Water Transport
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Water Transport Learning Objectives 1. Describe how root hair cells are adapted to take up water by osmosis. 2. Define osmosis as the movement f water molecules from an area of higher concentration of water to an area of lower concentration of water through a partially permeable membrane.
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Water Transport. Learning Objectives Describe how root hair cells are adapted to take up water by osmosis. Define osmosis as the movement f water molecules from an area of higher concentration of water to an area of lower concentration of water through a partially permeable membrane. - PowerPoint PPT Presentation
Transcript of Water Transport
Water Transport
Learning Objectives
1. Describe how root hair cells are adapted to take up water by osmosis.
2. Define osmosis as the movement f water molecules from an area of higher concentration of water to an area of lower concentration of water through a partially permeable membrane.
Leaves have pores called stomata to allow carbon dioxide into the leaf.These pores can allow water to leave the leaf, so the plant loses water.
To reduce loss the leaf is coated in a wax cuticle to stop the water vapour escaping through the epidermis.
Leaves usually have fewer stomata on
their top surface to reduce this water loss.
The water inside a leaf can escape
by diffusion.
Osmosis – the diffusion of water
• Osmosis is the movement of water from a high water concentration (HWC) to a lower water concentration (LWC) through a partially permeable membrane.
How osmosis works
• Which side of the container has more water molecules?
• Where would you say is the higher water concentration?
• Where is the lower water concentration?
• Which way will the water molecules travel to make it equal water concentrations on both sides?
• Water molecules travelled to the side of the container where there was more sugar, and so less water.
• It was able to do this because the membrane in between the two sides is partially
permeable
Osmosis and plants
• Osmosis is important to plants. They gain water by osmosis through their roots.
• Water moves into plant cells by osmosis, making them turgid or stiff so that they are able to hold the plant upright.
Plant cells are flaccid. This means that they have lost water by osmosis.
The plant has become soft and droopy.
Plant cells are turgid. This means that they have gained water by osmosis.
The plant has become firm, keeping it upright.
Roots
• Plants absorb water from the soil by osmosis.
• Root hair cells are adapted for this by having a large surface area to speed up osmosis.
• The absorbed water is transported through the roots to the rest of the plant where it is used for different purposes:– used in photosynthesis– supports leaves and shoots by keeping the cells rigid– cools the leaves by evaporation– transports dissolved minerals around the plant
Water will move into the root hair cells from a HWC to a LWC by osmosis
http://www.youtube.com/watch?v=2TtQQLC66RI
