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Compare rod and cone cells.(3)
- rod, cone
- sensitive to low light specialized (more bleached in bright;
- not as sensitive to bright light (color specialized)
- sensitive to all wavelengths (monochrome vision);
- three types cells sens to red, green, blue light = color vis
- groups rods send info to single nerve fibre in optive nerve;
- passage fr single cone cell to single nerve fibre (higher visual acuity)
- wider FOV absent in fovea;
- less inretina more in fovea = smaller FOV
Explain the processing of visual stimuli,
- visual process stimuli begins in retina
- response o each point on retina infl by neighbouring regions
- each ganglion cell receives signals fr rods and cones in certain area retina = receptive / visual field
- visual fields = circular with round centre and surround
- when light falls on photoreceptor, responds by firing more freq and inhibits adjacent cells fr firing = lateral inhibition
- receptive field on retina can be drawn representing excitatory ganglia in centre, inhibitory ganglia on peripheries (on centre off surround)draw pic / annotate
- + in centre, - in surround
- off: ganglion decrease neural activity less freq firing with more light , more light = more inhibitory
- center: excitatory, increase with neural activity more freq firing with more light
- edge enhancement occurs within retina and can be demonstrated with hermann grid illusion
- purpose is to provide a greater contrast at the edges of objects
- lateral inhibition makes neighborhood dark objec appear lighter, vice versa
- retina uses contrast instead absolute light intensity to recog objects
- hermann grid = ganglion cells aimed at intersection has greater proportion inhibitory surround stimulated by white strips -> more inhibited than cells above and image = grey due to lower excitation
- in pathways: smaller prop inhibitory surround stimul by light, less lateral inhibition @ centre, area = white
- vice versa in centre of squares (eyes scanning)
- if stare on centre, visual fields in fovea smaller than other parts retina
- -way in which the brain collects and integrates information from the eyes to create the perception of seeing
- -Bipolar cells in retina combine the impulses fr rod or cone cells and pass them onto sensory neurons o optic nerve
- -Axons o ganglion cells form optic nerves tt carry sensations fr eyes to brain
- -Optic nerves fr two eyes meet at optic chiasma near centre o base o cerebral cortex
- -due to optic chiasma, right brain processes info fr left visual field vice versa
- -optic nerves form synapses in the lateral geniculate nucleus with neurones from the primary visual cortex
- -brain is able to integrate the 2 dimensional information of the retina back into a 3 dimensional perception
Label a diagram of the ear.
Explain how sound is perceived by the ear
incl roles eardrum, bones middle ear, oval and round windows, hair cells cochlea (4)
- Eardrum(tympanum): Sounds waves =vibrate, ear drum move rapidly toward and away fr middle ear; eardrum picks up sounds vibrations fr air and transmits them to middle ear
- Bones o middle ear: Series o 3 small bones (ossicles) in middle ear, each touches next, role= transmit sound waves fr eardrum to oval window; role in sound amplification, both tympanum + ossicles increase force at oval window
- Oval and round windows: OW =membranous structure tt transmits sound waves to fluid o cochlea; fluid is incompressible, a second membranous window is needed (round window), when oval window moves toward cochlea, round window moves away fr it, so fluid in cochlea can vibrate freely w/o changing volume
- Hair cells: Cochlear tube has membr w/ receptors =hair cells, have hair bundles attached, stretch fr one membrane to another-when sound waves pass through cochlea, hair bundles vibrate, resonating with particular frequency; allows for detection o diff freq o sound, when vibrate, hair cells send msgs across synapses and on to brain via auditory nerve
Describe the social organization of honey bee colonies and one other non-human example.
- social animals live in groups, interaction behavior = social behviour
- live in colonies up to 60k bees, = super organism tt lives or die together, can reprod to form more colonies by swarming
- 3 castes
- queen: 1, fertile fem lays eggs, produces pheromone to control activ workers + attract drones, mates once perhaps w/ several drones and stores sperm
- drones: fee hundred short lived, fertile males who do nothing to help colony survive, main task = mating, near end season ejected fr colony so mate w/ other queens + spread colony's genes
- workers: infertile females who do all work, collect nectar / pollen, convert pollen = honey, secrete wax for comb, feed and tend larvae, guard hive
need to know dance bees communication?
social organization naked mole rat colonies
- live in colonies of up to 80 individuals, in burrow systems in parts of East Africa.
- One dominant female mole rat acts like a queen bee = only female in the community to reproduce, mating with one males
- 'Frequent workers' dig the tunnels and bring food.
- Infrequent workers' are larger and occasionally help with heavier tasks.
- 'Non-workers' live in the central nest, keeping the breeding female and her young offspring warm and defending the colony if it is attacked.
Outline how natural selection may act at the level of the colony in the case of social organisms.
- natural selection: Individuals who survive to reproduce pass on their genes into the next generation = Successful genes = more frequent in the population.
- colony = super organism
- either colony as whole survives and reprod or entire colony dies, no genes passed on
- indiv cannot survive alone
- natural selec allows for survival and reproduction only at colony lvl
Discuss the evolution of altruistic behaviour using two non-human examples.
- darwinian fitness = contribution indiv makes to gene pool o next gen relative to contribu o other indiv
- altruistic behav = when harmful to self , but helpful to another
- honeybees when worker dies while defending colony or feeding larva when it is not parent
- naked mole rats when workers dig food and bring back to feed queen + soldiers, defend colony against invading snake
- altruistic behav explained by fact tt indiv colony closely genetically related, so helping rear off or protect = ensures survival own genes
- parental care not considered alt b/c increases fitness indiv showing
- vamp bats regurgitat blood to feed bat tt hasn't fed
- reciprocal altruism = benefit group, might get back
Outline two examples of how foraging behaviour optimizes food intake, including bluegill fish foraging for Daphnia. / starling
- Defn: animals search for food=foraging.
- Animals optimize food intake by foraging
- Bluegill sunfish live in ponds, prey on small invertebrates, incl Daphnia
- When low density of prey, bluegill sunfish consume all sizes of them.
- At medium prey densities, bluegill sunfish consume only prey of moderate or larger sizes.
- At high prey densities they mostly consume large prey, some medium size.
- Consuming small numbers of large prey takes less energy than otherwise, hence the preference for large prey.
- At low prey densities, smaller prey have to be eaten as well, to get enough food in total.
- Starlings birds feed young mainly with crane-fly larvae
- Obtain by probing into soil w/ beak= less efficient at probing for larvae, as number held in their beaks increases
- Fewer journeys back to the nest, the less time and energy is used in transporting the larvae to the offspring
- Optimum number larvae to catch and carry back to the nest depends on the distance between the foraging area and the nest
- As the distance increases, the optimum number (total number) of larvae increases.
Explain how mate selection can lead to exaggerated traits.
- Exaggerated traits inclu peacock tails
- Some species of animal have characteristics or behaviour patterns that seem to be developed excessively
- The long and brightly coloured tail feathers of a peacock = only used during courtship, to try to attract a female
- Other times, the tail feathers = encumbrance, hindering rapid movement, especially during attacks by predators.
- may be the explanation for the evolution of an exaggerated trait: any individual that survives, despite the exaggerated trait, must be well-adapted in other so is a good mate to choose
- e.g. lion’s mane
animals show rhythmical variations in activity
Outline two examples illustrating the adaptive value of rhythmical behaviour patterns.
Many animals show rhythmical patterns, usually follow either a diurnal (daily) or an annual (yearly) cycle.
- 1. Moonrats = nocturnal. Live in Asia, lowland forests and mangroves.
- excellent sense of smell = forage at night when much of their prey is active
- -insects and other invertebrates
- Less vulnerable to predation at night, day they rest in holes among tree roots or in hollow logs, where unlikely discovered.
- 2. Red deer Reproduction follows annual cycle in red deer
- Males/females sexually active in fall (autumn)
- Males fight to establish dominance over groups of females
- Advantage is that if the females start gestation in the fall, the offspring are born in spring.
- Most food available in spring/ summer for feeding offspring
- Type of season breeding gives the offspring the greatest chance of survival.
state that some presynaptic neurons
excite pos-synaptic transmission and others inhibit post-synaptic transmission
Explain how decision-making in the CNS can result from the interaction between the activities of excitatory and inhibitory pre-synaptic neurones at synapses.
- Summation: effect produced by release o both excitatory and inhibitory neurotransmitters fr two or more presynaptic neurons into synapses associated w/ single postsynaptic neuron;
- at the postsynaptic membrane, production o action potential depends upon summative effect reaching threshold lvl for tt neuron.
- inhibitory neurotransmitters import. =prioritizing sensory information reaching brain, allowing background sensory information to be ignored
Explain how psychoactive drugs affect the brain and personality by either increasing or decreasing post-synaptic transmission.
- post-synaptic membrane contains receptors for the normal neurotransmitters. Normally when the neuro transmitter attaches to these receptors it either:
- Depolarise the post synaptic neurone resulting in an action potential
- Hyperpolarise the post synaptic neurone resulting in no action potential
- drug can therefore change post synaptic output by:
- Blocking or enhancing the depolarising neurotransmitter
- Blocking or enhancing the hyperpolarise neurotransmitter
- Psychoactive drugs are those that alter the state of mind by changing (stopping or enhancing ) the activity at the post synaptic neurone.
- Psychoactive drugs characteristically create either calm or excite moods.
- excitatory psychoactive drugs: increase synaptic transmission by promoting synaptic transmission at excitatory synapses, or inhibiting transmission at inhibitory synapses
- Inhibitory psychoactive drugs: decrease synaptic transmission opp o above
List three examples of excitatory and three examples of inhibitory psychoactive drugs.
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