Plant Structure & Transport Chapter 13 Objectives: OB46: Associate the transport of water and minerals in the plant with the xylem and the transport of food in the plant with phloem OB47: Carry out simple experiments to show the path of water through plant tissue, and show that water evaporates from the surface of a leaf by transpiration

Typical Plants Have: Leaves stem roots Flowers

Shoot & Root Systems Typical plant has: a)Shoot system – all parts above the ground e.g. stem, leaves, buds, flowers b) Root system – all parts below ground

Functions of Parts of Plant PartFunction Root1.Anchors plant in the ground. 2.Takes in water and minerals from the soil 3.Some roots store food e.g. carrot Stem1.Holds up the leaves, flowers and fruits 2.Carries water and minerals from the roots to leaves and flowers 3.Carries food made in the leaves to other parts of the plant Leaves1. Makes food and oxygen in photosynthesis 2. Allows for the exchange of oxygen and carbon dioxide gas. 3. Allows the loss of water vapour. Flowers1. Sexual reproduction and to produce seeds.

Function of leaves Trap light energy for photosynthesis Exchange of gases – oxygen and carbon dioxide

Structure of leaf Wide Helps to catch more light energy Thin Helps get carbon dioxide from bottom to top of leaf for photosynthesis

Leaf structure Greener on top CO 2 gets in here

Leaf diagram – palisade layer CO 2 Most chlorophyll

Leaf cell Position? Upper surface of leaf Features? Box shape Chloroplasts Function? Photosynthesis

Gas exchange Leaves are designed to allow carbon dioxide to get to the main chlorophyll layer at the top of the leaf They have small holes called stomata on the under surface Each hole is open & closed by 2 guard cells

Stoma is a small hole usually on under surface of leaf Its size is controlled by 2 guard cells closed open

Stoma function is for gas exchange in the leaf Carbon dioxide oxygen Guard cell Provided plant is photosynthesising

Stomata open and close at different times of the day When it is light the plant needs CO 2 for photosynthesis so the stoma open At night (darkness) they close

Gas exchange Carbon dioxide enters the leaf through the stomata for photosynthesis and oxygen leaves the leaf as a waste product of photosynthesis

Transport in Plants Plants have a transport system to move food and wastes around the plant. The transport tissue in a plant consists of fluid filled tubes called xylem and phloem.

Xylem & Phloem Xylem – Carries water and minerals from the roots upwards to the leaves and flowers. Phloem – Carries food e.g. glucose made in the leaves to all the other parts of the plant.

Passage of water and minerals through a plant 1.Water is taken into the roots of a plant from the soil 2.It travels up the stem to the leaves in the xylem 3.In the leaves some of the water is used to make food in photosynthesis 4.The remaining water passes out of the leaves into the air. Draw fig 13.4 pg 81

Experiment to show that water is lost from a plant Pg. 82 T/B Method: 1.Set up apparatus as shown in diagram 2.Mark the level of water in each test tube at the start of the experiment. 3.Set the tubes aside for two to three days 4.Again mark the level of water in each test tube.

Result Result: The level of water in the test tube with the seedling (test tube A) has fallen. The level of water in the other test tube (test tube B) stays the same Conclusion: The fall of the water level in test tube A with the seedling suggests that water has passed through the plant and out into the air.

Wheat seed Root hairs Fragile parts of cells that grow from the main root They massively increase the surface area for absorption

Root hair cells (x150)

Root ‘B’ has had the hairs damaged - Toughened root cap

To show the path of water through plant tissue Apparatus: Beaker, knife, cutting board, celery, Food dye. Method: 1.Set up apparatus as shown in diagram 1.Leave the celery for a few days. 2.Remove the piece of celery and describe the appearance of the leaves and stem.

4. Place the piece of celery on a cutting board and using a knife cut across the stem. 5. Look at the cut stem. Results: The veins in the leaves of the celery will be a red colour. Tiny red dots will be found at the edge of the stem. These are the transport tubes that carry the water.

Conclusion: Water travels up through the stem and into the Leaves. The red dots represent the xylem tubes which carry water up the plant.

Transpiration Transpiration is the loss of water vapour from the surface of a plant. Water is lost through tiny openings in the leaves called stomata. As water is lost from the stomata more water is pulled up through the plant and this process is called the transpiration stream.

Functions of Transpiration 1.To bring water needed for photosynthesis from the roots to the leaves 2.To carry minerals dissolved in water up the plant 3.To cool the plant

Experiment: To show that water evaporates from the surface of a leaf by transpiration Required: two plants, blue cobalt chloride paper, plastic bags, rubber bands. Note: Blue cobalt chloride paper turns pink if water is added. Method: 1.Set up apparatus as shown in 2.diagram. 3.Leave the plants in a warm bright place for several hours. 4.The plastic bags covering the soil in each pot prevent evaporation of water

5. After several hours remove the bag covering each plant. 6. Test the liquid formed with blue cobalt chloride paper Result: Droplets of a colourless liquid have collected inside the plastic bag covering the leaves of the plant (a). There are no droplets of liquid in bag from plant (b). The droplets of liquid turned the blue cobalt chloride paper pink Conclusion: The liquid formed in bag (a) is water. No water formed in bag (b) which was the control. Therefore water is lost from the leaves of the plant.

Junior Cert Past Papers 2009 Paper > Question 1 > Part a