1. NEUROBIOLOGY AND BEHAVIOUR
Option E
IB Biology
Miss Werba

2. OPTION E – NEUROBIOLOGY & BEHAVIOUR
STIMULUS and RESPONSE
E.2
PERCEPTION of STIMULI
E.3
INNATE and LEARNED BEHAVIOUR
E.4
NTs and SYNAPSES
E.5
THE HUMAN BRAIN
E.6 FURTHER STUDIES IN BEHAVIOUR
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3. THINGS TO COVER Definitions of stimulus, response & reflex
Role of the following in response to stimuli:
Receptors
Relay neurons
Motor neurons
Synapses
Effectors
Draw & label a diagram of a flex arc for a pain withdrawal reflex
How natural selection can affect animal behaviour
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4. INTRODUCTION OF TERMS Command term = DEFINE
Stimulus: A change in the environment that is detected by a receptor
Response: A change in an organism resulting from a stimulus
Reflex: A rapid and involuntary (unconscious) response to a stimulus

5. THE RESPONSE TO STIMULI Command term = EXPLAIN
Receptors:
specialized cells designed to generate a neural signal when stimulated
transform stimuli into electrical nerve impulses
eg. thermal energy into action potentials
Sensory neurons:
transfer the nerve impulse to the CNS
enter the dorsal root of the spinal cord
Relay neurons: (interneurons or connector neurons)
transfer the nerve impulse within the CNS

6. THE RESPONSE TO STIMULI Command term = EXPLAIN
Motor neurons:
transfer nerve impulses from the CNS to an effector
exit from the ventral root of the spinal cord
Effectors: (muscles or glands)
produce a response to the stimulus
Synapses:
junctions between two nerve cells
synaptic transmission of a signal requires chemical neurotransmitters

7. THE RESPONSE TO STIMULI Command term = EXPLAIN
Sensory neurons:
receptor organs
CNS
Relay neurons:
motor neurons
sensory neurons
Motor neurons:
effectors
CNS

8. THE PAIN WITHDRAWAL REFLEX Command term = DRAW and LABEL
Reflexes are rapid and unconscious responses
eg. The response to pain
Reflexes are the product of natural selection (evolution):
Rapid and unconscious responses allow for danger avoidance with minimal harm to the organism – so pain is a good thing!
The pain reflex is a spinal reflex
Means that it is moderated by the spinal cord rather than the brain.
Shorter paths therefore faster responses and no conscious decisions needed!

9. THE PAIN WITHDRAWAL REFLEX Command term = DRAW and LABEL

10. THE PAIN WITHDRAWAL REFLEX Command term = DRAW and LABEL

11. THE PAIN WITHDRAWAL REFLEX Command term = DRAW and LABEL

12. NATURAL SELECTION & BEHAVIOUR Command term = EXPLAIN
Natural selection is Charles Darwin’s theory of Evolution.
It’s the process by which the frequency of an inheritable characteristic changes as a result of environmental selection pressures.
These beneficial inheritable traits are called adaptations.
They can include instinctive behaviours, such as migrating, foraging, hunting, communication, etc.

13. NATURAL SELECTION & BEHAVIOUR Command term = EXPLAIN
Examples are the best way to explain natural selection and its effect on behaviour.
Examples:
Blackcap migration patterns
Butterfly mate preference
Any other example that you wish to use is fine too 

14. E.1.4
EXAMPLE 1: BLACKCAPS
Scientific name: Sylvia atricapilla (S. atricapilla)
Common name: the blackcap bird
Breeds during the Summer in Germany .

15. E.1.4
EXAMPLE 1: BLACKCAPS
Normal behaviour: chicks hatch and fly SW towards Spain for Winter (to avoid harsh Winter conditions)
Alternate behaviour: some chicks hatch and fly NW towards UK
Advantage of alternate:
It’s closer and birdfeeders provide easy sources of food
Birds can return to Germany faster and be more reproductively successful

16. E.1.4
EXAMPLE 1: BLACKCAPS
Natural selection: genes for NW migration passed on to offspring; population begins to change over time
Experimental evidence: they swapped the eggs in the nests of the two groups, and the NW chicks that hatched still flew NW when they migrated for the Winter

17. EXAMPLE 2: BUTTERFLIES Scientific name: Heliconius cydno (H. cydno)
Common name: the Heliconius butterfly
Heliconius butterflies exhibit mate preference for butterflies with particular colour markings.

18. E.1.4
EXAMPLE 2: BUTTERFLIES
Normal behaviour: huge range of colours and individuals mate with any other variant
Alternate behaviour: Yellow butterflies developed preference for yellow mates
Advantage of alternate:
Yellow pigment may be easier to see
May be occupying a particular niche that the colour suits

19. E.1.4
EXAMPLE 2: BUTTERFLIES
Natural selection: Yellow butterflies are becoming reproductively isolated through sexual selection. Will likely result in speciation over time.
Experimental evidence: observations show preferential mating, hybrids are not as well adapted to the local niches

20. Sample questions Q1 True or false?
1. The difference between sensation and perception is whether information about a stimulus reaches the central nervous system.
2. Once transmission along a neuron starts it can't be stopped without damaging the neuron.
3. Sensory nerve cells act as the decision-making cells to sum up all signals for certain stimuli.
4. Neurons often have many short dendrites and a long axon.
5. A sensory neuron of the peripheral nervous system take nerve impulses from sensory receptors to the motor neurons
6. Nerve impulses go from sensory neurons in sense organs directly to the muscles and glands that respond.
7. A nerve impulse is the way a sensory neuron receives information.
8. In humans, transmission of nerve impulses across a synaptic cleft is carried out by neurotransmitters.
9. The central nervous system consists only of the brain.
10. Information about touch detected on the left side of the body is transmitted to the brain in the dorsal columns of the spinal cord.
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21. Sample questions A1 F T
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22. Sample questions Q2
Identify the mean time until the laying of the first eggs in the control group of Zebra finches. [1]
Calculate the percentage decrease between the mean time until the laying of the first eggs in pairs of Zebra finches exposed to intra-colony sounds and in pairs exposed to extra-colony sounds. Show your working. [2]
Evaluate the effect of the recorded colony sounds on the reproductive pattern of laying eggs in Zebra finches. [3]
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23. Sample questions Q3 Q4 Define the terms stimulus and reflex. [1]
Explain the role of the neurons used in the pain withdrawal reflex. [3]
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24. Sample questions A2 15 days [1]
(4 days /13 days) × 100 = 31% or 30.8% or 30.77%; [2]
both types of sound decreased mean time to egg laying; extra-colony sound decreased time more than intra-colony; both types of sound increased (mean) number of eggs laid; same (increase in) egg number with intra- and extra-colony sound; no information on sample sizes/number of pairs/egg size; competition (implied/perceived) leads to earlier egg laying [3]
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25. Sample questions A3
stimulus: change in environment; reflex: rapid, unconscious /involuntary response; 2 A4
sensory neurons receive information from receptors; transmit nervous impulses to the central nervous system; relay neurons in the central nervous system transmit the information from sensory neurons to motor neurons; motor neurons send impulse to effector; 3 max
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