Explain the effect enzymes have on chemical reactions

Enzymes decrease the activation energy, Enzymes increase the rate of the reaction, Enzymes provide a site where reactants can be brought together.

Enzymes are like catalysts which enhance the rate of reaction by lowering the activation energy.

All the biochemical reactions are slow because of transition state barriers. These transition state barriers are an intermediate state before the formation of products. Transition state is a high energy state and it requires a lot of energy to cross this state but we can not produce this much energy in our body. That is why an enzyme is must to catalyze any bio-chemical reaction because enzyme provides an alternate pathway which requires very low energy to proceed.

Enzymes have certain active sites wherein substrates fit in and interact with each other with the help of their functional groups and interaction of these substrates subsequently leads to product formation.

phylogenetic tree is the tree of life or evolution tree. it shows the different branches of evolution. the sequence goes like tissues - coelom - backbone - endoskeleton - segmentation

ya the other dude is right