There are following four major groups of microorganisms:
(i)   Bacteria
(ii)   Fungi
(iii)   Protozoa
(iv) Algae.
In addition viruses are also considered as fifth group of microorganisms.

• Winnowing is the process of separating grains from chaff.
• Threshing is the process of loosening edible part of grain from husk and straw to which it is attached.

The major gas that contributes to absorption of heat is carbon dioxide. Other greenhouse gases are methane, nitrous oxides, CFCs, and ozone.

Harmful effects of microorganisms:

1. Bacteria: Causes various diseases such as typhoid, diarrhea, and cholera.
2. Fungi: Causes a large number of diseases in plants and in animals such as rust diseases in plants, fruit rot in apple, red rot in sugar cane and ring worm disease in human beings.
3. Algae: Algal boom in water (rapid growth of algae) causes poisonous effect after they die, which in turn results in the death of aquatic organisms.
4. Protozoa: Causes Amoebic dysentery, pyorrhoea and sleeping sickness etc.
5. Virus: Cause small fox, common cold, influenza, herpes, hepatitis, polio and rabies.

Mitosis

• Mitosis is a continuum of changes but biologists like break down the stages of mitosis into four main stages, prophase, metaphase, anaphase and telophase.
• The focus in this class is on an understanding of the process and not a memorization of phases.
• The only phase name you will need to remember is metaphase.
• In mitosis the nuclear membrane is broken down, spindle fibers (microtubules) attach to the chromatids at the centromere and pull apart the chromatids.
• When the chromatids reach separate ends of the cells the spindle fibers disintegrate and a nuclear membrane rebuilds around the chromosomes making two nuclei.
• Each nucleus is identical to the original nucleus as it was in G1.

Meiosis

• Meiosis is the form of nuclear cell division that results in daughter cells that have one half the chromosome numbers as the original cell.
• In organisms that are diploid, the end result is cells that are haploid. Each daughter cell gets one complete set of chromosomes, i.e., one of each homologous pair of chromosomes.
• In humans this means the chromosome number is reduced from 46 to 23.
• The only cells that undergo meiosis will become sperm or eggs.
• The joining together of a sperm and egg during fertilization returns the chromosomes number to 46.
• Cells that undergo meiosis go through the cell cycle including the S phase so begin the process with chromosomes that consist of two chromatids just as in mitosis.
• Meiosis consists of meiosis I and meiosis II. In meiosis I homologous chromosomes are separated into different nuclei.

Substances are classified into two types. They are,

Pure Substance:  A substance which is made of one kind of particle.
Examples - iron, aluminium, silver and gold.

Mixtures:  A substance which contains two or more different particles is known as mixtures.
Example: Salt solution is made up of two components, salt and water. Therefore,salt solution is a mixture.

Jute fiber

• Jute fiber is used  for making carpets,gunny bags,ropes and bags.
• Source of earning money.
• Used as a packing material.

Cotton

• Apparel - Wide range of wearing apparel: blouses, shirts, dresses, childrenswear, active wear, separates, swimwear, suits, jackets, skirts, pants, sweaters, hosiery, neckwear.
• Home Fashion - curtains, draperies, bedspreads, comforters, throws, sheets, towels, table cloths, table mats, napkins

A main pipeline is laid in the field.Perpendicular pipes having rotating nozzles at the top are joined to the main pipelines at regular intervals.When water from a tube-well is allowed to flow through the main pipelines under pressure with the help of a pump,it escapes from the rotating nozzles.This water gets sprinkled on the crop plants as if it is raining.
Advantages
1) It is more useful for the uneven land where sufficient water is not available.
2) It is very useful for sandy soil.

The process of conversion of atmospheric nitrogen into nitrogenous compounds and making it available for plants is called as nitrogen fixation. The organisms which fix nitrogen to plants are called as nitrogen fixers. Microorganisms in the soil convert atmospheric nitrogen into ammonium compounds, thereby enabling the survival of plants and animals.
 

• Microorganisms make up a large part of the planet’s living material and play a major role in maintaining the Earth’s ecosystem.
• Microorganisms are divided into seven types: bacteria, archaea, protozoa, algae, fungi, viruses, and multicellular animal parasites ( helminths ).