IBDP Online Test Series By iitianacademy
Comprehensive Test Preparatory package targeted towards IBDP
Question
Outline how the human brain can reorganize itself following a stroke.
State the area of the human brain that may have been damaged when the following symptom is present:
A lack of muscle control on the left side of the body
State the area of the human brain that may have been damaged when the following
symptom is present.
Difficulty in swallowing
Answer/Explanation
Markscheme
activities/functions spread across the brain
OR
activities/functions taken over by other areas of the brain
right motor cortex
OR
right cerebral hemisphere
medulla «oblongata»
Question
The graph shows the correlation between the cerebral cortex mass and the number of neurons in the cerebral cortex of three groups of mammals (rodents, primates and insectivores). Each point indicates the mean number from different research studies for the species.
[Source: S Herculano-Houzel (2009) Frontiers in Human Neuroscience, 3, p 31, Frontiers Research Foundation
State which group has the lowest percentage of cerebral cortex mass.
Suggest advantages of the cerebral cortex containing a high percentage of the brain’s neurons.
Suggest a role for the cerebral cortex in rodents such as rats and mice.
Explain how the cerebral cortex in humans differs from other mammals.
Answer/Explanation
Markscheme
rodents
a. more neurons means more synapses/connections
b. higher cognitive ability
c. capacity for information processing increased
OWTTE
[Max 2 Marks]
a. sensory function
b. information processing
c. memory/learning
d. motor function
Do not accept “language”
[Max 1 Mark]
a. parts/lobes/proportions more highly developed in humans «than in other animals»
b. folding/wrinkles/sulci/gyri
c. increases surface area
d. larger mass of cerebral cortex «relative to body mass»
e. enables higher order functions
Do not accept answers that only refer to the “brain” in general instead of the “cortex”
[Max 3 Marks]
Question
Explain two methods that scientists have used to determine the different functions of the brain.
Answer/Explanation
Markscheme
first method: [3]
a. name of first method eg: lesion studies
b. how the first method works eg: carry out an autopsy
c. what can be learned from the first method eg: relate the position of the lesion to observed changes in behaviour
second method: [3]
d. name of second method eg: fMRI
e. how the second method works eg: inject dye into blood OR active parts of the brain have dyed blood flowing to them
f. what can be learned from the second method eg: known stimulus activates specific region of the brain that is detected
Allow other verifiable methods.
Question
The images show the early stages and completed outcome of the process of neurulation.
Label the parts I and II on the images.
Structure Y will eventually elongate to form two structures. State the names of these two structures.
1.
2.
State the condition that arises if the closure of structure X is incomplete during embryonic development.
The diagrams show a rat brain and a human brain. They are not drawn to scale.
Distinguish between the cerebral cortex of the human brain and of the rat brain.
Answer/Explanation
Markscheme
a. I: neural groove/plate/fold
b. II: ectoderm
a. brain
b. spinal cord
spina bifida
a. human cortex larger than rat cortex
b. human cortex proportionally larger than other brain parts than rat cortex OWTTE
c. surface area «of cortex» larger for humans
d. more infolding of the surface of the cerebral cortex in humans
Question
Outline the development of axons in immature neurons.
State one activity controlled by the medulla oblongata.
Answer/Explanation
Markscheme
a. axon grows from an «immature» neuron
b. chemical stimuli trigger the growth/direction of axon
c. only one axon develops per neuron
d. some axons extend beyond neural tube to reach other parts of body
gut muscles / heart rate/cardiac centre / vasomotor / breathing/ventilation rate / reflex centre of vomiting/coughing/sneezing/swallowing
Question
Outline the neural control of the process of swallowing.
Describe an example of learned behaviour.
Answer/Explanation
Markscheme
a. «usually» autonomic reflex
b. «usually» involuntary/automatic
OR
not controlled consciously
c. coordinated by medulla «oblongata»
d. can be voluntary/consciously controlled «by cerebral cortex»
a. learned behaviour is behaviour that is taught or received through experience
Allow other definition.
b. named organism
eg: Chimpanzees.
Allow human, people, etc, providing it is explicitly written.
c. named/description of behaviour
eg: Sticks used to spear juicy grubs.
eg: learning a language.
Question
D-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), the two main psychoactive ingredients of the Cannabis sativa plant, have distinct symptomatic and behavioural effects. Functional magnetic resonance imaging (f MRI) was used in healthy volunteers to examine their effects on the parahippocampus, an area of the brain related to emotions and on the visual cortex. The effects are as shown.
Outline the benefits of using fMRI in this experiment.
Compare and contrast the effects of THC and CBD on the areas of the brain studied.
State the function of the visual cortex.
Answer/Explanation
Markscheme
a. «fMRI» allows imaging through magnetic resonance
b. to measure the amount of activity/blood flow in different parts of the brain
OR
to identify the parts of the brain that are activated
c. non-invasive/indirect observation/real time observation
a. THC causes a negative/inhibitory mean activation of parahippocampus whereas CBD causes a positive/excitatory one
OR
THC and CBD cause opposite effects on parahippocampus
b. both cause a positive/excitatory «mean activation» of the visual cortex
c. «magnitude» of mean activation of both ingredients is minute on parahippocampus compared to visual cortex/OWTTE
d. mean activation due to THC lower than CBD for both «parahippocampus and visual cortex»
OR
mean activation due to THC lower than placebo whereas higher for CBD for both
e. other valid comparison/contrast between the two drugs
processing visual information/signals from the optic nerve/OWTTE
Question
Label the numbered parts of the reflex arc.
State the type of human sensory receptor that detects motion, gravity and stretch.
State the part of the brain responsible for coordination and balance, especially during athletic competition such as the Olympics.
Outline control of heart rate by the medulla oblongata.
Answer/Explanation
Markscheme
Award [1] for every two correct up to [2 max].
I: sensory/afferent neuron;
II: interneuron/relay neuron;
III: motor/efferent neuron;
IV: effector/muscle;
mechanoreceptor
cerebellum
a. (autonomic nerve signals from medulla oblongata) can override pacemaker;
b. parasympathetic stimulation decreases heart rate;
c. parasympathetic/vagus nerve runs from the medulla oblongata to the heart;
d. sympathetic nerves from medulla (travel down spinal cord where) synapse with other nerves before going to heart;
Question
The evolution of increased body size in mammals has been accompanied by an increase in life span. Another variable that could affect life span is brain size. Data was analysed from 47 mammalian species.
State the relationship between brain mass and maximum life span.
Identify the group with the widest range of brain mass.
Compare the brain mass and life span of primates and marsupials.
Discuss how a larger brain size and longer life span might have contributed to the evolution of these species.
Answer/Explanation
Markscheme
as brain mass increases life span increases / positive/direct relationship/correlation
other placental mammals
Do not accept answers stating only numerical values without comparative wording.
a. larger brain size allows for higher intelligence/better cognition/more complex brain functions;
b. more efficient food finding / escape from predators;
c. longer life span favours parental care / survival for more reproduction;
d. (these advantages) favour natural selection which leads to evolution;
Question
Label the following diagram of the eye.
Outline how the pupil reflex can be used to indicate brain death.
The diagram below shows a synapse where the neurotransmitter is dopamine and some of the processes that take place during nerve transmission.
Explain the effect of cocaine on neurotransmission at a synapse.
Answer/Explanation
Markscheme
I iris
II vitreous humour
III choroid
IV fovea (do not accept yellow spot)
Award [1] for every two correct answers.
a. pupil normally constricts when light is shone on it;
b. light detected in the retina and impulse sent to brain;
c. lack of (motor) response indicates no brain processing taking place/brain death;
a. dopamine initiates depolarization of post-synaptic membrane;
b. cocaine binds to (transporter) carrier proteins/proteins in pre-synaptic membrane;
c. cocaine blocks reabsorption (of dopamine);
d. cocaine causes dopamine build up in synaptic cleft/space;
e. so stimulus continues/cocaine is excitatory;
Question
The diagram shows the structure of the human ear.
Label structures I and II
I. …………………………………………………….
II. …………………………………………………….
Outline how sounds are perceived in the cochlea, including the name of the cell type involved.
Identify a function of the parts of the brain by using numerals II to V to complete the chart. Hypothalamus has been completed for you.
Discuss how the pupil reflex can be used as a test for brain death.
Answer/Explanation
Markscheme
I: pinna;
II: ear drum / tympanic membrane; (both needed)
cilia/hair/hair bundles of hair cells vibrate with (cochlear) liquid/fluid movement
Award [1] for any two correct responses.
a. pupil reflex is controlled by autonomic nervous system/brain/midbrain; (do not accept medulla)
b. light shone into the eye would normally cause pupil contraction;
c. no pupil reflex indicates that synapses are not functioning;
d. can indicate brain death but not necessarily / OWTTE;
Question
The following images identify brain activity associated with a specific function.
Label the indicated areas on the images.
X:
Y:
State the diagnostic tool used for functional analysis in the images.
Using the table below, distinguish between rod cells and cone cells.
Answer/Explanation
Markscheme
“>
Accept pons/brain stem in place of medulla oblongata
functional magnetic resonance imaging / fMRI
Accept FMRI.
Award [1] for each correct row.
Question
Define the term stimulus.
Outline the functions of the following parts of the brain.
Medulla oblongata:
Outline the functions of the following parts of the brain.
Hypothalamus:
Explain the effects of psychoactive drugs on synaptic transmission.
Outline how endorphins act as painkillers.
Answer/Explanation
Markscheme
stimulus is a change in the (internal/external) environment that can be detected
medulla oblongata: controls autonomic functions of the body such as heart rate/blood pressure/ventilation/swallowing/vomiting/digestion/cranial reflexes
hypothalamus: links nervous and endocrine systems/produces hormones secreted by posterior pituitary/controls hormonal secretion by pituitary/maintains homeostasis such as control of body temperature/hunger/thirst/fatigue/circadian cycles
psychoactive drugs may increase or decrease transmission (to the post-synaptic membrane);
may increase the release/delay the breakdown/interfere with storage/uptake/reabsorption of neurotransmitters;
may mimic the action of neurotransmitters;
inhibitory drugs may reduce the effect of excitatory neurotransmitters/increase the effect/release of inhibitory neurotransmitters;
inhibitory drugs can hyperpolarize the post-synaptic neuron;
endorphins released by pituitary gland (during stress, injury or exercise);
endorphins block transmission of impulses at synapses involved in pain perception;
bind to receptors in the membrane neurons (involved in) sending pain signal;
block release of neurotransmitters;
Question
Identify the parts of the brain indicated on the diagram below.
Outline the unconscious control of the heart rate.
Describe different aspects of the processing of visual stimuli.
Answer/Explanation
Markscheme
I. cerebral hemisphere / cerebrum;
II. hypothalamus;
III. cerebellum;
IV. medulla oblongata;
Award [1] for any two of the above.
heart can contract without nervous stimulation/myogenic contractions;
SA node is pacemaker/generates heart beat/initiates each cardiac cycle;
epinephrine/adrenalin speeds up the heart rate;
autonomic/sympathetic and parasympathetic nervous system control;
sympathetic speeds up heart rate;
parasympathetic/vagus nerve slows heart rate (back to normal/resting rate);
edge enhancement is greater perception at edges of light/dark areas;
caused by processing in two types of ganglion cell in retina;
contralateral is processing left field of view in right side of brain / vice versa;
cross over between left and right sides in the optic chiasma;
convergence is combining impulses from groups of (rod/cone) cells;
done by bipolar cells in retina;
Question
The diagram below is a cladogram.
State a function of each of the following parts of the human brain.
(i) Cerebellum
(ii) Hypothalamus
Identify the two most closely related organisms.
Identify the species to which the Bonobo is most distantly related.
Describe one type of barrier that may exist between gene pools.
Answer/Explanation
Markscheme
(i) (coordinates) unconscious motor functions/balance and movement
(ii) (maintains) homeostasis/thermoregulation/appetite/thirst / coordinates endocrine systems / secretes hormones/regulating factors
(common) chimpanzee and bonobo
gibbon
named barrier;
description of its action;
results in terms of gene pools;
e.g.:
behavioural barrier;
different populations mate at different times of year thus preventing interbreeding;
allele frequencies become different in the two gene pools/separates gene pools / sympatric speciation;
Question
Discuss the concept of brain death and how it can be diagnosed.
Answer/Explanation
Markscheme
it is a legal/medical definition of death;
some cases of coma are irreversible / some cases of coma may recover;
damage in the medulla (oblongata) is generally permanent;
doctors have to diagnose damage to decide treatment;
use tests of brain stem function to decide whether to preserve patient’s life / without brain stem function life cannot continue;
test pupil reflex / shine light into eye;
if pupils do not constrict with light this suggests brain death;
more than one test used to diagnose brain death;
no response to pain or cranial reflexes;
legal/ethical definition needed for organ donation / long term use of life-support machines may be inappropriate / bioethical considerations;
Question
The diagram below shows a section through the ileum.
The diagram below shows the structure of the retina. Label I and II.
Label I and II.
Distinguish between rods and cones.
Outline the pupil reflex.
Discuss the use of the pupil reflex in testing for brain death.
Answer/Explanation
Markscheme
I: ganglion cell
II: bipolar cell/neuron
(both needed)
I: lacteal
II: longitudinal/smooth muscles / muscularis mucosa
(both needed)
To award [2 max] responses need to be compared.
Responses do not need to be shown in a table format.
rapid unconscious response to change in light intensity / controls amount of light entering eye to prevent damage to retina/to see in darkness;
in bright light circular muscles in iris contract causing pupil to constrict / in dim light longitudinal/radial muscles in iris contract causing pupil dilation;
constriction by parasympathetic NS / dilation by action of sympathetic NS;
pupil reflex is a brain stem reflex / shows activity in the medulla oblongata;
pupil reflex must be absent in brain death;
pupil reflex is possible in coma victims where motor function is absent;
pupil reflex alone not enough to diagnose brain death;
other criteria include coma/absence of response to pain in all extremities/ absence of brain stem reflexes/lack of respiratory movements;
some cases of coma irreversible / some cases may recover;
doctors need to diagnose damage to decide treatment/long-term life support /organ donation;
Question
The following diagram shows a section through the spinal cord.
Outline one function for each of the following parts of the brain.
Label cells X and Y.
X: …………………………………………………….
Y: …………………………………………………….
Outline the direction of nerve impulses through the cells labelled X and Y.
Define the term reflex.
State whether the following psychoactive drugs are excitatory or inhibitory, using the table below.
Answer/Explanation
Markscheme
X: (cell body of) sensory neuron;
Y: (cell body of) motor neuron;
(both needed)
from the sensory neuron/X to the motor neuron/Y
a rapid and unconscious response (to a stimulus / of the nervous system)
Award [1] for every two correct responses.
Question
Discuss the concept of brain death and the use of the pupil reflex in testing for brain death.
Answer/Explanation
Markscheme
whole brain death is brain stem and cerebrum;
failure of pupil to respond to light indicates brain stem death;
without brain stem function, life cannot continue;
cerebrum involves higher order brain function;
non-functioning cerebrum with functioning brain stem is vegetative state;
some would argue this is the death of the person;
though brain stem function alone may be able to maintain homeostasis;