Life processes such as nutrition, respiration, transportation, excretion, etc. are essential for maintaining life.
Alveoli provide a surface for the exchange of gases. An extensive network of blood vessels is present in the wall of the alveoli. By lifting our ribs and flatten the diaphragm, the chest cavity becomes spacious. Air is sucked into the lungs and alveoli. The oxygen from the breath, diffuses into the blood and CO2 from the blood brought from the body, diffuses out into the air.
|(a) Trypsin||(i) Pancreas|
|(b) Amylase||(ii) Liver|
|(c) Bile||(iii) Gastric glands|
|(d) Pepsin||(iv) Saliva|
Ans. (a)- i (b)- iv (c)- ii (d)- iii
An organism uses outside raw materials mostly in the form of food and oxygen. The raw materials required by an organism can be quite varied depending on the complexity of the organism and its environment.
The role of saliva in the digestion of food:
→ It moistens the food for easy swallowing.
→ It contains a digestive enzyme called salivary amylase, which breaks down starch into sugar.
Leaves of a healthy potted plant were coated with vaseline. Will this plant remain healthy for long? Give reasons for your answer.
If leaves of a healthy potted plant are coated with Vaseline, it will clog the stomatal pores on leaves. Blockage of stomata will stop transpiration and exchange of gases from leaves. Transpiration plays an important role in ascent of sap in plants. Hence, lack of transpiration will stop ascent of sap. Moreover, stoppage of exchange of gases would also stop respiration and photosynthesis in leaves. This will result in death of leaves and finally the plant would die due to lack of food.