A bacteriophage is a type of virus that infects bacteria. In fact, the word "bacteriophage" literally means "bacteria eater," because bacteriophages destroy their host cells. Bacteriophages kill bacteria by making them burst or lyse. This happens when the virus binds to the bacteria. A virus infects the bacteria by injecting its genes (DNA or RNA). The phage virus copies itself (reproduces) inside the bacteria.

Classification is the systematic arrangement of animals and plants in groups or categories according to established criteria specifically

These errors are a consequence which can be traced and may arise at any stage of inquiry, viz planning and execution of the survey and collection, processing and analysis of data.
some of the non-sampling errors are:

1. Errors in Data Acquisition It arises from the recording of incorrect responses.
2. Non-response Errors It occurs, if an interviewer is unable to contact a person listed .
3. Sampling Bias It occurs when the sampling plan is such that some members of the target population could not possibly be included.

These errors are a consequence which can be traced and may arise at any stage of inquiry, viz planning and execution of the survey and collection, processing and analysis of data.

The Sampling Error is the difference between the result of studying a sample and the result of the census of the whole population.

The Full form of NSSO is National Sample Survey Office.

A sample is a smaller, manageable version of a larger group. It is a subset containing the characteristics of a larger population.

Scope and importance of Statistics:

1. Statistics and planning: Statistics is indispensable into planning in the modern age which is termed as “the age of planning”. Almost all over the world the govt. are re-storing to planning for economic development.

2. Statistics and economics: Statistical data and techniques of statistical analysis are immensely useful in solving economic problem such as determination of wages and price, time series analysis, demand analysis.

3. Statistics and business: Statistics is an responsible tool of production control. Business executive are relying more and more on statistical techniques for studying the much and desire of the valued customers.

Economic problem arises because of scarcity of resources and unlimited human wants.

(i) Wants are unlimited:

(a) This is a basic fact of human life. Human wants are unlimited.

(b) They are not only unlimited but also grow and multiply very fast. 

(ii) Resources are limited:

(a) The resources to produce goods and services to satisfy human wants are available in limited quantities. Land, labour, capital and entrepreneurship are the basic scare resources.

(b) These resources are available in limited quantities in every economy, big or small, developed or underdeveloped, rich or poor. Some economies may have more of one or two resources but not all the resources. Moreover the resources have alternate uses.

(c) For example, Indian economy has relatively more labour but less capital and land. The U.S. economy has relatively more land but less labour. No economy in the world has all the resources in abundance. (iii) Resources have alternative uses:

(iii) Generally a resource has many alternative uses.

(b) A worker can be employed in a factory, in a school, in a government office, self employed and so on.

(c) Like this, nearly all resources have alternative uses. But the problem is that which resource should be put to which use.

So, the economy has to decide as to how to utilise theser resources and which will be the best alternative for utilising the resources so that wants are satisfied to the maximum and the economy moves towards solving their central problems.

It refers to a situation in which the supply of a good is lesser  in relation to its demand.

• Booting.
• Memory Management.
• Loading and Execution.
• Data Security.
• Disk Management.
• Process Management.
• Device Controlling.
• Printing Controlling.