Because of its fur's color. As in its name, brown bear's fur's are brown. Their fur being brown, makes it easier for them to be spotted in snow. So their prey will see them easily and will have higher chance to escape. Thats the reason its difficult for them to hunt in snow.
Poisning by 2-deoxyglucose syops the glycolysis process which leads to cardiovascular and respiratory symptoms. Due to property of inhibiting the enzyme reqquired for glycolysis, glucokinase. So, there is no ATP production takes place.
