Question

If thylakoids are removed and kept in culture medium having C$O_2$ and H${}_{2}O$ and exposed to light; they cannot form hexose sugars as end products because

• A. Light trapping device is absent.
• B. Pigments P-700 and P-680 are not linked.
• C. CO${}_2$ assimilating enzymes are absent.
• D. CO${}_2$ assimilation cannot occur in light.

Answer 1

The correct option is C CO${}_2$ assimilating enzymes are absent.

Photosynthesis is the synthesis of carbohydrates from water and CO${}_2$. Photosynthesis is divided into 2 parts. Light and dark reactions. Light reactions occur in thylakoids. Light reactions need light to produce organic energy molecules (ATP and NADPH). Dark reactions make use of these organic energy molecules (ATP and NADPH). This reaction cycle is also called Calvin Benison Cycle, and it occurs in the stroma. ATP provides the energy, while NADPH provides the electrons required to fix the CO${}_2$ (carbon dioxide) into carbohydrates. If thylakoids are removed and kept in culture medium having CO${}_2$ and H${}_2$O and exposed to light; they cannot form hexose sugars as end products because enzymes required for dark reactions are absent here which are present in stroma. Thus, option C is correct.