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Why does jasmine bloom only in the night?

Nastic movement is responsible for blossoming of flowers. Usually this movement takes place in a flat plant part oriented relative to the plant body and produced by diffuse stimuli causing disproportionate growth or increased turgor pressue in the tissues of one surface. It normally occurs in leaves and petals which are bilaterally symmetrical.

          Changes in the environment send a signal to the plant and result in a differential growth between the upper and lower surfaces of petals resulting in blossoming of flowers and different conditions.

            In case of jasmine, this response occurs due to stimulus caused by the change over from brightness to darkness.

            As there is more growth on the upper sides (epinastic movement) of the petals, the flower opens. If there is more growth on the lower side of petals the flower closes (hyponastic movement).

Why and how does the sunflower always face the Sun?

Certain flowers such as sunflower are attracted to the sun strongly. They begin the day facing east and then follow the sun. This is because of a phenomenon called phototropism.

         Phototropism is a growth-mediated response of a plant to stimulation by visible light. The response is stimulated by a hormone called auxin present in the stem.

   Auxins promote lengthwise growth of plants. The auxin, beta-indylacetic acid (IAA), is formed either from the amino acid, tryptophan, or from the breakdown of carbohydrates known as glycosides.

They promote growth by acting on the chemical bonds of carbohydrates on the cell wall. In positively phototropic plants when one side of the plant is shaded, greater quantities of auxin are produced on the darker side. This causes that side of the plant to grow fast. In the case of sunflower, the phenomenon is pronounced so as to make the flower turn towards the sun.

Why does the Kurinji flower only once in 12 years?

Before flowering, a plant must attain the ripe-to-flower condition. To attain this condition the plant must complete a period of vegetative growth. Attainment of this condition does not automatically lead to the initiation of flower primordial.

            Certain environmental condition must follow. Temperature and the duration of light and dark periods within the 24 hour cycle are the two important environmental factors that influence the initiation of flower primordial in a plant that has attained ripe-to-flower condition. The response of a plant to this aspect of light is called photoperiodism.

            When appropriate photo period is given to a plant that has attained the ripe-to-flower condition, this metabolism is altered. This results in the formation of flower stimulus, which may be a hormone (florigen).

            When this flower stimulus is translocated to the shoot apex, the vegetative shoot apex is transformed to reproductive shoot apex, which results in the initiation of flower primordium.

            In natural conditions, the period taken to attain the ripe-to-flower condition and the period taken to obtain appropriate photoperiod differ widely among different plant species. Kurinji (Strobilanthes kunthianus) needs a period of 12 years for having to be subjected to a cycle conducive to flowering.

 

What is terminator gene technology? How is it used to help our farmers?

 

 

 

     

      On March 3, 1998, a joint patent (US patent No: 5723765) has been granted to United States Department of Agriculture (USDA) and the Delta and Pine Land Company, Mississippi in the name of ‘Control of Plant Gene Expression’. Mr. Hope Shand, Research Director, Rural Advancement Foundation International (RAFI), christened it as ‘Terminator technology’ as the hybrid seeds containing it do not germinate after one generation.

            The terminator technology is an extremely complex technology in which two gene systems are brought together to stop the normal process of embryo development, leading to the failure of seed germination. The gene systems are: Gene System I (Gene A) and Gene System II (Gene B and C).

            The gene system I consist of a gene ‘A’ which produces the ribosome inactivating protein (RIP), which is lethal to the growing embryo. Gene ‘A’ is linked to a transistently active LEA Promoter, ‘PA’, through a blocking sequence. A recombinase specific excision sequence (LOX sequence) flanks the blocking sequence on either side.

            The gene system II consists of a gene B linked to a promoter, PB the gene B encodes for a recombinase which is specific to the LOX sequence of the gene system I. A third gene C produces a repressor protein which blinds to the promoter PB and prevents the expression of gene B. The gene B can be depressed by exogenous application of tetracycline.

            To develop a variety of seeds with functional terminator system, two cells of the same crop are transferred with the gene system I and II separately. As a result, one transgenic is obtained with unexpressed gene A due to the presence of blocking sequence between gene A and its promoter PA and another transgenic is obtained with gene system II having repressor of gene B. To recombine these two systems into one, the obtained transgenic are hybridized and normal hybrid seeds are obtained. Since the gene A does not express, the seeds obtained remain viable. Upon treatment of the seeds with tetracycline, the antibiotic is absorbed by the seeding tissue. Since tetracycline acts as an inducer of gene B, it depresses the gene and recombinase is produced. The recombinase removes the intervening blocking sequence between gene A and its promoter PA. Thus PA comes in proper orientation with gene A and the gene ready for expression. The promoter specifically expresses during early embryo development. As a result, the seeds germinate normally in that generation and give rise to normal crop and seeds. But the seeds obtained do not germinate as the embryo gets aborted due to expression of gene A. so long as gene B remains repressed in absence of tetracycline, gene A is not expressed leading to production of viable seed.

            There are reports that this technology is presently being incorporated into two crops viz., tobacco and cotton. But it is a matter of time that it can be incorporated into other crops as well. This technology is not yet introduced into our country.

            It is premature to predict its impact on our farmers. However, we can visualize its utility in curbing the spurious practice of selling F2 seeds of a hybrid variety as F1 seed.

 

What makes a cola foam up when you put a pretzel in it?

The cola foaming up when a pretzel is put in it is a physical interaction, not a chemical reaction. It works with other carbonated beverages too. Carbonated beverages when opened and released from pressure or supersaturated solutions of gas with more carbon dioxide dissolved in the beverage than would be possible at normal pressures.

 Left alone for two hours, the drink would slowly lose the gas and go flat. Sodium chloride particles seem to provide an especially good surface for gas to collect on, form bubbles and quickly rise to the surface and escape.

Why does boiled water lose taste?

 

 

 

 

 

 

Naturally occurring water contains quite a few substances dissolved in it. For example, it contains gases such as oxygen and carbon dioxide, sulphates and carbonates of calcium and magnesium, and other elements such as iron depending the nature of the soil. These constitutes impart not only taste but also hardness to the water. Due to boiling, the dissolved gases are released and hardness is removed. Insoluble carbonates and hydroxides are formed which get deposited on the surfaces and the bottom of the vessel as scales. Their separation from water deprives it of its taste.

Does cold water extinguish fire faster than hot water?

 

       

 

 

 

            Cold water extinguishes fire faster. It’s easy availability, non-toxicity, high specific heat, low    boiling point, high latent heat of evaporation, high volume expansion, water to steam, makes it suitable for fire extinguishing.

        In case hot water is used, the heat absorbed from the source (fire), by a definite quantity, to reach its boiling point will be far lesser vis-a-vis the same quantity of cold water. However, the other parameters will remain the same. Colder the water, faster would be the extinction of the fire.

Why are soap bubbles and oil layers coloured?

 Coloured bands on soap bubbles and oil layers are caused by interference of light waves with themselves. Sunlight is a composite of seven colours (violet, indigo, blue, green, yellow, orange and red, in that order) each of which lies in a specific wavelength range. For example, violet light has a wavelength of 380 nanometers (one nanometer is a billionth of a metre) and red, above 600 nm.

Light waves falling on any thin film are partially reflected from the top and bottom surfaces of the film. A wave reflected from the bottom surface has to travel a longer distance than the one reflected from the top. This difference in distance travelled by the waves, called path difference, leads to a difference in the phases of the light waves. (The phase describes the electric and magnetic fields associated with light waves.) This phase difference depends on the thickness of the film at the point of reflection and angle of viewing. If two waves are ‘out of phase’, then they cancel each other (destructive interference) and if they are ‘in phase’ they add up (constructive interference.) Thus the regions of the spectrum (colours) which interfere constructively can be seen whereas those which interfere destructively are lost. Even if there is a slight variation in the thickness of the film, it will be coloured differently. 

How does carbon change into diamond?

 Carbon changes into diamond and graphite in the depths of the earth under high pressure and temperature. The process might have taken millions of years. A French scientist, Moissan, verified this theory by experiment. He heated carbon (as charcoal) and iron together in an electric furnace at 3,500 degrees Celsius. Carbon dissolved in the molten iron and the mass was cooled suddenly by dipping in water. Then it was put in acid. The iron dissolved and the residue was found to contain a few very small diamonds (less than one millimeter in size) and some graphite. These results were confirmed by others too. Today diamonds are mass-produced by this method.

Artificial diamonds have the same structure, density and hardness as natural diamonds, but are very small. They are also opaque to x-rays. Hence they are used mostly for making hard-edged cutting tools and dies and for cutting and polishing natural diamonds, and not for making ornaments.