Science World

A study blog! Subjects: Physics, Chemistry and Biology.

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Nomenclature Of Organisms

Nomenclature refers to naming of living organisms. For plants, scientific names are based on ICBN (International Code for Botanical Nomenclature) and for animals, they are based on ICZN (International Code for Zoological Nomenclature).

Binomial Nomenclature by Carolus Linnaeus

Each name must have two components - Generic name and the Specific epithet. For example: Mangifera indica for mango.

Universal Rules of Nomenclature

Biological names are generally in Latin and written in italics. They are latinised or derived from Latin irrespective of their origin.

The first word represents genus while the second represents species.

When handwritten, both words have to be separately underlined.

The first word, denoting the genus, starts with a capital letter while all else is in small letters.For example: Panthera leo for lion.

Name of the scientist appears after the specific epithet in abbreviated form. For example: Mangifera indica Linn.

Toutonym

Both the genus and species name are the same. For example: Ratus ratus for rat.

NOTE: Nomenclature comes under the branch of study called Systematics.

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What is living?

When we talk of living many distinct features come to mind like growth, reproduction or metabolism. Lets us try to come up with a definition of ‘living’ by looking at these features briefly:

Growth: Increase in mass or number of individuals is termed as growth. But growth cannot be taken as a defining feature of the because specific conditions have to be explained first so that it contains all of the living organisms.

Reproduction: Although it is an all-inclusive characteristic of the living there are those organisms which can not reproduce(for example: mules, sterile worker bees, etc.). Hence, it too can’t be taken as a defining property. 

Metabolism: All of the reactions (anabolic and catabolic) occurring in our body, is metabolism. But reactions performed in the labs is neither living nor non-living.

Cellular organisation: It is a defining feature of life forms. no non-living object has cells.

Consciousness: Each and everyone of the organism, from simple to the most complex, can sense and respond to their surrounding. All organisms are ‘aware’ of their environment. Human beings are the only organisms having self-consciousness. Thus, this becomes a defining property of living organisms.

Thus, summing up, we came with the following defining of living:

Living organisms are self-replicating, evolving and self-regulating interactive systems capable of responding to external stimuli.

But when it comes to human beings, living state becomes all the more difficult to define. Patients in coma, supported by machines replacing heart and lungs, are those living or non-living?

Share your thoughts in the comments below, I would love to hear them!

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Stoichiometry

The word stoichiometry has been derived from two Greek words: stoicheion- element and metron- measure.

Thus, stoichiometry deals with the calculation of mass/volume of reactants and products in a chemical reaction. 

Solving these problems:

The easiest approach to solve such problems involves the following steps:

Write down the balanced chemical equation.

Write the relative number of moles and relative masses of the reactants and products below their formulae

In case of a gaseous substance, write down 22.4 litres at STP below the formula in place of 1 mole

Calculate the asked quantity by unitary method

Note that if the reaction takes place in solution, the given molarity/normality must be converted into moles/grams.

Limiting Reagent

The reactant which is present in lesser amount ( in moles) is called the limiting reagent because it gets consumed early and stops the reaction to proceed further. Remember to convert the given amount into moles to identify the limiting reagent.

You can ask any doubts regarding this concept in the ask mail! Hope you found it helpful.

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Mole Concept

Mole is a Latin word meaning "huge pile" of materials.

As atoms and molecules are very small and their number is very large even in a little amount of substance, the mole concept was introduced.

According to the National Institute of Standards and Technology (NIST), the definition of the mole :

The mole is the amount of a substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon-12; its symbol is "mol." When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.(source)

Basically, one mole is that amount of substance having Avogadro’s number of atoms/ molecules. 

Avogadro’s number = 6.022 × 10 23  

Or, one mole is the amount of a substance that contains as many particles as there are atoms in exactly 12 grams of the c-12 isotope.

Uses :

The mole concept finds many uses in the calculation of

the actual mass of a single atom/molecule

the number of atoms/molecules in a given substance

the number of atoms/molecules in a given volume of gas

the sizes of individual atoms/molecules