• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

The general structure of a leaf is built to do specific, needed functions.

Extracts from this document...

Introduction

LEAF SRTUCTURE The general structure of a leaf is built to do specific, needed functions. However the main function for most leaves is ultimately photosynthesis. Other functions include: water storage/regulation; gaseous exchange; protection (for example - spikes on cacti); and trapping food in some cases (for example Venus flytraps). The annotated diagram I have drawn below shows an example of the main structures inside a dicot leaf: This shows the structure of a general dicot leaf. The xylem and phloem are shown - indicating where the vein (vascular bundle - xylem vessels) is in the leaf cross section. Throughout the leaf the veins branch a lot to distribute water and minerals and therefore the minerals (mainly magnesium and iron) needed for chlorophyll are taken directly and easily fast the palisade mesophyll and therefore each chloroplast can receive the necessary minerals without difficulty. Also nitrogen compounds needed for protein synthesis are brought through minerals transferred by the same process of diffusion through the mesophylls. ...read more.

Middle

The advantages of the waxy cuticle are mainly to reduce water loss through transpiration but also to provide a small barrier against water-borne infections/diseases and also to stop damage from rain drops in some 'heavy rain' areas. There are no disadvantages of the waxy cuticle that I can see that affects the plant itself. As the plant must be able to control this water exchange the plant has evolved stomatal pores. There are shown on the diagram as stoma, openings in the leaf controlled by 'doors' called guard cells. The stoma also control gaseous exchange in the leaf. The plant needs CO2 for respiration and it needs a way of getting rid of the waste product from respiration, O2. This is all controlled by the guard cells which open and close at specific times during the day to regulate all effecting factors of the plant. Below is a diagram taken from www.emc.maricopa.edu that shows simple diagram of a stomatal pore. ...read more.

Conclusion

This then creates a very big problem for the plant, as it is not producing enough 'food' for the plant to survive upon. The plant usually gets round this problem by terminating the leaf and only using the fully functional leaves until the plant can grow a replacement. The epidermal cells themselves act as a barrier. They are mainly to defend the inner tissues from, in some cases herbivores, dehydration or pathogens. The layers are both on the top and bottom of every leaf and are usually one cell thick. These cells do not have chloroplasts, which would seem a reasonable idea for the plant to think about. A secondary function of the epidermal cells is to produce and replace the waxy cuticle in areas, which it may wear thin or get destroyed for one reason or another. It can also produce the waxy cuticle to different thicknesses, which would be sensible in hotter, drier climates and therefore, in theory, reduce loss of water by transpiration to a greater extent. However this may not always be possible in the cases of extremely hot climates, such as deserts. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Green Plants as Organisms section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Green Plants as Organisms essays

  1. Find out where the stomata are located, on the upper or lower epidermis of ...

    Safety: Safety goggles were worn when looking down the microscope, to prevent serious accidents in case someone is pushed. Apparatus: Nail Varnish Sticky tape Leaves 2 Glass slides Microscope Method: The method was carried out on the following leaves : Grape Ivy: This plant originates from South Africa and is a climbing plant.

  2. Experiment to Compare Stomata Density in Different Dicotyledonous

    I also predict that the stomata density will decrease in the upper epidermis due to the waxy cuticle and the increased water loss due to sun exposure (and thus increased heat exposure), through transpiration here. After looking at different plants you would expect most of then to be well adapted

  1. Compare stomatal densities of the upper and lower epidermis of a leaf.

    This can be investigated by means of a perometer, an instrument for measuring the resistance to the flow of air through a leaf. If you attach a perometer to a leaf and take measurements of its resistance to airflow at intervals, you will find that there is a generally less resistance during daylight hours than at night.

  2. Absorption Spectrum of Chlorophyll.

    However, running conditions greatly affect Rf values. Instead, a reference compound should relate the positions of the experimental compound with others. Mobility of individual pigments is affected by the degree of saturation of the tank with solvent, the type of paper used, whether it is equilibrated with the solvent, and the amount of pigment applied (Goodwin, 1965).

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work