Frank Brothers Solutions for ICSE Class 10 Biology Chapter 7 Circulatory System

Solution 1: Answer: Circulatory system: It is a system of organs that takes part in the flow of materials in the body of an organism inside an extracellular fluid.
Circulatory system in humans:
1. The right atrium receives deoxygenated blood from all the parts of the body through large veins called vena cava.
2. When the right atrium is full of blood, it contracts and the blood is forced into right ventricle.
3. When the right ventricle is full of blood, it contracts and the blood is pumped into the pulmonary trunk.
4. From right ventricle, the pulmonary artery carries the blood to the lungs for oxygenation.
5. The oxygenated blood returns to the heart via pulmonary veins that empty into the left auricle.
6. When the left auricle contracts, the blood passes into the left ventricle by the opening of bicuspid valve.
7. On contraction of the left ventricle, the blood is pumped into the artery called aorta.
8. The aorta branches into vessels which transports blood to the heart and all the body parts.
In simple words: The circulatory system is like a delivery network where the heart acts as a pump to move blood carrying oxygen and nutrients to all body parts, then brings back waste products.

📝 Teacher's Note: Use a simple analogy of a delivery truck system where the heart is the central depot, arteries are highways going out, and veins are return routes. Draw the path on the board to help visual learners.

🎯 Exam Tip: Always mention that the right side handles deoxygenated blood and left side handles oxygenated blood - this is a key point examiners look for.

Solution 2: Answer:
1. The SA is also called the pacemaker because it establishes the basic frequency at which the heart beats. It starts each heart beat and sets the pace for the whole heart.
2. There is no mixing of deoxygenated and oxygenated blood in the human heart because of double circulation of blood where the blood passes twice through the heart and the right half of the heart is concerned with pumping deoxygenated blood while the left is concerned with pumping of oxygenated blood.
3. The closed circulatory system is more efficient than the open system because in closed system the blood flows inside arteries or veins all the time which stops the mixing of blood with other bodily fluids and helps the transport of the blood around the body.
4. The left ventricle possess a thicker wall than the right ventricle because it pumps the blood at a higher pressure since blood from the left ventricle goes to all areas of the body while the right ventricle only has to pump blood to the lungs which is a much shorter distance, therefore less pressure is required.
In simple words: The heart has special features - SA node controls timing, separate chambers prevent blood mixing, closed tubes keep blood contained, and the left side is stronger because it has to pump blood much farther.

📝 Teacher's Note: Compare the SA node to a conductor of an orchestra - it sets the rhythm for everything. Use hand gestures to show the difference in wall thickness between ventricles.

🎯 Exam Tip: Remember "SA = pacemaker", "double circulation = no mixing", "closed system = more efficient", and "left thicker = more work" for quick recall.

Solution 3: Answer:

In simple words: Arteries are like strong highways taking fresh blood away from the heart to body parts, while veins are like return roads bringing used blood back to the heart.

📝 Teacher's Note: Have students feel their pulse on their wrist (artery) and explain they can't feel veins the same way because arteries have thicker walls and higher pressure.

🎯 Exam Tip: Remember "A for Away" (arteries carry blood away) and "V for Back" (veins bring blood back) to avoid confusion in exams.

Solution 4: Answer: The functions of blood plasma: It transports gases and other materials, maintains blood pH, body immunity, body heat regulation and also regulates the osmotic pressure of the blood.
In simple words: Blood plasma is like the liquid part of blood that carries everything around, keeps the body's chemistry balanced, helps fight infections, and controls temperature.

📝 Teacher's Note: Explain that plasma is about 90% water and acts like a delivery service - it's the vehicle that carries all the important stuff around the body.

🎯 Exam Tip: List at least 4 functions of plasma: transport, pH balance, immunity, and temperature regulation to score full marks.

Solution 5: Answer: Double circulation means during one circulation blood passes twice through the heart. It includes both pulmonary and systemic circulation. It is necessary as it keeps oxygenated and deoxygenated blood separate.
In simple words: Double circulation is like blood taking two trips through the heart - first to get oxygen from lungs, then to deliver oxygen to the body - keeping clean and dirty blood separate.

📝 Teacher's Note: Draw a figure-8 pattern to show how blood goes heart→lungs→heart→body→heart, emphasizing it passes through the heart twice per complete cycle.

🎯 Exam Tip: Always mention "twice through heart" and "prevents mixing" when explaining double circulation - these are key scoring points.

Solution 6: Answer: The materials which are carried by the blood are: oxygen, carbon dioxide, water, digested food, organic wastes, hormones and antibodies.
In simple words: Blood carries everything the body needs (oxygen, food, water, hormones) and takes away everything the body doesn't want (carbon dioxide, waste products).

📝 Teacher's Note: Create two columns on the board - "Things blood brings" and "Things blood takes away" to help students categorize the materials.

🎯 Exam Tip: Remember to include at least 6-7 materials and mention both useful substances (oxygen, nutrients) and waste products (CO₂, organic wastes).

Solution 7: Answer: The main function of erythrocytes is to transport the respiratory gases – CO₂ and O₂.
In simple words: Red blood cells are like tiny delivery trucks that carry oxygen from lungs to body parts and bring carbon dioxide back to be exhaled.

📝 Teacher's Note: Explain that erythrocytes = red blood cells and their disc shape helps them squeeze through tiny blood vessels efficiently.

🎯 Exam Tip: Always write "respiratory gases - CO₂ and O₂" to show you understand it's both gases, not just oxygen.

Solution 8: Answer:
1. Fibrinogen
2. Phagocytosis
3. Haemoglobin
4. Auricular systole
5. Angiology
6. Pericarditis
7. Tricuspid valve
8. Foramen ovale
9. Polycythemia
10. Lubb
In simple words: These are important terms related to blood components, heart functions, and circulatory system processes.

📝 Teacher's Note: Create a vocabulary bank with these terms and have students write simple definitions for each to build their understanding of circulatory system terminology.

🎯 Exam Tip: Learn the spelling of these technical terms as they often appear in fill-in-the-blank questions.

Solution 9: Answer:
1. Histone
2. Foramen ovales
3. Nerve
4. RBC
5. Albumin
In simple words: These are additional biological terms related to cellular components and blood elements.

📝 Teacher's Note: Connect these terms to previous learning - RBC links to erythrocytes, albumin to plasma proteins, helping students see the connections.

🎯 Exam Tip: Pay attention to exact spelling and abbreviations like RBC which examiners often test.

Solution 10: Answer:
1. Inferior vena cava, superior vena cava and coronary sinus
2. Ventricles
3. Function of bicuspid valve: It prevents the reverse flow of blood from the left ventricle into the left auricle.
4. Function of tricuspid valve: It prevents the reverse flow of blood from the right ventricle into the right auricle.
In simple words: The major veins bring blood back to the heart, ventricles are the pumping chambers, and heart valves work like one-way doors to prevent blood from flowing backward.

📝 Teacher's Note: Use the analogy of doors with hinges that only open one way to explain valve function - this visual helps students remember the concept.

🎯 Exam Tip: Always mention "prevents reverse flow" when describing valve functions - this is the key phrase examiners expect.

Solution 11: Answer: [Heart diagram with labeled parts including Sinoatrial node, Atrioventricular node, Right atrium, Pericardial fluid, Left Atrioventricular Aperture, Bundle of HIS, Pericardium, Right Ventricle, and Purkinje fibres]
In simple words: This diagram shows the internal structure of the heart with its electrical conduction system and major chambers clearly labeled.

📝 Teacher's Note: Point out each structure on a large heart model while students follow on their diagrams. Emphasize the electrical pathway from SA node to AV node to Bundle of HIS.

🎯 Exam Tip: Practice labeling heart diagrams regularly as they frequently appear in exams. Focus on correct spelling of terms like "Purkinje" and "sinoatrial".

Solution 12: Answer:
1. (c) Pulmonary vein
2. (b) Thebasius valve
3. (d) Aorta
4. (e) Pulmonary arch
5. (a) Clotting
In simple words: These are matching answers connecting heart structures with their correct names and functions.

📝 Teacher's Note: Use this as a quick revision exercise, asking students to explain why each match is correct to reinforce their understanding.

🎯 Exam Tip: Read all options carefully in matching questions before selecting - some answers may seem similar but have different specific functions.

Solution 13: Answer:
1. (d) 5 l
2. (c) Left ventricle
3. (b) Capillaries
4. (a) bone marrow
5. (c) 120 days
6. (a) myogenic
7. (a) Eustachian valve
8. (c) ventricle
9. (b) 70-80
10. (c) Monocytes
11. (d) 90%
12. (c) William Harvey
13. (b) Spleen
14. (d) all the above
15. (d) O
In simple words: These multiple choice answers cover important facts about blood volume, heart rate, blood cell lifespan, and other key circulatory system measurements.

📝 Teacher's Note: Create mnemonics for key numbers like "5 liters of blood", "120 day RBC lifespan", and "70-80 heartbeats per minute" to help students remember.

🎯 Exam Tip: Memorize the key numerical values - blood volume (5L), normal heart rate (70-80), RBC lifespan (120 days) as these are frequently tested.

Solution 11:
Answer: [Heart diagram with labeled parts including Sinoatrial node, Atrioventricular node, Right atrium, Pericardial fluid, Left Atrioventricular Aperture, Bundle of His, Pericardium, Right Ventricle, and Purkinje fibres]

📝 Teacher's Note: Use this diagram to trace the path of electrical impulses through the heart, starting from the SA node. Have students point to each structure as you explain the cardiac conduction system.

🎯 Exam Tip: Memorize the sequence: SA node → AV node → Bundle of His → Purkinje fibres. This electrical pathway question appears frequently in exams.

Solution 12:
1. (c) Pulmonary vein
2. (b) Thebasius valve
3. (d) Aorta
4. (e) Pulmonary arch
5. (a) Clotting
Answer: 1. (c), 2. (b), 3. (d), 4. (e), 5. (a)

📝 Teacher's Note: This is a matching exercise. Create similar activities where students match heart structures with their functions to reinforce anatomical knowledge.

🎯 Exam Tip: In matching questions, eliminate obvious pairs first, then work through the remaining options systematically.

Solution 13:
1. (d) 5 l
2. (c) Left ventricle
3. (b) Capillaries
4. (a) bone marrow
5. (c) 120 days
6. (a) myogenic
7. (a) Eustachian valve
8. (c) ventricle
9. (b) 70-80
10. (c) Monocytes
11. (d) 90%
12. (c) William Harvey
13. (b) Spleen
14. (d) all the above
15. (d) O
Answer: Multiple choice answers as listed above

📝 Teacher's Note: These are rapid-fire questions covering all major circulatory system concepts. Use this as a quick review session before tests to identify knowledge gaps.

🎯 Exam Tip: For questions like #14 "all the above," verify each option individually before selecting - don't assume it's correct just because it's an option.