Q17. What are called external parts of the body?
Ans. The parts of the body that can be seen are called the external parts of the body.
Q18. What is organ system?
Ans. The group of organs that perform a specific function is called the organ system.
Q19. Who tells the body parts what to do?
Ans. Our brain collects information from our surroundings and then tells the body parts to move.
Q20. What are the functions of tongue?
Ans. The tongue helps to taste things. It also helps to rotate the food in the mouth and mix it well the saliva.
Q21. Name the organs of the excretory system.
What are the main organs of the excretory system?
Ans. The main organs of the excretory system are kidneys, ureters, urinary bladder and urethra.
Q22. What would happen if digestive system did not work properly?
Ans. If digestive system will not work properly then absorption of nutrients will not occur and the body will be devoid of nutrient and energy.
Q23. Write the work performed by the brain.
Ans. The brain controls our thoughts, memory and speech, movement of the arms and legs, and the function of many organs within our body.
Q24. Write the function of arteries.
Ans. Arteries are the blood vessels that carry the oxygenated blood (oxygen rich blood) from the heart to the different parts of the body.
Q25. Write the function of veins.
Ans. Veins are the blood vessels that carry the deoxygenated blood (blood with less oxygen and more carbon dioxide) to the heart.
Q26. What is the first stage of digestion?
Where does the process of digestion starts? Describe briefly.
Ans. The process of digestion starts in the mouth. When we chew food, the teeth break the food into small pieces and mix it with the saliva in our mouth. This is the first step of digestion.
Q27. What is the main function of lungs?
Ans. The main function of the lungs is the process of gas exchange called respiration (or breathing). In respiration, oxygen from incoming air enters the blood, and carbon dioxide, a waste gas, leaves the blood.
Q28. What is the function of mucus and fine hair in nostrils?
Ans. We breathe in and breathe out air from our nose. The hair in our nose cleans the air before letting it in. There is a sticky substance called mucus, secreted inside the nose, which prevents dust and germs from getting into the lungs.
Q29. How digestion takes place in stomach?
How does stomach help in the digestion of food?
How is food digested in the stomach?
Ans. The stomach is like a muscular bag. The food gets churned into a fine paste in the stomach. The stomach wall then releases digestive juices that mix well with the food. These juices break down the proteins in the food.