CBSE Class 10 Science 2019 · Paper 31/5/1 · Question 9(b)

(a) National parks conserve wildlife in its natural habitat. Human interference (grazing, felling trees, construction, heavy tourism) creates disturbances in the protected area and upsets its ecological balance; left in their pristine form, the parks remain self-sustaining and their biodiversity is preserved. (b) Recycling uses some energy, because the material has to be collected, transported and processed (for example melted or pulped) to make a new object. In reuse, the same object is used again and again as it is, for example refilling bottles or jars, so little or no energy is spent. Hence reuse is better than recycling.