Why is the Calvin cycle considered a dark reaction? It occurs only at night.
It requires an absence of light.
It turns the plant dark green.
It can proceed in the dark.

The Calvin cycle is a dark reaction because it requires an absence of light.

Explanation:

desert perennials often survive by remaining dormant during dry periods of the year, then springing to life when water becomes available. most annual desert plants germinate only after heavy seasonal rain, then complete their reproductive cycle very quickly.

a covalent bond, specfically triple bond