Why is replication called "semi-conservative"?

Which of the following systems in absorbing oxygen and releases carbon dioxide

Ecosystems involve living organisms interacting with non-living things in a productive way; how is photosynthesis an example of this? answer, i will give brainiest to first person to get it right.

The first three phases of the cell cycle are collectively known as (1 point) play audio cellular respiration. telophase. mitosis. interphase.