Maharashtra Board Class 8 Science Chapter 11 Human Body and Organ System Solutions

Std 8 Science Chapter 11 Human Body And Organ System Question Answer Maharashtra Board

Class 8 Science Chapter 11 Human Body And Organ System Question Answer Maharashtra Board

 

Question 1. Find out my partner.

Question a.

Group 'A'	Group 'B'
1. Heartbeats	a. 350 ml
2. RBC	b. 7.4
3. WBC	c. 37° C
4. Blood donation	d. 72 per min
5. Normal body temperature	e. 50-60 lakh/mm³
6. pH of oxygenated blood	f. 5000-6000 per mm³

Answer:

Group 'A'	Group 'B'
1. Heartbeats	d. 72 per min
2. RBC	e. 50-60 lakh/mm³
3. WBC	f. 5000-6000 per mm³
4. Blood donation	a. 350 ml
5. Normal body temperature	c. 37° C
6. pH of oxygenated blood	b. 7.4

In simple words: This table correctly matches human body parameters in Group 'A' with their corresponding values or descriptions in Group 'B', such as heartbeats with 72 per minute and normal body temperature with 37°C.

🎯 Exam Tip: Memorizing normal ranges for vital signs and blood components is crucial for biology exams. Pay attention to units and typical values.

 

Question 2. Complete the following table.

Question a.

Organ systems	Organs	Functions
1. Respiratory system
2. Circulatory system

Answer:

Organ systems	Organs	Function
1. Respiratory system	Nose	For inhalation and exhalation. The air is filtered and made little warm when breath passes through nose.
	Pharynx	Common passage for food and air. Leads to trachea and oesophagus.
	Wind pipe (Trachea)	Takes air to lungs. Bifurcates into two bronchi.
	Lungs	Provides space for respiratory gaseous exchange.
	Alveolus	Actual gaseous exchange by taking in oxygen and giving out carbon dioxide.
	Diaphragm	By contractions and relaxation it makes breathing movements possible.
2. Circulatory system	Heart	Muscular pump that can send the blood throughout the body.
	Arteries	Carry blood away from heart to all the parts of the body. Except for pulmonary artery, all other arteries carry oxygenated blood to supply oxygen to each and every cell.
	Veins	Carry blood to the heart. Except for pulmonary veins all other veins carry deoxygenated blood from all the body cells to the heart.
	Blood capillaries	Each important vital organ is provided with capillary network. Exchange of oxygen, nutrients, hormones, vitamins, etc. takes place through the capillary wall. Such useful substances are sent towards the cells and waste materials are taken from the cells.
	Blood cells	Various functions depending upon the type of blood cells. RBC: Carrying oxygen and carbon dioxide. WBC: Soldiers of the body. Produce antibodies and fight against germs of diseases. Platelets: Carry out important function in blood clotting.
	Plasma	Many proteins present in the plasma which carry out definite functions. Plasma also gives fluidity to the blood.

In simple words: This table details the respiratory and circulatory systems, listing their key organs like lungs and heart, and explaining their primary functions, such as gas exchange for respiration and blood pumping for circulation.

🎯 Exam Tip: Understanding the specific role of each organ within its system is fundamental. Focus on how each part contributes to the overall function of the body system.

 

Question 3. Draw neat and labeled diagrams.

Question a. Respiratory system.

Answer:
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र मानव श्वसन प्रणाली को दर्शाता है। इसमें नाक गुहा, ग्रसनी, स्वरयंत्र, श्वासनली, ब्रोन्किओल्स, फेफड़े, एल्वियोली और डायाफ्राम जैसे अंग शामिल हैं। यह प्रणाली शरीर में हवा के प्रवेश और निकास, और फेफड़ों में गैसीय विनिमय को दिखाती है।
In simple words: The diagram of the respiratory system shows how air enters through the nasal cavity, passes through the pharynx, larynx, and trachea, then into the lungs where gas exchange occurs in the alveoli, all facilitated by the diaphragm.

🎯 Exam Tip: For diagrams, ensure all key parts are correctly labeled and the overall structure clearly represents the system. Practice drawing and labeling to improve accuracy.

 

Question b. Internal structure of heart.

Answer:
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र हृदय की आंतरिक संरचना और रक्त परिसंचरण को दर्शाता है। इसमें हृदय के विभिन्न कक्ष (दायां आलिंद, बायां आलिंद, दायां निलय, बायां निलय), वाल्व (ट्राइकस्पिड, बाइकस्पिड, सेमिनार वाल्व) और प्रमुख रक्त वाहिकाएं (महाधमनी, फुफ्फुसीय धमनियां और नसें, वेना कावा) शामिल हैं। यह हृदय के माध्यम से रक्त के प्रवाह की दिशा को स्पष्ट करता है।
In simple words: This diagram illustrates the internal parts of the heart, showing the four chambers (atria and ventricles), the valves that regulate blood flow, and the major arteries and veins involved in circulating blood to and from the body and lungs.

🎯 Exam Tip: When drawing the heart, clearly differentiate between oxygenated and deoxygenated blood flow, and accurately label all chambers, valves, and associated blood vessels.

 

Question 4. Explain with reasons.

Question a. Human blood is red coloured.

Answer: The red colour of human blood is due to hemoglobin which is a red coloured conjugated protein with iron that is present on the red blood cells. Therefore, it looks red.
In simple words: Human blood is red because it contains hemoglobin, a protein rich in iron, found within red blood cells, which gives it its characteristic color.

🎯 Exam Tip: When explaining biological phenomena, always link the observable characteristic (red color) to the underlying chemical or cellular component (hemoglobin with iron) for a complete answer.

 

Question b. Upward and downward movement of diaphragm occurs consecutively.

Answer: The breathing movements are possible due to contraction and relaxation of the diaphragm. The rib muscles also help in these movements. When the ribs rise and diaphragm is lowered at the same time, then there is a decrease in pressure on lungs. This causes movement of air into the lungs at the time of inhalation. On the other hand, when ribs come back to their normal position and diaphragm is risen, then pressure on the lungs increases. This causes movement of the air out of the body through the nose in the form of exhalation. These movements are possible only due to consecutive upward and downward movement of the diaphragm.
In simple words: The diaphragm's continuous up-and-down movement, aided by rib muscles, creates pressure changes in the lungs; when it lowers, air rushes in (inhalation), and when it rises, air is pushed out (exhalation), enabling breathing.

🎯 Exam Tip: Focus on the cause-and-effect relationship: diaphragm movement leads to pressure changes, which in turn drive air movement for breathing. Understanding this mechanism is key.

 

Question c. Blood donation is considered to be superior of all donations.

Answer: Blood cannot be manufactured by any artificial chemical process. The only way to obtain blood is by donations of blood from a live donor. Blood is needed at times of emergency. The life of person can be saved if timely blood transfusion is given to the needy victim or a patient. Since such donation can save a valuable human life, it is called superior of all donations.
In simple words: Blood donation is considered superior because blood cannot be artificially created; it saves lives during emergencies like accidents or surgeries, directly contributing to human survival.

🎯 Exam Tip: Emphasize the unique nature of blood (cannot be manufactured) and its direct life-saving impact to justify its "superior" status in donations.

 

Question d. Person with 'O' blood group is considered as 'universal donor'.

Answer: Person with 'O' blood group does not have any antigen on his/her RBCs. The 'O' type blood thus cannot cause clotting reactions in the body of the recipients. Such persons with 'O' blood group can donate blood to any person having any blood group therefore they are considered as 'universal donor'.
In simple words: Individuals with 'O' blood group are universal donors because their red blood cells lack A and B antigens, preventing immune reactions and making their blood safe for transfusion to people of any blood type.

🎯 Exam Tip: The key concept here is the *absence of antigens* on Type O RBCs. Clearly state this immunological basis to score well.

 

Question e. Food must have limited amount of salts.

Answer: More salt in diet means more sodium ions. These extra sodium salts cause rise in blood pressure. Such condition is called hypertension. This condition can be dangerous and fatal in some cases. Therefore, one must keep control over sodium content of the food.
In simple words: Limiting salt intake is crucial because excessive sodium leads to high blood pressure (hypertension), a dangerous condition that can be life-threatening.

🎯 Exam Tip: Connect excess salt (sodium ions) directly to increased blood pressure and then to the health risk (hypertension) for a clear and concise explanation.

 

Question 5. Answer the following questions in your own words.

Question a. Explain the functional correlation of circulatory system with respiratory, digestive and excretory system.

Answer:
1. Three systems viz. respiratory, digestive and circulatory always work in coordination.
2. Digestive system helps in breaking down complex food molecules into simple soluble nutrients at the end of the digestion process.
3. The soluble nutrients are absorbed in the circulating blood in the villi of the intestine.
4. The blood carries these nutrients to each cell during its circulation.
5. The respiratory system helps the oxygen from the air to be absorbed in the blood.
6. This process takes place in alveolus present in lungs. The oxygen is absorbed in the blood and through haemoglobin it is taken to every cell of the body. At the same time the unwanted carbon dioxide produced in each cell is given out in a process of gaseous exchange.
7. The soluble nutrients, and chiefly glucose is metabolized with the help of oxygen-producing energy. Thus, all the three systems bring about coordinated functions to keep the body alive.
In simple words: The circulatory system acts as a transport network, carrying nutrients from the digestive system and oxygen from the respiratory system to every cell, while also taking waste products to the excretory system, demonstrating their interconnectedness for sustaining life.

🎯 Exam Tip: Focus on the "transport" role of the circulatory system as the central link connecting the intake (digestive, respiratory) and removal (excretory) functions of other systems.

 

Question b. Explain the structure and function of human blood.

Answer:
I. Structure, i.e. components of the human blood: Human blood is a fluid connective tissue consisting of blood plasma and blood corpuscles suspended in it.
1. Plasma: Plasma is the fluid part of the blood which is pale yellow in colour. It is slightly alkaline in nature. It has 90-92% water, 6-8 % proteins and 1-2 % inorganic salts.
It contains proteins such as albumin, globulin, fibrinogen, etc. There are inorganic ions such as Ca, Na and K.
2. Blood cells:
a. Blood cells are mainly of three types, viz. RBCs, WBCs and blood platelets. They are produced in the red bone marrow.
b. RBCs are small, circular and enucleated cells. They are full of haemoglobin which is essential in transporting oxygen. RBCs are red blood cells which are 50-60 lakh per cubic millimetre. Their life span is 100-127 days.
c. WBCs are large, nucleated and colourless. They are of five subtypes, viz. neutrophils, basophils, eosinophils, monocytes and lymphocytes. They are 5-10 thousands per millimetre of blood.
d. Platelets are very small disc-shaped blood cells which are 2.5-4 lakh per cubic millimetre of blood.
II. Function of human blood:
1. Transport functions:

• Gases: Oxygen is carried via blood from lungs to cells in various parts of body and carbon dioxide from tissues to lungs.
• Nutrients: Simple nutrients like glucose, amino acids, fatty acids are taken up by blood from wall of alimentary canal and transported up to each cell in the body.
• Waste materials: Nitrogenous wastes like ammonia, urea, creatinine are released by tissues into blood which carries those to kidney for excretion.
• Enzymes and hormones: Blood transports the enzymes and hormones from the site of their production to the site of their action.

2. Protection: Antibodies are produced in the blood and they protect the body from microbes and other harmful particles.
3. Thermoregulation: Body temperature is maintained constant at 37 °C by vasodilation and vasoconstriction.
4. Maintaining the balance of minerals like Na, K in the body.
5. If bleeding occurs at the injury, platelets and a protein called fibrinogen of the blood form a clot and seal the injury.
6. Functions of blood cells:

• RBCs: With haemoglobin it carries out transport of respiratory gases.
• WBCs: Soldiers of the body. Produce antibodies and give immunity to body.
• Platelets: Help in blood clotting.

In simple words: Human blood is a fluid tissue composed of plasma and blood cells (RBCs, WBCs, platelets); it transports oxygen, nutrients, hormones, and waste, fights infections, regulates body temperature, maintains mineral balance, and aids in clotting to sustain life.

🎯 Exam Tip: When describing blood, divide your answer into structure (plasma, cell types and their characteristics) and functions (transport, protection, regulation, clotting) for a comprehensive overview.

 

Question c. Explain the importance and need of blood donation.

Answer: Blood can never be synthesized artificially. There is no substitute for natural blood. Every healthy person possesses about 5 litres of blood in his or her body. In case of haemorrhage i.e. blood loss, the blood volume may reduce which can result into threat to life. Moreover, the loss of blood should be immediately taken care of, otherwise it may cost the life. Therefore blood transfusion is very crucial in case of victims of accidents, patients of surgeries or mothers who suffer from blood loss during childbirth (parturition). Some diseases such as thalassemia, blood cancer, etc. also need regular transfusions. Therefore, blood is always needed in many such conditions. Blood donation is only option for such transfusions.
In simple words: Blood donation is vital because artificial blood doesn't exist, and transfusions are crucial for saving lives during severe blood loss from accidents, surgeries, childbirth, or chronic diseases like thalassemia, making donors the sole source of this essential resource.

🎯 Exam Tip: Highlight the irreplaceable nature of human blood and list several critical medical scenarios where blood transfusions are indispensable to underscore the importance of donation.

 

Question 6. Explain the differences.

Question a. Arteries and veins.

Answer:

Arteries	Veins
1. Arteries carry blood away from the heart to the tissues of the body.	1. Veins carry blood from the tissues of the body back to the heart.
2. Arteries are located deeper within the body.	2. Veins are usually located superficially beneath the surface of the skin.
3. Arteries are thick walled	3. Veins are thin walled.
4. Arteries do not have valves.	4. Veins have valves.
5. Arteries would generally remain open if blood flow stopped, due to their thick muscular layer.	5. Veins would collapse if blood flow stops.
6. Except pulmonary artery, all arteries carry oxygenated blood.	6. Except pulmonary vein, all veins carry deoxygenated blood.
7. Arteries are more muscular than veins, which helps in transporting blood that is full of oxygen efficiently to the tissues.	7. Veins are less muscular than arteries, but contain valves to help keep blood flowing in the right direction, usually toward the heart.
8. There is maximum blood pressure in the arteries.	8. There is minimum blood pressure in the veins.

In simple words: Arteries carry oxygenated blood away from the heart under high pressure, are thick-walled, and generally lack valves, while veins carry deoxygenated blood back to the heart under lower pressure, are thin-walled, and contain valves to prevent backflow.

🎯 Exam Tip: When comparing arteries and veins, focus on direction of blood flow, blood pressure, wall thickness, and presence/absence of valves as key distinguishing features.

 

Question b. External and internal respiration.

Answer:

External respiration	Internal respiration
1. Intake of air from the outside into the body and release of air from the body to outside is called external respiration.	1. Exchange of gases between cells and tissue fluid is called internal respiration.
2. External respiration occurs between cells and the external environment.	2. Internal respiration occurs only in the cells of the body.
3. It involves processes of inspiration and expiration.	3. It involves movement of O2 from blood into tissue fluid and movement of CO2 from tissue.
4. External respiration involves breathing and gaseous exchange.	4. Internal respiration involves neither breathing nor gaseous exchange.
5. Oxygen combines with haemoglobin in external respiration.	5. Chemical reactions occur in the cells to form energy.

In simple words: External respiration is the breathing process, exchanging gases between the body and the environment, involving inhalation and exhalation. Internal respiration, however, is the gas exchange between blood and body cells, where cells utilize oxygen and release carbon dioxide to produce energy.

🎯 Exam Tip: Distinguish external respiration as the macro-level breathing process involving lungs and atmosphere, and internal respiration as the micro-level gas exchange and energy production within cells.

 

Question 7. Which health parameters of blood donor should be checked?

Answer: Blood donor should be healthy. He or she should have good haemoglobin's content. The RBC and WBC count should also be normal. They should not carry any parasites in their blood such as malarial parasite or dengue virus. The donor should not be HIV positive or should not have any infectious diseases. He should not have any addictions such s drug-abuse or alcohol consumption.
In simple words: A blood donor must be healthy, with normal hemoglobin, RBC, and WBC counts, free from parasites (like malaria) or viruses (like HIV, dengue), infectious diseases, and drug or alcohol abuse, to ensure safe donation.

🎯 Exam Tip: Focus on a holistic health assessment covering blood counts, absence of infectious agents (parasites, viruses), and a healthy lifestyle (no addictions) for a complete answer.

 

Question 8. Fill in the blanks using appropriate words given in the bracket. (hemoglobin, alkaline, diaphragm, red bone marrow, acidic, voluntary, involuntary,)

Question a. RBCs of the blood contain ..........., an iron compound.

Answer: RBCs of the blood contain haemoglobin, an iron compound.
In simple words: Red blood cells (RBCs) contain hemoglobin, which is an iron-containing compound responsible for oxygen transport.

🎯 Exam Tip: Remember that hemoglobin is the key iron-containing protein in RBCs, crucial for their function.

 

Question b. ........... is present between thoracic and abdominal cavity.

Answer: Diaphragm is present between thoracic and abdominal cavity.
In simple words: The diaphragm, a muscular partition, separates the thoracic (chest) cavity from the abdominal cavity.

🎯 Exam Tip: The diaphragm's anatomical location and its role in separating the body cavities are important to recall.

 

Question c. Cardiac muscles are ...........

Answer: Cardiac muscles are involuntary.
In simple words: Cardiac muscles, which make up the heart, contract and relax automatically without conscious control, meaning they are involuntary.

🎯 Exam Tip: Differentiating between voluntary and involuntary muscles is a basic concept; remember cardiac muscle's unique involuntary nature.

 

Question d. pH of oxygenated blood is ...........

Answer: pH of oxygenated blood is alkaline.
In simple words: Oxygenated blood has a pH slightly above 7, indicating it is alkaline.

🎯 Exam Tip: Recall that normal blood pH is slightly alkaline (around 7.35-7.45), which is a key physiological parameter.

 

Question e. Production of RBCs occurs in ...........

Answer: Production of RBCs occurs in red bone marrow.
In simple words: Red blood cells are continuously produced in the red bone marrow, primarily located in flat bones and the ends of long bones.

🎯 Exam Tip: Know the primary site of blood cell formation, which is the red bone marrow.

 

Question 8. Find odd one out.

Question a. A, O, K, AB, B.

Answer: K (All others are blood groups.)
In simple words: 'K' is the odd one out because A, O, AB, and B are recognized human blood groups, while 'K' is not.

🎯 Exam Tip: Be familiar with the main ABO blood groups to quickly identify non-blood group options.

 

Question b. Blood plasma, platelets, blood transfusion, blood corpuscles.

Answer: Blood transfusion (All others are components of blood.)
In simple words: 'Blood transfusion' is the odd one out as it is a medical procedure, whereas blood plasma, platelets, and blood corpuscles (cells) are all natural components of blood.

🎯 Exam Tip: Understand the difference between blood components and medical procedures involving blood to correctly identify the odd item.

 

Question c. Trachea, alveoli, diaphragm, capillaries.

Answer: Capillaries (All others are parts of respiratory system. Capillaries exist throughout the body.)
In simple words: 'Capillaries' are the odd one out because trachea, alveoli, and diaphragm are all primary components of the respiratory system, while capillaries are blood vessels found throughout the entire body, including in the respiratory system but not exclusively.

🎯 Exam Tip: Identify the core system being discussed (respiratory) and select the option that belongs to a broader, distinct system (circulatory, even if present in the respiratory system).

 

Question d. Neutrophils, globulins, albumins, prothrombin.

Answer: Neutrophils (All others are proteins present in the plasma.)
In simple words: Neutrophils are a type of white blood cell, making them the odd one out, as globulins, albumins, and prothrombin are all proteins found in blood plasma.

🎯 Exam Tip: Distinguish between different blood components - cells (like neutrophils) versus plasma proteins (like globulins, albumins, prothrombin).

 

Question 10. Read the following paragraph and identify the disease.

Answer: Today, her child became one and half year old. However, that child does not seem to be healthy and happy. It was continuously crying and gradually becoming weak. It has shortness of breath. Its nails have become blue. The heart of the child is not functioning properly. Bluish nails show lack of oxygen, thus the baby may be suffering also from respiratory problems.
In simple words: The symptoms described, including shortness of breath, bluish nails, and a weak, crying child with an improperly functioning heart, strongly suggest a severe congenital heart defect or a condition causing chronic lack of oxygen (cyanosis).

🎯 Exam Tip: Look for key symptoms like "shortness of breath" and "bluish nails" (cyanosis), which indicate insufficient oxygen and often point to cardiac or severe respiratory issues in infants.

 

Question 11. Your neighboring uncle has been diagnosed with hypertension. What should he do to keep his blood pressure within normal range?

Answer: Hypertension has many causes. Try to find out what is the exact cause. Is it lack of exercise, obesity, lots of fast and junk food consumption, over-intake of salt, mental tension, etc. He should visit a proper physician and take prescribed blood pressure control medicines. He should never miss a single tablet. He should avoid salty and preserved food. He should practice yoga and meditation. He should also undertake some stress- management techniques.
In simple words: To manage hypertension, your uncle should identify and address underlying causes like diet or stress, consult a doctor for prescribed medication, adhere to the dosage, avoid salty foods, and adopt lifestyle changes such as exercise, yoga, meditation, and stress management.

🎯 Exam Tip: For managing chronic conditions like hypertension, emphasize a multi-faceted approach: medical consultation and adherence, dietary modifications, and lifestyle changes (exercise, stress reduction).

 

Project:

 

Question a. Collect information about various modern treatments on heart diseases.

 

Class 8 Science Chapter 11 Human Body And Organ System Important Questions And Answers

 

Rewrite The Statements After Correcting Them:

 

Question 1. Cells need supply of insoluble nutrients and oxygen for the energy production.

Answer: Cells need the supply of soluble nutrients and oxygen for the energy production.
In simple words: Cells require soluble nutrients and oxygen for energy production, as insoluble nutrients cannot be directly used.

🎯 Exam Tip: Understand that nutrients must be in a soluble form to be absorbed and utilized by cells for metabolic processes.

 

Question 2. Respiratory system and respiration begins with mouth.
Answer: Respiratory system and respiration begins with nose.
In simple words: The respiratory system starts with the nose, not the mouth, as it's the primary entry point for air.

🎯 Exam Tip: Knowing the correct starting point of bodily systems is crucial for foundational understanding and can be a common point of confusion.

 

Question 3. A lung is present on either sides of heart in abdominal cavity.
Answer: A lung is present on either sides of heart in thoracic cavity.
In simple words: Lungs are located in the chest cavity (thoracic cavity), not the abdominal cavity.

🎯 Exam Tip: Correctly identifying the location of major organs within body cavities is a key anatomical concept.

 

Question 4. Continuous upward and downward movement of diaphragm is necessary to bring about the beating of heart.
Answer: Continuous upward and downward movement of diaphragm is necessary to bring about the breathing.
In simple words: The diaphragm's movement is essential for breathing, not for the heartbeat, which is regulated by the heart's own electrical system.

🎯 Exam Tip: Differentiate between the functions of the diaphragm (respiration) and the heart (circulation) to avoid common misconceptions.

 

Question 5. Blood vessels which carry the blood away from heart are called veins.
Answer: Blood vessels which carry the blood away from heart are called arteries.
In simple words: Arteries carry blood away from the heart to the body, while veins carry blood back to the heart.

🎯 Exam Tip: Clearly understand the primary function and direction of blood flow for arteries versus veins.

 

Question 6. William Harvey described the blood groups in man.
Answer: William Harvey described the mechanism of circulation in the body.
In simple words: William Harvey is known for discovering blood circulation, not blood groups, which were discovered by Karl Landsteiner.

🎯 Exam Tip: Accurately associating scientists with their major discoveries is important for general knowledge in science.

 

Question 7. Capillaries unite together to form the arteries.
Answer: Capillaries unite together to form the veins.
In simple words: Capillaries merge to form venules, which then combine to form veins, returning blood to the heart.

🎯 Exam Tip: Understand the sequence of blood vessels: arteries branch into arterioles, which become capillaries, then venules, and finally veins.

Match The Columns/Find Out My Partner

 

Question 1.

Group 'A'	Group 'B'
1. William Harvey	a. Blood group AB.
2. Carl Landsteiner	b. A, B, O blood group system.
3. Decastello and Sturli	c. Mechanism of circulation of blood.

Answer:

Group 'A'	Group 'B'
1. William Harvey	c. Mechanism of circulation of blood.
2. Carl Landsteiner	b. A, B, O blood group system.
3. Decastello and Sturli	a. Blood group AB.

In simple words: William Harvey discovered blood circulation, Carl Landsteiner identified the A, B, O blood group system, and Decastello and Sturli discovered the AB blood group.

🎯 Exam Tip: Matching scientists with their contributions is a common question format; focus on key discoveries like circulation and blood groups.

Complete The Following Table

 

Question 1.

Type	Systolic pressure	Diastolic pressure
Normal blood pressure
Primary hypertension
Hypertension stage - I
Hypertension stage - II

Answer:

Type	Systolic pressure	Diastolic pressure
Normal blood pressure	90-119 mmHg	60-79 mmHg
Primary hypertension	120-139 mmHg	80-89 mmHg
Hypertension stage - I	140-159 mmHg	90-99 mmHg
Hypertension stage - II	> 160 mmHg	> 100 mm

In simple words: This table categorizes different blood pressure readings, distinguishing between normal, primary hypertension, and two stages of hypertension based on systolic and diastolic measurements.

🎯 Exam Tip: Memorize the normal and hypertensive ranges for blood pressure, as these are critical health indicators often tested.

Define The Following Terms

 

Question 1. Inhalation:
Answer: Inhalation is taking in air through the nose from the surrounding.
In simple words: Inhalation is the process of breathing air into the lungs from the external environment.

🎯 Exam Tip: A clear, concise definition of basic biological processes like inhalation is fundamental.

 

Question 2. Exhalation:
Answer: Exhalation is giving out the air back to the outer environment.
In simple words: Exhalation is the process of releasing air from the lungs back into the environment.

🎯 Exam Tip: Understand exhalation as the expulsion of air, the counterpart to inhalation in the breathing cycle.

 

Question 3. External respiration:
Answer: The processes of inhalation and exhalation both together are called external respiration.
In simple words: External respiration is the overall process of breathing, involving both taking air in and pushing it out.

🎯 Exam Tip: Distinguish external respiration (breathing) from internal and cellular respiration (gas exchange at cellular level).

 

Question 4. Internal respiration:
Answer: Exchange of gases between cells and tissue fluid is called internal respiration.
In simple words: Internal respiration is the exchange of oxygen and carbon dioxide between the blood and body cells.

🎯 Exam Tip: Focus on the location of internal respiration - between blood and body tissues - to differentiate it from external respiration.

 

Question 5. Cellular respiration:
Answer: Production of energy in the form of ATP from oxidation of glucose and other soluble nutrients is called cellular respiration.
In simple words: Cellular respiration is the biochemical process within cells that breaks down nutrients to produce energy (ATP).

🎯 Exam Tip: Cellular respiration is key to understanding energy production; remember its purpose is ATP generation from food.

 

Question 6. Thermoregulation:
Answer: Maintenance of the body temperature to a constant level by performing vasoconstriction or vasodilation is called thermoregulation.
In simple words: Thermoregulation is the body's ability to maintain a stable internal temperature, primarily through adjusting blood flow.

🎯 Exam Tip: Note the mechanisms like vasoconstriction and vasodilation as examples of how thermoregulation occurs.

 

Question 7. Blood pressure:
Answer: Pressure exerted by the flowing blood on the blood vessel wall is called blood pressure.
In simple words: Blood pressure is the force of blood pushing against the walls of arteries as the heart pumps.

🎯 Exam Tip: Understand blood pressure as a measure of force on vessel walls, crucial for cardiovascular health.

 

Question 8. Systolic pressure:
Answer: The maximum blood pressure exerted by the flowing blood when the heart is contracting is called systolic pressure.
In simple words: Systolic pressure is the higher number in a blood pressure reading, indicating the pressure when the heart beats and pushes blood.

🎯 Exam Tip: Remember systolic pressure relates to the heart's contraction (pumping phase).

 

Question 9. Diastolic pressure:
Answer: The minimum blood pressure exerted by the flowing blood when the heart is not contracting but receiving (i.e. relaxing) the blood is called diastolic pressure.
In simple words: Diastolic pressure is the lower number, representing the pressure in the arteries when the heart is at rest between beats.

🎯 Exam Tip: Diastolic pressure is linked to the heart's relaxation phase (filling phase).

 

Question 10. Hypertension or High Blood Pressure:
Answer: The blood pressure value of 140-159 mm Hg which is more than the normal blood pressure is called hypertension or high blood pressure.
In simple words: Hypertension, or high blood pressure, refers to persistently elevated blood pressure readings above the healthy range.

🎯 Exam Tip: Be aware of the numerical thresholds for diagnosing hypertension, as they define a significant health condition.

 

Question 11. Sphygmomanometer:
Answer: The instru-ment used for measuring blood pressure is called sphygmomanometer.
In simple words: A sphygmomanometer is a medical device used to measure blood pressure, typically involving an inflatable cuff.

🎯 Exam Tip: Knowing the name of instruments used in medical diagnosis is often a direct recall question.

 

Question 12. Hematology:
Answer: The branch of medical science in which the blood, haemapoietic organs (organ that produce blood cells) and blood disorders are studied is called haematology.
In simple words: Hematology is the study of blood, blood-forming organs, and blood-related disorders.

🎯 Exam Tip: Understand hematology as the specialized field focusing on all aspects of blood and its diseases.

Answer The Following Questions In One Or Two Sentences Each

 

Question 1. What are the heart sounds and why are they produced?
Answer: There are two types of heart sounds, one is 'lubb' and other is 'dub'. These are produced due to closure of the heart valves.
In simple words: Heart sounds, "lubb" and "dub," are caused by the closing of the heart's valves during each heartbeat.

🎯 Exam Tip: Remember that heart sounds are valve-related; "lubb" comes from AV valve closure, "dub" from semilunar valve closure.

 

Question 2. What is blood circulation?
Answer: The process of pumping the blood to all the parts of the body and bringing it back again to the heart is called the blood circulation.
In simple words: Blood circulation is the continuous movement of blood, pumped by the heart, throughout the body and back.

🎯 Exam Tip: Understand circulation as a complete circuit of blood flow, essential for nutrient and oxygen delivery.

 

Question 3. Name any four proteins present in the blood plasma.
Answer: The proteins present in the blood plasma are albumin, globulins, fibrinogen and prothrombin.
In simple words: Key proteins in blood plasma include albumin, globulins, fibrinogen, and prothrombin.

🎯 Exam Tip: Familiarize yourself with these specific plasma proteins and their general roles (e.g., albumin for osmotic pressure, fibrinogen for clotting).

 

Question 4. Which inorganic ions control the function of muscles and nerves?
Answer: Calcium, sodium and potassium control the functions of muscles and nerves.
In simple words: Calcium, sodium, and potassium ions are crucial for the proper functioning of both muscles and nerves.

🎯 Exam Tip: These ions (electrolytes) are vital for nerve impulse transmission and muscle contraction; their balance is critical.

 

Question 5. What is the basis on which blood group is determined?
Answer: The antigen present on the RBCs: and the antibodies present in the plasma of I the blood determine the type of blood group. The genes of parents are responsible for the type of blood group that the child inherits.
In simple words: Blood groups are determined by specific antigens on red blood cells and corresponding antibodies in the plasma, inherited from parents.

🎯 Exam Tip: Focus on antigens (on RBCs) and antibodies (in plasma) as the key factors defining blood groups.

 

Question 6. Under which conditions, blood is required for donation?
Answer: Whenever there is hemorrhage, the patient requires blood. Such patients are accident victims, those who excessively bleed, women during childbirth (parturition) and for patients undergoing surgeries.
In simple words: Blood donation is crucial for accident victims, patients with severe bleeding, women during childbirth complications, and those undergoing surgery.

🎯 Exam Tip: Be aware of the critical medical scenarios where timely blood transfusions are life-saving.

 

Question 7. How much blood is collected from a person during donation?
Answer: About 350 ml of blood is collected from a person during donation.
In simple words: Typically, around 350 ml of blood is collected from a donor in a single donation.

🎯 Exam Tip: Remember the standard volume of blood collected in a typical donation for practical knowledge.

 

Question 8. When is National Voluntary Blood Donation Day observed?
Answer: National Voluntary Blood Donation Day is observed on 1st October every year.
In simple words: National Voluntary Blood Donation Day is celebrated annually on October 1st.

🎯 Exam Tip: Note important awareness days related to health and public service, as these can be general knowledge questions.

Explain The Differences

 

Question 1. Atria and ventricles:
Answer:

Atria	Ventricles
1. Atria are the upper chambers of the heart.	1. Ventricles are the lower chambers of the heart.
2. Atria are the smaller receiving chambers.	2. Ventricles are the larger distributing chambers.
3. Atria are thin walled chambers having lesser blood pressure.	3. Ventricles are thick walled chambers with greater blood pressure.
4. Atria do not have inlet valves.	4. Ventricles have inlet valves.
5. Right atrium receives deoxygenated blood from whole body through the inferior vena cava (lower body), superior vena cava (from upper body). It pumps blood into right ventricle.	5. Right ventricle pumps deoxygenated blood received from right atrium to lungs for oxygenation which is known as pulmonary circulation.
6. Left atrium receives oxygenated blood from lungs through pulmonary veins. It pumps blood into left ventricle.	6. Left ventricle pumps oxygenated blood received from left atrium to whole body. This is called systemic circulation.

In simple words: Atria are the heart's upper, thin-walled receiving chambers with lower pressure, while ventricles are the lower, thick-walled pumping chambers that generate higher pressure for blood distribution.

🎯 Exam Tip: Understand the structural and functional differences between atria and ventricles, especially their roles in receiving and pumping blood and their wall thickness.

 

Question 2. RBCs and WBCs:
Answer:

RBCs	WBCs
1. RBCs are red in colour due to haemoglobin present in them.	1. WBCs are colourless as there is no pigment in them.
2. RBCs are produced in red bone marrow.	2. WBCs are produced mostly in bone marrow. But they are also produced in lymph nodes, spleen, etc.
3. RBCs are smaller in size and rounded in shape.	3. WBCs are larger in size and are of different shapes.
4. RBCs have an average lifespan of 120 days.	4. Life span of WBCs vary according to their role. They have a life span from a few days to 3 weeks.
5. Normal RBC count is 50-60 lakh RBCs per cubic mm. of blood.	5. Normal WBC count is 5 thousands to 10 thousands per cubic mm. of blood.
6. Their function is to transport the respiratory gases (Oxygen and Carbon Dioxide).	6. Their main function is to produce antibodies and fight against the infections. Thus they are called soldiers of the body.

In simple words: RBCs are red, contain hemoglobin for oxygen transport, are smaller, live longer, and are more numerous, while WBCs are colorless, larger, defend against infection, and have a shorter, variable lifespan.

🎯 Exam Tip: Pay attention to the key distinctions: color (hemoglobin), primary function (transport vs. immunity), size, lifespan, and count, for RBCs and WBCs.

Give Scientific Reasons

 

Question 1. A very large number of alveoli is present in lungs, which are covered over by capillary network.
Answer: Due to very large number of alveoli the surface area of the lungs is increased many a times for the gaseous exchange. The alveoli are covered over by capillary network for rapid gaseous exchange. The oxygen is taken in the body and at the same time carbon dioxide is given out of the body only by the gaseous exchange occurring at the alveolar surface.
In simple words: The numerous, highly vascularized alveoli maximize the surface area for efficient gas exchange, allowing oxygen to enter the blood and carbon dioxide to exit rapidly.

🎯 Exam Tip: The structure of alveoli (numerous, thin-walled, surrounded by capillaries) is perfectly adapted for their function of gaseous exchange; emphasize surface area.

 

Question 2. Heart is covered by double layered pericardial membrane.
Answer: Pericardium is the protective double membrane that covers the heart. In between the two layers of this membrane there is protective fluid. The pericardium and the fluid together protect the heart from friction and mechanical shock. Since heart is a vital organ, it is well protected by such pericardial membrane.
In simple words: The heart is enclosed by a double-layered pericardial membrane with fluid between layers to protect it from friction and physical shock, being a vital organ.

🎯 Exam Tip: Understand that the pericardium's double-layered structure and fluid are critical for the heart's protection and smooth function.

 

Question 3. Veins are provided with valves.
Answer: Valves prevent the backflow of the blood. Blood in the veins is not under great pressure so it is likely that it may flow back. But valves prevent such movements. Therefore they are provided with valves.
In simple words: Veins have valves to prevent blood from flowing backward, especially since blood pressure is low in veins and gravity could cause pooling.

🎯 Exam Tip: The presence of valves in veins is a crucial adaptation to ensure unidirectional blood flow back to the heart against gravity and low pressure.

Write Short Notes On The Following

 

Question 1. Cellular respiration:
Answer:
1. During respiration, the glucose molecules along with some other soluble nutrients are slowly oxidized with the help of oxygen in each cell.
2. In this process the energy is released in the form of ATP, \( \text{CO}_2 \) and water vapours are produced.
3. These products are not needed for the body and hence given out of the body in exhalation.
4. This process of cellular respiration is shown by the following reaction:
\( \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 = 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{Energy (38ATP)} \)
In simple words: Cellular respiration is the process where cells use oxygen to break down glucose and other nutrients, producing ATP energy, carbon dioxide, and water as byproducts.

🎯 Exam Tip: Memorize the chemical equation for cellular respiration and understand its three main outputs: energy (ATP), carbon dioxide, and water.

 

Question 2. Lung:
Answer:
1. Pair of lungs is the main respiratory organ in the human body. They are located in thoracic cavity.
2. They are present on either sides of heart.
3. Each lung has double layered pleural membranes.
4. Trachea bifurcates into two bronchi. Each bronchus enters lung on its side and
5. At the end of each bronchiole there is alveolus. Alveolus is surrounded by capillary network.
6. Each alveolus is extremely thin walled and hence gaseous exchange can occur through diffusion here. Due to thousands of alveoli, the lung surface is increased many a times.
7. Deoxygenated blood coming from heart by pulmonary arteries is purified here in the lungs.
8. It is mixed with oxygen due to gaseous exchange and returned back to the heart by pulmonary veins. Lungs thus continuously help in oxygenation of blood with the help of all of the alveoli.
In simple words: Lungs are the primary respiratory organs in the chest, protected by pleural membranes, where oxygen enters the blood and carbon dioxide is removed through millions of tiny, capillary-rich alveoli.

🎯 Exam Tip: Focus on the hierarchical structure of the respiratory tree (trachea, bronchi, bronchioles, alveoli) and the role of alveoli in gas exchange, enhanced by their vast surface area.

 

Question 3. Diaphragm:
Answer:
1. Diaphragm is a muscular partition that divides the thoracic and abdominal cavity.
2. Located at the base of thoracic cage, it is very important in breathing movements.
3. Diaphragm can undergo consecutive upward and downward movements.
4. These movements along with movements of thoracic cage cause rise and fall of the pressure in the thoracic cavity.
5. Rising up of ribs and lowering of diaphragm causes the decrease in air pressure which makes the air to move into the lungs through nose. This is inhalation.
6. When the pressure rises in the thoracic cavity again, the air is given out. This is exhalation.
7. This is caused due to ribs returning to their original position and rising diaphragm. This simultaneously increases the pressure in thoracic cavity.
In simple words: The diaphragm is a crucial muscle separating the chest and abdomen, whose rhythmic contraction and relaxation create pressure changes in the thoracic cavity, driving the processes of inhalation and exhalation.

🎯 Exam Tip: Emphasize the diaphragm's role in creating pressure differentials for breathing; its downward movement aids inhalation, upward aids exhalation.

 

Question 4. Structure of human heart:
Answer:
1. Human heart is four chambered muscular organ.
2. The size of the heart is about one's own fist and its weight is about 360 gm.
3. For protection, it is covered over by double-layered pericardium.
4. The wall of the heart is made up of cardiac muscles which are involuntary in nature. They have the capacity of rhythmic beating.
5. The upper two chambers are called right and left atrium and lower two chambers are called right and left ventricle.
6. Between right atrium and right ventricle there is tricuspid valve which guards the opening. Similarly between left atrium and left ventricle there is bicuspid valve.
7. On entire right side of the heart there is deoxygenated blood.
8. On entire left side of the heart there is oxygenated blood.
9. Right atrium receives deoxygenated blood by superior and inferior vena cava. These two major veins bring deoxygenated blood from entire body to the heart.
10. Left atrium receives oxygenated blood from lungs by pulmonary vein.
11. Right ventricle sends the deoxygenated blood to lungs for oxygenation, through pulmonary artery.
12. Left ventricle supplies oxygenated blood to entire body through systemic aorta.
In simple words: The human heart is a four-chambered, muscular organ, protected by pericardium, with atria receiving blood and ventricles pumping it; the right side handles deoxygenated blood, and the left side pumps oxygenated blood throughout the body.

🎯 Exam Tip: Understand the four chambers, the major blood vessels entering and leaving each, and the role of valves in ensuring one-way blood flow.

 

Question 5. Human Blood Groups:
Answer:
1. The A, B, O blood group system is the most popular and medically important blood group system of human beings.
2. The blood group is determined due to antigenic protein present on the RBCs and the antibody present in the plasma.
3. The four main groups of human blood are A, B, AB and O.
4. According to the presence or absence of Rh antigen the blood groups are further said to be Rh-positive or Rh-negative.
5. This makes total eight blood groups which are taken into consideration at the time of blood transfusions.
6. Blood groups are dependent on genes and are thus hereditary in nature.
In simple words: Human blood groups (A, B, AB, O, and Rh factors) are determined by specific antigens on red blood cells and antibodies in plasma, are genetically inherited, and are critical for safe blood transfusions.

🎯 Exam Tip: Focus on the ABO and Rh systems, understanding that antigens on RBCs and antibodies in plasma dictate compatibility for transfusions, and that blood groups are inherited.

Answer The Following

 

Question 1. How do the organisms like amoeba, earthworm, cockroach, plants, various aquatic animals, bird, respire? Prepare a chart.
Answer:

Organisms	Mode of respiration	Respiratory organ
Plants	Aquatic (Water plants) Terrestrial (Land plants). Compared to animals, plant roots, stems and leaves respire at a very lower rate.	Roots, stems, and leaves of plants exchange gases for respiration separately. Leaves have tiny pores or stomata. Exchange of gases takes place through these stomata and lenticels (present in stems). The oxygen, taken in through stomata is used by the cells in the leaves to break down glucose into carbon dioxide and water.
Amoeba	Diffusion though water	Diffusion through the body membrane.
Earthworm	Diffusion through soil	Earthworms have no special respiratory organs. Gases are exchanged through the moist skin and capillaries.
Cockroach	Absorption through air	There are many branching tubes which start from openings, called spiracles. Spiracles are present on the surface of the cockroach. Air enters the cockroach's body through the spiracles. Air passes into the trachea and moves on into the tracheoles and finally into the body tissues.
Aquatic Animals	Absorption through water. Can take up only dissolved oxygen.	Gills absorb oxygen dissolved in water.
Birds	Terrestrial respiration.	Lungs and air sacs attached to the lungs. Air sacs give buoyancy also.

In simple words: Different organisms have evolved various ways to respire; plants use stomata, amoeba and earthworms use diffusion through their body surface, cockroaches use spiracles and tracheae, aquatic animals use gills, and birds use lungs and air sacs.

🎯 Exam Tip: This comparative chart highlights the diversity of respiratory mechanisms across different life forms; understand the relationship between the mode of respiration and the specific respiratory organ.

Diagram - Based Questions

 

Question 1. Sketch and label structure of alveolus showing gaseous exchange.
Answer:
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र फेफड़ों में वायुकोष्ठिका (एल्वियोली) की संरचना और गैसीय विनिमय प्रक्रिया को दर्शाता है। इसमें दिखाया गया है कि एल्वियोली कैसे छोटे, गुब्बारे जैसे थैले होते हैं जो रक्त वाहिकाओं (कैपिलरी) के एक नेटवर्क से घिरे होते हैं, जहाँ ऑक्सीजन वायुकोष्ठिका से रक्त में प्रवेश करती है और कार्बन डाइऑक्साइड रक्त से वायुकोष्ठिका में निकलती है ताकि हवा के साथ बाहर निकाला जा सके।

In simple words: The diagram illustrates an alveolus, a tiny air sac in the lungs, surrounded by capillaries, demonstrating how oxygen diffuses from the alveolus into the bloodstream and carbon dioxide diffuses from the blood into the alveolus for exhalation.

🎯 Exam Tip: For diagrams like this, focus on correctly labeling the alveolus, capillary, and indicating the direction of oxygen and carbon dioxide exchange.

 

Question 2. Sketch and label artery and vein showing structural difference between the two.
Answer:
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र धमनी (आर्टरी) और शिरा (वेन) की संरचनात्मक भिन्नताओं को स्पष्ट रूप से दिखाता है। इसमें दर्शाया गया है कि धमनी की दीवारें मोटी और मांसपेशीय होती हैं, जबकि शिराओं की दीवारें पतली होती हैं और उनमें रक्त के एकतरफा प्रवाह को सुनिश्चित करने के लिए वाल्व होते हैं। यह उनके संबंधित कार्यों- रक्त को हृदय से दूर ले जाने और रक्त को हृदय तक वापस लाने- को दर्शाता है।

In simple words: The diagram shows the structural differences between an artery and a vein: arteries have thick, muscular walls to withstand high pressure, while veins have thinner walls and valves to prevent backflow of low-pressure blood.

🎯 Exam Tip: When comparing arteries and veins, highlight the differences in wall thickness (arteries thicker), lumen size (veins larger), and the presence of valves (only in veins).

 

Question 3. Draw a diagram to show formation of capillaries. Also show how capillaries form a vein.
Answer:
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र दर्शाता है कि कैसे धमनियों से निकलने वाली छोटी धमनियाँ (धमनिकाएँ) शाखाओं में बँटकर पतली केशिकाएँ (कैपिलरी) बनाती हैं, और फिर ये केशिकाएँ जुड़कर छोटी शिराएँ (शिराकाएँ) और अंततः शिराएँ (वेन) बनाती हैं, जो रक्त को हृदय की ओर वापस ले जाती हैं। यह रक्त परिसंचरण प्रणाली में केशिका नेटवर्क की महत्वपूर्ण भूमिका को स्पष्ट करता है जहाँ पोषक तत्वों और गैसों का विनिमय होता है।

In simple words: The diagram illustrates how arteries branch into tiny capillaries for exchange, which then converge to form venules, eventually leading to veins that return blood to the heart.

🎯 Exam Tip: This diagram is crucial for understanding the complete blood flow pathway: arteries -> arterioles -> capillaries -> venules -> veins. Focus on the transition points.

MCQs Based On Experiments

I. Human Respiratory System

 

Question 1. From which organ does respiratory system of man begin?
(a) Trachea
(b) Lungs
(c) Alveolus
(d) Nose
Answer: (d) Nose
In simple words: The human respiratory system starts with the nose, which filters and warms the inhaled air.

🎯 Exam Tip: Identify the correct entry point of the respiratory tract; the nose is the primary organ for air intake.

 

Question 2. Which of the statement given below is correct?
(a) Wind pipe is present in front of food pipe.
(b) Food pipe is present in front of wind pipe.
(c) Wind pipe and food pipe are not near each other.
(d) Wind pipe is same as oesophagus and food pipe is called trachea.
Answer: (a) Wind pipe is present in front of food pipe.
In simple words: The windpipe (trachea) is located in front of the food pipe (esophagus) in the neck and chest.

🎯 Exam Tip: Remember the anatomical arrangement: the trachea is anterior to the esophagus, which is why choking can occur if food "goes down the wrong pipe."

 

Question 3. Which type of respiration includes inhalation and exhalation?
(a) Internal respiration
(b) External respiration
(c) Cellular respiration
(d) None of the above
Answer: (b) External respiration
In simple words: External respiration is the act of breathing, encompassing both inhaling air and exhaling it.

🎯 Exam Tip: Differentiate external respiration (breathing in/out) from internal respiration (gas exchange at tissues) and cellular respiration (energy production in cells).

 

Question 4. How many molecules of ATP are produced from one molecule of glucose ?
(a) 26
(b) 36
(c) 38
(d) 40
Answer: (c) 38
In simple words: The complete breakdown of one glucose molecule during cellular respiration typically yields 38 ATP molecules.

🎯 Exam Tip: This is a key numerical fact in bioenergetics; remember 38 ATP as the maximum yield from glucose oxidation.

 

Question 5. Where is sound box located in the body?
(a) At the beginning of the wind pipe.
(b) At the beginning of the food pipe.
(c) At the end of the wind pipe.
(d) At the end of the food pipe.
Answer: (a) At the beginning of the wind pipe.
In simple words: The sound box, or larynx, is situated at the top of the windpipe (trachea).

🎯 Exam Tip: Locate the larynx (voice box) at the upper part of the trachea, responsible for sound production.

II. Structure Of Heart

 

Question 1. What is the location of a bicuspid valve in human heart?

 

Question 5. Which chambers of the heart are called receiving chamber?
(a) Both atria
(b) Right ventricle
(c) Left ventricle
(d) Only left atria
Answer: (a) Both atria
In simple words: The atria are the upper chambers of the heart that receive blood, with the right atrium receiving deoxygenated blood from the body and the left atrium receiving oxygenated blood from the lungs.

🎯 Exam Tip: Identifying the roles of the atria as "receiving chambers" and ventricles as "pumping chambers" is fundamental to understanding heart function.