Atom And Molecule


An atom is the smallest unit into which matter can be divided without the release of electrically charged particles.

It also is the smallest unit of matter that has the characteristic properties of a chemical element.

The atom is the basic building block of all matter.

Atoms are very small, they are smaller than anything that we can imagine or compare with.

More than millions of atoms when stacked would make a layer barely as thick as a sheet of paper.

Most of the atom is empty space.

The rest consists of a positively charged nucleus of protons and neutrons surrounded by a cloud of negatively charged electrons.


Atomic mass

Atomic mass is the average mass of atoms of an element, calculated using the relative abundance of isotopes in a naturally-occurring element.

Atomic mass indicates the size of an atom.

Although the mass is the sum of all the protons, neutrons and electrons in an atom.


A molecule is in general a group of two or more atoms that are chemically bonded together, that is tightly held together by attractive forces.

A molecule can be defined as the smallest particle of an element or a compound that is capable of an independent existence and shows all the properties of that substance.

Atoms of the same element or of different elements can join together to form molecules.



Compounds composed of metals and non-metals contains charged species. The charged species are known as Ions.

An ion is a charged particle and can be negatively or positively charged.

Negatively charged ion is called an ‘anion’ and the positively charged ion, a ‘cation’.

A group of atoms carrying a charge is known as a polyatomic ion.

BIOLOGY: The Living World


Characteristics of Living Organisms : Growth, reproduction, metabolism, cellular organization, consciousness (ability to sense environment), self-replicating and self regulation.
• Reproduction and growth are NOT defining properties.
• Metabolism, cellular organization and consciousness are defining properties.


Term used to refer to the number of varieties of plant and animals on earth.
Nomenclature: standardize the naming of living organism such that a particular organism is known by the name all over the world.
Identification: nomenclature or naming is only possible when the organism is described correctly and we known to what organism the name is attached to.
Need for classification: To organize the vast number of plants and animals into categories that could be named, remembered, studied and understood.

Rules for Nomenclature

1.Latinized names are used, written in italics
2.First word represents the genus, second word is species name.
3.Printed in italics; if handwritten then underline separately.
4.First word starts with capital letter while species name written in small letter.

ICBN: International Code of Botanical Nomenclature (for giving scientific name to plants.)

ICZN: International Code of Zoological Nomenclature (for giving scientific name to animals.)

Taxonomy: Study of principles and procedures of classification.
Binomial Nomenclature: Given by Carolus Linnaeus. Each scientific name has two components – Generic name + Specific epithet.
Systematics: It deals with classification of organisms based on their diversities and relationships among them. Term was proposed by Carolus Linnaeus who wrote ‘Systema Naturae’.

Taxonomic Hierarchy: Arrangement of various steps (categories or taxa Species → Genus → Family → Order → Class → Phylum (for animals) /Division (for plants) Kingdom→


All the members that can interbreed among themselves and can produce fertile offsprings are the members of same species. This is the bio-logical concept of species proposed by Mayer.
Three Domains of Life: Proposed by Carl Woese in 1990 who also proposed the six kingdom classification for living organisms. The three Do-mains are Archaea, Eubacteria and Eukarya.



Storehouse of dried, pressed and preserved plant specimen on sheets.
Botanical Garden: Collection of living plants for reference.
Taxonomical aids: Zoological Park (Places where wild animals are kept in protected environment.)

• Keys (Used for identification of plant and animals on the basis of similarities and dissimilarities.)
• Fauna: (Index to animal species found in a particular area)
• Flora (Index to plant species found in a particular area.)
• Manuals (Provide information for identification of name of species in an area.)
• Monograph (Contain information on one taxon.)


Fibers And Plastics

Fibers and fabrics play a large role in everyday applications. A fiber is a hair-like strand of material. They are the smallest visible unit of a fabric and are denoted by being extremely long in relation to their width (at least 100 times longer than it is wide). Fibers can be spun into yarn and made into fabrics.

Synthetic fibers are a subset of the larger area of textiles. Textiles can be natural or synthetic. Natural fibers include cotton, fur, wool, etc. Regenerated fibers are natural materials that have been processed into a fiber structure. Regenerated fibers such as cellulose and wood pulp are used to make materials such as rayon and acetate. Synthetic fibers are man made from chemicals. They are generally based on polymers and are stronger than natural and regenerated fibers



These are the most widely used semisynthetic fibres. They are derived from cellulose and are available in three different varieties— viscose, cuprammonium (or cupro) and acetate rayons.



The first synthetic fibre obtained was of this class. Polymers obtained by the reaction between certain sets of organic (carbon-containing) compounds form a melt which can be spun into filaments. The special property of these filaments is that they can be stretched several times their original length. Terylene and Dacron belong to this class of synthetic fibres. Terylene is used to make clothes. In general, polyesters are used to make textiles, bottles and insulating tapes.




Polyamides (nylons):

Nylon 6 and nylon 6, 6 are the most important fibres of this class. Nylon 6 is made of an organic compound which contains six carbon atoms. Nylon 6, 6 is made of a more complicated monomer. Nylon was first made in 1935.


It was intended to be a substitute for silk and was used in place of silk in parachutes in 1941, when the USA entered World War II. Nylon is very suitable for women’s wear. Having a high tensile strength, nylon is also used for making ropes.




Acrylic fibres are a substitute for natural wool. These polymers decompose without melting. So, they are dissolved in a suitable solvent and the solution is forced through spinnerets to obtain filaments. The filaments can be cut into staples and the staples spun into yarns.
Acrylic fibres are crimpy (i.e., wavy) and not straight like polyester or nylon fibres. So acrylic yarns appear to be bulky and compete with wool. They are generally used to make knitwear, upholstery and artificial furs.





Materials that can be reshaped (remolded) by applying heat and pressure. Most plastics are made from synthetic resins (polymers) through the industrial process of polymerization. Two main types of plastics are thermoplastics and thermosets.







Exponents rules


Exponents are shorthand for repeated multiplication of the same thing by itself. For instance, the shorthand for multiplying three copies of the number 5 is shown on the right-hand side of the “equals” sign in (5)(5)(5) = 53. The “exponent”, being 3 in this example, stands for however many times the value is being multiplied. The thing that’s being multiplied, being 5 in this example, is called the “base”.
This process of using exponents is called “raising to a power”, where the exponent is the “power”. The expression “53” is pronounced as “five, raised to the third power” or “five to the third”.




The Cell,(comes from Latin word cella,meaning “small room”) is the smallest unit of life. It is basic structural,functional, and biological unit of all living organisms.
Cell was discovered by Robert Hooke in 1665.
Cells are often called the “building blocks of life”.
All plants and animals are made of cells.
Organisms are classified as Unicellular (consisting of single cell,such as bacteria) and Multicellular (consisting of multiple cells,such as Plants and Animals).
Number of cells are varies from species to species.Human contains more than 10 trillion cells.
Most of cells are visible only under microscope.

Types of cells
There are two types of cells:
Prokaryotic cells: Single celled organisms.
Doesn’t contains Nucleus.
Eukaryotic cells: Single or multi cellular organisms.
Contains Nucleus.

Prokaryotic cells
The first form of life on Earth.
Prokaryotic cell is a unicellular organism lacking membrane bound organelles.
Most of prokaryotic cells are unicellular.They are generally small in size.
There Nucleur region is not well defined as they lack a Nucleus but it is known as Nucleoid.

Eukaryotic cells
Eukaryot are those organisms whose cells have a Nucleus and other organelles enclosed within membrane.
Eukaryotic organisms may be unicellular or multi-cellular and only Eukaryotes form multi-cellular organisms consists of many kinds of tissue made up of different types of cells.
They are generally larger in size.
Plants and animals cells are Eukaryotic cells.
Contains more than one chromosomes.


All cells posses DNA except for red blood cells.



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A microprocessor is a computer processor which incorporates the functions of a computer’s central processing unit (CPU) on a single integrated circuit (IC), or at most a few integrated circuits.

The first use of the term “microprocessor” is attributed to Viatron Computer Systems describing the custom integrated circuit used in their System 21 small computer system announced in 1968. The microprocessor, also known as the Central Processing Unit (CPU), is the brain of all computers and many household and electronic devices.

The computer you are using to read this page uses a microprocessor to do its work. The microprocessor is the heart of any normal computer, whether it is a desktop machine, a server or a laptop. The microprocessor you are using might be a Pentium, a K6, a PowerPC, a Sparc or any of the many other brands and types of microprocessors, but they all do approximately the same thing in approximately the same way.


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How Microprocessor work

A microprocessor executes a collection of machine instructions that tell the processor what to do. Based on the instructions, a microprocessor does three basic things:

A microprocessor can make decisions and jump to a new set of instructions based on those decisions.

2. Using its ALU (Arithmetic/Logic Unit), a microprocessor can perform mathematical operations like addition, subtraction, multiplication and division. Modern microprocessors contain complete floating point processors that can perform extremely sophisticated operations on large floating point numbers.

3.A microprocessor can move data from one memory location to another.

Crops and production (II)


Manure is an organic substance. Manure is made by decomposing organic matter like animal waste and plant residue.
To prepare manure, farmers dump animal wastes like cow dung and plant wastes like hay and leaves in pits at open places. These wastes are decomposed by micro-organisms and get converted into manure.


1. Manure makes the soil porous and increases the water holding capacity of soil
2. It improves the texture of the soil.
3. Manure increases the number of useful microbes in the soil. Hence it is considered better than fertilizers.


Fertilizers are inorganic salts made in factories.


1. Fertilizers are rich in a specific plant nutrient such as nitrogen, phosphorous or potassium
2. Fertilizers are more soluble in water and can be quickly absorbed by plants.


1.Excessive use of chemical fertilisers reduces soil fertility.
2. Fertilisers reduce porous nature of soil which leads to water logging.
3.When fertilisers are washed away by rain water, it leads to water pollution.

Advantages of Manure over fertilizers

When compared, organic manure is more desirable and effective than fertilisers. Because:
1. Manure increases the soil capacity allowing to hold it water in large quantity.
2. The interchange of gases becomes easy since manure has made the soil penetrable.
3. The number of friendly microorganisms are increased.
4. The smoothness of the soil has also been increased due to addition of manure.


IRRIGATION:-  is the method in which a controlled amount of water is supplied to plants at regular intervals for agriculture. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall. Additionally, irrigation also has a few other uses in crop production, which include protecting plants against frost,[1] suppressing weed growth in grain fields[2] and preventing soil consolidation.[3] In contrast, agriculture that relies only on direct rainfall is referred to as rain-fed or dry land farming


Traditional methods:-

irrigation often include pulley systems that are used to deliver water to soil, vegetation, flowers, and/or other forms of plant life. For many farmers who can’t afford expensive spray systems that are pre-timed for near-perfect results, lower-priced, traditional methods of irrigation, such as ra-hats, chain pumps, or lever systems (also known as Dhe Kli) can be very cost-effective. Here is a look at the most common methods of low-tech irrigation:

Pulley Systems

• Pulleys are used to carry buckets of water where they are needed. Much like clotheslines that use pulleys to move clothes nearer or further away, pulley systems for irrigation are designed to cut down on the amount of manual labour needed to take care of gardens or farmland. Since pulleys automate part of the process, they are a cheap and useful way to carry water to plants and soil. Pulleys must be installed aboveground – they may be tied to stakes that are buried in the earth – strong rope will hold the pulley-based irrigation system together.

Chain Pumps

• These ancient Chinese irrigation systems use round metal discs and a long loop of metal chain to water soil and plants. Each metal disc runs through a pool of liquid, and each disc collects some water during this process. When the chain is pulled, the metal disc rises up to the top, and the water held inside pours out, hydrating the earth and flora. This low-cost method of traditional irrigation has been practised for centuries.

Lever Systems

• Lever systems allow the user to control the speed of irrigation by choosing slow, medium or fast water flow; however, the lever system method is not as ancient, or inexpensive, as other methods mentioned here.

Traditional irrigation systems allow farmers or hobbyists to keep their plants and soil moist, which creates the right atmosphere for the growth of healthy plants.

MODERN METHODS of irrigation help save water. They are given below:

This system is more useful on uneven land, having fewer water supplies. In this method,water is supplied using pipes to one or more central locations within the field. When water is allowed to flow under high pressure with the help of a pump, it gets sprinkled on the crops.


In this system , water delivered at or near the roots of plants , drop by drop . This is the most efficient method of irrigation as there is no wastage of water at all. This method is important in areas where water availability is poor.

The Weed Problem

Weeds grow in gardens, whether we like it or not. They compete with plants and lawn grass for water and nutrients and they grow everywhere, making the garden less attractive. To solve this problem, they must be removed.
However, for various reasons, weeds often grow back. Here are some of the most common reasons:
• They were not removed completely and part of their roots stayed in the soil. The left-over roots allow them to grow again.
• The garden is surrounded by woods or non-landscaped areas that contain a lot of weeds, and their seeds get carried by wind or birds to residential yards.
• If they were not completely removed (all the weeds and all their roots), this makes it easier for them to return.
• They might reappear because the lawn is not dense enough and the empty spots invite weeds to settle down and spread.

Removing Weeds

Digging out plants: Plants with bulbs, tubers and corms must be completely removed from the soil by digging out. Often these plants will reproduce from broken off pieces.
• You will need to prepare the area by removing as much ground vegetation as possible (such as mulch or ground debris)
• Using a small trowel, dig a narrow channel next to the stem until you reach the main bulb, then dig the main bulb up.
• Check the soil for any adjoining or loose bulbets. These must also be removed with a substantial amount of soil and bagged.
• Follow up on a regular basis.


This technique is useful for weeds such as asparagus fern, which have their growing points below the surface of the soil. (corms, rhizomes or tufted fibrous root systems).
• Grasp the leaves or stems of the plant and hold them firmly so that the base of the plant is visible. Any weeds with sharp leaves or stems should be cut back first.
• Insert a knife close to the base of the plant at an angle, with the tip well under the root system.
• Cut through the roots close to the base of the plant. Make sure that the hard crown or base of the plant where the roots begin is completely removed. It may require several cuts.
• Hang the crowned plant matter up off the ground.
• Follow up on a regular basis.

Hand pulling:

This requires holding the plant stem as close as possible to the base of the plant. Gently tug the plant. This will loosen the soil and allow the plant to come free. The plant may be hung up off the ground or piled in a heap.
Winding up: This process is suitable for plants with surface or climbing runners such as Morning glory.
• You need to locate a runner, gently pull it along the ground towards you. Roll the runners up for easy removal. Continue doing this until all the runners have been rolled up. Small fibrous roots growing from the runners can be cut with a knife.
• You should locate the main root system whilst removing the runners. When you do, remove it manually.
• Do not leave any bits of stem or large roots, as these may reshoot.
• Bag or compost the runners/roots.
• Follow up on a regular basis.



is the process of gathering a ripe crop from the fields. Reaping is the cutting of grain or pulse for harvest, typically using a scythe, sickle, or reaper. On smaller farms with minimal mechanization, harvesting is the most labor-intensive activity of the growing season. On large mechanized farms, harvesting utilizes the most expensive and sophisticated farm machinery, such as the combine harvester. The term “harvesting” in general usage may include immediate postharvest handling, including cleaning, sorting, packing, and cooling.
• The completion of harvesting marks the end of the growing season, or the growing cycle for a particular crop, and the social importance of this event makes it the focus of seasonal celebrations such as harvest festivals, found in many religions


Food storage

allows food to be eaten for some time (typically weeks to months) after harvest rather than solely immediately. It is both a traditional domestic skill and, in the form of food logistics, an important industrial and commercial activity. Food preservation, storage, and transport, including timely delivery to consumers, are important to food security, especially for the majority of people throughout the world who rely on others to produce their food. Food is stored by almost every human society and by many animals. Storing of food has several main purposes:
• Storage of harvested and processed plant and animal food products for distribution to consumers

• Enabling a better balanced diet throughout the year
• Reducing kitchen waste by preserving unused or uneaten food for later use
• Preserving pantry food, such as spices or dry ingredients like rice and flour, for eventual use in cooking
• Preparedness for catastrophes, emergencies and periods of food scarcity or famine
• Religious reasons (Example: LDS Church leaders instruct church members to store food)
• Protection from animals or theft


Animal source foods

Animal source foods : include many food item that comes from an animal source such as meat, milk, eggs, cheese and yogurt. Many individuals do not consume or consume little by either personal choice or necessity as may not be accessible or available to these people.