Biology 5

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;

1 of 10

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;

2 of 10

What is a reflex?

Rapid response to stimulus; Which is automatic

3 of 10

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

4 of 10

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

5 of 10

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

6 of 10

Explain the advantages of endothermy over ectothermy.

Enzymes at optimum temperature; Metabolic reactions proceed more quickly; Better able to survive in different environment;

7 of 10

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;

8 of 10

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

9 of 10

Suggest why glucose concentration decreases in a diabetic.

Glucose is used in cell respiration; Glucose enters cell and is converted to glycogen

10 of 10

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Biology 5

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Other cards in this set

Card 2

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Card 4

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Card 5

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Back

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