Mesophytes:
mesophytes:Mesophytes are plants that are adapted to living in temperate places (like New Zealand) where there is usually not really high or low temperatures or too dry or wet. This causes mesophytes to have adaptations for both maintaining water balance and getting enough light. Mesophyte adaptations which help them to maintain water balance fall into three categories; Stomata adaptations, stem and leaf adaptations and root adaptations. This is because they live in places that usually don’t have a shortage of raw materials such as water and light. They need water in order to carry out life processes and to grow so that they can create their own food and also be a shelter for other organisms in their habitat. Water for mesophytes is also needed for temperature control to keep the plants cool so that the enzymes don’t denature and they can carry out processes. (Roberts, 2011)(Jones, 2015)(Class Notes,2015)(Wikipedia, 2015)
What affects the rate of transpiration in mesophytes?All five factors affect the rate of transpiration in mesophytes. Humidity affects the rate of transpiration as mesophytes live in temperate zones where it is not too wet or too dry resulting in it sometimes it being humid causing the rate of transpiration to decrease. Temperature can sometimes be a factor if it gets too warm as it causes the water on the stomata to be evaporated into the atmosphere faster which causes the plant to supply more water to try by osmosis to try and decrease the concentration gradient between the inside of the leaf and the outside of the leaf. It also causes the water molecules to move faster (have more kinetic energy) which causes a higher rate of osmosis and therefore a higher rate of transpiration. Soil moisture affects the rate of transpiration in mesophytes because if more water is in the soil, the plant will take in as much water as the need until it’s cells become full of water, causing less water movement up the plant as soil moisture increases.This causes the rate of transpiration to decrease because less water is moving up the plant to the leaves. If the soil is too dry, no water will move up the plant to the leaves so the rate of transpiration will decrease and the plant to wilt. Wind speed affects the rate of transpiration because mesophytes don’t have their stomata in sunken pits like xerophytes which means that as the wind speed increases, more water is wiped off the stomata and therefore the plant tries to decrease the concentration gradient between the inside and outside of the leaf by giving up more water, this causes the rate of transpiration to increase. Light intensity affects the rate of transpiration because as the light intensity increases, so does the temperature which causes more water to be evaporated which causes the rate of transpiration to increase. Although mesophytes have many factors that affect transpiration, they have adaptations to maintain water balance and decrease water loss. (Roberts, 2011)(Jones, 2015)(Class Notes,2015) (Fieldtrip to the Hamilton Gardens)(Wikipedia, 2015)
Adaptations mesophytes have to maintain water balance:Stomata adaptationsAdaptations that the stomata in mesophytes do to prevent water loss. The stomata is where most of the water is lost with mesophytes. A structural adaptation that mesophytes do to decrease this is that most plants in this plant group have their stomata on the underside of the leaf. This means that when transpiration and evaporation does occur, the water vapour get trapped by the leaf and doesn’t go straight into the atmosphere which means that there is a micro climate under the leaf which increases the humidity and concentration on the outside of the leaf which decrease the concentration gradient between the inside and the outside of the leaf meaning less water is lost due to osmosis ( as osmosis is the movement of water molecules from an area of high concentration to an area of low concentration), causing the amount of water lost to decrease. (Roberts, 2011)(Jones, 2015)(Class Notes,2015) (Loretocollegebiology.weebly.com, 2015)(Feildtrip to Hamilton Gardens)(Wikipedia, 2015)
Stem/leaf adaptationsAdaptations that mesophyte plants have in their leaves and stems that are different to the other plant groups. A structural adaptation that mesophytes have is that there leaves are held out horizontally to increase the amount of light absorption for photosynthesis, this also is also because their cells are full of water and turgid. Most also have a waxy cuticle on the upper epidermis which causes no water to evaporate out of it and no water to lost out the top of the plant that has the most light intensity decreasing the rate of transpiration. Places like the tropical greenhouse have mesophytes with really large leaves. This is because water is not an issue and they can afford to lose water to transpiration, so they focus more on increasing the surface area and gaining enough light for photosynthesis to create glucose which can be used for respiration creates ATP (energy) as a product. Another behavioral adaptation is that the leaves on the top of the plant are smaller as they have more access to light which means the light intensity is higher so they minimise the size of the leaves to decrease the rate of transpiration out of them as there is less surface area. Some mesophytes also have hairs on the underside of the leaf by the stomata which traps water and reduces the concentration gradient between the outside and the inside of the leaf and thus decreases the water lost through the leaf. The leaf has also adapted so that the lower epidermis layer of the leaf can both let carbon dioxide in and oxygen out. (Roberts, 2011)(Jones, 2015)(Class Notes,2015) (Loretocollegebiology.weebly.com, 2015)(Feildtrip to Hamilton Gardens)(Wikipedia, 2015)
Root adaptationsMesophyte roots go deep into the soil to not only anchor the plant but to also get water. An adaptation that mesophytes (and the other two plant groups also have) The roots have small root hairs which increase the surface area so that the plant can absorb as much water and minerals like nitrogen, phosphorus and potassium through the roots so that they can be used to help the plant grow and carry out life processes, therefore helping them to maintain water balance, this is a structural adaptation. By having roots that travel deep and spread out in search of water is a behavioural adaptation because the roots are searching for water which get absorbed through the roots via osmosis and is then transported against gravity by water cohesion and the transpiration pull up the stem towards the leaves, this is related to water balance as it is about how the plant gets its water. (Roberts, 2011)(Jones, 2015)(Class Notes,2015) (Loretocollegebiology.weebly.com, 2015)(Feildtrip to Hamilton Gardens)
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Examples of mesophytes
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