To experimentally demonstrate that carbon dioxide is released during the process of respiration.

 

Aim

To experimentally demonstrate that carbon dioxide is released during the process of respiration.

Principle/Theory

The process of respiration is biochemically carried out wherein food, glucose to be precise is oxidized and energy is released. In this experiment, gram seeds (moistened) are used. The purpose of using these seeds is that they release carbon dioxide and are respiring actively. The released carbon dioxide is consumed by the solution of KOH.

Material Required

• Soaked gram seeds
• U-shaped delivery tube
• Conical flask
• Blotting paper (moist) /cotton wool
• Thread
• Water
• Beaker
• Test tube
• Rubber cork with a single hole
• Freshly prepared KOH solution (20%)
• Vaseline

Procedure

• Germinate close to 25 seeds. This can be done by wrapping them in moist blotting paper or cotton wool for around 3 to 4 days
• Set up the germinated or sprouted seeds in the conical flask. Spray some water into the flask to dampen the seeds
• With the help of a thread, suspend the conical flask containing the test tube having a freshly prepared 20% KOH solution.
• Use the rubber cork to seal the opening of the conical flask.
• One edge of the U-shaped glass delivery tube present in the conical flask should be inserted through the hole in the rubber cork. The other edge should be placed into a beaker that is saturated with water
• All attachments of the set-up should be sealed. This can be done using vaseline to create an air-tight environment
• The initial water level present in the U-shaped delivery tube needs to be marked.
• Leave the experimental set-up uninterrupted for 1 to 2 hours. Observe the fluctuations in the water level in the tube.

Observation

Careful observation after a certain period of time reveals that the water level in the U-shaped delivery tube has risen in the beaker.

Conclusions

The rise in level water indicates that carbon dioxide is released as a result of germinating gram seeds during the process of respiration in the conical flask. The carbon dioxide that is released in the process is absorbed or consumed by the KOH solution that is suspended in the test tube in the conical flask, creating a vacuum or a void in the flask resulting in the upward water movement in the tube. Hence, the water level in the tube changes.

Precautions

• The seeds that are to be germinated needs to be moistened
• Air-tight environment for all the connections in the experimental set-up
• The KOH solution that is used needs to be freshly prepared
• Care needs to be taken to ensure that one end of the delivery tube is placed in the conical flask. The other edge is submerged in the water of the beaker
• The tube that contains the KOH solution needs to be suspended carefully

Detection of Albumin in Urine

 

Sulphosalicylic Acid Test

Procedure

• Take 2 ml urine sample in a measuring cylinder from the urine sample bottle.
• Take a test tube and pour the urine in the test tube.
• Using a dropper, take some sulphosalicylic acid.
• Add few drops of sulphosalicylic acid in the test tube containing urine. A whitish color appears in the solution.
• Using a test tube holder, hold the test tube firmly and heat it gently upon a burner.
• A whitish or cloudy turbid solution indicates the presence of albumin in the urine sample.

Study of distribution of stomata

 

 Lab Procedure

• Pluck one fresh leaf of a four-o’clock plant.
• Take two watch glasses and pour some distilled water into the both watch glasses.
• Split the leaf from the four-o’clock plant obliquely.
• Take the peel from the upper surface of the leaf using the forceps.
• Place the peel into a watch glass containing water.
• Take another peel from the lower surface of the leaf using the forceps.
• Place the peel into the other watch glass containing water.
• Using a dropper, take few drops of Safranin solution and put it into the two watch glasses.
• Take two clean glass slides and place the leaf peel on the slides one by one, using a brush.
• Take a blade and cut a small rectangle or square piece from each peel.
• Take some glycerine using a dropper and put one drop of glycerine on both slides.
• Take a cover slip and place it gently on the peel with the help of a needle.
• Take the glass slide and place it under compound microscope.
• Observe under the microscope.
• Count the number of stomata in the peels of both upper and lower epidermis of the leaf appearing in the microscopic field.

Observations

• The number of stomata is greater in the lower epidermis, and fewer are present in the upper epidermis of the leaf taken from a four-o’clock plant.

Precautions

• The curling of the peel should be avoided.
• Always use a brush to transfer the peel from watch glass to the slide

XI BIO LAB WORK-Pigment separation by using paper chromatography

 

 Procedure

• Take a few freshly plucked green spinach leaves.

• Using scissors,  cut the spinach leaves into small pieces and let them fall into the mortar.

• Take a measuring cylinder that contains 5ml of acetone and pour it into the mortar.

• Grind the spinach leaves using the mortar and pestle.

• Place the extract into a watch glass using a spatula.

• Take a strip of filter paper having a narrow notch at one end of the strip.

• Take a pencil and a scale and draw a horizontal line with a pencil about 2-3 cm away from the tip of the notch.

• Put a drop of the pigment extract in the middle of the line with the help of a capillary tube.

• Allow the drop to dry and repeat till four or five drops are placed on the paper.

• Take the chromatographic chamber and pour ether acetone solvent in it.

• Fold one end of the filter paper strip and staple it.

• Using a thread, hang the filter paper strip in the chromatographic chamber.

• The loading spot should remain about 1 cm above the solvent level.

• Leave the chromatographic chamber undisturbed for some time.

• We can observe, as the solvent moves through the paper, it spreads the different pigments of the mixture to various distances.

• When the solvent rises about 3/4th up the strip, remove the strip carefully and let it dry.

XI Biology lab work- to test sugar in urine.

 

1.Benedict's Test

Materials required:

Test tube, test tube holder, urine sample, measuring cylinders, Benedict’s solution and burner.

Procedure:

• Take 2 ml urine sample in a measuring cylinder from the urine sample bottle.
• Take a test tube and pour the urine sample in it.
• Take 5 ml Benedict’s reagent in a measuring cylinder.
• Add Benedict’s reagent to the test tube that contains urine sample.
• Using a test tube holder, hold the test tube firmly and heat it for 2 minutes on the burner.
• Keep shaking the test tube while heating.
• A yellow precipitate appears which indicates the presence of sugar in urine.
• Depending upon the concentration of sugar in the urine, either green, yellow, or brick red precipitates are formed.

2.Fehling's test

Materials required

Test tube, test tube holder, urine sample, measuring cylinders, Fehling’s solution A, Fehling’s solution B and burner.

Procedure

• Take 2 ml urine sample in a measuring cylinder from the urine sample bottle.
• Take a test tube and pour the urine sample in it.
• Take 2 ml Fehling’s solution A in a measuring cylinder.
• Add Fehling’s solution A to the test tube that contains urine sample.
• Take 2 ml Fehling’s solution B in a measuring cylinder.
• Add Fehling’s solution B to the test tube that contains urine sample.
• Using a test tube holder, hold the test tube firmly and heat it gently for 2 minutes on the burner.
• Keep shaking the test tube while heating.
• A green precipitate appears which indicates the presence of traces of sugar in urine.
• Depending upon the concentration of sugar in the urine, either green, yellow or brick red precipitates are formed.