Back to Revision NotesQ1.
Hormones have a major influence on what an animal does,[Bk. 1: 2.9,
5.3.1; Bk. 4: 4.4.2; Bk. 5: 5.2.11] but control is ultimately the responsibility
of the nervous system as it, via the motor system, controls muscle contraction.
Hormones affect:
1) signal effects: the stimuli that one animal presents to another
(e.g. smell - mice [Bk. 5: 4.3.5], size - most mammals, colour - fish/birds
[Bk. 1: 2.5, 2.9], structures - deer/birds, sound - deer/birds/toads/frogs).
2) central effects: the way in which such stimuli are processed (e.g.
by altering brain structures during development - rats/birds [Bk. 4: 4.4.2,
4.4.3]).
3) peripheral effects: effects on organs other than the brain affecting
the ability of animals to respond (e.g. via stress hormones - mammals [Bk.
5: 5.2.1], reproductive hormones - rats [Bk. 2: 10.3.2] / doves[Bk. 1:
9.2.2] / zebra finches [Bk. 4: 4.4.3], circadian hormones - mammals [Bk.
5:3.9.1]).
Structure: 4 marks
Content: max. 12 marks
definition of hormones, etc. 4
marks
effects and examples 8 marks
interaction with external stimuli etc.
4 marks
Understanding: 6 marks
There are three main reasons:
1) survival - there is a struggle for existence and only some survive
[Bk. 1: 4.3.1, 4.3].
2) developmental factors (e.g. caste - ants [Bk. 4: 4.3.1) / mole rats
[Bk. 1:10.4.1], song - zebra finches [Bk. 1: 5.6], hormones - rats [Bk.
1: 5.3.l] / people (infertility) [Bk. 4: 4.5.5]).
3) mate choice (e.g. finding a mate, being chosen by a mate - territories-/displays/competitors
(red deer [Bk. 1: 4.3.8], fish/birds [Bk. 1: 9.4], frogs [Bk. 3: 2.2.5-2.2.8]).
Structure: 4 marks
Content: max. 12 marks
survival 4 marks
development 8 marks
mate choice. 4 marks
completion/integration
4 marks
Understanding: 4 marks
Need to emphasise differences - not just an account of "the synapse".
Differences: e.g. electrical vs. chemical; excitatory vs. inhibitory;
different neurotransmitters.
Time: e.g. summation, Hebbian synapse, potentiation.
Mostly Book 2.
Structure: 4 marks
Content: max. 12 marks
differences 10 marks
time related 4 marks
Understanding: 6 marks
1st part) The output from one receptor is compared with that of adjacent
receptors via a comparator cell. If the receptor in question excites the
comparator cell and adjacent receptors inhibit the comparator cell the
output of the comparator cell will reflect the balance between inhibition
and excitation; it will in effect compare the two types of input. Assuming
that the system is wired up appropriately so that equal stimulation of
the receptors evokes a nil response from the comparator, then any response
from the comparator will mean a luminance discontinuity across the receptors.[Bk.
3: 4.3.2]
2nd part) Largely. Colour: bipolar cells and opponency; motion: the
basic motion detector receives input from two receptors in neighbouring
retinal positions (delayed inhibition; velocity gradients : detectors add
together the responses from neighbouring individual motion detectors which
are selective for opposite directions of motion); stereopsis: comparison
of the images of the two eyes [Bk. 3: 4.4, 4.5, 4.6].
Structure & Understanding: 4 marks
Content: max. 12 marks
luminance discontinuities 10
marks
other information 10 marks
Learning alters the brain in such a way as to create memories which
affect future behaviour. Memories also allow interpretation and recognition
of stimuli [Bk. 1: 6.1]. There are several types of learning (associative,
non-associative and complex [Bk. 1: 6.3]), though whether non-associative
learning affects the brain is unclear [Bk. 4: 5.7.1]. Changes in the brain
consequent upon learning fit the Hebbian synapse model [Bk. 4: 5.4]. Numerous
changes of and to synapses have been reported [Bk. 4: 5.5]. The processes
by which these changes come about have been investigated in both the hippocampus
following LTP (LTP has many parallels with place learning in the Morris
water maze [Bk. 4: 5.7.3]) and the chick following passive avoidance learning
[Bk. 4: 5.7.4]. These changes may have a short-term, temporary component,
accounting for short-term memory and/or may result in long term, permanent
changes, accounting for long-term memory [Bk. 2:11.4; Bk. 4: 5.8].
It is not clear how these changes in individual synapses encode particular
memories.
Structure: 4 marks
Content: 12 marks
Understanding: 4 marks
This question could possibly be addressed in terms of Tinbergen's four
answers [Bk. 1:1.1.1].
Circadian rhythms are those with periods of about a day [Bk. 5: 3.1].
They have been shown to be endogenous, but are usually entrained by a zeitgeber
[Bk. 5: 3.2.2, 3.2.3].
In evolutionary terms, extant mammalian species have a circadian rhythm
because their ancestors had circadian rhythms and they were more successful
than mammals without circadian rhythms.
In functional terms, the rhythm enhances activity at appropriate times
of day [Bk. 5: 3.2.2, 3.2.3]. It also permits mating at appropriate times
of the year [Bk. 5: 3.9.1].
In developmental terms, the suprachiasmatic nucleus grows in the right
place (i.e. just above the optic chiasma) and has connections to other
appropriate structures (e.g. via retinohypothalamic tract) and is able
to secrete melatonin from the pineal gland [Bk. 5: 3.9.1].
In causal terms, the suprachiasmatic nucleus, entrained by the day
night cycle, causes the release of melatonin from the pituitary. Melatonin
is a timing hormone which influences reproduction in seasonal breeders
[Bk. 5: 3.9.1] and synchrony of internal rhythms in mammals.
Structure: 4 marks
Content: 12 marks
Understanding: 4 marks
This question is about direct competition [Bk. 1: 4.3.2] and assessment
[Bk. 5: 4.5 -4.8].
Direct competition is where one animal wants exactly the same resource
(e.g. food, territory, mate) as another animal, at the same time. Tussles
ensue but if the resource is of low value to both or one of the participants
then one will leave or flee. If the resource is of high value to both participants
(e.g. stags competing for mates) then they may establish their respective
resource holding potential (RHP) in a roaring display. One stag will back
down if it detects an asymmetry (i.e. that it is weaker). IF neither stag
detects an asymmetry, then severe fighting occurs. Toads also use correlated
asymmetries to assess the RHP of males in amplexus. They will only attack
if they detect an asymmetry in their favour (i.e. they have a lower pitched
croak and are therefore bigger). Where a resource is important but neither
limited nor permanent (e.g. sunspots in a wood), then an uncorrelated asymmetry
(e.g. residence) may be used to resolve the dispute.
Displays have evolved which provide information about RHP to conspecifics.
Only in the absence of an asymmetry when the resource is of high value,
does direct competition lead to severe injury or death.
Dominance hierarchies could also be mentioned.
Structure: 4 marks
Content: 12 marks
theory 6 marks
examples 6 marks
Understanding: 4 marks
It is possible to consider the recovery of function and the recovery of structure. Language can be permanently disrupted following brain damage (e.g. Broca's area [Bk. 2: 11.2; Bk. 6: 6.3.3, 6.3.4]), as can memory (e.g. amnesic syndrome [Bk. 2: 11.4]). Arguably, Alzheimer's and Parkinson's diseases are also brain damage and there is no recovery from them [Bk. 6: 3.7.1; Bk. 6: 4.3.2]. Some recovery from stroke and head injuries is possible [Bk. 6: 5.2.1; 5.2.2]. However, if such damage occurs in infancy, then recovery is possible [Bk. 2: 11.3.2; Bk. 6: 5.3]. There is limited axon sprouting [Bk. 6: 5.4.2] and pathway restructuring [Bk. 6: 5.4.3] as well as reversal of oedema [Bk. 6: 5.4.1]. (Intervention to aid recovery could feature in this account (e.g. grafts [Bk. 6: 5.5]).
Structure: 4 marks
Content: 12 marks
Understanding: 4 marks
The neurological symptoms of normal ageing (as opposed to pathological
ageing) are related to memory (especially short term and working memory,
but also prospective and semantic), sensory input and speed of performance.
Though highly practiced skills are retained (e.g.chess playing) and wisdom
improves. There is little loss of cognitive or other intellectual functions.
Schizophrenia is a psychosis in which the patient experiences life
in a disturbed way owing to delusions, hallicunations or misinterpretations.
Onset is usually between 16-45 years of age. Pre-senile dementia (early
onset Alzheimers) may occur in people in their forties and some of the
symptoms are similar. Many though, (memory loss, disorientation, incontinence)
are not similar. A major distinction is that the brains of schizophrenics
look more or less normal (apart from minor differences (enlargement) of
the ventricles and asymmetries between left and right hemispheres) whilst
those with Alzheimer's disease are littered with senile plaques and neurofibrillary
tangles. The neurotransmitters invoked in these two conditions are different
(Alzheimer's: acetylcholine; Schizophrenia: dopamine, serotonin).
There is some overlap in symptoms between schizophrenia and pre-senile
dementia but there is no overlap in the biology underlying those symptoms.
Structure: 4 marks
Content: 12 marks
schizophrenia 6 marks
ageing 6 marks
Understanding: 4 marks
| Back to Questions |
Back to Revision Notes |