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

GAS EXCHANGE IN DICOT PLANTS In order to carry on photosynthesis, plant need a supply of carbon dioxide and also a means of disposing

Extracts from this document...

Introduction

DERRICK OKRAH GAS EXCHANGE IN DICOT PLANTS In order to carry on photosynthesis, plant need a supply of carbon dioxide and also a means of disposing oxygen. Again in other to carry on cellular respiration, plant cells need oxygen and a means of disposition carbon dioxide. Unlike animals, plants have no specialized organs for gas exchange. There are several reasons they can get along without them. REASONS Each part of the plant takes care of its own gas exchange needs. Although plants have an elaborate liquid transport system, it does not participate in gas transport. Roots, stems, and leaves respire at rates much lower than are characteristic of animals. Only during photosynthesis are large volumes of gases exchanged and each leaf is well adapted to take care of its own needs. ...read more.

Middle

The loose packing of parenchyma cells in leaves, stems, and roots provides an interconnecting system of air spaces. Gases diffuse through air several thousand times faster than through water. Once oxygen and carbon dioxide reach the network of intercellular air spaces (arrows), they diffuse rapidly through them. Oxygen and carbon dioxide also pass through the cell wall and plasma membrane of the cell by diffusion. The diffusion of carbon dioxide may be aided by aquaporin channels inserted in the plasma membrane All plant cells respire all the time, and when illuminated plant cells containing chloroplasts also photosynthesise, so plants also need to exchange gases. The main gas exchange surfaces in plants are the spongy mesophyll cells in the leaves. ...read more.

Conclusion

In addition, during the hours of daylight photosynthesis increases the oxygen concentration in the sub-stomatal air space, and decreases the carbon dioxide concentration. This increases the concentration gradients for these gases, increasing diffusion rate. The palisade mesophyll cells are adapted for photosynthesis. They have a thin cytoplasm densely packed with chloroplasts, which can move around the cell on the cytoskeleton to regions of greatest light intensity. The palisade cells are closely packed together in rows to maximise light collection, and in plants adapted to low light intensity there may be two rows of palisade cells. The spongy mesophyll cells are adapted for gas exchange. They are loosely-packed with unusually large intercellular air spaces where gases can collect and mix. They have fewer chloroplasts than palisade cells, so do less photosynthesis. ...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. Gaseous Exchange and Ventilation.

    Breathing is called expiration. The volumes in the lungs decrease. The intercostal muscles relax. The ribcage moves downwards. The diaphragm relaxes and moves upwards. The volume in the thorax decrease. The pressure in the thorax is less than in the lungs.

  2. Animal / Plant Gas Exchange.

    Every life has to breathe, or respire. Here are the basic steps of respiration: * an animal breathes in or inhales air into the lungs * oxygen in the air is transferred to the blood * blood carries (circulates) the oxygen to every cell in the animal.

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