Biology 5

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Describe the sequence of events leading to the release of acetylcholine and its binding to the post synaptic membrane.
Action potential arrives; Calcium ions enter synaptic knob; Vesicles fuse with membrane; Acetylcholine diffuses across synaptic cleft; Binds to receptors postsynaptic membrane;
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How do chloride ions inhibit the transmission of nerve impulses by post synaptic neurones?
Hyper polarised; Stimulation does not reach threshold level so no action potential; Depolarisation does not occur due to less effect of sodium ions;
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What is a reflex?
Rapid response to stimulus; Which is automatic
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Describe the role of calcium ions in the contraction of myofibrils.
Calcium ions move tropomyosin; To reveal binding sites on actin; Allowing myosin heads to bind to actin; Actomyosin formed; Activates ATPase
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Explain the benefit of many slow fibres in the muscle of endurance athletes.
Endurance athletes exercise for long periods of time; Respire aerobically; So lactate does not accumulate; Slow fibres adapted to aerobic respiration; As have many mitochondria; Site of Kreb’s cycle; Electron transport chain; Producing a lot of ATP
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Describe the process involved in thermoregulation in response to a large decrease in external temperature
Hypothalamus; Has receptors which detect temperature changes of blood; Receives impulses from receptors in skin; Nerve impulses transmitted; Results in vasoconstriction, Shivering, release of thyroxine, increase in metabolic rate; Negative feedback
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Explain the advantages of endothermy over ectothermy.
Enzymes at optimum temperature; Metabolic reactions proceed more quickly; Better able to survive in different environment;
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Explain why its is more important to show the standard deviation of values rather than the range
SD shows spread of majority; SD less affected by extreme values;
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Descrive the role of insulin in the control of blood glucose concentration.
Increase in blood sugar; Binds to receptors on liver/muscle cells; Leads to more glucose entering cells by activating carrier proteins; Glucose leaves the blood; Insulin activates enzymes in liver; Glucose entering cell converted to glycogen
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Suggest why glucose concentration decreases in a diabetic.
Glucose is used in cell respiration; Glucose enters cell and is converted to glycogen
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Other cards in this set

Card 2

Front

How do chloride ions inhibit the transmission of nerve impulses by post synaptic neurones?

Back

Hyper polarised; Stimulation does not reach threshold level so no action potential; Depolarisation does not occur due to less effect of sodium ions;

Card 3

Front

What is a reflex?

Back

Preview of the front of card 3

Card 4

Front

Describe the role of calcium ions in the contraction of myofibrils.

Back

Preview of the front of card 4

Card 5

Front

Explain the benefit of many slow fibres in the muscle of endurance athletes.

Back

Preview of the front of card 5
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