Sunday 30 June 2013

Hydrophytes , Mesophytes and Xerophytes all have specialised adaptations which allow them to maintain water balance in different environments for their survival . Hydrophytes for example have specialised adaptations to maintain water balance to survive in a water rich environment , whereas xerophytes have specialised adaptations to maintain water balance in order to survive in an environment with a lack of water .

LEAVES:

Hydrophytes , Mesophytes and Xerophytes all have leaves which contain stomata and a waxy cuticle . Hydrophytes that are fully submerged have no stomata or waxy cuticle as these are not required , instead stomata and the waxy cuticle are found on floating parts of the leaf , by having stomata and the waxy cuticle on the floating part of the leaves it allows efficient gas exchange and prevents excess transpiration on very hot days , so hydrophytes can successfully maintain a water balance that is optimum for successful photosynthesis and respiration . In contrast xerophytes have a very thick waxy cuticle and few stomata , by having few stomata and thick waxy cuticle xerophytes are able to slow the rate of transpiration and to reflect light therefore keeping the plant cool , this allows xerophytes to maintain a water balance that is optimum for successful photosynthesis and respiration . Mesophytes also have stomata and a waxy cuticle on both the lower and upper epidermis to prevent excess transpiration on hot days or in wind , the stomata are located on the lower epidermis which is cool , so therefore reduces transpiration , this allows mesophytes to maintain a water balance that is optimum for successful photosynthesis and respiration .

Both mesophytes and xerophytes both lose their leaves in extreme weather conditions . Mesophytes that experience to snow or extremely cold weather , lose all their leaves and become dormant when exposed to these conditions , by losing their leaves and becoming dormant, mesophytes reduce the rate of transpiration , photosynthesis and respiration , this allows them to maintain a water balance at which they can survive and are therefore able to survive in periods extreme cold / snow . Xerophytes however lose their leaves and become dormant in periods of extreme heat or dry , such as droughts , by losing their leaves and becoming dormant, xerophytes are able to reduce the rate of transpiration , photosynthesis and respiration , this allows them to also maintain a water balance at which they can survive and are therefore able to survive in periods or extreme heat / dry .

CELLS:
Hydrophytes , Mesophytes and Xerophytes all have specialised tissue , which has different adaptations to allow photosynthesis and respiration to be carried out . Hydrophytes and Mesophytes both have air spaces around their leaf cells , by having very large air spaces around their leaf cells , hydrophytes aid the buoyancy of the leaves , so are able to get closer to the surface for photosynthesis , this also facilitates the diffusion of minerals and gases , and are therefore able to maintain water balance optimum for successful photosynthesis and respiration . By having air space around their leaf cells , mesophytes allow light to be reflected from spongy mesophyll , up to the palisade layer where it can be absorbed and used for photosynthesis . In comparison xerophytes , such as succulents have special tissue which store water , by having tissue which store water xeropyhtes are able to maintain a water balance which is optimum for successful photosynthesis and respiration , as the stored water can be used in droughts or when there is no moisture in the soil or air .

ROOTS:
Hydrophytes and Xerophytes both have roots which are specifically adapted to the environments in which these plant live . Hydrophytes usually have small roots , as minerals and gases that are needed for photosynthesis and respiration are dissolved in surrounding water and diffused directly in the leaves , so therefore roots are only needed for anchorage and stability , by having small roots hydrophytes are able to maintain a water balance which is optimum for successful photsynthesis and respiration , as the roots are not needed for diffusion of minerals and gases therefore they don't absorb water as this is in excess . In comparison to many xerophytes which have very deep root systems , which are able to absorb water deep in soil/sand , by having deep root systems xerophytes are to
absorb all available water and are therefore able to maintain a water balance which is optimum for successful photosynthesis and respiration . Cacti which are xerophytes have very shallow root systems , which absorb water in the top layers of soil / sand , by having shallow roots cacti are able to also absorb most available water , and are therefore able to maintain a water balance which is optimum for successful photosynthesis and respiration.















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