Plasmolysis through the effect of Isotonic for std 10 to 12

Practical-2
AIM :-
Study of Plasmolysis through the effect of Isotonic, Hypotonic as well as Hypertonic Solutions
of Sodium Chloride and  Potassium Chloride on Mounted Epidermal Cells of Tradescantia leaf.
INSTRUMENTS AND MATERIALS : -
Slide, Cover slip, Microscope, Dropper, Blotting paper, Tradescantia leaf, Water, Glycerine, NaCL solution, KCL solution.

Plasmolysis through the effect of Isotonic for std 10 to 12

Conclusion :-
This a kind of exosmosis. When living plant cell is placed  in a concentrated solution of sugar or salt plasmolysis is induced in them. Normally living cells are turgid as concentrated of vacuolar sap is lower than the surrounding solution water from the cell starts moving outside through exosmosis.

Oxygen is evolved during photosynthesis. Std 10 to 12

AIM :  To show that oxygen is evolved during photosynthesis.

PRINCIPLE :  During photosynthesis photolysis of water takes place  and oxygen is released.

Equation for oxygen evolved during photosynthesis.

MATERIALS       :  Beaker, funnel, test tube, twig of Hydrilla, water.

  

Oxygen evolved during Photosynthesis

Bubble comes out 

Oxygen evolved during photosynthesis

Result :

Air bubbles released from the cut end of plant twigs move up through the funnel and get collected in the test tube.

Conclusion :

The oxygen produced during photosynthesis moves up in thee form of bubbles and getts collected in the test tube.

Application : 

During photosynthesis oxygen evolved and released in the atmosphere. It can be shown to the students by the above experiment.           

Photosynthesis, Plant converts solar energy into chemical energy.

 To demonstrate that the light is necessary for photosynthesis.


AIM  :  To demonstrate that the light is necessary for photosynthesis.


PRINCIPLE :  During the process of photosynthesis plant converts solar energy into chemical energy ( glucose ). This experiment indicates that without light, food cannot be synthesized.

MATERIALS :  Ganong’s screen, a twig, iodine, ventilated box,  etc.

Plant with leaf

Photosynthesis, light is necessary.

Cobalt Chloride paper on leaf.

Sun light makes Photosynthesis process.

Result (Observation) :

The positive iodine test shows presence of starch only is the region where letter “A” was cut in the black paper.

Conclusion :

The final product of the photosynthesis is starch. It is found in the leaf only when all the essential factors for the photosynthesis are available to the plant. The iodine test shown that starch is manufactured in the region exposed to the light, while the region of the leaf which was covered with black paper does not show any starch.

Application :

From this experiment we can demonstrate to the students that for the synthesis of starch, light is necessary.

Stomata in Lower Epidermis of leaf, Biology std 10 to 12

To study the stomata present in the epidermis of leaf by preparing a temporary slide.

AIM :   To study the stomata present in the epidermis of leaf by preparing a temporary slide.

PRINCIPLE :  As the lower epidermis is not directly exposed to sunlight it contains more number of stomata. This reduces the rate of transpiration.

MATERIALS :  Leaf of Hibiscus, Nagervel (betel leaves) or Maize, slides, forceps, scalpel or blade, Microscope

Lower and Upper Epidermis of Nagarvel leaf.

Scratch of Nagarvel leaf on Lower epidermis

Stomata view in Microscope.

Stomata viewed in Microscope

Enlarge view of  stomata.

Result

Maximum number of stomata are visible as the lower epidermis has more number of stomata. In Hibiscus and Nagarvel the guard cells of stomata are been shaped while in Maize they are dumb-bell shaped.

Conclusion :

By this method stomata can be seen and counted under the microscope.

Application :

This is an easy method to show the stomata to the students.

ISOTOPES AND RADIO-ISOTOPES Science for 8 to 12

Isotopes : 
 Atoms of a given element, have the same atomic number, that is they contain the same number of protons. However, they may contain different numbers of neutrons. They correspond to the same element and are chemically indistinguishable; they have different mass numbers 
(Iso means same, tope means same place; they occupy the same place in the periodic table).

Therefore atoms of the same element having same number of protons 
(atomic number but different number of neutrons (different mass numbers), are called isotopes. Isotopes may be naturally occurring or artificially made.

Example : Normal hydrogen (protium) 1H1 deuterium 1H2 and tritium 1H3 are the isotopes of hydrogen. 6C11, 6C12 and 6C14 are the isotopes of carbon. Uranium has two isotopes namely 92U235 and 92U238.

Radio-istopes : The term radio-isotope is the shortened from of radioactive isotope. If the isotope of an element is radioactive, then the isotope is called. radio-isotope, referred to as radio-nuclide. At least one radio-isotope of every element is available. Over a thousand of them can be made artificially, mostly in nuclear reactors using slow neutrons as bombarding particles.

Examples : Cobalt-60 an isotope of cobalt is radioactive; It is usually refereed to as radio-cobalt. Radio-iodine (I131), radio-iron (Fe59) radio-sodium (Na24), radio-phosphorous (P30), radio-cobalt (Co60), radio-sulphur (S35) and radio-carbon (C14) are some of the radio-isotopes.

Uses of Radio – Isotopes : Radio-isotopes find applications is various fields, some are listed below.

Radio-phosphorous is used in agriculture to determine the kind of phosphate required for a given soil and crop.

Radio-iodine is used in the treatment of overactive thyroid glands and radio-cobalt in the treatment of cancer, Radio-sodium is used to study the action of medicines.

Radio-cobalt or radio-iridium is used in industry to check machine parts.

Radio-carbon is used to estimate the age of fossils and archaeological specimens.

POINTS TO REMEMBER

 Spontaneous disintegration of certain unstable atomic nuclei with the emission of certain radiations is called radioactivity.

 Becquerel rays are the radiations emitted by radioactive elements.

 The elements from atomic number 81 to 92 are found to be radioactive.

 The radioactive radiations are alpha (alpha) particles, beta (beta) rays and gamma (Gama) radiations.

  (alpha) - particles are nothing but helium nuclei, 
- rays are stream of electrons and 
- radiations are high energy photons.


 The changing of one element into another is known as transmutation. Original atom is parent atom and the new atom produced is the daughter atom.

 Half life of a radioactive element is the time taken by a radioactive sample of that element, to get reduced to half its mass.

 Half life varies from microseconds to billions of years.

 The phenomenon by which radioactivity is induced in an element, is called Induced radioactivity or artificial 

radioactivity.

 When a stable aluminum atom is bombarded by (alpha) particles it becomes radio phosphorus.

Atoms of the same element having same number of protons (atomic number) but different number of neutrons (different mass number) are called isotopes.

Isotopes of Hydrogen are Normal Hydrogen (protium) (1H1), Deuterium (1H2) and Tritium (1H3)

Isotopes of Carbon are 6C11, 6C13, and 6C16,

Isotopes of Uranium are 92U235 and 92U238

It the isotope of an element is radioactive, then the isotope is called radio isotope, referred to as radio nuclide. Radio nuclides are manufactured in nuclear reactors.

INDUCED RADIOACTIVITY science for 8 to 12

The phenomenon by which radioactivity is induced in an element, is called induced radioactivity or artificial radioactivity.

When a stable nucleus is bombarded with a high energy particle, it gets changed into another which is often radioactive. For example, when aluminum is bombarded by a (alpha) particles, it produces radio-phosphorus.

15P30 which is radioactive with a half life about 3 minutes, decays to a stable isotope of silicon by emitting a positron (positive electron) which has the same mass as electron, but positive charge.

Curie Joliot and her husband Frederick. Joliot were the first to discover induced radioactivity in 1934. They were awarded 1934. Nobel prize in chemistry. They bombarded elements aluminium and boron with a particles. They observed that the targets continued to emit radiations even after the removal of the a source. The radiations consisted of positrons.