independent study questions part 1 Flashcards
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
suggest one advantage to the behaviour shown in the diagram (1 mark)
remains in shade so avoids predators
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
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
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
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
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
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
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
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
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
the pea seedlings were kept in the dark after each treatment. Explain why this was necessary. (1 mark)
seedlings are phototropic
what conclusion can be made from the results for treatment B? (1 mark)
cells in root tip respond to gravity
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
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
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
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
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
explain in terms of pressure, why the semi lunar valves open (1 marks)
pressure is greater in ventricle than artery
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
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
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
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
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
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
