Experimental investigation

Experimental investigation

 Put some powdered iron and some powdered sulphur in a china dish. 

Mix them thoroughly. Now bring a magnet near them 

You will find that the powdered iron in the mixture is attracted by the magnet. 

The magnet can be used to completely separate iron and sulphur.

 

Activity : Experimental Investigation - Carbon dioxide is necessary for photosynthesis

Activity : Experimental Investigation - Carbon dioxide is necessary for photosynthesis

1. Take a destarched potted plant. Take a conical flask and put some potassium hydroxide into it. 

2. Potassium hydroxide absorbs the carbon dioxide. 

3. Insert one leaf into this conical flask through a split cork. 

4. Leave the plant in sunlight for few hours. 

5. After few hours take out this leaf from conical flask and remove it from the plant.

6. Take another leaf from the same plant.

7. Test both these leaves for presence of starch.

8. You will observe that the leaf from the conical flask does not turn blue - black while was exposed to atmospheric air turns blue - black. 

9. This shows that carbon dioxide is necessary for photosynthesis. 

Activity : Experimental Investigation - Chlorophyll is necessary for photosynthesis

Activity : Experimental Investigation - Chlorophyll is necessary for photosynthesis

1. The leaves of plants, such as Coleus and Croton, are partly green and partly non - green. They are known as variegated leaves. 

2. Chlorophyll is present only in their green portions.

3. Select such a leaf from a plant that has been exposed to sunlight for a few hours and draw its outline on a sheet of paper.

4. Indicate the green and non-green areas on the drawing. 

5. Test the leaf for starch. 

6. Compare the parts stained blue - black with the drawing.

7. Which parts of the leaf turn blue - black?

8. Why does the non - green portion not show the presence of starch?

Activity : Experimental Investigation - To Show that rate of photosynthesis is affected by light.

Activity : Experimental Investigation - To Show that rate of photosynthesis is affected by light.

1. Fill a beaker 3 quarters with water. Put some Hydrilla plants in it. 

2. Cover the plants with a glass funnel.

3. Carefully invert a test tube full of water over the stem of the funnel.

4. Keep the arrangement in sunlight. You will find bubbles of a gas escaping from the leaves of the plant.

5. Keep the plant away from sunlight now.

6. You will observe that the number of bubbles have decreased in the shady place. 

Activity : Experimental Investigation - To show that light is necessary for photosynthesis

Activity : Experimental Investigation - To show that light is necessary for photosynthesis

1. Take a potted plant and destarch its leaves by keeping it in dark for 2 days.

2. Take a black paper and cut a simple "L" shape in it by using a stencil.

3. Cover one leaf with this paper.

4. Leave the set up in sunlight for 4 - 6 hours.

5. Detach the leaf and test it for presence of starch.

6. You will observe that only the part of the leaf that could get sunlight through the cut out design as well as the other exposed parts of the leaf turn blue - black showing the presence of starch.

Activity : Experimental Investigation - To test a leaf for starch

Experimental Investigation - To test a leaf for starch

Activity:  Pluck  a leaf from  a plant which has been exposed to sunlight. 

2. Boil it for about 5 minutes in water to softer it.

3. Place it in a test tube containing alcohol.

4. Place the test tube in a beaker of water and warm the water gently until the alcohol begins to boil.

   (caution: Do not allow the water in the beaker to boil).

5. The alcohol will dissolve the chlorophyll and the leaf will lose its green colour.

6. Wash the leaf in warm water to remove the alcohol.

7. Now spread the leaf out flat on a white tile and pour iodine solution on it.

8. Remove the leaf from the iodine and wash it with water.

9. Hold it up against the light.

10. You will observe that parts of the leaf become blue - black.

11. These parts of the leaf have starch in them.

The simplest method of testing whether photosynthesis has taken place is to find out if starch is present in a leaf.

Kids Experiments -Simple machines and tools - How a Lever works

Kids Experiments -Simple machines and tools - How a Lever works

Materials : wooden ruler, textbook, a desktop

Procedure: Lay a ruler on your desk with part of it hanging over the edge. Place  textbook on the other end. Try to lift the book by pressing down on the part of the ruler that is sticking out. Repeat this procedure several times. Move the book, closer to the edge by pulling on the ruler. Continue until the book is right at the table's edge.

Things to think about during the experiment:

• What simple machine was used in this experiment?
• was it easier to lift the book with a short or a long ruler?
• Can you think of a time when you used a simple machine like this?

Conclusion: The ruler is a lever in this experiment. The edge of the table is the fulcrum & the book is the load. It is easier to move an object, like the book, when the fulcrum is closer to the load.