What would happen to plants and animals on Earth if the biogeochemical cycles were disrupted and stopped? Explain by giving a few examples. [Pg. No. 265]

Biogeochemical cycles, such as the carbon cycle, oxygen cycle, nitrogen cycle, and water cycle, are essential for maintaining life on Earth. These cycles continuously recycle important substances between living organisms and the environment. If these cycles were disrupted or stopped for a long time, plants and animals would not be able to survive.
The consequences of disruption of biogeochemical cycles for plants and animals on planet Earth are as follows:
(1) Disruption of water cycle: If the water cycle stopped, rainfall would decrease and water would not be regularly returned to land. Plants would not get enough water for photosynthesis and growth, and animals would face a shortage of drinking water.
(2) Disruption of carbon cycle: If the carbon cycle were disturbed, the balance of carbon dioxide in the atmosphere would be affected. Plants need carbon dioxide for photosynthesis, so less availability or imbalance of $\mathrm{CO}_{2}$ would affect food production in plants and disturb food chains.
(3) Disruption of oxygen cycle: If the oxygen cycle stopped, oxygen would not be replenished properly in the atmosphere and water bodies. Animals and many other organisms would not get enough oxygen for respiration.
(4) Disruption of nitrogen cycle: If the nitrogen cycle stopped, plants would not receive usable nitrogen compounds such as nitrates. As a result, they would not be able to make enough proteins, leading to poor growth. This would also affect herbivores and then carnivores.
(5) Effect on ecosystems: Since plants form the base of most food chains, any disturbance in these cycles would reduce plant growth, disturb animal populations, and damage the balance of ecosystems.
Thus, biogeochemical cycles are necessary because they maintain the continuous supply and recycling of essential materials required for life.