01.Nutrition

Nutrition

Definition           

The process of providing or obtaining the food necessary for health and growth is known  as Nutrition

                                                                 (Or)

Procurement of Nutrients is Known as Nutrition.

Autotrophic Nutrition

•       “Autotrophic nutrition is a process where an organism prepares its own food from a simple inorganic material like water, mineral salts and carbon dioxide in the presence of sunlight.”

•       the process of photosynthesis makes plants “The universal food providers” for all living organisms.

Photosynthesis

•       Photosynthesis is a process by which green plants containing chlorophyll, produce food substances [glucose & starch] from CO₂ and H₂O using light as source of energy and release O₂ into atmosphere.

Equation of Photo-Synthesis:

·         C.B. Van Niel in  1931 formulated and Proposed an equation for photosynthesis.

•       we can state that photosynthesis is the basic energy source for most of the living world.

Experiment-01:

•       Aim :- To prove that presence of starch in leaf

•       Apparatus :- Boiling tube, methylated spirit, beaker, leaf, water, mesh, tripod stand, Bunsen burner, dropper, dilute iodine solution, petri dish

•       Precaution :- (i) Do not heat the spirit lamp directly on the flame.

  (ii) Be careful while your boiling and removing the leaf.

•       Procedure:-

1.  Take a leaf of potted plant. (soft and thin leaves and well exposed to sunlight)
2. First boil the leaf in water then transfer this leaf into a test tube containing methylated spirit.
3. Boil this tube in a water bath.
4. Chlorophyll dissolves in spirit and the leaf becomes pale, due to removal of chlorophyll.
5. Take the leaf carefully from test tube by using a brush.
6. Spread the leaf in a Petri dish and add a few drops of iodine/ betadine solution on it.

Observation:

•      The presence of starch will be indicated by a bluish black color.

Result :

•       We Proved the Presence of starch in leaf

Air and Photosynthesis

·         Joseph Priestley (1733-1804) in 1770 performed a series of experiments that revealed the essential role of air on the growth of green plants

·          Oxygen was discovered by Priestley in 1774. The name oxygen was coined later by Lavoisier in the year 1775.

·          Priestley observed that a candle burning in a closed bell jar, soon gets extinguished. Similarly, a  mouse would soon suffocate in a closed space of the bell jar.

·         He concluded that a burning candle or an animal, both somehow, damage air.

·         When he placed a mint plant in the same bell jars, he found that the mouse stayed alive and the candle when lighted from outside continued burning.

·         Priestley hypothesized as follows: ‘Plants restore the air what breathing animals and burning candles remove’.

·          Priestley’s experiment confirmed that gaseous exchange was going on and plants were giving out a gas that supported burning and was essential for the survival of animals.

·          Massive amounts of gaseous exchange occur through the stomata (usually present in leaves) as long as they are open .While plants also carry on gaseous exchange through loose tissues in the stems, roots etc.

·         Experiment-02

·         Aim - Carbon dioxide is necessary for Photosynthesis (Mohl’s half leaf experiment)

·         Apparatus – Potted plant, Wide Mouthed Bottle, Split Cork, KOH Solution, Petri Dish, Betadine/Iodine Solution

·         Precautions-1.The part of the leaf kept inside the bottle should not touch potassium hydroxide (KOH) solution.
                      2.The apparatus should be kept air tight by applying grease or Vaseline.

·          

·         Procedure-

·         We need a destarched plant to start with.

·         We need to keep the plant in the dark for nearly three days to remove the starch (destarch).

·         By placing the plant in dark the starch is removed from the leaves.

·         Take a wide mouthed transparent bottle.

•    Put potassium hydroxide (KOH) pellets or potassium hydroxide solution in the bottle. Potassium hydroxide                               absorbs carbon dioxide.

•       Insert splitted cork in the mouth of the bottle.

•       Insert one of the leaf of destarched plant (through a split cork) into transparent bottle containing potassium hydroxide pellets/potassium hydroxide solution. Leave the plant in sunlight.

•       After a few hours, test this leaf and any other leaf of this plant for presence of starch

•       Spread the leaf in a Petri dish and add a few drops of iodine/ betadine solution on it.

•       The leaf part which was exposed to the atmospheric air and light becomes bluish-black, and the one inside the bottle containing potassium hydroxide which absorbs carbon dioxide in the bottle remains colorless. This proves that carbon dioxide is necessary for photosynthesis.

Experiment-3

•       Aim-to observe oxygen is evolved during photosynthesis in the presence of light

•       Materials required : Beaker (2), funnel (2), test tubes (2),  Hydrilla (any other aquatic submerged plant), black paper, bucket-full of water, incense stick, match box.

Procedure :

1. Arrange the apparatus as shown in the Fig-5 and make two identical sets with water plant (like Hydrilla).
2. Take the whole set under a bucket of water and invert a water filled test tube over the stem of  funnel
3. (This will help to retain the water column in the test tube).
4. Take the set up out of the bucket and keep it under sunlight.

5. Arrange the second set in the same way, cover it with black   paper/cloth. Keep them under shade.

6. You would see that in place of water there is air that fills in the set up kept in sun.

7. It is actually a gas that will be collected in the test-tube.

Observation - Test the gas in the test-tube by inserting a glowing match stick or incense stick which would  burst into flames. This shows the presence of oxygen.

Result-This shows the presence of oxygen.