Prepare a similar apparatus, with a pot empty of any cultivated plant.

Put some clear lime water in a small beaker, and leave it exposed to the atmospheric air.

4. Leave the 3 apparatus for some time.

Observation:

Lime water becomes turbid in (1) only.

Interpretation:

In (1), the green plant in the pot has respired and produced CO2 gas, which causes the turbidity of lime water in the beaker. The bell-jar was covered with a black piece of cloth in order to keep light away from the plant and to stop the process of photosynthesis (which uses up CO2 inside the bell-jar which has been released due to respiration).

In (2) and (3), the lime water shows no turbidity due to the small percentage of CO2 whether in the air of the bell-jar or in the atmospheric air.

Experiment 2:

To illustrate the process of alcoholic fermentation:

Put a sugary solution (or molasses diluted with double of its volume with water) in a conical flask. Add a piece of Yeast and mix it thoroughly.

Close the flask with a stopper of rubber through which a delivery tube passes.

Dip the free end of the tube into a beaker containing lime water.

Leave the apparatus in a warm place for several hours.

Observation:

Gas bubbles are seen on the surface of the solution in the flask.

Lime water has become turbid.

Conclusion:

Turbidity of lime water is a proof that CO2 gas has been evolved, as a result of the anaerobic respiration of yeast.

N.B.:

There is another kind of fermentation called acid fermentation carried out by several kinds of bacteria. It produces an acid instead of alcohol. Many milk products such as cheese, butter, and yoghurt are manufactured by this kind of fermentation.

Seeds of Angiosperms too, have the power to respire anaerobically, if they are kept under anaerobic conditions.

Revision VI

Respiration in Livings.

1. Give the scientific term that represents each of the following:

A. Extraction of energy from bonds of food molecules manufactured by plants or eaten by animals. (-------------------------------)

B. Compounds that store energy extracted from food molecules. (---------------------)

C. The universal currency of energy in living cells. (-------------------------)

D. The 3 sub-units that form ATP molecule. (----------------------------------------------)

E. The amount of energy released when a molecule of ATP is hydrolyzed. (--------------)

F. The substance commonly used by the majority of livings during the cellular respiration. (----------------------------)

G. The non organ part of the cytoplasm. (---------------------------)

H. The stage of cellular respiration that takes place in the cytosole. (-------------------)

I. The stages of cellular respiration that takes place inside the mitochondria. (-----------------------------------------------)

J. The electron carrier molecules. (----------------------------)

K. The break down of the glucose molecule. (---------------------------)

L. Co-enzymes which act as Hydrogen carriers. (-------------------------------------)

M. The stage of respiration that take place in both aerobic and anaerobic respiration. (-----------------------------------)

N. The products of Glycolysis. (------------------------------------------------------------)

O. The products of Pyruvic acid oxidation. (-----------------------------------------------)

p. The 1^st. compound formed during Krebs cycle. (---------------------------------------)

Q. The 2- Carbon compound that joins Krebs cycle. (---------------------------------------)

r. The 1^st. 3- Carbon compound formed during cellular respiration. (-------------------)

S. The net energy released during Glycolysis in ATP molecules. (-------------------------)

T. In its presence, Pyruvic acid molecules pass to the mitochondria. (---------------------)

U. The form to which proteins and fats are broken down to join Krebs cycle. (---------)

Date: 2015-12-11; view: 914