Form 3 Transport System in Plants

Can you compare the condition of the plant shown below?AB

When the soil around the roots of a plant lacks water

OR the rate of loss of water is faster than the rate of absorption of water, the cell in the plant will contain less water and fail to support the plant.The plant BECOMES WILT.

TRANSPIRATIONis a process by which water is lost in the form of water vapour from the surface of a plant into the air by evaporation.

The leaf consists of a single layer of epidermal cell that covers both the upper and lower surfaces of the leaf.Epidermal cell secrete waxy cuticle covering the outer surface of the leaf that will reduce water loss during transpiration.Much of water loss during transpiration in plants takes place through the stomata found in the leaf

Figure below shows the structure of the epidermis of a leaf and its stomata.The cells that control the opening and closing of a stomata are GUARD CELLS.

Water vapour is lost through the stomata. Gases such as oxygen and carbon dioxide diffuse in and out of the leaf through the stomata during photosynthesis and respiration.

Rate of transpirationMainly through stomataSo number of stomata affects its rate of transpiration.The rate of transpiration also affected by environmental factor :Light intensityTemperatureHumiditywind

Light intensity

The higher the light intensity, the higher the rate of transpiration.Temperature

The higher the temperature, the higher the rate of transpiration.Humidity

The higher the humidity, the lower the rate of transpiration.Wind

The higher the air movement, the higher the rate of transpiration.

Important roles of TranspirationProduces cooling effect on the leaves. So it helps them to withstand high temperatures.Help in transportation of water and mineral salts in plant.

During transpiration, absorbed water and dissolved mineral salts are sucked up from the roots, up the stem and then to its leaves.

The transport system in plants consists of two conducting tissues that is :

- xylem - phloem.

The xylem transport water and mineral salts from roots to leaves for photosynthesis and to replace water lost during transpiration.The phloem transport food produced in leaves by photosynthesis to other parts of plants.The xylem and phloem found in vascular bundle.

Are the patterns of the vascular bundles in the roots, stem and leaves similar or different ?

Question :

Activity 2.3 : Transport of water via the xylem

DayDateAimTo investigate the pathway of water in a herbaceous plantApparatusConial flask.Material Eosin solutionProcedureFigure 2.17The roots of a balsam plant is washed carefully with waterThe roots of the balsam plant is immersed in eosin solution in a conical flask.After about 30 minutes, thin transverse section of a leaf, a stem and a root is cut using a razor blade.Each section is examined under a microscope and labelled diagram of each observed section is draw.

Activity 2.2 : The stomata in the epidermis of a leaf

DayDateAimTo identify the stomata in the epidermis of a leaf under a microscope.ApparatusMicroscope.Material Spider lily leavesProcedureA thin layer of nail varnish is brushed on the lower epidermis of a leaf.The nail varnish is let dry.The layer of nail varnish is peel off by using forceps.A slide of the layer of nail varnish is prepared.The slide is examined under a microscope.The stomata is drawn and labelled.