Answer
The tendency of silicon atom to form more bonds is less when compared to carbon.
Work Step by Step
Step 1:
Carbon and silicon belong to same group IV, so they can have similar properties, carbon belongs to period 2, and silicon belongs to period 3. The size of silicon is large when compared to carbon. There is an empty d orbital which screens the valence orbital from the nucleus. Hence the tendency of silicon atom to form more bonds is less when compared to carbon.
Step 2: Silicon has valance electrons in its 3rd energy level. The bonds formed by silicon will be weaker than those formed by carbon. Hence, it cannot form long polymers. Moreover, when silicon bonds with oxygen, the interaction is so strong that it is very difficult to split. SiO2 exists as a solid and not as a gas. Thus, it cannot support photosynthesis either.
