Higher Biology Answer

Hi,

I have just completed my first Higher Biology Essay and would like to know whether it covers all aspects of the question and whether the format and information is correct.

The question is -

By means of 2 examples, show how the differences between the structure of cells in different tissues are related to the different functions of these tissues.

If there is anything wrong or missing from the essay please can you identify where, and what has to be fixed because I really want to make sure it is correct, because I think it is a difficult essay.

Here is what I have-

A tissue is a group of cells specialised to perform a particular function or functions. When one tissue is compared to another, for example phloem compared to xylem, variation in cell structure becomes clear.

Structural variation in realtion to function exists as each cells structure is exactly tailored to suit its function. When a new cell has been formed by cell division, it becomes specialised by undergoing physical and chemical changes until its size and shape are suited to its future role in a particular tissue.

The end walls of the cells belonging to a sieve tube are perforated to allow the cytoplasmic strands move from one cell to another carrying food. These are called sieve plates. The function of the sieve tube is to transport soluble carbohydrates.

This structure is related to the specialist features of the xylem tracheid, which is a hollow spindle-shaped cell, whose ends overlap. The tracheid cell is also composed of lignified walls. This gives structural support to the plant.

The companion cells contain a large nucleus , which controls the movement of soluble carbohydrates down the sieve tube. This structure is related to the specialised features of the xylem vessels. They are long, hollow tubes that allow water to easily move up through the plant. These hollow tubes are strengthened by rings or spirals of lignin that helps to support the plant.

Thanks for any help.