Do past year papers. Especialy if it's from midyear or prelims.
I did my school past year midyear paper 2005 2006 and 2007 and
during my bio exam 2 days ago, 2-3 open ended and one structure
essay was similar.
Also, work on answering technique. If for example they ask for "how
does a plant support itself." (4marks)
you will have to cover 2 main reasons why cause it's 4 marks. 2
marks for each point.
The cell wall(impt words) of the xylem thicken with ligin as
they mature, help as structural support, prevent plant from
collasping.
-Turgid cells. This is because there is a higher h2o potential
and hence water will enter the cells by osmosis. The plant cells
will therefore be turgid and be erect and upright. This helps the
plant support itselves, especially in young plants as they need to
grow upwards and be upright so as to recieve maximum sunlight for
photosynthesis.
You have to kinda throw all u know inside the essay Q. this is
so that the teacher cannot - 0.5 marks so u can get the full 4
marks (:
All the best!