Back to Revision NotesQ1.
Functional up to 8 marks
relative reproductive effort, male invests little in sperm, but may
mate with many females; female invests relatively more in eggs (ova) and
may mate only once, thus it is in her interests to choose carefully. If
parental care is involved then mate choice may be affected by the mating
system adopted.
Causal up to 12 marks
8 marks for: Species recognition - unique signals (e.g. bombykol),
preferred stimuli (song in crickets, flash sequence in fireflies), sexual
imprinting, developmental sequence (e.g. bird song [indigo birds]), peripheral
filtering (frogs), sign stimuli.
4 marks for: Individual choice - females may choose males using
such things as size, displays (behavioural and plumage), nest quality,
territory size, competition with other males. Males may choose females
according to size, colour.
Book 1: §2.8, 5.4.1, 5.4.2, 5.5.5, 9.3.1, 9.3.2, 9.4; Book 3: §2.2.
The meaning is a particular short period early in the life of the organism during which it shows enhanced responsiveness to certain stimuli. The relevance is firstly that the stimulus has to be present at that time and secondly that subsequent behaviour may be dependent on what happened during a sensitive period. 5 marks
Examples include bird song, imprinting, host recognition, decision points (in ants), binocular cells in the visual system, similarly the aural system, organizing effects of hormones. Some may cite the effects of drugs or diseases during development - these are exemplars of vulnerable periods because the effects are debilitating/abnormal. For each example (minimum of three for max. marks) should explain the nature of the sensitive period and how it has been demonstrated. 5 marks per example.
Book 1: §1.2.3, 5.5.2; Book 4: §4.3.1(b), 4.3.3, 4.4.2, 4.4.3,
4.5.3 [cf vulnerability, 4.5.4].
(A) A basic account of the anatomy and function of the spinal cord needed here. Diagram. 5 marks
(B) CNS pathways, efferent and afferent, segmental organization, layered structure. Sensory cell bodies in dorsal root, motor cell bodies in ventral root. 7 marks.
(C) Reflexes- how organised, reciprocal antagonist inhibition, contralateral compensation, control of rhythmic walking. Proposed site of the pain gate. 8 marks.
Alternatively, if (A) embedded within (B) and (C), then 10 marks each for (B) and (C).
Book 2: §8.2, 8.3, 8.5, 9.3, 9.5.1, 9.5.2, Book 3: §5.2.4,
5.7, 5.8.4.
Students with a good imagination will come up with a wide range of possibilities. We are not too interested in the feasibility that something could actually occur, but marks should be awarded for the logic behind the explanation. Give credit for organisation of the answer, and appropriate use of headings. Other forms of heading are equally acceptable, e.g. psychological, anatomical, physiological, neurochemical, etc.
(a) Peripheral Nervous System 7 marks
(i) Nociceptor endings could be absent, or present but not functioning.
(ii) There could be an absence of small diameter afferent axons (Aδ
& C fibres).
(b) Central Nervous System 13 marks
(i) Nociceptive neurons (2nd order, T-cells) in the dorsal horns could
be absent, or if present, the synapses with nociceptive afferents could
be abnormal or absent.
(ii) There could be an imbalance in the normal pattern of inputs from
small and large diameter afferents, with the latter predominating. i.e.
the 'gate' is permanently closed.
(iii) There could be abnormal release of neurotransmitters, e.g. high
levels of endogenous opioids.
(iv) There could be some abnormality of ascending nociceptive pathways,
e.g. spinothalamic or spinoreticulothalamic tracts.
(v) The sensory pathways might be normal, but there is some dysfunction
of the brain structure involved in the processing of nociceptive inputs.
Book 3: §5.2.2, 5.2.3, 5.2.4, 5.4.2, 5.4.3, 5.5.2, 5.7, 5.8.
Mostly this is about the fact that axons grow towards a particular target guided by chemotropic substances, chemotactic processes (e.g. guidepost cells), pathways (e.g. laminin) and other axons (i.e. cell adhesion molecules) - axons that grow together stay together. 10 marks
Students may start at an earlier developmental stage with neurons born in particular places and migrating to particular locations.
Axons making contact with appropriate targets at the right time survive due to chemotrophic substance. The activity of axons is also important (cat LGN, rat superior colliculus) 10 marks
Book 4: §2.4, 3.2, 3.3, 3.4, TV.
Students could point out that the statement refers to intraspecific conflict, not predation. The answer should be in terms of costs and benefits. Fighting is costly (injury, exhaustion, lost time, susceptibility to predation both during and after) so should be avoided. It is necessary to compete by fighting (direct competition) when the benefits are high. 8 marks
"Last resort" suggests that other means of settling the dispute, whilst possible, have failed. These other means use assessment of resource holding potential, other correlated asymmetries or on some occasions uncorrelated asymmetries (ownership of a sunspot). Thus on the occasions when these other means don't lead one animal to retreat, there will be a fight, Many species do fight, some to the death. Appeasement displays used by some animals could be mentioned as reason for limitation to the amount of fighting. 12 marks.
Book 5: §4.5, 4.6, 4.7, 4.8, TV.
Stress 10 marks
Occurs when flight or fight is necessary, but not possible. Students
should describe what conditions might lead to such a situation and also
the underlying physiology. They should refer to the ANS, the hypothalamic-pituitary-adrenocortical
system, corticosteroids, ACTH, and the normal way of closing the loop through
negative feedback actions of corticosteroids. However, the system is in
open-loop when under stress.
Chronic and bad effects 10 marks
Students may describe von Holst's shrews (stressed animals had larger
adrenals). Active vs. passive strategies in stressful situations. Enduring
(long-lasting) stress is a bad thing because it results in circulatory
system pathology, lack of control and depression, suppression of the immune
system.
Book 5: §5.1, 5.2, 5.3, 5.5.
8 marks for:
Discussion of cognition and the dependence of cognitive functions on
other functions which change with age (e.g. processing capacity, processing
speed, working memory capacity and sensory and perceptual changes).
4 marks each for each of the manifestations:
i) Attention - vigilance (detecting change in a long sequence of stimuli)
age differences if too fast, too prolonged or too reliant on preceding
states; selective attention, older people more easily distracted; divided
attention (dichotic listening, multiple tasks), older people perform less
well and more slowly.
ii) Learning and memory - older people more slowly conditioned to eye-blink,
require more practice to reach same level of performance (e.g. violin,
German), poorer performance on forward and backward digit span, poorer
episodic memory (cf. semantic memory).
iii) Language - reduced syntactic complexity, greater difficulty with
spoken vs. written language.
iv) Thinking - differences apparent rather than real (due to poor strategies,
or reduced memory).
Max. mark limited to 20!
Book 6: §2.3, 2.4, 2.5.
7 marks for neurological (N), 7 for Psychiatric (P) and 6 for compare and contrast.
Both "present" as behavioural disorders; neurological disorder (N) dependent on neuroanatomy and neurophysiology, psychiatric disorder (P) not so dependent; Descartes dualism; in N the focus of attention becomes the associated "organic" disease (e.g. the substantia nigra) which can be studied (loss of dopamine-secreting cells, pathways between the striatum, substantia nigra, globus pallidus and thalamus), treated (use of L-DOPA, the dopamine precursor), possible cured (brain grafts); in P there is no such focus, the symptoms are individualistic, study (various [unproven] causes: psychological, labelling, family, grounded social, mismatch between the "real" world and their perception of it; biological: an imbalance of neurotransmitters supposed (based on effects of drugs which alter the imbalance), genetic, treatment (various, dependent on presumed cause) and cure (not forthcoming).
Book 6: §1.2.3, 1.4, 4.3.1, 4.3.2, 5.5, 7.5, 7.6, 7.7.
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