Life Processes in Living Organisms — Science STD 9 — Question

• The digestive system is responsible for digestion of food. i.e. breaking down complex insoluble food into simpler soluble form.
• The digestive system is made up of alimentary canal and digestive glands.
• The alimentary canal is a long and muscular tube of varying diameter which extends from the mouth to the anus.
• The digestive glands associated with alimentary canal are salivary glands, gastric glands, liver and pancreas.
• The process of digestion includes various stages wherein the food passes through the different organs of the alimentary canal and there it is digested part by part with the help of various enzymes secreted from the digestive glands.
• After the food is digested, the important nutrients are absorbed into the blood and the undigested food and residue of digested food is removed out of the body through the anus.

(b) Respiratory system:

• Respiration is the process of release of energy from the assimilated food.
• The respiratory system consists of nose, pharynx, larynx, trachea, bronchi and lungs (alveoli).
• Oxygen enters our body through breathing.
• This oxygen is taken to the cells and with the help of oxygen, food is oxidized into the cells to release energy in the form of ATR
• During this process, carbon dioxide and water vapour are given out as by-products which are given out during breathing.

Thus, the digestive and respiratory systems work in co-ordination with each other to produce energy from food.