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Miracle Learning Centre Science Tuition Question on Circulatory System (O Level Science Tuition/IP Science Tuition/Secondary Science Tuition)

Fig. 3.1 shows three stages in the cardiac cycle.

(a) (i) Name the blood vessels labelled F and G. F __________________________________ G __________________________________ (ii) Explain why the walls of the atria have thinner muscle than the walls of the ventricles. _________________________________________________________ _________________________________________________________ _________________________________________________________ _____________________________________________________ (b) Describe what is happening to the following parts of the left side of the heart at stage K as shown in Fig. 3.1: • left atrium • left ventricle • aortic valve. _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ (c) Letters A to F below refer to events which occur during a cardiac cycle. Put the letters into the boxes to show the correct sequence. The first one has been done for you. A Semi-lunar valves open B Blood enters the atria C Ventricles contract D Atrioventricular valves open E Blood flows into the ventricles F Atria contract Answer: B _______________ _____ _____ (d) Atrial Septal Defect (ASD) is a condition in which there is a hole in the wall separating the left and right atria. Explain how this will affect the flow of blood through the heart and suggest some of the possible effects of this condition. _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ ____________________________________________________________ Miracle Learning Centre Answer to Science Tuition Question on Circulatory System. (O Level Science Tuition/IP Science Tuition/Secondary Science Tuition) 1 (a) (i) Name the blood vessels labelled F and G. F inferior vena cava G pulmonary artery (ii) Explain why the walls of the atria have thinner muscle than the walls of the ventricles. ventricles pump blood to further organs ( to lungs/to whole body); atria pump blood, to ventricles/shorter distance; correct reference to pressure; e.g. ventricles have to push blood further so blood under higher pressure or create higher pressure R atria at lower pressure or ventricles receive blood at higher pressure (b) Describe what is happening to the following parts of the left side of the heart at stage K as shown in Fig. 3.1: • left atrium • left ventricle • aortic valve.

(c) Answer: BFDECA (d) Atrial Septal Defect (ASD) is a condition in which there is a hole in the wall separating the left and right atria. Explain how this will affect the flow of blood through the heart and suggest some of the possible effects of this condition. 1 blood passes from left to right atria 2 because of higher pressure in left atrium 3 mixing of oxygenated and deoxygenated blood 4 blood would flow from right atrium to right ventricle to lungs 5 there would be more than excess blood to the lungs (due to increased pressure from right ventricle) [4points] Effects: 6 high blood pressure in lungs 7 enlargement and weakening of right atria and ventricle/ heart failure 8 shortness of breath; 9 fainting/ fatigue [2 points] Learn from our Science Tuition Questions and Answers. Miracle Learning Centre Call 6463 8756 or sms 8128 8342/9839 9908. (Specialist in Science and Maths) for Primary, Secondary and JC levels. Miracle Learning Centre specialises in Science tuition, Maths tuition, Chemistry tuition and Physics tuition classes.