes was traced on the side of a tank
Name the type of behaviour shown. Give a reason for your answer (2 marks)

kinesis
movement is random

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suggest one advantage to the behaviour shown in the diagram (1 mark)

remains in shade so avoids predators

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describe 3 changes in the root tip cells between stages A and D (3 marks)

formation of vacuole
formation of starch grain
cells get longer

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the scientists hypothesis was that there was a relationship between the starch grains in the root tip cells and the bending and direction of growth of lateral roots
does the information in the diagram support this hypothesis? Give reasons for your answer (3 marks)

grows sideways as grains form
more bending as grains increase in number
more elongation of cells downwards as starch grains increase

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Explain how this distribution of IAA causes the root to bend (2 marks)

IAA at bottom of root where high IAA concentration inhibits expansion of cells
IAA at top of root where low IAA concentration leads to expansion of cells

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give one conclusion about the response of maggots which is supported by these results (1 mark)
give evidence from the table for your conclusion (1 mark)

maggots prefer red rather than green
more in red than green but light intensity the same

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the chi squared test was used to analyse the data. For the results obtained suggest one null hypothesis which might be analysed by a chi squared test (1 mark)

no difference in response to different light intensities

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It was suggested that the movement of the maggots might have been influenced by the Earths magnetic field. Suggest one simple way of repeating the investigation which would avoid this possibility (1 mark)

place magnets around the box to create an alternative magnetic field

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the biologist concluded that the worms’ behaviour demonstrated taxis
How do these results support this conclusion (2 marks)

taxis is a directional response
moved towards temperature they were cultured in

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Using the information provided, suggest an explanation for the worms’ behaviour on the glass surface in the absence of food (3 marks)

hungry so seeking food
move towards temperature they were cultured in
associate this temperature with food

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In each experiment, the biologist exposed the surfaces to light that was dim and even, so he could see where the worms went
Apart from seeing where the worms went, suggest two reasons why it was importing that the light was dim and even (2 marks)

dim light is like their normal environment
even light because worms might move away from bright light
dim light ensures that heat from light is not a variable

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the pea seedlings were kept in the dark after each treatment. Explain why this was necessary. (1 mark)

seedlings are phototropic

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what conclusion can be made from the results for treatment B? (1 mark)

cells in root tip respond to gravity

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Suggest how IAA could have caused results for
treatment A (2 marks)
treatment C (2 marks)

treatment A
more IAA on lower side
lower side grows slower

treatment C
less IAA produced
lower side grows faster

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what type of behaviour was shown by the termite from group B? (1 mark)
give evidence for your answer (1 mark)

taxis
moves towards light

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explain what the results from group A suggest about the factors controlling the behaviour of winged termites (3 marks)

gravity
antennae involved
doesn’t respond to light as they are unable to see

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suggest one advantage to the termites from group C of the behaviour shown in the investigation (2 marks)

helps them to reach the surface
produce new colonies

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which of the blood vessels D to G
carries oxygenated blood to the heart (1 marks)
carries deoxyganted blood to the lungs (1 mark)

G
E

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explain in terms of pressure, why the semi lunar valves open (1 marks)

pressure is greater in ventricle than artery

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when a wave of electrical activity reaches the AVN, there is a short delay before a new wave leaves the AVN. Explain the importance of this short delay ( 2 marks)

allows the atria to empty
before the ventricles contract

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use information from the table to explain how training has caused the resting heart rate of this athlete to be lower (2 marks)

increase in volume of heart
cardiac output is the same so must be increase in stroke volume

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explain why it takes time for the rod cells to recover their sensitivity to light after moving into darkness (2 marks)

rhodopsin broken down by light time for photosynthesis

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use information in figures 1 and 2 to explain the differences in sensitivity of rod cells to red and green light (2 marks)

rhodopsin absorbs green light more readily than red
after re synthesis less intense green light needed to break down rhodopsin than red light

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suggest an explanation for the difference in sensitivity of rod cells to the white and green spots after 30 minutes ( 1 mark)

white has high proportion of wavelengths to which rhodopsin not sensitive

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describe how a pacinian corpuscle produces a generator potential when stimulated (3 marks)

increases pressure changes stretch mediated sodium ion channel sodium channels open and sodium ions flow in depolarisation leading to generator potential

why do these data suggest about the control of heart rate by the parasympathetic and sympathetic nervous systems in response to changes in arterial blood pressure? (3 marks)

parasympathetic greater effect than sympathetic parasympathetic keeps heart rate down as blood pressure increases sympathetic keeps heart rate up as blood pressure increases

nocturnal mammals are active at night describe how the number and distribution of rods and cones across the retina would differ in a nocturnal mammal from the number and distribution in a human explain the answer (3 marks)

more rods and no cones present rods show retinal convergence rhodopsin bleached at low light intensities

when the image is focused on the fovea, the person sees the object in colour explain why (3 marks)

colour detected by cone cells fovea contains only cone cells three types of cone cells each sensitive to different wavelengths

vision using the fovea has high visual acuity but low sensitivity to light compared with vision using other parts of the retina (1 mark)

each receptor in fovea connected to separate neurone

explain why vision using other part of the retina has high sensitivity to light (3 marks)

many rods in other parts of retina rhodopsin in receptors very sensitive to light receptors connected in groups to ganglion cell

a woman takes moderate exercise explain what causes her heart rate to increase while she exercises (6 marks)

rate of respiration increases in muscle cells carbon dioxide concentration increases chemoreceptors in aortic bodies impulses to cardioaccelerator centre increased frequency of impulses along sympathetic pathway to sink atrial node

describe the route taken when electrical impulses are transmitted from the sinoatrial node to the muscles of the ventricles in a healthy heart (2 marks)

through cardiac muscle to atrioventricular node along bundle of His

explain how information from these ECG traces suggests that the damage to the dissected heart is unlikely to have affected the sinoatrial node (2 marks)

sinoatrial node in the right atrium trace from healthy person is identical to the trace for the diseased heart in the region of the atria

describe how the resting potential is established in an axon by the movement of ions across the membrane (2 marks)

active transport of Na+ out of axon diffusion of K+ out of axon

sodium and potassium ions can only cross the axon membrane through proteins explain why (2 marks)

can not pass through phospholipid bilayer because water soluble

not every stimulus in figure 2 produced an action potential explain why (3 marks)

requires greater stimulation to reach threshold to cause depolarisation

explain what causes the change in membrane potential between points A and B the change in membrane potential between points B and C (4 marks)

A and B: sodium channels more permeable to sodium ions enter by diffusion sodium ions have positive charge from negative to positive potential B and C: sodium channels close membrane more permeable to potassium potassium ions leave by diffusion sodium

when a neurone transmits a series of impulses its rate of oxygen consumption increases explain why (3 marks)

more respiration more energy supplied for active transport of ions

A myelinated axon conducts impulses faster than a non-myelinated axon explain this difference (3 marks)

in myelinated action potential depolarisation only at node in myelinated nerve impulses jumps from node to node in myelinated action potential impulse does not travel along whole length

a student who read this investigation concluded that there was a relationship between the amount of myelin in a person’s brain and whether or not they had dementia Do these data support these conclusion. Give reasons for your answer? (4 marks)

all dementia results lower than control group error bars do not overlap so differences are possibly significant dementia may be due to other factors only small sample sizes more data required

one reason that reaction time is slower when body temperature falls is because nerve impulse conduction is slower. Explain how a lower temperature leads to slower nerve impulse conduction. (2 marks)

slower diffusion of ions

other than temperature, give two factors that affect the speed of nerve impulse conduction (2 marks)

myelination axon diameter

suggest the conditions that the researcher used when obtaining her data for 0 seconds (1 mark)

keep everything the same at room temperature

explain how the researcher could use her raw data to find the mode the range (2 marks)

the mode : find the most common result range : highest and lowest result

a student reading the researchers report concluded that the difference between the results for 30 seconds and 45 seconds was significant. Do you agree with this conclusion. Explain your answer. ( 3 marks)

standard error bars overlap reference to data so difference is not significant

serotonin diffuses across the synaptic gap and binds to a receptor on the post synaptic membrane describe how this causes depolarisation of the post synaptic membrane (2 marks)

causes sodium ion channels to open sodium ions enter cell and cause depolarisation

it is important that a neurotransmitter such as serotonin is transported back out of synapses. Explain why (2 marks)

if not removed keeps binding to receptors keeps causing depolarisation in post synaptic membrane

The scientists concluded that MDMA affects movement by binding to serotonin receptors how do these results support this conclusion? (3 marks)

movement in all groups same before MDMA MDMA increases movement in Group L Group K is a control

Different substances are involved in coordinating responses in animals Synapses are unidirectional. Explain how acetylcholine contributes to a synapse being unidirectional. (2 marks)

acetylcholine released in pre synaptic side receptors in post synaptic binds on post synaptic side

Describe the evidence from the graph that curve A represents the volume of gastric juice produced by nervous stimulation (2 marks)

rapid response short duration

Describe the sequence of events leading to the release of acetylcholine and its binding to the post synaptic membrane (4 marks)

depolarisation occurs calcium ions enter synaptic knob vesicles fuse with membranes acetylcholine diffuses across synaptic cleft

the binding of GABA to receptors on postsynaptic membranes causes negatively charged chloride ions to enter postsynaptic neurones. Explain how this will inhibit transmission of nerve impulses by postsynaptic neurones. (3 marks)

inside becomes more negatively charged stimulation does not reach threshold level depolarisation does not occur so reduces effect of sodium ions entering

One form of epilepsy is due to insufficient GABA. GABA is broken down on the postsynaptic membrane by the enzyme GABA transaminase. Vigabatrin is a new drug being to treat this form of epilepsy. The drug has a similar molecule structure to GABA. Suggest how Vigabatrin may be effective in treating this form of epilepsy. (2 marks)

inhibits enzyme which breaks down GABA more GABA available to inhibit neurone

a different form of epilepsy has been linked to an abnormality in GABA receptors. Suggest and explain how an abnormality in GABA receptors may result in epilepsy. (3 marks)

receptors have different tertiary structure so not complementary GABA cannot bind inhibition of neuronal activity does not occur

During an epileptic seizure muscular contractions may occur. In which part of the brain would neuronal activity produce muscular contractions of the right leg? (2 marks)

motor area left cerebral hemisphere

using all of the information, suggest how cocaine leads to feelings of pleasure (3 marks)

cocaine binds changes shape of transporter transporter cannot move dopamine through membrane dopamine remains in synapse leading to feelings of pleasure

scientists isolated a mutated gene for the dopamine transporter protein. Name one method that the scientists could have used to produce many copies of the mutated gene in the laboratory (1 mark)

polymerase chain reaction

what is a DNA probe? (2 marks)

bases complementary to DNA radioactively labelled so that it can be detected

explain how the mutation leads to the production of a protein that transports dopamine but it not affected by cocaine (3 marks)

mutation changes base sequence of DNA changing amino acid sequence changes tertiary structure of protein

describe how calcium ions are involved in synaptic transmission (2 marks)

nerve impulses causes ca to enter pre synaptic neurone ca entry causes fusion of vesicles with pre synaptic membrane causes exocytosis

This synapse only transmits information from neurone A to neurone B and not from B to A. Give one reason why (1 mark)

neurotransmitters only from A

explain why cocaine is bind to the dopamine transporter as shown in figure 1 (2 marks )

dopamine and cocaine have similar shapes cocaine can fit transporter

Dopamine is released at synapses in parts of the brain where pleasure is perceived. Using information from figure 1 and 2, explain how the use of cocaine can result in feelings of pressure. (3 marks)

cocaine blocks transport of dopamine out of gap dopamine concentration rises continues to bind to receptors

explain the importance of reflex actions (3 marks)

automatic adjustments to changes in environment avoiding damage to tissues role in homeostasis

describe the sequence of events which allows information to pass from one neurone to the next neurone across a cholinergic synapse (6 marks)

impulses causes calcium ions to enter axon vesicles move to presynaptic membrane acetylcholine released acetylcholine diffuses across synaptic cleft binds with receptors on postsynaptic membrane sodium ions enter postsynaptic neurone

give two differences between cholinergic synapse and a neuromuscular junction (2 marks)

neurone to neurone and neurone to muscle action potential in neurone and no action potential in muscle