Category Science

It is true that a red flag agitates a bull?

    It is generally believed that anything red makes a bull angry and causes it to attack. Therefore, the bull fighter has to have a bright red cape and use a red cloth.

            The truth is that if the bull fighter had any other coloured cloth he would be able to accomplish the same reaction from the bull. Bulls are colouring blind.

            Many experiments were conducted where they used white cloth and got the bulls to behave in the same way as with the red cloth.

            The reason is the movement of the cap and not colour of the cloth brings about the reaction in the bull. Anything waved in front of a bull would excite it.

What imparts fragrance to flowers, fruits and species?

            Fragrance in flowers, fruits and spices is due to a wide variety of essential oils (volatile liquids) present in them. They are mostly insoluble in water but freely soluble in alcohol, ether and vegetable mineral oils. They are not oily to touch.

            The oils may be grouped into five classes, according to their chemical structure alcohols, esters, aldehydes, ketones, lactones and oxides.

            The fragrance may be in leaves (as in sage, thyme and mint), in bark (as in cinnamon and cassia), in wood (as in cedar and sandalwood), in flower petals (as in rose and violet), in seeds (as in anise and caraway), in roots, in fruit rind (as in orange) or in resinous gums secreted from the tree (as in camphor and myrrh).

            The oils are formed generally in the green parts of the plant, and with plant maturity, transported to other tissues particularly to flowering shoots. The exact function of an essential oil in a plant is unknown – it may be to attract insects for pollination, or to repel harmful insects, or it may simply be a metabolic intermediate.

            Dr. Palaniappan of Pudukkottai, TN, writes: aroma associated with cinnamon, vanilla and cuminum are due to carbonyl group of aldehydes and ketone. Aromatic aldehydes such as cinnamaldehyde and vanillin are found in cinnamon and vanilla respectively. Cumaldehyde (p-isopropyl benzaldehyde) is found in the volatile oil of cuminum. Aliphatic esters namely methyl n-butyrate and ethyl n-butyrate are found in apples and pineapples. Benzyl acetate, an aromatic ester imparts fragrance to jasmine. Spices and condiments contain monoterpenoids with two isoprene units and sesquiterpenoids with three isoprene units. Eugenol in clove, linalool in coriander, zingiberene in zingiber, menthol in mint, cineol in cardamom and anethole in feoniculum are a few examples. Sandalwood contains a terpenoid called santol in the wood cells.

Fruits were supposed to attract animals. So what is the point of lemons tasting, so sour? Are there any animals which actually like the taste? Did we breed lemons from ones that were sweeter? Or do an

            Plants use many methods to distribute their seeds and succulent fruits such as lemons are not necessarily designed to be eaten. Many, such as blackberries and plums, are bitter until the seeds are ‘ready, while others, apples and many tropical fruits are designed to encourage pecking by birds, which scatters the seeds. Another group including figs and senna pods encourage animals to eat the fruits without digesting the seeds, allowing the seeds to pass undamaged through the animals, be it a mouse and elephant.

Yet other fruits remain unappetizing to animals until they drop to the ground, where they are eaten or scattered when fully rips or rotten.

Lemons come into this category, though it is possible that monkey, baboons or other animals may be fascinated by the bitterness and attack them earlier, giving  themselves an unexpected dose of vitamin C and, of greater benefit to the tree, subsequently spitting out the pipe. 

            Many citrus trees that are natives of and regions have sour fruits to discourage animals from eating it. The flesh of a lemon is there for three main reasons: to add weight so that it will roll a long way after it falls from the tree. To dissuade foraging animals from eating the seeds before they can develop and to supply water and nutrients as the flesh rots around the germinating seeds. The main aim of any seed is to propagate the species, not to feed the local animals. Animals benefit only as a side effect of plants wanting to use them as a form of transport for their seeds.

            The trouble with citrus fruits is that they have been cultivated for so long that nobody knows what their original seeds dispensers actually were. In cultivation, however, they do seem to be eaten by monkeys. May be monkeys like acid tastes more that more than people do. Many tropical fruits are dispersed by becoming over ripe, falling to the ground and being eaten by animals. May be the acid in citrus fruits was meant to act as a deterrent to these foraging animals  so that the fruits and the seeds the contained were left to grow where fell. 

How do trees reduce air pollution?

            Plants can prevent pollution of environment in many ways. However, the answer is restricted to prevention of air pollution by trees.

            The major components of atmosphere are nitrogen (78.08 per cent) and oxygen (20.95 per cent) (major) with minor components are argon and carbon dioxide (0.0314 per cent) and many trace elements such as neon, helium, nitrous oxide, methane, carbon monoxide, sulphur dioxide, ozone, ammonia and aerosols (colloidal sized particles) are also present.

            The ratio of these components is changing very fast due to increased human activities like fossil fuel burning, afforestation and changes in land use. They result in the liberation of tones of carbon dioxide, carbon monoxide, methane and aerosols into the atmosphere. The server human interference over the last century is said to have strained the buffering capability of nature.

            Trees help reduce the pollution in more than one way. First, they act as sink for carbon dioxide. Through photosynthesis they synthesize carbohydrates using carbon dioxide, water and sunlight. This way thousands of tonnes of carbon dioxide are trapped by the trees. By the same process, trees release oxygen, which is needed by other living organisms. They also help in cooling of the atmosphere by transpiration, a process in which water is given up by plants as vapour. I addition, aerosols and dust particles (components of atmosphere pollution) settle on the dense foliage of trees. Thus trees, especially the tall ones with dense foliage around houses and industrial establishments, reduce aerosol and dust pollution by acting as barriers or curtains.

Why do vegetables such as cucumber, snake gourd and bottle gourd sometimes taste bitter?

   Bitterness is cucumber and other cucurbitaceae vegetable is due to the presence of compounds called cucurbitacins. Chemically these are tetra-cyclic triterpenes having high oxidative levels. They occur in nature as free glucosidesor as complicated mixtures, at high concentrations, in fruits and roots, for example in a wild variety of cucumber called Cucumis hardwikii.

            High temperatures above 92 degrees have been implicated in the increase f bitterness in fruits, although there is no evidence to support this. Conversely more bitter cucumbers are seen growing during the cooler growing season.

Beetroot contains a red colour pigment called betacyanin. Does it aid in the formation of blood cells in any way?

            Betacyanin is a group of phenolic pigment present mainly in eight plant families. Betanin is one type and is present in Beta Vulgaris beetroot. Betanin occurs in hydrolyzed with sugars as betanidin, a reddish pigment in beets.

            Structurally this pigment is not a vitamin or provitamin or a cofactor to act as an extrinsic factor in the formation of blood cells. But recent studies have shown many phenolics and flavonoids present in the plant kingdom have anti-oxidant properties and prevent free radical reactions from taking place in our body.

            Free radical reactions like free oxygen, superoxide, peroxide are one cause for the ageing of cells. These phenolics and flavonoids scavenge the oxidants and prevent the free radical reaction and hence stop the ageing of cells.

            Since Betanin present in beetroots is also a phenolic compound might have these anti-oxidant properties and stop free-radical reaction and prevent ageing of our body cells.