Worksheets › Class 11 › Environment and Sustainable Development › Cheat sheet
Class 11 Environment and Sustainable Development: cheat sheet
CBSE Social Science. What the environment does for us, carrying and absorptive capacity, global warming and ozone depletion, sustainable development and the strategies for it.
Key ideas
- The environment supplies resources, assimilates waste, sustains life through biodiversity and gives aesthetic services.
- Carrying capacity holds when extraction stays below regeneration and wastes stay within the absorptive capacity.
- Renewable resources (forests, fish, sun, wind) are not used up if managed; non-renewable ones (coal, petroleum) are exhausted by use.
- Global warming comes from more greenhouse gases; ozone depletion comes from CFCs and halons and lets in ultraviolet rays.
- Sustainable development meets present needs without harming the ability of future generations to meet theirs.
- Strategies include LPG and gobar gas in villages, CNG in cities, wind and solar power, mini-hydel plants, traditional knowledge, biocomposting and biopest control.
Remember
| Sustainable yearly cut | regrowth % × stock ÷ 100 |
| Stock after a year | stock + regrowth − amount cut |
| Within absorptive capacity | number of polluters = capacity ÷ waste each (round down) |
| After a rise since a base year | base × (100 + rise %) ÷ 100 |
| Output of panels | panels × units each a day × days |
| Key years | CPCB 1974; Appiko movement 1983; Kyoto 1997; SDGs set 2015, to be met by 2030 |
Watch out
- Rounding up the number of factories a lake can support: only whole factories within the limit count.
- Calling coal or petroleum renewable.
- Mixing up carrying capacity with absorptive capacity (absorbing waste is only one part).
Worked example
A forest has 150,000 trees and regrows 10% of the starting stock each year. (a) What is the sustainable yearly cut? (b) If 27,300 trees are cut each year instead, how many are lost each year? (c) After 5 such years, how many trees are left (taking regrowth as fixed)? (d) Which rule of sustainable development is broken?
Working: 10% of 150,000; 27,300 − 15,000; 150,000 − 5 × 12,300
Answer: (a) 15,000 (b) 12,300 (c) 88,500 (d) renewable resources must not be extracted faster than they regenerate
Practise Environment and Sustainable Development
Revise with this page, then practise: every Environment and Sustainable Development sheet in the app is new, with an answer key and working.
Coming soon for Android and iPhone.