AQA OCR Edexcel AS Biology Answers The Heart Circulatory system

A Level Biology The Heart and Circulatory Answers Total Marks:/34 2022 AQA, OCR, Edexcel A Level Answer Marks 1. a) i) Movement of fluid in one direction ii) iii) – The heart causes high pressure in the arteries - The elastic tissue helps to regulate pressure -Smooth muscle helps to redistribute blood/ vasoconstriction, vasodilatation. iv) Forces blood to flow in one direction/ prevents back flow of blood. b) i) – Heart and lungs - Heart and rest of the body 1 mark 8 marks 2 marks 1 mark 2 marks Type Away/Towards Characteristics A ARTERY AWAY Large proportion of muscle and elastic tissue in the walls B VEIN TOWARDS -Wide lumen -valves -less elastic and muscle C ARTERIOLE AWAY -smaller, branched arteries -much narrower -muscular walls D CAPILLARIES AWAY The membrane is only one cell thick so there is a very short diffusion pathway.