The transition zone between two ecosystems or vegetational regions is termed as:

In which of the following ecosystems is the sun not the primary source of energy?

Phytoplankton $\rightarrow$ Submerged plant stage $\rightarrow$ Floating plant stage $\rightarrow$ Reed-swamp stage $\rightarrow$ Marsh-meadow stage $\rightarrow$ Scrub $\rightarrow$ Forest. What type of succession does this sequence represent?

$A$ sedimentary cycle that also has a small gaseous component is found in

In which of the following,both pairs have the correct combination?

The total quantity of global carbon is distributed such that $1\%$ is carbon in the atmosphere and $71\%$ is carbon dissolved in the oceans.