General Science Solutions Solutions for Class 8 Science Chapter 11 Human Body And Organ System are provided here with simple step-by-step explanations. These solutions for Human Body And Organ System are extremely popular among Class 8 students for Science Human Body And Organ System Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the General Science Solutions Book of Class 8 Science Chapter 11 are provided here for you for free. You will also love the ad-free experience on Meritnation’s General Science Solutions Solutions. All General Science Solutions Solutions for class Class 8 Science are prepared by experts and are 100% accurate.

Page No 82:

Question 1:

Find out my partner.

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


 Group 'A'  Group 'B'
 1. Heart beats  d. 72
 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
 6 pH of oxygenated blood  b. 7.4

Page No 82:

Question 2:

Complete the following table.

 Organ system  Organs  Functions
 1. Respiratory     
 2. Circulatory system    




Organ system

 Organs  Functions
 1. Respiratory 


Wind pipe

Traps dust particles and microbes and prevents their entry in the respiratory system.

Acts as a passage for the entry of air into the wind pipe.

Acts as a passage through which air passes into the lungs.

Exchange of gases occurs in lungs.
 2. Circulatory        system Heart

Blood vessels

The main organ from where circulation of blood to different body parts occurs.

Closed system of vessels which help in circulation of blood.

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Question 3:

Draw neat and labeled diagrams.
a. Respiratory system
b. Internal structure of heart.


a. Respiratory system

b. Internal structure of heart

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Question 4:

Explain with reasons.
a. Human blood is red colured.
b. Upward and downward movement of diaphragm occurs consecutively.
c. Blood donation is considered to be superior of all donations.
d. person with 'O' blood group is considered as 'universal donor'
e. Food must have limited amount of salts.


a. Human blood is red in colour due to the presence of the respiratory pigment haemoglobin. Haemoglobin is a pigment which is red in colour and thus imparts red colour to the blood.

b. Diaphragm is a muscular partition which is present between the thoracic cavity and abdominal cavity. During the process of breathing, the upward and downward movement of diaphragm occurs simultaneuosly. When we inhale, the ribs rise up while the diaphragm lowers down simulatenously causing a decrease in pressure on lungs. This results in the moving of air into lungs through nose. As the ribs return to their original position, diaphragm rises up leading to the increase in pressure inside the lungs. This results in moving of the air outside the nose.

c. Blood donation is considered superior of all donations because it can save someome's life. Most of the lives are lost due to blood loss during surgeries, accidents or cases where regular blood transfusion is required. These lives can be saved, if adequate amount of blood is available.

d. Person with 'O' blood group is considered as 'universal donor' because such an indivisual can donate blood to a person having any other blood group.

e. Food must have limited amount of salts as we require limited amounts of these in our body. Excessive salts in food can lead to accumulation of water in different parts of the body such as arms, legs etc. and lead to edema. Too much salt leads to increase in the blood pressure as well.

Page No 82:

Question 5:

Answer the follwing questions in your own words.
a.Explain the functional correlation of circulatory system with respiratory, digestive and excretory system.
b.Explain the structure and function of human blood.
c.Explain the importance and need of blood donation.


a. The functional corelation between circulatory system with respiratory, digestive and excretory system is as follows:

We already know that during respiration exchange of gases occurs in the lungs. The respiratory system causes the diffusion of oxygen into the blood and the diffusion of CO2 out of the blood. The oxygen is then transported to cells of the body via the circulatory system. 
The digestive system is responsible for producing nutrients by breaking complex molecules into simpler ones. The circulatory system then tranports these nutrients to different cells and tissues. 
The excretory system is responsible for the elmination of waste products from the body. These waste products are transported by blood to the excretory system.

b. Blood is a fluid connective tissue that flows in blood vessels. It is composed of two components- plasma and blood cells. 

Plasma is a yellowish colour fluid, made up of water (~90%) and some dissolved nutrients, proteins, hormones and waste products. 

Blood consists of three types of blood cells. These are

i. Red Blood Cells: They contain a red pigment called haemoglobin, which transports oxygen to all body cells.

ii. White Blood Cells: They fight against germs that enter the body. Thus, they protect the body from diseases.

iii. Platelets: When we get injured, bleeding stops after some time. This happens because of the activity of platelets, which help in the clotting of blood.

Functions of blood:

  • It transports nutrients and oxygen to the different parts of the body.

  • It also carries waste materials (from the different parts of the body) to be removed by the excretory organs.

  • Chemical messengers like hormones are transported by the blood.

  • Protects the body from disease carrying germs.

  • Helps to maintain a constant body temperature.

c. Blood donation is one of the biggest donations of an inidivisual towards their society. Blood loss can occur under circumstances of accidents, during surgeries or in case of diseases which require blood transfusion. Adequate amount of available blood can save many lives. It does not harm or effect the body of the donor and the amount of blood which is donated is recovered within 24 hrs.
This donated blood can be stored and used as and when the requirement arises.


Page No 82:

Question 6:

Explain the differences.
a. Arteries and veins.
b. External and internal respiration



External respiration
Internal respiration
1. It occurs between the body and external environment. It occurs at the cellular level.
2. It is a mechanical process. It is a chemical  process.
3. It can be both- voluntary and involuntary action. It is only an involuntary action.


1. Carries blood towards organs and away from heart. Carries blood towards heart and away from organs.
2. Carries fully oxygenated blood Carries deoxygenated and CO2 enriched blood.
3. Blood flows with high pressure and jerks,. Blood flows with low pressure and smoothly.
4. Have no valves Have valves to prevent backflow of blood.
5. Walls are elastic. Walls are non-elastic.
6. Are Deeply placed. Are superficial.
7 Branched and decreases in size. Unites and increases in size
8. Can constrict and dilate Cannot constrict.
9. Have thick and muscular walls Have thin and less muscular walls.
10. Smallest artery is called arteriole Smallest vein is called Venules.

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Question 7:

Which health parameters of blood donor should be checked?


The following parameters of blood donors have to be checked prior blood donation:

1. Age – There is a set age before which and after which blood donation can be done or not respectively.​
2. Weight – Weight of individuals is also an important factor as underweight indivisuals are not allowed to donate blood. In underweight indivisuals, the likelihood of having a reaction such as dizziness and fainting following donation are higher.

3. Heart, lung, and blood disease – Donors are enquired about any prior history of heart, lung, or blood diseases. People with heart disease, heart valve conditions, irregular heartbeat, disease of the blood vessels in the brain, heart failure, and certain lung conditions may be excluded from blood donation. Certain blood diseases such as iron deficiency anemia or chronic leukemia may also lead to exclusion.

4. Other medical conditions – Any other medical condition such as diabetes, hypertension, hypotension, fever etc. are also checked before blood donation.

5. Recent surgery – People with recent surgery are not allowed for donating blood. However, after an year of surgery they can donate blood but only if healing is complete and they have resumed full activity.

6. Pregnancy – Women who are pregnant are not permitted to donate blood during pregnancy and for six weeks after the pregnancy ends.

Page No 82:

Question 8:

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

a. RBCs of the blood conatin _________, an iron compound.

b. ____________ is present between thoracic and abdominal cavity.

c. Cardiac muscles are_______

d. pH of oxygenated blood is________

e. Production of RBCs occurs in__________


​a. RBCs of the blood conatin hemoglobin, an iron compound.

b. Diaphragm is present between thoracic and abdominal cavity.

c. Cardiac muscles are involuntary.

d. pH of oxygenated blood is alkaline.

e. Production of RBCs occurs in red bone marrow.

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Question 9:

Find odd one out.
a. A, O, K, AB, B.
b. Blood plasma, platelets, blood transfusion, blood corpuscles.
c. Trachea, alveoli, diaphragam, capillaries.
d. Neutrophils, globulins, albumins, prothrombin.            


a. A, O, K, AB, B - K is the odd one out because it is an inorganic ion while rest of the four are types of blood groups.
b. Blood plasma, platelets, blood transfusion, blood corpuscles- Blood transfusion is the odd one out because it is a techniques for transfer ing of blood from donor to repeient. Rest of the three are components of blood.
c. Trachea, alveoli, diaphragam, capillaries- Capillaries are the odd one out because they are a part of the circulatory system while rest of the three are parts of the respiratory system.
d. Neutrophils, globulins, albumins, prothrombin- Neutrophils are the odd one out because they are a type of blood cell. Rest of the three are components of the plasma.         

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Question 10:

Read the following paragraph and identify the disease.

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.


From the above mentioned symptoms, it seams like the child is suffering from some kind of respiratory disorder/circulatory disorder. He has problem in breathing and his nails have become blue which means there is low level or lack of oxygen circulating in the red blood cells. It is known as cyanosis.
It occurs when enough oxygen is not present in blood, thus making the skin or membrane below the skin turn purplish-blue.

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Question 11:

Your neighboring uncle has been diagnosed with hypertension. what should he do to keep hsi blood pressure within normal range?


The following methods can be adopted to keep the blood pressure within normal range:

  • loose the extra weight
  • exercise or do yoga regularly
  • eat a healthy balanced diet containing fruits and vegetables
  • reduce the amount or salt in food
  • avoid alcohol and smoking
  • reduce the amount of stress by indulging in your favourite activities
  • regular monitoring of blood pressure 

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