1. Alteration or destruction of the physical habitat.
2. Stratospheric ozone depletion.
3. Chemical pollution of water and air.
4. Global climate change resulting from a variety of human activities.

Answer: (1) Alteration or destruction of the physical habitat

1. Are nutrient-poor environments.
2. Are nutrient-rich environments.
3. Are rich in silica and iron.
4. Contain unlimited nitrogen.

Answer: (1) Are nutrient-poor environments

1. Standing crop.
2. Trophic efficiency.
3. Net primary productivity.
4. Gross primary productivity.

Answer: (1) Standing crop

The fundamental difference between materials and energy is that