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10 Cards in this Set
- Front
- Back
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What is the definition of hydrophyte? |
A plant adapted to living in water or when the ground is very wet |
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What is the definition of xerophyte? |
A plant adapted to living in dry conditions |
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What are the three places to consider weather conditions for availability of water differ? |
1) Terrestrial plants - normal conditions 2) Xerophytes - arid conditions 3) Hydrophytes - wet conditions |
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What 4 features does terrestrial plants have to prevent water loss? |
1) A waxy cuticle reducing evaporation from the upper epidermis 2) Stomata are closed during the night but needs to be open during the day to allow CO2 in for photosynthesis 3) Stomata are located on the underside of the leaf as being on the top would increase evaporation due to direct sunlight heating the leaf 4) Deciduous plants lose their leaves in winter when the ground may be frozen and when temperatures may be too slow for photosynthesis also less sunlight |
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Name the four features of the cacti (xerophyte) in which they have to reduce water loss |
Cacti have the following features: 1) Cacti are succulents - they store water in their stems which become fleshy and swollen. The stem is often ribbed or fluted so that it can expand when water is available 2) The leaves are reduced to Spines this reduces the surface area of the leaves. When the total Leaf surface area is reduced less water is lost by transpiration 3) The stem is green for photosynthesis 4) The roots are very widespread in order to take advantage of any rain that does fall |
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Name another three xerophytic features |
1) Closing the stomata when water availability is a low reduce water loss and so reduce the need to take up water 2) Some plants have a low water potential inside their leaf cells. This is achieved by maintaining a high salt concentration in the cells. The low water potential reduces the evaporation of water from the cell surfaces as the water potential gradient between the cells and the leaf air spaces is reduced. 3) A very long tap root that can reach water deep underground |
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What are the conditions that xerophytes live in and what are the 5 features they have to reduce water loss? Name an example |
Example: Marram grass These live on sand dunes any water drains away very quickly the conditions are usually windy and the sand is also salty these have the following features: 1) The leaf is rolled longitudinally so that air is trapped inside - the air becomes humid, which reduces water loss from the leaf. The leaf can roll more tightly in very dry conditions 2) There is a thick waxy cuticle on the outer side of the rolled Leaf to reduce evaporation 3) The stomata are on the inner side of the rolled leaf, so they are protected by the enclosed airspace 4) The stomata are in pits which is also folded and covered by hairs these adaptations help to reduce air movement and therefore loss of water vapour 5) The spongy mesophyll is very dense with less air spaces so there is less surface area for evaporation of water |
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Name an example of a hydrophyte and the other issues they are faced with |
An example of a hydrophyte is water lilies These plants have easy access to water, but are faced with other issues such as getting oxygen to the submerged tissues and keeping afloat - they need to keep their leaves in the sunlight for photosynthesis |
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Name three features in which hydrophytes are adapted |
1) Many large air spaces in the leaf. This keeps the leaves afloat so that they are in the air and can absorb sunlight 2) The stomata are on the upper epidermis so that they are exposed to the air to allow gaseous exchange 3) The leaf stem has many large air spaces. This helps with buoyancy but also allows oxygen to diffuse quickly to the roots for aerobic respiration |
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How do hydrophytes transpire? |
The water will not evaporate into water or into the air that has a very high humidity. If water cannot leave the plant the transpiration stream stops and a plant cannot transport mineral ions up to the leaves. Many plants contain specialised structures at the tips or margins of the leaves called hydathodes. These release water droplets which evaporates from the leaf surface |
