Question

the calvin cycle and the krebs cycle are referred to as cycles of chemical reactions because they
occur inside organelles.
start over continually.
are part of the carbon cycle.
allow energy to flow in ecosystems.

Explanation:

The Calvin cycle (in photosynthesis) and the Krebs cycle (in cellular respiration) are cyclic. In the Calvin cycle, RuBP (ribulose - 1,5 - bisphosphate) is regenerated to continue the carbon - fixation process. In the Krebs cycle, oxaloacetate is regenerated to accept an acetyl - CoA molecule and start the cycle again. So, they are called cycles because they start over continually.

Answer:

start over continually.