GSEB Solutions for Class 7 Science and Technology – Digestive System, Respiratory System and Circulatory System (English Medium)
GSEB SolutionsMathsScience
Exercise 79:
Solution 1(a):
Yes, the colour of the bread turns blue-black because of the presence of starch.
Solution 1(b):
The colour of the chewed bread turns into brown as the starch in the bread converts into sugar.
Exercise 83:
Solution 1(a):
Pulse is due to the expansion of an artery caused by the ejection of blood into the arterial system by the contractions of the heart.
Exercise 86:
Solution 1:
- Human Respiratory System
Sr.No. | Part of the system | Function |
1 | Nose | Contains mucus and hair that prevent entry of microorganisms by filtering the air. |
2 | Trachea | Transports the air a person breathes in through his nose or mouth, into the lungs. |
3 | Bronchus | Allow the passage of air and prevention of infection by preventing pathogens from going further into the lungs. |
4 | Lung | Receives air (oxygen) from the atmosphere through the nose and mouth with every inhale, and allows the transfer of oxygen to pass into the blood stream. |
- Human Digestive System
Sr.No. | Part of the system | Function |
1 | Mouth | With the help of teeth and tongue, salivary glands secrete saliva that contains ptyalin which digests starch and converts it into simple sugar. |
2 | Oesophagus | Transports food from the mouth to the stomach. |
3 | Stomach | Mixes the food with stomach acid to break it down and digests it and also uses pepsin to break down proteins in our food. |
4 | Small intestine | Responsible for absorbing most of the nutrients found within our food. It digests all types of food (carbohydrates, proteins, and fats) with the help of pancreatic juices. The duodenum absorbs the nutrients from the digested food and transfers them into the blood stream. |
5 | Large intestine | Reabsorb water and maintain the fluid balance of the body. Stool, or waste left over from the digestive process, is passed through the large intestine first in a liquid state and ultimately in a solid form. |
6 | Rectum | Act as a temporary storage site for faecalmatter before it is eliminated from the body through the anal canal. |
7 | Anus | Passage of waste out of the body that controls the expulsion of feces. |
- Circulatory System
Sr. No. | Function |
1 | Blood is poured to the right atrium. |
2 | Oxygenated blood is poured in the left atrium. |
3 | Blood moves to the right ventricle due to contraction of the right atrium and the opening of the tricuspid valve. |
4 | Blood moves to the left ventricle due to contraction of the left atrium and the opening of the bicuspid valve. |
5 | Blood moves to the lungs. |
6 | Blood moves to different organs of the body due to contraction of left ventricle. |