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www.GOALias.blogspot.comBoojho has seen in televisionprogrammes that whales anddolphins often come up to thewater surface. They even releasea fountain of water sometimeswhile moving upwards. Why dothey do so?dioxide. In the cells oxygen is used tobreak down glucose into carbon dioxideand water as in other organisms. Inplants each part can independently takein oxygen from the air and give outcarbon dioxide. You have already learntin Chapter 1 that the leaves of the plantshave tiny pores called stomata forexchange of oxygen and carbon dioxide.10.6 B10.6 BREATHINGUNDER WATERCan we survive in water? There are manyorganisms which live in water. How dothey breathe under water?You have studied in Class VI thatgills in fish help them to use oxygendissolved in water. Gills are projectionsof the skin. You may wonder how gillshelp in breathing. Gills are well suppliedwith blood vessels (Fig. 10.10) forexchange of gases.GillsPaheli wants to know whetherroots, which are undergroundalso take in oxygen? If so, how?Like all other living cells of theplants, the root cells also needoxygen to generate energy. Roots takeup air from the air spaces presentbetween the soil particles (Fig. 10.11).Soil particlesRoot hair10.7Fig. 10.10 Breathing organs in fish10.7 DO PLANTSALSO RESPIREESPIRE?Like other living organisms, plants alsorespire for their survival as you havelearnt in Class VI. They also take inoxygen from the air and give out carbonAir spaceFig. 10.11 Roots absorb air from the soil116SCIENCE