RBSE Solutions Class 8 Science Chapter 7 Blood Circulation

Blood Circulation Textbook Questions Solved

I. Multiple Choice Questions

 

Question 1. Amount of water in the blood plasma is about:
(a) 70%
(b) 90%
(c) 10%
(d) 45%
Answer: (b) 90%
In simple words: Blood plasma is mostly water. About 90% of it is water, which helps carry things around the body.

🎯 Exam Tip: Remember this percentage as it's a key characteristic of blood plasma composition.

 

Question 2. Red blood corpuscles are also known as:
(a) RBC
(b) WBC
(c) Platelets
(d) Pulse
Answer: (a) RBC
In simple words: Red blood corpuscles are usually called RBCs for short. They carry oxygen in the blood.

🎯 Exam Tip: Know the common abbreviations for blood components, as they are often used interchangeably.

 

Question 3. Which of the following causes red colour of the blood?
(a) filerin
(b) antigen
(c) haemoglobin
(d) platelets
Answer: (c) haemoglobin
In simple words: Haemoglobin is a special protein inside red blood cells. It gives blood its red color and helps carry oxygen.

🎯 Exam Tip: Haemoglobin is vital for oxygen transport and is the primary reason for blood's red color. This is a fundamental concept.

 

Question 4. How many times does the heart of an adult man beats?
(a) 50 times
(b) 72 times
(c) 110 times
(d) 120
Answer: (b) 72 times
In simple words: An adult heart usually beats about 72 times every minute when a person is resting. This keeps blood flowing around the body.

🎯 Exam Tip: The average resting heart rate for an adult is around 60-100 beats per minute, with 72 being a commonly cited average.

 

Question 3. Impure blood is brought back to the heart by................
Answer: Impure blood is brought back to the heart by veins. Veins carry deoxygenated blood from the body tissues back to the heart.
In simple words: Veins are the blood vessels that carry dirty blood (blood without much oxygen) back to your heart.

🎯 Exam Tip: Remember that veins typically carry deoxygenated blood back to the heart, except for the pulmonary veins which carry oxygenated blood to the heart.

 

Question 4. Blood containing carbon dioxide is purified in the .................
Answer: Blood containing carbon dioxide is purified in the lungs. In the lungs, carbon dioxide is released, and oxygen is absorbed into the blood.
In simple words: When blood has carbon dioxide, it goes to the lungs to get clean. The lungs help remove carbon dioxide and add fresh oxygen.

🎯 Exam Tip: The lungs are the primary organs for gas exchange, where blood releases carbon dioxide and picks up oxygen.

Blood Circulation Very Short Answer Type Questions

 

Question 1. Name the corpuscles that clots the blood.
Answer: The corpuscles that help blood clot are called thrombocytes, also known as platelets. These small cells stop bleeding after an injury.
In simple words: Thrombocytes, or platelets, are tiny parts of your blood that make it thicken and stop bleeding when you get a cut.

🎯 Exam Tip: Thrombocytes (platelets) are essential for hemostasis, the process of stopping blood flow after vessel injury.

 

Question 2. What keeps the blood in liquid form?
Answer: Plasma, the liquid part of blood, is what keeps blood in its liquid form. It is mostly water and helps transport blood cells and other substances.
In simple words: Plasma is the watery part of your blood that makes it stay like a liquid, not solid.

🎯 Exam Tip: Plasma is the largest component of blood by volume and is crucial for maintaining blood fluidity and transporting various substances.

 

Question 3. How many chambers are there in the heart?
Answer: The human heart has four chambers. These chambers work together to pump blood throughout the body efficiently.
In simple words: Your heart has four main rooms inside it.

🎯 Exam Tip: Remember the four chambers: two atria (upper) and two ventricles (lower).

 

Question 4. How many types of antigens are there?
Answer: There are two main types of antigens, 'A' and 'B', that determine a person's blood group. These antigens are found on the surface of red blood cells.
In simple words: There are two main kinds of antigens, A and B. These help decide your blood type.

🎯 Exam Tip: Antigens on red blood cells (A and B) and antibodies in plasma (anti-A and anti-B) are the basis of the ABO blood grouping system.

Blood Circulation Short Answer Type Questions

 

Question 2. How many types of blood corpuscles are there? Name them.
Answer: There are three main types of blood corpuscles, which are also called blood cells. These are:
1. Red Blood Cells (RBC) or erythrocytes. They carry oxygen.
2. White Blood Cells (WBC) or leukocytes. They fight infections.
3. Thrombocytes or platelets. They help blood clot. Each type has a specific role in keeping the body healthy.
In simple words: There are three kinds of blood cells: red ones that carry oxygen, white ones that fight germs, and platelets that stop bleeding.

🎯 Exam Tip: Learn the full names (erythrocytes, leukocytes, thrombocytes) as well as their abbreviations and primary functions.

 

Question 3. Why are white blood cells called the soldiers of our body?
Answer: White blood cells (WBCs) are called the soldiers of our body because they protect us from disease-causing viruses and bacteria. They identify and destroy harmful invaders, just like soldiers defending a country.
In simple words: White blood cells are like soldiers because they defend our body against germs and sickness.

🎯 Exam Tip: This analogy is common. Focus on the immune function of WBCs and how they combat pathogens.

 

Question 4. Write the functions of blood.
Answer: Blood has several vital functions in our body:
1. It carries oxygen (O\( _2 \)) from the lungs to all body parts and carbon dioxide (CO\( _2 \)) from the body parts back to the lungs.
2. It transports nutrients and waste products throughout the body.
3. It protects our body from diseases by fighting foreign viruses and bacteria.
4. It helps to stop bleeding by forming blood clots when the body gets injured.
5. It carries antigens and antibodies, which are important for immunity.
6. It helps to maintain the body's temperature. Blood is truly the river of life within us.
In simple words: Blood carries oxygen, food, and waste, fights germs, stops bleeding, and keeps our body temperature steady.

🎯 Exam Tip: Be sure to list at least 4-5 major functions of blood, focusing on transport, protection, and regulation.

 

Question 5. What will happen if clot is not formed on injury?
Answer: If a blood clot is not formed after an injury, the person would continuously bleed. This could lead to severe blood loss, which can be very dangerous or even fatal. Blood clotting is a natural process to prevent excessive bleeding.
In simple words: If blood does not clot after an injury, a person would keep bleeding a lot, which is very dangerous.

🎯 Exam Tip: Emphasize the severity of uncontrolled bleeding and the critical role of clotting in preventing it.

 

Question 1. Describe the structure of heart with diagram.
Answer: The heart is a muscular, hollow organ about the size of a fist, located in the middle of the chest, slightly to the left. Its vital role is to continuously pump blood throughout the body, supplying cells with essential oxygen and nutrients. The heart is divided into four chambers to prevent the mixing of oxygen-rich and carbon dioxide-rich blood. The two upper chambers are called auricles (atria), and the two lower chambers are called ventricles. A muscular wall, the septum, divides the heart lengthwise into left and right sides.
Each side of the heart has a valve separating its upper atrium from its lower ventricle. When the heart muscles contract, blood is squeezed through the atria and then through the ventricles. The circulation process involves:
- The right auricle receives carbon dioxide-rich blood from various parts of the body.
- The right ventricle then pumps this blood to the lungs, where carbon dioxide is released and oxygen is absorbed.
- The left auricle receives oxygen-rich blood returning from the lungs via the pulmonary veins.
- The left ventricle then pumps this oxygen-rich blood, through the aorta, to all parts of the body.
The septum ensures complete separation of the left and right sides, preventing the mixing of oxygenated and deoxygenated blood. The heart also has several valves that ensure blood flows in only one direction. At rest, the heart beats between 60-80 times a minute. During physical activity or stress, this rate can increase to over 200 beats a minute. The rhythmic contraction and expansion of the heart create the pulse, which doctors check to assess health.

In simple words: The heart is a strong, four-chambered pump. It uses different sides and valves to keep oxygen-rich blood separate from carbon dioxide-rich blood, sending them to the body and lungs as needed.

🎯 Exam Tip: When drawing diagrams, clearly label all four chambers, the septum, and general blood flow directions (oxygenated vs. deoxygenated). Accuracy in labels is key.

 

Question 2. Write a short note on
(a) Blood group
(b) Blood bank
Answer:
(a) Blood group: Karl Landsteiner classified human blood into different blood groups based on the presence of specific antigens on red blood cells and antibodies in the plasma. The major ABO blood groups are A, B, AB, and O. Knowing a person's blood group is very important for safe blood transfusions and for forensic purposes.

(b) Blood Bank: A blood bank is a facility, typically run by governments or social service organizations, where donated blood is collected, processed, and stored for medical use. Ideally, blood for transfusions should come from relatives, but when this is not possible, blood banks provide suitable alternatives. To prevent blood from clotting and to preserve it, substances like sodium citrate are added. Blood can usually be stored safely in blood banks for up to 30 days. These facilities are essential for managing emergencies and maintaining a steady supply of safe blood for patients.
In simple words: Blood groups classify blood types for safe transfusions. A blood bank collects and stores donated blood, adding chemicals to keep it fresh for use when needed in hospitals.

🎯 Exam Tip: When explaining blood groups, clearly mention antigens and antibodies. For blood banks, highlight preservation methods and their importance in healthcare.

Blood Circulation Additional Questions Solved

I. Multiple Choice Questions

 

Question 1. The scientist who discovered blood transportation:
(a) Leuvan Hooke
(b) William Harvey
(c) Robert Hooke
(d) Landstiener
Answer: (b) William Harvey
In simple words: William Harvey was the scientist who figured out how blood moves around in a circuit inside our bodies.

🎯 Exam Tip: William Harvey's discovery of blood circulation was a major breakthrough in medicine, so remember his name.

 

Question 2. Blood is purified in:
(a) Heart
(b) Lungs
(c) Kidney
(d) Spleen
Answer: (b) Lungs
In simple words: Blood gets cleaned in the lungs. There, carbon dioxide is removed, and fresh oxygen is added.

🎯 Exam Tip: Clarify that 'purified' in this context means oxygenation and carbon dioxide removal, which primarily occurs in the lungs.

 

Question 3. One of the following is an antigen not found in human blood
(a) A
(b) B
(c) Rh
(d) O
Answer: (d) O
In simple words: O is a blood group type, but it does not represent an antigen itself in the same way A, B, and Rh do. Blood group O means that A and B antigens are absent.

🎯 Exam Tip: Understand that blood groups are defined by the *presence* or *absence* of specific antigens (A, B, Rh factor) on red blood cells.

 

Question 4. The person who is a universal donor with blood group-
(a) A
(b) B
(c) AB
(d) O
Answer: (d) O
In simple words: People with blood group O are called universal donors because their blood can be given to anyone, regardless of their blood type, without causing a bad reaction.

🎯 Exam Tip: Memorize that 'O' is the universal donor, and 'AB' is the universal recipient.

 

Question 5. Which of these is responsible for blood clotting?
(a) Red blood cells
(b) White blood cells
(c) Haemoglobin
(d) Platelets
Answer: (d) Platelets
In simple words: Platelets are tiny cells in your blood that help it clot and stop bleeding when you get a cut or injury.

🎯 Exam Tip: Platelets are critical for hemostasis; their absence or dysfunction can lead to bleeding disorders.

 

Question 6. A person injured in a road accident, with blood group 'O' can be given blood with, which of the following blood group:
(a) from 'A' and 'O'
(b) from 'B' and 'O'
(c) from 'AB' and 'O'
(d) only from 'O'
Answer: (d) only from 'O'
In simple words: A person with O blood group can only get blood from another person with O blood group. This is because their body would react to any other blood type.

🎯 Exam Tip: Blood group O individuals are universal donors but can only receive blood from other O group individuals.

 

Question 7. The thinnest blood vessels in the human body are
(a) arteries
(b) veins
(c) capillaries
(d) any of these
Answer: (c) capillaries
In simple words: Capillaries are the smallest and thinnest blood vessels in your body, where oxygen and nutrients actually pass into the cells.

🎯 Exam Tip: Capillaries are the site of exchange of gases, nutrients, and waste products between blood and tissues due to their thin walls.

 

Question 9. When you feel your pulse, what you actually feel is blood rushing through the-
(a) arteries
(b) veins
(c) capillaries
(d) all of these
Answer: (a) arteries
In simple words: Your pulse is the feeling of blood pushing against the walls of your arteries as your heart beats.

🎯 Exam Tip: The pulse is typically felt in arteries close to the skin surface, reflecting the pressure wave from the heart's contractions.

 

Question 10. Blood cells that protect the body from diseases-
(a) RBCs
(b) WBCs
(c) Blood platelets
(d) all of these
Answer: (b) WBCs
In simple words: White blood cells, or WBCs, are the blood cells that fight off sickness and protect your body from germs.

🎯 Exam Tip: Understand the primary role of WBCs in the immune system and their importance in fighting infections.

 

Question 11. The device used to hear the heartbeat is called
(a) thermometer
(b) stethoscope
(c) sphygmomanometer
(d) microscope
Answer: (b) stethoscope
In simple words: A stethoscope is a medical tool that doctors use to listen to your heart and other sounds inside your body.

🎯 Exam Tip: Know the functions of common medical instruments, especially those related to the circulatory system.

 

Question 12. The deficiency of haemoglobin causes
(a) blood cancer
(b) anaemia
(c) weakness
(d) flow blood
Answer: (b) anaemia
In simple words: If you don't have enough haemoglobin in your blood, it can cause a condition called anaemia, making you feel tired and weak.

🎯 Exam Tip: Anaemia is directly linked to low haemoglobin levels, which impairs oxygen transport in the blood.

 

Question 13. Human heart beats in a minute:
(a) 60 times
(b) 62 times
(c) 72 times
(d) 80 times
Answer: (c) 72 times
In simple words: On average, a healthy human heart beats about 72 times in one minute to keep blood moving throughout the body.

🎯 Exam Tip: The average resting heart rate is a fundamental physiological parameter; 72 beats per minute is a widely accepted typical value.

 

Question 15. RBC's are WBC's in size:
(a) larger than
(b) smaller than
(c) equal to
(d) some time larger, sometime smaller
Answer: (b) smaller than
In simple words: Red blood cells (RBCs) are generally smaller in size compared to white blood cells (WBCs). This difference in size relates to their different functions.

🎯 Exam Tip: While RBCs are more numerous, WBCs are typically larger and have various shapes, reflecting their diverse roles in immunity.

Blood Circulation Very Short Answer Type Questions

 

Question 1. Which scientist is given the credit of discovering blood groups?
Answer: Karl Landsteiner is credited with discovering the ABO blood groups. His work made blood transfusions much safer.
In simple words: Karl Landsteiner was the scientist who found out about different blood groups.

🎯 Exam Tip: Remember Karl Landsteiner's name and his significant contribution to blood typing, which revolutionized transfusion medicine.

 

Question 3. Name the 'universal recipient' and 'universal donor' blood groups.
Answer: The 'universal recipient' blood group is AB. The 'universal donor' blood group is O. This means AB can receive blood from all types, and O can donate blood to all types.
In simple words: Blood group AB can get blood from anyone (universal recipient), and blood group O can give blood to anyone (universal donor).

🎯 Exam Tip: This is a key fact in blood biology; ensure you remember which blood groups correspond to universal recipient and donor.

 

Question 4. Where are antigens and antibodies found in blood?
Answer: Antigens are found on the surface of red blood corpuscles (RBCs). Antibodies, on the other hand, are present in the blood serum, which is the liquid part of blood after clotting. These components are vital for the immune response.
In simple words: Antigens are on red blood cells, and antibodies are in the watery part of your blood called serum.

🎯 Exam Tip: Clearly differentiate between the location of antigens (on cells) and antibodies (in plasma/serum) for blood group understanding.

 

Question 5. What is the function of blood platelets?
Answer: The primary function of blood platelets (thrombocytes) is to assist in blood clotting. When an injury occurs, platelets gather at the site and form a plug, helping to stop the blood flow. This prevents excessive blood loss.
In simple words: Blood platelets help your blood clot to stop bleeding when you get hurt.

🎯 Exam Tip: Platelets are essential for hemostasis, the process that prevents and stops bleeding from damaged blood vessels.

 

Question 6. Name the doctor who invented stethoscope?
Answer: The stethoscope was invented in 1816 by a French doctor named René Laennec. This invention greatly improved doctors' ability to listen to internal body sounds.
In simple words: A French doctor named R. Laennec invented the stethoscope in 1816.

🎯 Exam Tip: Laennec's invention of the stethoscope was a significant advancement in medical diagnosis, particularly for heart and lung sounds.

 

Question 7. Name the diseases caused by blood infection?
Answer: Blood infections can cause several diseases, including AIDS (Acquired Immunodeficiency Syndrome), anaemia, polycythemia (a disorder of too many red blood cells), and hepatitis (inflammation of the liver, which can sometimes be transmitted through blood). These conditions show the critical role of blood health.
In simple words: Blood infections can cause diseases like AIDS, anaemia, too many red blood cells (polycythemia), and hepatitis.

🎯 Exam Tip: Focus on understanding how infections can compromise blood health and lead to systemic diseases.

 

Question 8. Define pulse rate.
Answer: Pulse rate is defined as the number of heart beats per minute. It reflects how fast your heart is pumping blood.
In simple words: Pulse rate is how many times your heart beats in one minute.

🎯 Exam Tip: The pulse rate is an important vital sign, indicating the rate at which the heart pumps blood through the arteries.

 

Question 10. What is heart beat?
Answer: A heartbeat is the sound produced by the rhythmic contraction and relaxation of the auricles (atria) and ventricles of the heart. These actions work together to pump blood.
In simple words: A heartbeat is the sound made when the top and bottom parts of your heart squeeze and relax to push blood.

🎯 Exam Tip: Understand that the "lub-dub" sound of the heartbeat corresponds to the closing of heart valves during the cardiac cycle.

Blood Circulation Solutions Short Answer Type Questions

 

Question 1. Define blood transfusion.
Answer: Blood transfusion is a medical procedure where blood, or components of blood, are transferred from a donor into the circulatory system of a recipient. It is performed when a person has lost a lot of blood due to injury or surgery, or needs specific blood components due to various medical conditions. Before a transfusion, compatibility testing is done to make sure the donor's and recipient's blood types are a good match.
In simple words: Blood transfusion means putting blood from one person into another person who needs it, often because they lost too much blood.

🎯 Exam Tip: Highlight the importance of compatibility testing before any blood transfusion to prevent adverse reactions.

 

Question 2. Why is blood necessary to all the parts of body?
Answer: Blood is essential to all parts of the body because it carries vital substances needed for life and removes waste products. It supplies oxygen and nutrients from digested food to various body tissues, providing the energy required for all bodily functions. Without this constant supply, cells would not be able to survive or perform their roles.
In simple words: Blood is needed everywhere in your body because it delivers oxygen and food to all your cells and takes away waste, helping everything work properly.

🎯 Exam Tip: Focus on blood's role as a transport system for oxygen, nutrients, and waste, which is fundamental to cellular function and survival.

 

Question 3. Write the main function of platelets.
Answer: Platelets, also known as thrombocytes, play a crucial role in the clotting of blood. Their main function is to stop bleeding by forming a plug at the site of injury, thereby preventing excessive blood loss. These are small, irregularly shaped cells that initiate the complex process of coagulation.
In simple words: The main job of platelets is to help your blood form clots and stop bleeding quickly when you get a cut.

🎯 Exam Tip: Emphasize that platelets are not just for clotting but are the *first responders* to blood vessel injury, forming the initial plug.

 

Question 4. How does oxygenated and deoxygenated blood not mixed together in heart?
Answer: Oxygenated and deoxygenated blood do not mix in the heart due to a strong muscular partition called the septum. This septum completely separates the left side of the heart (which carries oxygenated blood) from the right side (which carries deoxygenated blood). Additionally, the heart contains several valves that ensure blood flows in only one direction, preventing any backflow or mixing. This separation is crucial for efficient oxygen delivery to the body.
In simple words: A wall inside your heart called the septum keeps the clean blood (with oxygen) separate from the dirty blood (without oxygen), and special doors called valves make sure blood only flows one way.

🎯 Exam Tip: The septum is the primary structural barrier preventing blood mixing, complemented by the unidirectional flow ensured by heart valves.

 

Question 6. What are the criteria for donating blood?
Answer: There are specific criteria a person must meet to donate blood safely:
1. The donor must be between 18 and 60 years of age.
2. Their weight should be more than 45 kg.
3. They should not be suffering from serious diseases like Hepatitis B or C, Syphilis, or Malaria.
4. They should not have donated blood within the last three months.
5. They should not have undergone surgery in the last six months.
6. Their haemoglobin level should be more than 12.5 g/dL.
7. Their blood pressure should be normal.
8. Their body temperature should be around 37.5°C, and pulse rate normal.
9. Pregnant women are generally not eligible to donate blood. These rules ensure both donor safety and the quality of the donated blood.
In simple words: To donate blood, you need to be an adult, weigh enough, be healthy, not have donated recently, and have normal blood pressure and temperature. Pregnant women cannot donate.

🎯 Exam Tip: Remember key eligibility criteria for blood donation, especially age, weight, health status, and recent medical history.

 

Question 6. What precautions should be taken after blood donation?
Answer: After donating blood, certain precautions are important for the donor's well-being:
1. Drink plenty of liquids like milk, juice, or water for up to 24 hours after donation. This helps to replenish lost fluids.
2. Avoid strenuous exercise and heavy physical labor for up to 24 hours after donation. This allows the body to recover. Following these simple steps helps the body recover quickly and prevents any discomfort.
In simple words: After donating blood, drink lots of fluids and avoid hard work for a day to help your body recover.

🎯 Exam Tip: Advise donors to stay hydrated and avoid strenuous activities immediately after donation to prevent dizziness or fatigue.

 

Question 7. What is AIDS? Write its full form. By which test it can be detected?
Answer: AIDS stands for Acquired Immuno Deficiency Syndrome. It is a severe, incurable syndrome caused by the Human Immunodeficiency Virus (HIV) that weakens the body's immune system, making it vulnerable to various infections and diseases. AIDS can be detected by an ELISA (Enzyme-Linked Immunosorbent Assay) test, which looks for HIV antibodies in the blood.
In simple words: AIDS is a very serious sickness that stops your body from fighting germs. Its full name is Acquired Immuno Deficiency Syndrome, and it can be found using a test called ELISA.

🎯 Exam Tip: Know the full form of AIDS and HIV, and remember ELISA as a primary screening test for HIV infection.

Blood Circulation Long Answer Type Questions

 

Question 1. Describe the different blood groups and their compatibility for donation and reception.
Answer: Human blood is classified into different groups, primarily the ABO system, based on the presence or absence of specific antigens (A and B) on the surface of red blood cells (RBCs) and corresponding antibodies in the blood plasma. Karl Landsteiner discovered these blood groups, which are crucial for safe blood transfusions.

(a) Blood Group A: Individuals with blood group A have antigen A on their RBCs and anti-B antibodies in their serum. Approximately 25% of the population in India has 'A' blood group.
(b) Blood Group B: Individuals with blood group B have antigen B on their RBCs and anti-A antibodies in their serum. Around 35% of the population in India has 'B' blood group.
(c) Blood Group AB: Individuals with blood group AB have both antigen A and antigen B on their RBCs but no anti-A or anti-B antibodies in their serum. About 10% of people in India have 'AB' blood group.
(d) Blood Group O: Individuals with blood group O have neither antigen A nor antigen B on their RBCs but possess both anti-A and anti-B antibodies in their serum. Around 35% of the population in India has 'O' blood group.

The knowledge of blood groups is vital for blood transfusions, ensuring compatible blood is used to prevent severe immune reactions. Below is a compatibility chart detailing who can donate to whom and who can receive from whom:

Blood Group Compatibility Chart

From this chart, we can see:
- Universal Recipient: Individuals with blood group AB can receive blood from any blood group (A, B, AB, O).
- Universal Donor: Individuals with blood group O can donate blood to any blood group (A, B, AB, O).
This system also plays a significant role in legal matters, such as paternity disputes and criminal investigations, using genetic markers like blood groups.
In simple words: Blood groups like A, B, AB, and O are decided by tiny markers on red blood cells. Knowing these groups helps doctors give the right blood to people who need it, stopping bad reactions. Group O can give blood to anyone, and group AB can get blood from anyone.

🎯 Exam Tip: Clearly state the antigens and antibodies for each ABO blood group and explain why O is the universal donor and AB is the universal recipient. Include the compatibility table for full marks.

 

Question 2. Describe the main components of blood.
Answer: Blood is made up of two main components: plasma and blood cells.
1. Plasma: Plasma is a pale yellow, liquid part of the blood, making up about 55% of its volume. It contains roughly 92% water, with the remaining 8% composed of proteins, glucose, urea, minerals, and hormones. Plasma is responsible for carrying carbon dioxide, nutrients, waste products, and hormones throughout the body.
2. Blood cells: These are the solid components suspended in plasma, forming about 45% of blood volume. There are three main types of blood cells:
 a. Red Blood Cells (RBCs) or erythrocytes: These are small, biconcave disc-shaped cells present in large numbers. They contain haemoglobin, a red-colored pigment that binds to oxygen, helping in its transportation from the lungs to all body tissues. Haemoglobin gives blood its red color.
 b. White Blood Cells (WBCs) or leukocytes: These cells are crucial for the body's immune system. They help fight diseases by identifying and destroying infectious agents like viruses and bacteria, acting as the body's "soldiers." WBCs are generally larger than RBCs but are fewer in number.
 c. Platelets or thrombocytes: These are small, irregular cells that play a vital role in blood clotting. When a blood vessel is injured, platelets gather and form a plug, stopping the flow of blood. Together, these components ensure blood performs its many critical functions, maintaining health and life.
In simple words: Blood has two main parts: liquid plasma and solid blood cells. Plasma carries things like food and waste. Blood cells include red cells for oxygen, white cells for fighting germs, and platelets for stopping bleeding.

🎯 Exam Tip: Remember the two main components of blood (plasma and cells) and the three types of blood cells, along with their key functions.

 

Question 3. Differentiate between arteries and veins. What is the importance of capillaries in the circulatory system?
Answer:Arteries:
1. Arteries have thick and elastic walls. This helps them withstand the high pressure of blood coming from the heart.
2. They typically do not have valves, as the high pressure of blood ensures forward flow.
3. Blood flows through arteries at high pressure.
4. They carry oxygen-rich (pure) blood from the heart to all parts of the body (except the pulmonary artery).
Veins:
1. Veins have thinner walls compared to arteries.
2. They have valves at intervals to prevent the backflow of blood, especially when blood flows against gravity.
3. Blood flows through veins at low pressure.
4. They carry carbon dioxide-rich (impure) blood from body parts back to the heart (except the pulmonary vein).
Importance of Capillaries:
Capillaries are the thinnest and most numerous blood vessels in the body. Their walls are extremely thin, usually just one cell thick. This thinness is crucial because it allows for the efficient exchange of substances. Through these thin walls, oxygen, digested food, and hormones pass from the blood into the body's cells, while carbon dioxide and other waste products move from the cells into the blood to be carried away. Capillaries bridge the gap between arteries and veins, forming a vast network that reaches almost every cell.
In simple words: Arteries carry clean blood away from the heart with strong walls and high pressure. Veins carry dirty blood back to the heart with thin walls and valves. Capillaries are tiny blood vessels with very thin walls where oxygen, food, and waste are swapped between blood and body cells.

🎯 Exam Tip: When differentiating arteries and veins, focus on wall thickness, presence/absence of valves, and blood pressure. For capillaries, emphasize their role in nutrient/gas exchange due to their thin walls.

 

Question 2. Write a short note on
(a) Blood group
(b) Blood bank
Answer:
(a) Blood group: Karl Landsteiner classified human blood into four main groups: A, B, AB, and O. This classification is based on the presence or absence of specific antigens and antibodies in the blood.
Blood group A individuals have antigen-A on their red blood cells and antibody-b in their blood serum. About 25% of people in India have this blood group.
Blood group B individuals have antigen B on their red blood cells and antibody-a in their blood serum. Around 35% of people in India have this blood group.
Blood group AB individuals have both antigen-A and antigen-B on their red blood cells, but they do not have any antibodies in their blood serum. Approximately 10% of people in India have AB blood group.
Blood group O individuals do not have antigen A or antigen B on their red blood cells, but they have both antibody-a and antibody-b in their serum. This group is also called the Zero group. About 35% of people in India have O blood group.

Understanding blood groups is very important. It has made blood donation much easier and safer, which is a great help to society. When people need blood urgently due to accidents or illness, blood banks can provide the correct group. Blood groups also help in legal cases and identifying criminals through DNA tests. Donating blood helps those who have a blood deficiency. Group O is a universal donor, meaning people with O blood can give blood to anyone. Group AB is a universal recipient, meaning people with AB blood can receive blood from anyone.

Can give blood to:

• 'A' to 'A' and 'AB'
• 'B' to 'B' and 'AB'
• 'AB' to 'AB' only
• 'O' to 'A', 'B', 'AB', and 'O' (universal donor)

Can receive blood from:

• 'A' from 'A' and 'O'
• 'B' from 'B' and 'O'
• 'AB' from 'A', 'B', 'AB', and 'O' (universal recipient)
• 'O' from 'O' only

(b) Blood Bank: Blood should ideally be taken from family members. If that is not possible, blood can be obtained from government or private blood banks, which are often found in hospitals. To store blood, sodium citrate is added to keep it fresh. Blood can be safely stored in blood banks for up to 30 days.
In simple words: Blood groups like A, B, AB, and O tell us who can give and receive blood. This is vital for safe blood transfusions. Blood banks store blood and ensure it is safe to use by adding chemicals that keep it fresh.

🎯 Exam Tip: Remember the four main blood groups (A, B, AB, O) and their universal donor/recipient properties. Also, know the key functions of a blood bank for full marks.