Experiments: Plant Physiology

Fresh Water from a Plant

Tie a large plastic bag a tree branch that has a lot of leaves. Leave it for a few days.

It will collect the fresh water released by the leaves through a process called transpiration.

Collect Oxygen from Water Plants

Safety Rules:
Parent supervision
Take care with fire or heat

Materials you need are:
pondweed (from a fish tank or a lake)
a clear bowl
a clear jar (smaller in diameter than the bowl)
supports (e.g. cotton reels)

Set up the materials as in the diagram. Place the whole experiment where it gets enough light to photosynthesise but doesn't get too hot. Leave it for several hours. The oxygen should have collected in the upside-down jar. To test it carefully light a match and then lift the jar quickly, placing the lit match into the jar. If oxygen is present, the flame should get brighter for a short time.

In the process called photosynthesis, plants convert carbon dioxide gas and water in the presence of light and green chlorophyll to make sugar and oxygen gas.

Cheap Plant Propagation

What Makes Flowers Last Longer

Safety Rules:
Parent supervision
Take care with aspirin and household bleach (They are poisonous)
Wear gloves and goggles

Materials you need are:
several vases of the same size
flowers of the same type
an eyedropper
various household chemicals (e.g. sugar, aspirin, household bleach)

Test what chemicals added to the water in a vase make flowers last longer. Use the same size of containers, the same amount of water, and the same type and number of flowers. To these, add the different chemicals - one chemical in each container. Try sugar, aspirin or even 4 to 5 drops of household bleach.

Because flowers decay due to bacterial decomposition, the chemical which kills bacteria but does not harm the flowers will probably be the best.

Extract Chlorophyll from a Plant

Safety Rules:
Parent supervision
Take care with a knife
Take care with methylated spirits (It is flammable and poisonous)

Materials you need are:
a few plant leaves
a small amount of methylated spirits (also called denatured alcohol)
a mortar and pestle or similar to crush leaves
a spoon
a container
a strainer

Thoroughly crush the leaves and then add a small amount of methylated spirits to obtain a green mixture. Strain the mixture, keeping the green liquid. This contains chlorophyll.

By crushing the plant cells, you have exposed the green chlorophyll. The methylated spirits is used to dissolve the chlorophyll so it can be poured off.

Make a Terrarium

Safety Rules:
Parent supervision
Take care with a knife

Materials you need are:
an empty clear soft drink bottle (the largest you can find)
a sharp knife
some soil
some plants
some water

Cut the soft drink bottle horizontally so that you can keep the hard opaque plastic base and also the clear plastic part inside the base. The hard opaque base will be where you put the soil and your garden plants. Water this and then cover it with the inner clear plastic dome. It should require little watering as it keeps a very humid atmosphere inside the dome.