re fully hydrated.","markscheme":"- Muscle contraction during exercise requires energy released from an increased rate of aerobic respiration, which releases heat energy and raises internal body temperature. M1\n- The thermoregulatory centre in the hypothalamus detects this temperature rise and sends impulses via autonomic nerves to trigger vasodilation of skin arterioles, directing more warm blood to skin capillaries to facilitate heat loss. M1\n- Dehydration leads to a decreased blood plasma volume. M1\n- To maintain blood pressure and adequate perfusion to essential organs (or active muscles), the autonomic nervous system limits vasodilation to the skin (causing relative vasoconstriction), resulting in a lower relative skin blood flow. A1","marks":4,"order":2,"markingRubric":null,"explanation":null,"options":[]},{"id":"6da7d7a2-dcc8-4541-8f77-d81d53af7fdb","label":"d","content":"Suggest a method that could be used to monitor either the skin blood flow or the skin temperature of a volunteer during exercise.","markscheme":"- Attach electronic temperature sensors / thermistors to a specific, standardized location on the skin (e.g., the midpoint of the forearm). M1\n- Connect the sensors to a digital data logger to record temperature readings continuously or at fixed, regular intervals (e.g., every minute) throughout the exercise period. M1\n- Ensure the sensor probe is insulated from the ambient air currents (using an adhesive thermal patch) to ensure only skin conductive temperature is measured. A1","marks":3,"order":3,"markingRubric":null,"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"e769e109-b783-43ff-8f9f-89f2fb746653","revisionId":"bc6752d0-bf7a-4a32-b0d0-e53ec8d03505","questionNumber":null,"questionType":"LA","specification":"","difficulty":8,"difficultyBand":"hard","totalMarks":4,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"742ce3e7-e85b-4840-b2c0-f4c62ac1724d","label":null,"content":"Describe how blood glucose levels are returned to normal in a healthy human body when they rise above the optimum level, such as after eating a carbohydrate-rich meal.","markscheme":"- The rise in blood glucose concentration is detected by the $\\beta$-cells in the Islets of Langerhans within the pancreas. B1\n- This stimulates these cells to secrete the hormone insulin into the blood. B1\n- Insulin binds to specific glycoprotein receptors on the cell surface membranes of target cells (such as liver and muscle cells), which increases their permeability to glucose by triggering the incorporation of channel proteins (GLUT4). B1\n- This activates intracellular enzymes that catalyse the conversion of glucose to glycogen (glycogenesis), thereby lowering blood glucose concentration back to normal. B1","marks":4,"order":0,"markingRubric":null,"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null}],"subjectCode":"igcse_biology","summaries":[{"id":"1a6e48fc-2e4d-45ff-a50c-2badacc430fc","difficultyBand":"medium","calculatorUse":null,"totalMarks":3},{"id":"210654bc-aa98-4b91-accd-ccb0e116d4ad","difficultyBand":"medium","calculatorUse":null,"totalMarks":13},{"id":"2eaabc8a-0939-4b9f-97fa-8d059bf26884","difficultyBand":"hard","calculatorUse":null,"totalMarks":11},{"id":"2f9c6ebe-b29d-4544-80fa-74898cfe2773","difficultyBand":"easy","calculatorUse":null,"totalMarks":6},{"id":"4235546a-7aee-438c-8866-9dcf0bd9ee21","difficultyBand":"medium","calculatorUse":null,"totalMarks":9},{"id":"50a2cb13-fd26-426c-8ec8-6b527247c9a1","difficultyBand":"medium","calculatorUse":null,"totalMarks":9},{"id":"5136734e-1633-49df-b141-fd916b95a5c9","difficultyBand":"medium","calculatorUse":null,"totalMarks":8},{"id":"5f751cb6-7845-4190-a70f-71ece15ab48c","difficultyBand":"medium","calculatorUse":null,"totalMarks":11},{"id":"6b710159-99ea-4216-95c0-81ae1539c0d1","difficultyBand":"medium","calculatorUse":

Co-ordination and response

Question 3

Co-ordination and response Questions

Co-ordination and response

Question 3

Co-ordination and response Questions