Practicals for class X

Instructions 
To be written in Practical file .Diagram to be drawn only with sharp pencil (any one )
Index --whole aim is to be written in index clearly

 Experiment – 1

Aim
To prepare a temporary mount of a leaf peel to show stomata.
Theory

• Plants need oxygen for respiration and carbon dioxide for photosynthesis. The exchange of gases in plants occurs through the surface of stems, roots and leaves.
• On leaves there are plenty of small tiny pores called stomata.
• On the dorsal side of leaf more stomatal pores are present than the ventral surface of leaf.
• Through these pores, plants can also lose water by the process called transpiration.
• To avoid excess loss of water, the stomata pores closes and when gases are required, these pores open.
• This opening and closing of pores is monitored by guard cells.
• The guard cells swell when water flows into them, causing the stomata pore to open. When the guard cells shrink the stomata pores close.
• The guard cells contain chloroplast and nucleus in it. They are bean-shaped in dicots and dumb-bell shaped in monocots.
  

Materials Required

Freshly plucked leaf of Rheo or Tradescantia, petri dish, slide, coverslip, needle, forceps, brash, dropper, watch glass, filter paper, glycerine, safranin solution and microscope.

Procedure

1. Take a freshly plucked leaf (Rheo or Tradescantia).
2. Stretch the leaf with its dorsal (lower) part facing upwards.
3. Break the leaf by applying suitable pressure so that the epidermis projects from the leaf.
4. Cut the epidermis and put it in a petri dish.
5. Take a watch glass, add few drops of water and a drop of stain in it.
6. Transfer the small piece of epidermis from petri dish into the watch glass with the help of brash.
7. Allow the peel to remain in the stain for 2-3 minutes, so that it can take up the stain.
8. With the help of brush transfer the stained peel into a petri dish with water to remove the extra stain.
9. Now take a clean slide and place it on a filter paper. In the centre of the slide put a drop of glycerine and transfer the stained  peel from petri dish on the slide.
10. Gently hold the coverslip with the needle and place it on the peel. Avoid air bubbles formation.
11. Use the filter paper to clean the excess stain, water or glycerine that comes out from the coverslip sides.
12. Ensure that the slide is clean and place it under the microscope. First view it under low power (10X) and then under high power(45X).
13. Record your observations.
14. 

Observations

1. In an epidermal peel we see single layer of cells.
2. In between the epidermal layer small spots are seen.
3. When focused under powerful microscope the stomata pores are clearly seen.
4. Each stomata pore has two kidney-shaped cells called guard cells.
5. Each guard cell has one nucleus and many chloroplasts.

Conclusion
Epidermal layer of leaf peel has many stomata pores. Each stomatal pore has two kidney shaped guard cells, in dicots plants. Each guard cell has one nucleus and many chloroplasts.
Precautions

1. While removing the epidermal peel, ensure that you pluck the thinner scrap of leaf.
2. Do not overstain the peel.
3. Avoid air-bubbles formation while placing the coverslip.
4. The peel should not be folded.
5. The slide should be clean and dry before placing it under microscope.

Experiment no 2

 Test for release of CO2 during respiration in animals.

Materials Required
Two test tubes, a cork with two holes, two glass tubes, syringe, lime water.
Procedure

1. Take some freshly prepared lime water in two test tubes.
2. Fit cork with two holes in test tubes A and B.
3. Fix two glass tubes in this cork of test tube A as shown in the figure.
4. Exhale air into the tube and record your observations.
5. In another test tube B, which has lime water, pass air through syringe and record your observations.

(Note---in this diadram you dont have to draw face if you find it difficult)
Observation

• In test tube A, the lime water turns milky sooner than in test tube B.

Conclusion

1. The exhaled air contains lot of CO2 which turns lime water milky.
2. This proves that during respiration we exhale CO2 gas.

Precautions

1. The glass tube should be dipped in the lime water.
2. The lime water should be freshly prepared.

Experiment no 3

To test release of C02 by plants during respiration.
Materials Required
A conical flask, small test tube, cork, thread, germinating seeds, a bent tube, a beaker, water and freshly prepared lime water.
Procedure

1. Take two conical flasks, add germinating seeds with little water sprinkled over it.
2. Fix the mouth of conical flasks with cork in which a bent tube is fixed.
3. Suspend a small test tube containing KOH solution in it with the help of a thread in conical flask A.
4. Allow the mouth of the bent tube to be immersed in water in set-up A and in lime water in set-up B as shown below.
5. Record your observations after few hours.

Observations

1. In set-up A, the water level in the bent tube dipped in beaker increases after few hours.
   This is because the oxygen present in the conical flask is taken up by germinating seeds and CO2 released due to respiration is absorbed by KOH present in small tube. Hence, the air pressure in the flask reduces and water level rises.
2. In set-up B, the freshly prepared lime water turns milky. This is due to excess CO2 released into the test tube during respiration of germinating seeds.

Conclusion
This shows that CO2 is given out during respiration.
Precautions

1. Lime water should be freshly prepared.
2. KOH solution should be freshly prepared.
3. Germinating seeds should have lot of moisture in them.

Respiration Practical Class 10 Viva Voce

Question 1:Name the parts of the plant through which exchange of gases takes place.
Аnswer:
Stomata and lenticles.

IQuestion 2:

Is respiration a physical or chemical process?
Аnswer:Respiration is a chemical process. It takes place in cells.

Question 3:Name the part of cell in which final breaking down of food takes place and energy is released
Аnswer:Mitochondria

Question 4:Name two organisms that respire in absence of oxygen.
Аnswer:Bacteria and yeast.

Question 5:What are the end products of anaerobic respiration?
Аnswer:It is ethanol, carbon dioxide and energy.

Question 6:Name the energy currency for most of the cellular processes.
Аnswer:ATP, i.e., Adenosine tri phosphate.