Back to Revision NotesQ1.
Book 1.
Fitness is a measure of lifetime reproductive success compared to other
members of the population. In one year the only measures available are
those of partial fitness [number of matings, number of eggs, number of
viable offspring, number of offspring that fledge, number of offspring
that survive to next breeding season]. These data from the albino male
need to be compared to those of the rest of the male population. For all,
there is a difficulty of establishing paternity (unless albinism in crows
is dominant, even then the difficulty of comparison remains). The limitations
are that breeding success of (albino) offspring will not be known, nor
will subsequent year by year breeding success of the albino male. It may
only survive to breed once or twice, compared to six or seven times for
other males, for example; (albino) offspring may not breed until later
in life than other males; (albino) females may not hatch, may not breed
at all, or may lay lots of eggs.
Content 12: definition of fitness 2, study measures
5, shortcomings 5.
Style: 4
Understanding: 4.
Content:
Some discussion that communication is the exchange of information reducing
uncertainty; that "eavesdropping" complicates any definition; that many
species specific signals have evolved for intraspecific communication;
that it can involve any of the senses. 6 marks
Examples of the link between communication and specific behaviour - e.g. finding a mate; choosing a mate; direct competition (for territory/food/mates) especially between males; parental behaviour; group living (dominance/vigilance); eavesdropping and prey capture etc. Examples should be varied as to behaviour and sensory modality. 6 marks
Structure 4 marks
Understanding 4 marks
The following facts should be carefully woven into a coherent essay.
Central: Peri-aqueductal grey matter; peri-ventricular grey matter;
Raphe nuclei; stimulation produced analgesia; stress induced analgesia;
descending pathways; T cells; opioids (enkephalins, endorphins, dynorphins);
opiates (morphine); naloxone; serotonin; surgery (ascending pathways);
substance P; substantia gelatinosa; the gate. 8 marks
Peripheral; prostaglandins; bradykinins, nociceptors; C fibres; analgesics
(aspirin); local anaesthetics (lignocaine); efferent sympathetic (noradrenalin);
TENS; acupuncture. 8 marks
"Pain control" includes decreasing pain, moderating pain, and similar.
(Max for content = 12)
Structure 4 marks
Understanding 4 marks.
If not related to control, then reduce understanding so max. possible
mark is 16.
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, e.g. conditioning, non-associative e.g. habituation and complex [Bk. 1: 6.3]), though whether non-associative learning affects the brain is unclear [Bk. 4; 5.7.11.) 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 Long Term Potentiation (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.
Content 12: definitions of memory (STM, LTM etc.) 3,
changes 9
Structure: 4
Understanding: 4 .
This question should be addressed in terms of Tinbergen's four answers [Bk. 1:1.1.1] - developmental, causal, functional, phylogenetic: 2 marks each for good definitions.
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]. max 2 marks.
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. Possibly ensuring peak activity at appropriate times of day. max 2 marks.
In functional terms the rhythm enhances activity at appropriate times of day [Bk. 5: 3.2.2, 3.2.3], enhancing the possibility that conspecifics meet. (It should not be confused with photoperiodism, which permits mating at appropriate times of the year. [Bk. 5: 3.9.1]). max 2 marks.
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). The animal is able to secrete melatonin from the pineal gland [Bk. 5: 3.9.1]. max 2 marks.
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 synchrony of internal rhythms in mammals. max 2 marks.
Structure 4
Understanding 4
The basal ganglia comprise the striatum (the caudate nucleus and putamen), the globus pallidus and the substantia nigra. The CN is adjacent to the lateral ventricle and the P and GP are lateral to the thalamus. The SN is ventral to the thalamus. They are bilateral, midbrain structures with extensive connections to the cortex, he thalamus and each other. A principal dopamine pathway extends from the SN to the striatum. Inhibitory (GABA) pathways link the striatum to the GP and SN and thence to the thalamus via unknown inhibitory neurotransmitters. The thalamus has excitatory links to the motor cortex, which has excitatory input to the striatum. This describes the motor loop; there are other loops (to do with "movement of the eyes or integrating motivations such as hunger, sexual arousal and fear, and others involved in cognitive processes such as learning and memory"). The principal function is in sensory-motor integration, as exemplIfied by tremors and stiffness in hypo- and hyper-kinetic disorders such as Parkinson's Disease (PD) and Huntingdon's Disease (HD) when organisation within the basal ganglia breaks down.
Structure: 4
Understanding: 4
Content: either 4 for location (incl. parts), 4 for interconnections,
6 for function
or 6 for anatomy, 6 for function, 3 for
correct diagrams.
Reasonable marks if answer concentrates on PD and HD while including
appropriate, accurate details.
Ion channels are usually (course states always) selective for one ion. Movement of ions is called conductance and high conductance equals high movement. max 2 marks.
Passive channels: these are channels that are usually open; (e.g. low conductance K+ channels found on the axon). These can be non-specific. max 2 marks.
Voltage gated channels: in axon hillock and along axon; allow passage
of ions at particular
voltage (threshold) and close after a given interval. Vital to action
potential as sodium influx is first stage and halts when sodium channels
close and potassium channels open; vital to transmitter release as Ca+
influx at pre-synaptic bouton required. max 4 marks.
Ligand-gated channels: in post-synaptic membrane of cell body (and some receptors e.g. olfaction); allow passage of ions when appropriate ligand (usually a neurotransmitter) is present in synaptic cleft: Na+ and Ca+ channels result in small EPSPs which decay with distance, but can also summate; Cl- channels result in small IPSPs which decay with distance, but can also summate. Their (Na+ and Ca+) role is to supply the depolarisation upon which an action potential is born. max 4 marks.
Second messenger channels: ligand attaches to receptor and sets in train a biochemical cascade which results in opening ion channel. max 2 marks.
Active channels: e.g. transport molecules such as the Na+/K+ pump. max 2 marks.
Structure: 4 marks
Understanding: 4 marks.
Perceptual acuity declines with knock-on effects for cognition. Both long-term and short-term memory are affected. In working memory the amount of information that can be held in consciousness is reduced. Retrieval from long-term memory becomes more difficult. There is a decline in speed of processing and in multi-tasking. max 8 marks.
Difficulties in studying revolve around cross sectional studies with associated cohort effects and longitudinal studies with problems of practice effects and fatigue, as well as uncontrolled drop out. There is also the problem of very large variation in the effect of ageing. There are financial and practical problems in maintaining a research program over many years. Laboratory vs naturalistic studies; animal models. max 8 marks.
4 marks style
12 marks content: 8 psychological effects; 8 methodological
4 marks understanding
Students should attempt to clarify the distinction between neurological
(or organic) disorders and psychiatric (psychological or functional) disorders
by giving examples (e.g. Parkinson's, stroke and depression, schizophrenia
respectively). The implication of this mind/brain dichotomy for explanations
and for treatment should be explored. Current attempt to identify brain
correlates of schizophrenia have had limited success (enlarged ventricles;
left right asymmetries; altered levels of dopamine or GABA). Social and
life-history explanations may result in different treatment from biological
explanations. But if all are susceptible to treatment with drugs perhaps
they are all organic?
Content: 12 marks
Structure 4 marks
Understanding 4 marks
| Back to Questions |
Back to Revision Notes |