Unmethylated cytosines no dna methylation no methyl

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Unmethylated cytosines/ no DNA methylation/ no methyl markersaddedAcetylated histones/ acetyl group added to histoneGenes are expressed/ switched on1
Total3
HUMAN BIOLOGICAL SCIENCE19MARKING KEYSTAGE 3Question 39(13 marks)(a)(i)Name the type of nerve fibres found in the root labelled ‘X’.(1 mark)DescriptionMarksMotor/ efferent/ myelinated/ effector1Total1(ii)Identify the area shown as ‘Y’.(1 mark)DescriptionMarksWhite matter/ ascending tracts/ descending tracts1Total1(b)The skin and muscle fibres shown in the diagram are associated with a reflex arc.(i)Draw arrows on the diagram to show the direction of a nerve impulse through thisreflex arc.(1 mark)DescriptionMarks1Total1(ii)Statethreeimportant functional properties of reflexes.(3 marks)DescriptionMarks
(iii)State a reason why reflex arcs are important.(1 mark)DescriptionMarksProtective/ prevents (further) damage/ allows removal ofdanger before being aware.1Total1
HUMAN BIOLOGICAL SCIENCE20MARKING KEYSTAGE 3(c)CIPA is a rare congenital disorder caused by a mutation that prevents the formation ofnerve cells which are responsible for transmitting signals of pain.Would these nerve cells be located closer to the skin or to the muscle fibres, as shown onthe diagram? Explain your answer.(2 marks)DescriptionMarksSkin1Receptors for pain are at the ends of/in the sensory neuron1Total2(d)(i)On the diagram, draw the head of an arrow on the line labelled ‘A’ to show thedirection of impulses between the central and peripheral nervous systems. (1 mark)DescriptionMarksArrow head going away from CNS1Total1(ii)Where is information communicated to and from by the division shown as ‘B’ inthe diagram?(1 mark)DescriptionMarksFrom: Skin/ muscles/ exteroceptors/ proprioceptors/ bones/jointsTo: the CNS/ brain1Total1(iii)A medical condition called hyperhidrosis is caused by an over-activity of neuronssending impulses to the sweat glands. Symptoms of the condition are normally seenwhen a person feels nervous or stressed.Identify the division of the peripheral nervous system that would be affected by thiscondition and the main symptom you would expect to see in sufferers.(2 marks)DescriptionMarksSympathetic1Excessive sweating1Total2
HUMAN BIOLOGICAL SCIENCE21MARKING KEYSTAGE 3Section Three: Extended answer20% (40 Marks)Question 40(20 marks)(a)Outline the events involved in the nervous stimulation and subsequent contraction ofskeletal muscle. In your answer include the role of calcium ions.(9 marks)

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Term
Summer
Professor
N/A
Tags
DNA, MDMA

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