Answer:
1. B. carbon dioxide taken in from the surrounding air
2. A. Root
Step-by-step explanation:
Sugar beet plant carries out photosynthesis and stores the excess of the sucrose in its taproots. During the process of photosynthesis, the plant absorbs CO2 from the air, water from the soil and synthesizes organic sugars in the presence of sunlight.
Atmospheric CO2 contributes carbon and oxygen atoms to the formed sugars which in turn are stored in plant parts. Therefore, atmospheric CO2 makes most of the mass of the photosynthesizing plants such as sugar beets. The taproots of beet plants are modified into storage roots to store the excess of the organic sugars.