What would happen if phytoplankton of an ocean is completely destroyed for some reason? 1. The ocean as a carbon sink would be adversely affected. 2. The food chains in the ocean would be adversely affected. 3. The density of ocean water would drastically decrease. Select the correct answer using the codes given below:

Phytoplankton are microscopic marine algae that form the base of the ocean food web and play a critical role in global biogeochemical cycles.

1. The ocean as a carbon sink would be adversely affected. This is correct. Phytoplankton perform photosynthesis, absorbing vast amounts of carbon dioxide from the atmosphere and surface waters. They are a major component of the biological pump, which sequesters carbon into the deep ocean. Their destruction would significantly reduce the ocean's capacity to absorb and store carbon, thus adversely affecting its role as a carbon sink.

2. The food chains in the ocean would be adversely affected. This is correct. Phytoplankton are the primary producers in most marine ecosystems. They are consumed by zooplankton, which in turn are consumed by larger organisms like fish, and so on. Their complete destruction would remove the foundation of the marine food web, leading to the collapse of nearly all ocean food chains.

3. The density of ocean water would drastically decrease. This is incorrect. Ocean water density is primarily determined by temperature and salinity. While phytoplankton contribute to the overall biomass in the water, their mass is negligible compared to the vast volume and mass of ocean water. Their destruction would not cause a drastic or even significant change in the overall density of ocean water.

Therefore, statements 1 and 2 are correct.