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58 Cards in this Set
- Front
- Back
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How are nerve impule transmissions inhibited by postsynaptic neurones?
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* inside the neurone is more negatively charged
* so stimulation doesn't reach threshold level * so it isn't depolarised * so less Na+ ions enter |
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Describe the sequence of events which allows information to pass from one neurone to the next across a cholinergic synapse.
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* impulses cause calcium ions to enter the axon
* vesicles move to/ fuse with the presynaptic membrane * releases acetylcholine * acetylcholine diffuses across the synaptic cleft & binds with receptors on the postsynaptic membrane * sodium ions enter the postsynaptic neurone * postsynaptic membrane is depolarised * if above threshold, nerve impulse is produced. |
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How would the binding of another neurotransmitter on receptors on postsynaptic membranes inhibit the transmission of impulses by postsynaptic neurones?
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* the postsynaptic neurone is depolarised
* stimulation doesn't reach threshold level so action potential not produced * not depolarised * reduces effect of Na+ ions entering |
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How would the entrance of Cl- ions into the postsynaptic neurones inhibit the transmission od impulses by postsynaptic neurones?
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* the postsynaptic neurone is depolarised
* stimulation doesn't reach threshold level so action potential/ nerve impulse not produced * not depolarised * reduces effect of Na+ ions entering |
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How does inhibition of synaptic transmission by neurotransmitters occur?
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* neurotransmitter binds to receptors on the postsynaptic membrane
* acetylcholine cannot bind * stops/prevents depolarisation |
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What changes occur in the eyes when we focus?
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* ciliary muscles contract
* suspensory ligaments slacken * lens bulges due to elasticity * shorter focal length * eye muscles contract to move eyes in sockets * pupil gets biggger to expose more lens |
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What is the role of the speech association area in reading aloud?
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* selects correct word/ identifies word from past experience
* understands language * processes written word |
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What are the differences between a cholinergic synapse and a neuromuscular junction?
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* cholinergic synapse is neurone-to-neurone
* neuromuscular junction is neurone-to-muscle * action potential is produced in neurone NOT muscle (so only in cholinergic synapses) * some neuromuscular junctions have different neurotransmitters * muscle response is ALWAYS excitatory |
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How do the number of/ distribution of rods and cones across the retina differ between nocturnal and non-nocturnal mammals?
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* more rods and fewer cones
* rods at fovea (blind spot) * rods have high sensitivity * RHODOPSIN bleached at LOW light intensity * IODOPSIN (from cones) bleached at HIGH light intensities |
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How does the retina and ANS (autonomic nervous system) control the amount of light entering the eye?
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* photoreceptors - light sensitive
* action potentials/ impulses along the optic nerve to the brain * less light to enter = the contraction of circular muscles * more light to enter = contraction of radial muscles |
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How would the image of a near object be focused on the retina?
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* refraction at cornea
* ciliary muscle contracts * suspensory ligaments slacken * lens bulges/ fattens * light refracted more * lens has shorter focal length |
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What is the role of the Broca's area in reading aloud?
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* Broca's area is concerned with the control of muscles producing speech
* passes impulses to muscles to form words |
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What is the role of the visual cortex in reading aloud?
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* recieves impulses from eyes/ optic nerve
* interprets and passes impulses from visual cortex to visual association area |
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Describe the sequence of events leading to the release of acetylcholine and its binding to the postsynaptic membrane?
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* depolarisation occurs on postsynaptic membrane
* calcium ions enter synaptic knob due to impulses *vesicles fuse with the presynaptic membrane * acetylcholine is released * acetylcholine diffuses across the postsynaptic cleft and binds to receptors on the postsynaptic membrane |
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Describe the process of information transfer between neurones.
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* impulses cause calcium ions to enter the axon
* vesicles move to fuse with the presynaptic membrane * releases acetylcholine * acetylcholine diffuses across the synaptic cleft and binds with receptors on the postsynaptic membrane * sodium ions enter the postsynaptic neurone * postsynaptic membrane is depolarised * nerve impulses/ action potential is produced |
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How i the arm straightened after a reflex movement?
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* impulses from the brain (motor area) sent to muscles in arm
* these muscles are ANTAGONSTIC pairs * tricep contracts and bicep relaxes * this allows the arm to be straightened |
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How is the leg straightened after a reflex movement?
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* impulses from the brain (motor area) sent to the leg muscles
* quadracep contracts and hamstring relaxes * this allows the leg to be straightened |
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Explain how nerve impulses result in the shortening of sarcomeres.
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* impulses cause calcium ions to enter the axon
* vesicles fuse with the presynaptic membrane * acetylcholine is relased * acetylcholine binds to receptors on the postsynaptic membrane * postsynaptic membrane is depolarised * sodium ions enter * calcium ions released from the muscle binds to and displaces the tropomyosin * this exposes the binding sites on the actin molecules * actin is free to bind with myosin *AtPase breaks down ATP so energy is relased and used to form actino-myosin bridges * myosin head moves and pulls actin fillament * this is the ratchet mechanism * ATPase breaks down ATP so energy is used in breaking the actino-myosin bridges |
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Explain the importance of reflex actions.
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* an automatic, involuntary adjustment and response to environmental changes.
* allows fight or flight escape from predators * aids posture and balance * has a role in homeostasis e.g. temperature decrease = shivers, vasoconstriction, shunting, hairs stand on end |
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at the neuromuscular junction result in the shortening of sarcomeres.
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* impulses cause calcium ions to enter the axon
* vesicles fuse with the presynaptic membrane * this releases acetylcholine * acetylcholine diffuses through the postsynaptic cleft and binds to receptors on the postsynaptic membrane * sodium ions enter the postsynaptic neurone * the postsynaptic membrane becomes depolarised * calcium ions released from the muscle * the calcium ions bind with and displace the tropomyosin * this exposes the binding sites on the actin molecules so they are free to bind with the myosin molecules * the calcium ions stimulate ATPase to break down ATP * the energy released is used in the formation of actino-myosin bridges * the myosin head moves and pulls the actin filament * this is the RATCHET MECHANISM * ATPase is again stimulated to reak down ATP releasing energy to break the bridges |
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How will the band pattern change when the muscle / muscle fibril is contracted?
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* mediumly darkish-lightish (myosin only) zone narrows / gets smaller
* lightest band (actin only) section narrows / gets smaller * darkest (mixed filament) section gets wider |
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What causes the different bands seen in the muscle fibril?
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* lightest band = actin filaments only
* medium band (H zone)= myosin filaments only * darkest band = mixed cross-over area of both filament types |
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How would a decrease in the concentration of calcium ions disrupt the contraction mechanism?
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* less calcium ions to bind with the tropomyosin molecules
* tropomyosin not displaced so binding sites on actin molecules not exposed * so actin and myosin molecules don't bind * so actino-myosin bridges not formed so no ratchet mechanism * ATPase not stimulated so no energy from ATP |
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How is the resting potential of a neurone maintained?
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* active transport pumps Na+ ions out and K+ ions in
* neurone is less permeable to Na+ ions * neurone is more permeable to K+ ions * Sodium ions move in by diffusion and potassium ions diffuse out * outiside the neurone is MORE POSITIVE!! |
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How do the lateral and medial rectus muscles enable side-to-side movement?
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* antagonistic pairs
* as lateral recus contracts, medial rectus relaxes * this allows movement to one side * as medial rectus contracts, lateral rectus relaxes * this allows movement to the other side |
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Describe the way in which antagonistic muscles enable side-to-side movement.
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* antagonistic muscles work in pairs
* as muscle one contracts, muscle two relaxes * this allows movement to one side * as muscle two contracts, muscle one relaxes * this allows movement to the other side |
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Describe the role of calcium ions, ATP and tropomyosin in muscle contraction.
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* calcium ions enter and bind with the tropomyosin molecules
* tropomyosin is displaced * this exposes the binding site on the actin molecules * actin is free to bind with the myosin * calcium ions stimulate ATPase to break down ATP releasing energy * this energy is used in the formation of actino-myosin bridges *mysoin filament moves and pulls along the actin head * this is the RATCHET MECHANISM * ATPase is again stimulated to break down ATP * the energy released is used to break the actino-myosin bridges |
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Describe the role of calcium ions in muscle contraction
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* calcium ions bind with and displace the tropomyosin molecules
* this exposes the binding sites on the actin molecules so they are free to bind with the myosin forming bridges * calcium ions also stimulate ATPase to breakdown ATP to release energy for the forming and breaking of actino-myosin bridges. |
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Describe the role of ATP / ATPase in muscle contraction
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* ATPase breaks down ATP
* this releases energy * the energy is used in the formatino and breaking of actino-myosin bridges |
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What is a reflex?
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A reflex is a rapid, automatic, involuntary response to a stimulus / change in external environment.
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What are the principles of taxonomy?
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* hierarchy = smaller groups within larger groups
* phylogenics = common ancestry & evolutionary histories * characteristics = same/similar traits * similar anatomy * similar DNA |
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Describe the principles scientists use to classify organisms.
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* hierarchy = smaller groups within larger groups
* phylogenics = evolutionary histories & common ancestory * characteristics = same / similar traits * similar anatomical features * similar DNA |
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List the taxonomic groups in the correct order.
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Kingdom
Phyllum Class Order Family Genus Species Name |
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Describe the process of thermoregulation in response to a large decrease in external temperature.
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* the hypothalamus has receptors which detect the temperature change in the blood
* the skin receptors send impulses to the hypothalamus * the hypothalamus sends nerve impulses to the body * this results in vasoconstriction and shunting where the blood is directed to the core and diverted away from the skin so less heat is lost from the blood via evaporation * shiverring which generates heat via respiration * hairs stand on end to trap a layer of localised heat around the skin * thyroxine and adrenaline are released * this increase the metabolic rate and rate of respiration * this is a negative feedback response to the environmental change |
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What is the advantage of mitochondria in muscles having many cristae?
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* there is a larger surface area for the electron carrier system
* provides lots of ATP for muscular contraction. |
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What is homeostasis?
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Homeostasis is the maintanance of a constant internal environment.
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Nervous transmission is delayed at synapses because...?
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* the transmission is a chemical process rather than an electrical one
* transmission takes time e.g. the diffusion of acetylcholine across the postsynaptic cleft |
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Temperature has little influence on light absorption by photosynthetic organisms because...?
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* the absorption of light is a light dependant reaction not temperatrure dependant
* there is no direct enzyme involvement requiring a specific temperature |
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How can information about amino acid sequences be used to construct a phylogenetic tree?
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* those with similar sequences are more closely related
* the greater the difference in the sequence, the longer ago the group diverged |
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Why is colourblindness more common to men than women?
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* colourblindness gene is on X chromosome
* men only have 1 copy (X), women have 2 (XX) * coloublindness caused by recessive allele * only need 1 copy present to cause colourblindness * men don't have another chromosome to cancel out the affected gene * female must have both genes as recessive (only 25% chance of being colourblind compared to men having 75% chance) |
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What are the 5 kingdoms?
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Animalia
Plant Fungi Protocists Prokaryotes |
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Describe the role of glucagon in the control / regulation of blood-sugar concentration.
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* Glucagon binds to a specific receptor on the liver cell
* Activates enzymes in the liver * The glucagon is HYDROLYSED *The glucose is moved out of cells by FACILITATED DIFFUSION * this INCREASES the blood-glucose levels |
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What is epistasis?
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Epistasis is when the presence of one gene controls / inhibits the expression of another gene.
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Why is someone tall and thin more likely to suffer hypothermia than someone short and stout?
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* larger surface area/volume ratio
* less fat so less insulation * more heat lost via conduction |
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How can meiosis lead to genetic variation?
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* RANDOM ALIGNMENT OF CHROMOSOMES= different combinations of maternal and paternal chromosomes
* CROSSING OVER OF BIVALENTS AT CHIASMATA = different sections of DNA swapped * MUTATION = new/different genes |
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Why is sweast evaporation from the skin an effective body cooling method?
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* heat is lost during evaporation
* evaporation is an exothermic process * heat leaves blod and goes into external environment * cools the blood |
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What is a recessive allele?
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A recessive allele is the form of the gene which is only expressed in the phenotype in the absence of the dominant in the genotype.
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How could natural selection have resulted in the differences in frequency of phenotypes?
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* mutation
* different environments * selection by predation * survive to reproduce with advantageous traits * change in allele frequency in next generation * no gene flow between populations |
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Describe and explain how the inhibition of glycolysis will affect the electron chain transfer of ATP.
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* ATP production stops
* reduced NAD is released * no pyruvate * inhibits the links reaction and the krebs cycle * movement of electrons stops * no energy is released |
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How is ATP made during aerobic respiration?
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* ATP is produced in glycolysis
* involving the oxidation of glucose to pyruvate * ATP is produced directly from the krebs cycle * glycolysis produces reduced NAD+ / FAD+ transferring electrons to the electron transfer chain * the electrons are transferred down a chain of carriers aat decreasing energy levels * energy lost by electrons makes ATP |
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What is the role of chlorophyll in photosynthesis?
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* chlorophyll absorbs light energy
* raises energy level of electrons * excites electrons * forms ATP |
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Explain the role of ADH in the production of concentrated urine.
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* water potential of blood is too low and is detected by receptors in the hypothalamus
* pituitary gland releases more ADH * ADH increases the permeability of the collecting ducts * more water is reabsorbed into the blood by osmosis DOWN the concentration gradient |
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Describe how oxygen is produced in photosynthesis.
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* oxygen is produced in the ligth dependant reaction
* light energy is absorbed by chlorophyll * electrons excited and emitted * water dissociates * electrons replaced in chlorophyll |
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Explain the role of the loop of Henle in the absorption of water from the filtrate.
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* sodium ions are actively removed in the ascending limb
* the ascending limb is impermeable to water * sodium ions diffuse in through the descending limb * water diffuses out via osmosis * so there is a low water potential in the medulla / tissue fluid water leaves the collecting duct by osmosis DOWN the concentration gradient |
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How does the presence of abnormal insulin receptors result in a high blood-glucose concentration?
Why might the receptors be abnormal? |
*receptors may be abnormal due to a change in their tertiary structure
* receptors are a different shape so the insulin cannot bind * there is a reduced uptake of glucose into cells * no carrier proteins for glucose transport |
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How do kidneys prevent glucose appearing in the urine of a NON-DIABETIC person?
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* glucose is reabsorbed into the blood from the proximal tubule
* by active transport and involving membrane carriers |
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Give 4 similarities between chloroplast and mitochondrion structure.
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* both are double membrane structures
* smooth outer membrane * folded inner membrane with a large surface area * both have DNA * both have ribosomes |
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How does the ageing decrease in lens elasticity affect the ability of the eye to focus on near objects?
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* the lens cannot bulge as much as is less elastic
* therefore the refracting ability is reduced and there is a shorter focal area * images are focused BEHIND the retina instead |
