Plant Structure & TransportChapter 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 grounde.g. stem, leaves, buds, flowers

b) Root system – all parts below ground

Functions of Parts of PlantPart Function

Root 1. Anchors plant in the ground.2. Takes in water and minerals from the soil3. Some roots store food e.g. carrot

Stem 1. Holds up the leaves, flowers and fruits2. Carries water and minerals from the roots to leaves

and flowers3. Carries food made in the leaves to other parts of the

plant

Leaves 1. Makes food and oxygen in photosynthesis2. Allows for the exchange of oxygen and carbon dioxide gas.3. Allows the loss of water vapour.

Flowers 1. 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

CO2 gets in here

Leaf diagram – palisade layer

CO2

Most chlorophyll

Leaf cell Position?

Upper surface of leafFeatures?Box shape

ChloroplastsFunction?

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

oxygenGuard cell

Provided plant is photosynthesising

Stomata open and close at different times of the day

When it is light the plant needs CO2 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 PlantsPlants 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 & PhloemXylem – 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 xylem3. In the leaves some of the water is used to make

food in photosynthesis4. 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/BMethod: 1.Set up apparatus as shown in diagram2.Mark the level of water in each test tube at

the start of the experiment.3.Set the tubes aside for two to three days4.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 tissueApparatus: 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 theLeaves. 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 Transpiration1. 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 paperResult: 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 Papers2009 Paper > Question 1 > Part a