STD 7 Basic Science: Chapter 08 Breath and Blood of Life - Questions and Answers


Textbooks Solution for Class 7 Basic Science (English Medium) പ്രാണവായുവും ജീവരക്തവും | Text Books Solution Basic Science Chapter 08 Breath and Blood of Life | Teaching Manual & Teachers Handbook

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Chapter 08: Breath and Blood of Life - Questions and Answers 
I. Breathing
1. We breathe about —- times in a day
Answer: 20000

2. The process of inhaling air is
Answer: Inspiration

3. The process of exhaling air is
Answer: expiration

4. While inhaling, ribs get
Answer: Expands

5. While exhaling, ribs get
Answer: contracts

6. What is breathing?
Answer: Taking in atmospheric air into the lungs and sending it out along with carbon dioxide after absorbing oxygen is called breathing. 
Inhaling: Taking in air. ie, Inspiration 
Exhaling: Releasing air. ie, Expiration

7. Which main respiratory organ in human beings?
Answer: A pair of lungs is the main respiratory organ in human beings.

8. What is the difference between inspiration and expiration?
Answer: Inspiration is the action of inhaling air or taking in air into the lungs. Expiration is the action of releasing air with carbon dioxide from the lungs. 
Movement of the ribs
When inspiration and expiration take place, the rib cage expands and contracts respectively. 
What actually happens in this?
Rib cage expands - Inspiration occurs. Rib cage contracts - Expiration occurs.

9. Complete the table given in the textbook.
 While inhaling While exhaling 
  Rib cage expands  Rib cage contracts.
• While inhaling air the ribcage expands and exhaling air the ribcage contracts.
• The process of inhaling air is called inspiration and the process of exhaling air is called expiration.

II. Respiratory system in humans
10. Which are the main respiratory organs in a man? Where are they situated?
Answer: The main respiratory organs in humans are two lungs. They are, situated in the thoracic cavity surrounded by the rib cage.

11. What is the size of lungs?
Answer: The right lung is slightly larger than the left lung.

12. Which are the parts of the respiratory system?
Answer: 
• Nostrils - Openings in the nose.
• Trachea - A long tube. It is made up of 'C' shaped rings of cartilage.
• Bronchi (singular: Bronchus): They are the two branches of the trachea.
• Lungs: They are made of air sacs. Lungs are spongy. There is a left lung and there is a right lung. Lungs are not made of muscles.

13. Write the path of air during inhalation. 
Answer: Nostrils→ Trachea → Bronchi→ Lungs

III. During respiration
• When the lungs expand, air enters the lungs. 
• When the lungs contract, air goes out of the lungs. 
• The lungs are not made of muscles. So they cannot expand or contract on their own. 

Constructing a model of lungs
Cut a plastic bottle at its bottom and make a hole on its lid and insert a Y tube as shown in the picture. Tie two balloons on the arms of the Y-tube. Cover the open end of the bottle air-tight using a piece of balloon. You have constructed a model of the lungs. Now gently pull the middle part of the balloon strip downwards, then the balloons inside the bottle will expand.

14. Why do the two balloons inside the bottle expand when the tightly tied balloon is pulled downwards?
Answer: The space within the battle increases. So the pressure inside decreases. So air rushed from the outside into the balloons.

15. When the balloon strip is left free, the balloons Inside the bottle contract. Why? OR Why do the balloons in the bottle contract when the balloon is left free?
Answer: The space within the bottle was decreased. So the pressure in the bottle was increased. Then air rushed out.

16. What are the factors that help the expansion and contraction of the lungs?
• The muscular diaphragm at the bottom of the thoracic cavity.
• The muscles attached to the ribs. 

17. What is Diaphragm?
Answer: The diaphragm is a muscular layer that separates the thoracic and abdominal cavities.

Examine the Illustration
18. List the actions that take place during inhalation (inspiration).
Answer: 
• The diaphragm moves down.
• The volume of the thoracic cavity increases. 
• The pressure in the thoracic cavity decreases.
• Air enters the lungs.

19. List the actions that take place during exhalation (expiration).
Answer: 
• The diaphragm returns to its original position. (It lowers)
• The air pressure inside the thoracic cavity increases.
• Air is expelled from the lungs.

IV. Factors of inhaled and exhaled air
20. Analyse the table given below.
i. What are the components that vary in quantity in inhaled and exhaled air?
Answer: Oxygen, Carbon dioxide, Water vapour

ii. What are the components expelled through respiration?
ii. Which is the factor in the exhaled air that decreased when compared to the inhaled air? Why?
Answer: Oxygen. Oxygen that reaches the lungs is used for metabolic activities.

iii. Which factor in the exhaled air has increased when compared to the inhaled air? 
Answer: 
Carbon dioxide and water vapour.
They are formed during cellular respiration. 

iv. Which is the component whose volume did not change in the inhaled and exhaled air? 
Answer: Nitrogen. Nitrogen is not absorbed by the body. It is not formed during respiration.

Do the activities described in the textbook to know whether water vapour and carbon dioxide are present in the exhaled air.
Activity 1
Exhale air onto a mirror. Don't you see something like mist on the mirror? This is water vapour formed by the cooling of exhaled air on the mirror.

21. When exhaled air is directed onto a mirror, the surface of the mirror becomes misty. What is the reason?
Answer: Water vapour is formed during respiration. It came out through the exhaled air. It fell on the mirror and got stuck there. So the mirror became misty.

Activity 2
Fill two beakers up to half with clear lime water. Blow into one beaker with a straw. Pass atmospheric air repeatedly into the other beaker using a dropper.

22. Why did the clear lime water become milky when the air was blown into it?
Answer: When air was blown, it is exhaled air that comes out. The exhaled air contains carbon dioxide formed during respiration. It is this carbon dioxide that made lime water milky.

V. Diversity in respiration
23. Amphibians have two types of respiratory organs. How do they benefit from these? 
Answer: Amphibians live both on land and in water. When they are on land, they breathe using the lungs. When they are in water, they breathe using the skin. 

24. What is lime water?
Answer: Lime water is calcium hydroxide.

25. Which gas do plants breathe in? 
Answer: Plants breathe in oxygen.

26. We can say that plants send out both oxygen and carbon dioxide. Why?
Answer: When plants respite, they take in oxygen and release carbon dioxide. This carbon dioxide is used by plants for making food (photosynthesis). During photosynthesis, plants absorb carbon dioxide and release oxygen

Respiration in plants
Plants also take in oxygen from their surroundings and release carbon dioxide. This gaseous exchange occurs through minute pores in the leaves called stomata. The rate of respiration in plants is less when compared to animals.

27. What is respiration?
Answer: Respiration is the process by which organisms take in oxygen from the surroundings and release carbon dioxide.

VI. Inhaled air into the blood
28. What happens to the oxygen that reaches the lungs?
Answer: The oxygen mixes with the blood.

29. Where does blood carry this oxygen to? 
Answer: Blood carries oxygen to the cells.

30. Which gas does blood receive from cells? 
Answer: Carbon dioxide

31. What are the functions of blood?
Answer: 
• Blood carries oxygen to the cells.
• Blood carries carbon dioxide from the cells to the lungs.
• Blood carries the nutrients in the digested food to the cells.
• Carries urea from liver to kidneys.

32. Do all organisms have blood?
Answer: Some organisms have no blood.

33. Is the colour of blood in all organisms red?
Answer: No. The blood of some animals is colourless. 
eg: Cockroach

VII. In human blood
34. What is the colour of human blood? 
Answer: Red. 

35. Why is human blood red in colour?
Answer: It contains a red pigment called haemoglobin. So blood is red.

36. How does the transportation of food and other substances occur in insects?
Answer: The transportation of substances in insects takes place through the fluid-filled in their body cavities. Since haemoglobin is absent, it is not red in colour; nor does it have specific tubes to flow through. 

37. How does the transportation of substances occur in unicellular organisms?
Answer: There is no need for a separate mechanism to transport substances in unicellular organisms. The medium of transport is cytoplasm.

38. Which are the components of blood?
Answer: 
• Plasma - It is the fluid part of blood. Ninety per cent of it is water.
• Red blood cells
• White blood cells. There are five types.
• Platelets

39. Which organism has red sweat?
Answer: The hippopotamus

VIII. Blood circulation
40. What are the parts included in the blood circulatory system?
Answer: The blood circulatory system includes the heart, blood vessels and blood. 

41. What is called blood circulation?
Answer: Blood circulation is the flow of blood from the heart to all the parts of the body, and then from all the parts of the body to the heart. 

42. Which are the parts involved in blood circulation? 
Answer: 
• Heart
• Blood vessels 
• Blood

43. What are the types of blood vessels in the human body?
Answer: Three types, namely: 
• Arteries - Arteries, part of the circulatory system, are the blood vessels that bring oxygen-rich blood from the heart to all of the body’s cells. 
• Veins - Veins are blood vessels that carry blood towards the heart. 
• Capillaries - Capillaries are minute thin vessels that connect the Arteries and Veins

IX. The human heart
44. What are the peculiarities of the human heart?
Answer: 
• The heart is the centre of the blood circulatory system. 
• It is as big as one's fist.
• It is found in the thoracic cavity between the lungs, slightly towards the left side.
• There are ribs to protect the heart.
• A membrane called pericardium covers the heart. This is a double membrane.
• The human heart has four chambers.

45. Write down heart chambers present in different organisms?
Answer: 
i) earthworm- Five pairs of lateral heart
ii) fish- Two chambered heart
iii) reptiles- Three-chambered heart
iv) cockroach- Thirteen-chambered heart
vi) mammals- Four-chambered heart

X. Let's make a stethoscope
46. What is a stethoscope?
Answer: The stethoscope is a device used to know heartbeat. It was first made by the scientist Rene Laennec.

Improvise a stethoscope according to the description given in the textbook.
A model is given below. 
Materials needed
• Y tube 
• Funnel 
• Rubber (Plastic) Tube 
• Balloon strip
Procedure
Attach two pieces of the tube to the V-shaped arms of the Y tube.
Attach another piece of tube to the tail of the funnel. Fix the other end of this tube to the free arm of the Y tube. Fix the balloon strip to the mouth of the funnel so that the strip is tight. This acts as the diaphragm. Now the stethoscope is ready. Measure the heartbeat rate of your friends and record It.

XI. Health of heart and food habits
47. What are the measures to be practised to maintain the health of the heart?
Answer: 
Things to be taken care of to keep the heart healthy
• Avoid using too much salt. 
• Avoid smoking and drinking.
• Balanced diet
• Avoid fatty foods.
• Do exercise regularly. 

48. What are the important causes of heart disease?
Answer: 
• Improper diet
• Lack of exercise
• Smoking
• Drinking
• Continuous use of certain medicines
• Hypertension
• Diabetes
• Heredity

49. What do you have to say to those who ruin their health through unhealthy lifestyles? Prepare a poster and exhibit it in your class.
50. What first aid is to be given when a person has received a wound?
Answer: 
• Clean the wound with pure water.
• Press and hold the wound tightly.
• If the wound is on the hand, lift the hand up.
• If the blood flow does not stop, cover the wound with a clean cloth or bandage.
• Provide medical assistance, if needed.

Let us Assess
1. Which of the following is not a part of the breathing process?
a. Air pressure in the lungs increases
b. Air sacs expand
c. The diaphragm lowers
d. The thorax contracts
Answer: d. The thorax contracts

2. Which of the following is done first while giving first aid to a person whose trachea gets blocked?
a. Give water to drink
b. Sprinkle water on the face
c. Make him/her sit on a chair
d. Remove the block
Answer: d. Remove the block

3. Arrange in order the illustration of the parts of the human respiratory system.
Answer: Nostrils→ Trachea → Bronchi→ Lungs





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