AQA A-Level Biology - Tissue Fluid Question And Answers

AQA A-Level Biology - Tissue Fluid Question And Answers 1 (a) (i) An arteriole is described as an organ. Explain why. (1 mark) - ANS Made of different tissues. (ii) An arteriole contains muscle fibres. Explain how these muscle fibres reduce blood flow to capillaries. (2 marks) - ANS As muscle contracts, arteriole narrows, reducing size of lumen. (b) (i) A capillary has a thin wall. This leads to rapid exchange of substances between the blood and tissue fluid. Explain why. (1 mark) - ANS Short diffusion pathway. (b) (ii) Blood flow in capillaries is slow. Give the advantage of this. (1 mark) - ANS More time for exchange of substances. (c) Kwashiorkor is a disease caused by a lack of protein in the blood. This leads to a swollen abdomen due to a build up of tissue fluid. Explain why a lack of protein in the blood causes a build up of tissue fluid. (3 marks) - ANS Water potential in capillary not as low as there is less water removed by osmosis into capillary. 2) Describe how tissue fluid is formed and how it is returned to the circulatory system. (6 marks) - ANS High hydrostatic pressure forced fluid out. Large proteins remain in capillary. Low water potential in capillary due to plasma proteins. Water re-enters capillary by osmosis. Lymphatic system return excess fluid to circulatory system. 3) The diagram shows a tissue and cells surrounding a capillary [Diagram shows labelled tissue fluid, body cells, red blood cells and label F which points to substance surrounding red blood cells] (a) Name fluid F. (1 mark) - ANS Blood plasma (b) Give one way in which fluid F is different to tissue fluid. (1 mark) - ANS More proteins (c) (i) The blood pressure is high at the start of the capillary. Explain how the left ventricle causes the blood to be a high pressure. (1 mark) - ANS Contracts