Do biological systems contradict the second law of thermodynamics? by taking energy from their surroundings and synthesizing large, complex biological molecules, plants and animals tend to concentrate energy, not disperse it.

Biological systems do not contradict the second law of thermodynamics. Even in this case, entropy is still always increasing. Biological systems can only decrease their own entropy by using copious amounts of energy and by increasing entropy in their surrounding environment. Also, unfavorable anabolism reactions are always paired with more favorable reactions, such as the use of ATP in order to make the overall Gibb's free energy of the reaction negative.