Why do you think the branches are found only on one third of the trunks?
So that the leaves can compete with other trees to obtain the most sunlight from the highest point.

What do you notice about the undergrowth? Suggest reasons why.
The undergrowth is quite dense as there are many gaps inbetween the canopy layer which allows sunlight to reach the undergrowth.

DO YOU THUNK TEMASEK FOREST IS A PRIMARY FOREST OR SECONDARY FOREST? WHY? You are to cite evidences based on your observations.
It's a secondary forest because the forest is not dense. There is no clear interlocking canopy layer. Undergrowth is dense.