If you cannot find what you are looking for. Please visit our sitemap

Tuesday, 18 August 2015

Question Answers Related to Networking Management and Administration:

Question Answers Related to Networking Management and Administration:

Q: What is Access list and its types?
Access list are basically a set of commands, grouped together by a number or name that is used to filter traffic entering or leaving an interface. An access control list (ACL) is a table that tells a computer operating system which access rights each user has to a particular system object, such as a file directory or individual file. Each object has a security attribute that identifies its access control list.
Types of Access list:
Standard ACLs provides basic packet filtering in which match is based on only source IP address.The Basic Filtering process will be only carried through it.
Extended ACLs allows filtering not only on source address but also on destination addresses, protocol type and source and destination port numbers.There needed ACL's which the permit and deny of needed will be carried on this.

Q: Differentiate between SNMP V1, V2 and V3?
Ans: SNMPv1:
SNMPv1 was the first version of SNMP. Although it accomplished its goal of being an open, standard protocol, it was found to be lacking in key areas for certain applications. Later versions have addressed many of these problems.

SNMPv2c is a sub-version of SNMPv2. Its key advantage over previous versions is the Inform command. Unlike Traps, which are simply received by a manager, Informs are positively acknowledged with a response message. If a manager does not reply to an Inform, the SNMP agent will resend the Inform.
Other advantages include:
•    improved error handling
•    improved SET commands

SNMPv3 is the newest version of SNMP. Its primary feature is enhanced security.The "EngineID" Identifier in SNMPv3 uniquely identifies each SNMP entity. Conflicts can occur if two SNMP entities have duplicate Engine ID’s. The EngineID is used to generate the key for authenticated messages.

Q: Differentiate between Manager and Agent?
Ans: Manager: The manager sends a Get or GetNext to read a variable or variables and the agent's response contains the requested information if managed. The manager sends a Set to change a variable or variables and the agent's response confirms the change if allowed. The agent sends a Trap when a specific event occurs
Agent: The agent sends a Trap when a specific event occurs.

Q: Differentiate between MIB And SMI?
Ans: Management information base (MIB)
is a database used for managing the entities in a communications network. Most often associated with the Simple Network Management Protocol (SNMP), the term is also used more generically in contexts such as in OSI/ISO Network management model. While intended to refer to the complete collection of management information available on an entity, it is often used to refer to a particular subset, more correctly referred to as MIB-module.

SMI: The Structure of Management Information defines precisely how managed objects are named and specifies their associated data-types. SMI is based on object definition language called Abstract Syntax Notation One (ASN.1).

Q: What is Firewall? What are the available fireball in market?
In computing, a firewall is a network security system that controls the incoming and outgoing network traffic based on an applied rule set. A firewall typically establishes a barrier between a trusted, secure internal network and another network (e.g., the Internet) that is assumed not to be secure and trusted.
Type in market
Communication Information       Partial    Partial    Yes
Communication-derived State    No        Partial    Yes
Application-derived State          No           Yes     Yes
Information Manipulation           

Q: What is RFC?
A Request for Comments (RFC) is a publication of the Internet Engineering Task Force (IETF) and the Internet Society, the principal technical development and standards-setting bodies for the Internet.
An RFC is authored by engineers and computer scientists in the form of a memorandum describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems. It is submitted either for peer review or simply to convey new concepts, information, or (occasionally) engineering humor. The IETF adopts some of the proposals published as RFCs as Internet standards.

Q: What function is performed by the "Ping" monitoring tool?
Ans: Ping is used diagnostically to ensure that a host computer the user is trying to reach is actually operating. Ping works by sending an Internet Control Message Protocol (ICMP) Echo Request to a specified interface on the network and waiting for a reply. Ping can be used for troubleshooting to test connectivity and determine response time.

Q: What is RMON monitoring tool?
Ans: Remote Monitoring (RMON) is a standard specification that facilitates the monitoring of network operational activities through the use of remote devices known as monitors or probes. RMON assists network administrators (NA) with efficient network infrastructure control and management.

Q: What is the difference between Public and private IP?
A Private IP address is one used within a local area network. You need one unique address for each machine in the network, and these should be in an approved range which is not accepted on the internet. A public address is the address your network is allocated on the internet to make it possible to connect to other locations. If you use a modem or router with one network cable connected computer, you would have one private address on the computer and one public address on the internet side of the connection.

Public IP address changes every time you log onto the computer, since you are paying for a basic internet service. since there are so many people using the service, each time they log on, they appear in a different place on the internet backbone, thus changing their location. However, if you pay for a dedicated internet service such as a static internet service, you will have a dedicated location on the internet backbone. all websites have this, if they didn't you wouldn't be able to find the page again, because it would move.

Q: What is the difference between share and security permission?
Ans: Share Permission:

Share permissions are the permissions you set for a folder when you share that folder. The share permissions determine the type of access others have to the shared folder across the network. There are three types of share permissions: Full Control, Change, and Read.   
Private Permission:
It hasn't been shared with anyone else besides the owner. Only the file owner and users with “Modify All Data” permission can find and view this file, unless it is in a private library, then only the file owner has access to it.

Q: Write the procedure for server and client to Remote disk access with NFS in Linus?
Ans: The Network File System protocol (NFS) is used when disks need to be shared between Linux servers. Basic configuration is fairly simple, and this chapter will explain all the essential steps.

1-Installing NFS:
RedHat Linux installs nfs by default, and also by default nfs is activated when the system boots. You can determine whether you have nfs installed using the RPM command in conjunction with the grep command to search for all installed nfs package

2-Configuring NFS on The Server:
Both the NFS server and NFS client have to have parts of the NFS package installed and running. The server needs rpcbind, nfs, and nfslock operational, as well as a correctly configured /etc/exports file

3-Starting NFS on the Server:
Configuring an NFS server is straightforward: Use the chkconfig command to configure the required nfs and RPC rpcbind daemons to start at boot. You also should activate NFS file locking to reduce the risk of corrupted data.

4-Starting NFS on the Client:
Three more steps easily configure NFS on the client.Use the chkconfig command to configure the required nfs and RPC rpcbind daemons to start at boot. Activate nfslock to lock the files and reduce the risk of corrupted data.

5-Accessing NFS Server Directories from the Client:
In most cases, users want their NFS directories to be permanently mounted. This requires an entry in the /etc/fstab file in addition to the creation of the mount point directory

6-Activating Modifications To The /etc/exports File:
You can force your system to re-read the /etc/exports file by restarting NFS. In a non production environment, this may cause disruptions when an exported directory suddenly disappears without prior notification to users. Here are some methods you can use to update and activate the file with the least amount of inconvenience to others.

Q: What is the purpose of Active Directory, User Administration, Domain Controller, Additional Domain Controller?
Ans: Active Directory:
Active Directory serves as a central location for network administration and security. It is responsible for authenticating and authorizing all users and computers within a network of Windows domain type, assigning and enforcing security policies for all computers in a network and installing or updating software on network computers.

User Administration: The primary purpose of user administration is to provide information that helps systems make this determination. The central piece of user information that the SAS environment requires is one external account ID for each user. The SAS environment uses its copy of these IDs to establish a unique SAS identity for each connecting user. All of a user's group memberships, role memberships, and permission assignments are ultimately tied to their SAS identity.

Domain Controller: Domain Controller(DC) is a server that responds to security authentication requests (logging in, checking permissions, etc.) within the Windows Server domain. A Domain is a concept introduced in Windows NT whereby a user may be granted access to a number of computer resources with the use of a single username and password combination.

Additional Domain Controller: These additional domain controllers exist to provide fault tolerance. If the PDC fails, then it can be replaced by a BDC. In such circumstances, an administrator promotes a BDC to be the new PDC. BDCs can also authenticate user logon requests - and take some of the authentication load from the PDC.

Written By: Asad Hussain:

Sunday, 16 August 2015

Question Answers Related to Enterprise Application Development or Enterprise Java Beans (EJB).

Question Answers Related to Enterprise Application Development or Enterprise Java Beans (EJB).

Q What you mean by platform independence?
Ans: Platform independence means that the same program works on any platform (operating system) without needing any modification.Software that can run on any hardware platform (PC, Mac, Sun Sparc, etc.) or software platform (Linux, Mac OS, UNIX, Windows, etc.) has a platform independence behavior. In general, programs written in Java language can be executed on practically every platform.

Q What is the purpose of HTML?
Ans: The Hypertext Markup Language (HTML) is a standard for describing the structure and presentation of information via the Internet.
HTML is simply a markup language that instructs the browser how to "paint" the page to the screen. It contains the information to be displayed and instructions about the appearance of the display.

Q Why there is need to use XML in enterprise application?
Ans: The disparate distributed applications need a common platform to communicate with one another. Because XML is not specific to any proprietary platform, it can very well fit in that. XML is not tied to a limited set of tags defined by proprietary vendors. In other words, it contains metadata. It allows each specific industry to develop its own tag sets to meet its unique needs.
XML handles both forward and backward data compatibilities. It is good at describing hierarchical data in a standard way. The data can be specified separately from the structure. The data structure can be defined by using either DTD or XML schema.
XSL is powerful enough for the transformation of data between different applications. It is a language that can transform, filter, and sort XML data, define parts of an XML document, format XML data based on the data value, and output XML data to different forms such as screens, paper, or voice.
XML can be leveraged in many areas of enterprise application development. It can be used for data aggregation and management such as indexing, metadata, and so forth. It also can be used to exchange data among the distributed applications. XML schema provides the necessary elements for describing any kind of structured data.

Q Differentiate between State-full and Stateless Server?
Ans: A state-full server remembers client data (state) from one request to the next. Using a state-full file server, the client can send less data with each request. A state-full server is simpler.

A stateless server keeps no state information. Using a stateless file server, the client must specify complete file names in each request specify location for reading or writing re-authenticate for each request.
On the other hand a stateless server is more robust lost connections can't leave a file in an invalid state rebooting the server does not lose state information rebooting the client does not confuse a stateless server.

Q Define MVC?
Ans: The Model-View-Controller (MVC) pattern separates the modeling of the domain, the presentation, and the actions based on user input into three separate classes.
Model: The model manages the behavior and data of the application domain, responds to requests for information about its state (usually from the view), and responds to instructions to change state (usually from the controller).
View: The view manages the display of information.
Controller: The controller interprets the mouse and keyboard inputs from the user, informing the model and/or the view to change as appropriate.

Q What is the purpose of SOA?
Ans: Service-oriented architecture (SOA) is an approach used to create an architecture based upon the use of services. Services (such as Restful Web services) carry out some small function, such as producing data, validating a customer, or providing simple analytical services.
SOA makes it easier for software components on computers connected over a network to cooperate. Every computer can run any number of services, and each service is built in a way that ensures that the service can exchange information with any other service in the network without human interaction and without the need to make changes to the underlying program itself.

Q Define CMP bean?
Ans: A CMP bean is an entity bean whose state is synchronized with the database automatically. In other words, the bean developer doesn't need to write any explicit database calls into the bean code; the container will automatically synchronize the persistent fields with the database as dictated by the deployer at deployment time.
Q For what purpose application variables are used?
Ans: Application variables are the variables which remain common for the whole application. Their value can be used across the whole application… And they die only when the application stops or probably when they are killed forcibly. The ideal example for these kinds of variables is site counter. We can find out how many people accessed a particular site since the time it went live via application variables and incrementing the same on ever session start.

Q Write the names of all important components of EJB?
Ans: Name of important components of EJB.
  • EJB server(s)
  • EJB container(s)
  • Enterprise Beans
  • EJB clients
  • Other auxiliary systems (e.g. Java Naming and Directory Interface (JNDI) server, Java Transaction Service (JTS) ).

Q Differentiate between XSL and CSS?
Ans: XSL stands for Extensible Style sheet Language. The World Wide Web Consortium (W3C) started to develop XSL because there was a need for an XML-based Style sheet Language. XSL uses XML syntax, i.e., XSL is an XML vocabulary. Unlike CSS, XSL rules do not just apply styles to elements. XSL is a language for transforming an input document to an output document.
XSL = Style Sheets for XML
XSL originally consisted of three parts:
  • XSLT - a language for transforming XML documents
  • XPath - a language for navigating in XML documents
  • XSL-FO - a language for formatting XML documents
CSS stands for Cascading Style Sheets. CSS defines how HTML elements are to be displayed. CSS rules apply style only to html elements. CSS = Style Sheets for HTML.

Q What is RMI? Explain the purpose of its each component with the help of example.
Ans: The RMI (Remote Method Invocation) is an API that provides a mechanism to create distributed application in java. The RMI allows an object to invoke methods on an object running in another JVM. The RMI  provides remote communication between the applications using two objects stub and skeleton.
(1) RMI Server:
RMI Server contains objects whose methods are to be called remotely. It creates remote objects and applies the reference to these objects in the Registry, after that the Registry registers these objects who are going to be called by client remotely.
(2) RMI Client:
The RMI Client gets the reference of one or more remote objects from Registry with the help of object name. Now, it can be invokes the methods on the remote object to access the services of the objects as per the requirement of logic in RMI application. Once the client gets the reference of remote object, the methods in the remote object are invoked just like as the methods of a local object.
(3) RMI Registry:
In the Server side the reference of the object (which is invoked remotely) is applied and after that this reference is set in the RMI registry. When  the Client call the method on this object, it’s not directly call but it call by the reference which is already set in the Registry so first get the object from this reference which is available at RMI Registry then after calls the methods as per the requirement of logic in RMI application.

Q What do you mean by CORBA? Explain its life cycle by giving the name and purpose of each function that it is called in it.
Ans: The Common Object Request Broker Architecture (CORBA) is a standard defined by the Object Management Group (OMG) designed to facilitate the communication of systems that are deployed on diverse platforms. CORBA enables collaboration between systems on different operating systems, programming languages, and computing hardware. CORBA has many of the same design goals as object-oriented programming: encapsulation and reuse. CORBA uses an object-oriented model although the systems that utilize CORBA do not have to be object-oriented. CORBA is an example of the distributed object paradigm.
Life Cycle Service defines services and conventions for creating, deleting, copying and moving objects. Because CORBA-based environments support distributed objects, the Life Cycle Service defines conventions that allow clients to perform life cycle operations on objects in different locations.
A client that wishes to create an object issues a create request on an object supporting the LifeCycleObject interface. The object receiving the request is called the target.
A client that wishes to delete an object, issues a remove request on an object supporting the LifeCycleObject interface. The object receiving the request is called the target.
Move or copy:
A client that wishes to move or copy an object, issues a move/copy request on an object supporting the LifeCycleObject interface. The object receiving the request is called the target.

Q What do you mean by Java Mail API? What advantages are provided by this component in this website development over existing ones?
Ans: The JavaMail API provides a platform-independent and protocol-independent framework to build mail and messaging applications. The JavaMail API provides a set of abstract classes defining objects that comprise a mail system. It is an optional package (standard extension) for reading, composing, and sending electronic messages.
JavaMail provides elements that are used to construct an interface to a messaging system, including system
components and interfaces. While this specification does not define any specific implementation, JavaMail
does include several classes that implement RFC822 and MIME Internet messaging standards. These classes are delivered as part of the JavaMail class package.

Potential advantages include - Java mail is used to create personal mail filter, simple mailing lists and personal mail applications. Java mail also includes the capabilities to add the emailing process to an enterprise application or even to create a full-fledged e-mail client. Many companies in the industry have written new e-mail clients using Java Mail.

Written By: Asad Hussain

Tuesday, 11 August 2015

FSc Notes Biology Part 1 Chapter 14 Transport Definitions

FSc Notes Biology Part 1 Chapter 14 Transport Definitions

Active immunity:
The use of vaccines or antigens, which stimulates the production of antibodies in the body and makes the person immune against the disease or infections, is called active immunity.

Active transport:
The movement of molecules from lower to higher concentration by the expenditure of energy is called active transport.

The attraction of water molecules with the cell wall of the xylem cell is called adhesion. This helps water molecules to move up.

The antibodies are special types of proteins called immunoglobulin that are produce by the body in response of antigen.

It is a serum containing antibodies.

The antitoxin destroys the toxin produced by the invaders. Or these are the chemicals that neutralize the effect of toxins.

Apoplast pathway:
The movement of the ions through the extracellular pathway between the cells walls of the adjacent cells called apoplast pathway.

The blood vessels which carry the oxygenated blood away from the heart to different parts of the body are called arteries. All arteries carry oxygenated blood except pulmonary artery.

Artificial pacemaker:
The battery operated instrument which produces electrical stimulus in the heart is called artificial pacemaker.

Ascent of sap:
The upward movement of water and minerals through the xylem from roots to leaves is called ascent of sap.

The deposition of hard yellow plaque of lipid material in the inner most layer of the arteries is called atheroma.

The narrowing and hardening of the arteries is called atherosclerosis.

The flow of sap from the cut, pruned tapped or wounded plant with considerable forces is called bleeding.

Blood is a type of loose connective tissues. It is a medium composed of plasma and blood cells which have dissolved nutrients, gases, hormone, and wastes and it transport these materials to the body.

Blood pressure:
The measurements of the force which pushes up the blood against the walls of the blood vessels is called blood pressure. Or pressure exerted by the blood against the walls of arteries.

Blue baby:
The baby whose skin becomes blue due to mixing of oxygenated and deoxygenated blood is called blue baby. It is due to incomplete partitioning of inter arterial foramen.

The microscopic blood vessels with only one cell thick wall are called capillaries. From capillaries materials are exchanged between cell and blood.

Cardiac cycle:
The sequence of events taking place during completion of one heartbeat is called cardiac cycle. 0.08s time required to complete one cardiac cycle.

Cell mediated responses:
The responses in which T-lymphocyte directly kills the microorganisms by phagocytosis is called cell mediated response.

Cell sap:
Water plus dissolved salt and sugar present in large vacuole of the plants cells is called cell sap.

Closed circulatory system:
A circulatory system in which blood moves in close vessels is called closed circulatory system.

The force of attraction among the water molecules is called cohesion.

Cohesion tension theory:
The transpiration pull produce water tension in the xylem which pull the water upward and the cohesive and adhesive forces maintain the water column in the xylem.

Cuticular transpiration:
The loss of water in the form of water vapours through the cuticle of the leaves is called cuticular transpiration. 5-7 % of transpiration occurs through cuticular transpiration.

The relaxed period of heart is called diastole.

The recording of electrical potential of heart is called Electro-cardiogram. Graphical recording of the electrical current that cause cardiac rhythms is called ECG.

Thrombus may be dislodged and carried to some other part of the circulatory system. It is called embolus on the new location. When blood clot moves from one part to another through blood circulation is called as embolus.

Facilitated diffusion:
Diffusion through protein molecules of cell membrane is called facilitated diffusion. Or movement of molecules from high concentration to low concentration through carrier proteins is called facilitated diffusion.

The loss of liquid water through the water secreting glands or hydathodes  in leaves is called guttation. It is due to root pressure.

The discharge of blood from the broken blood vessels is called haemorrhage. It may be due to smoking, stress and high cholesterol diet, etc.

Heart attack or myocardial infarction:
Sometimes, embolus or locally formed thrombus blocks the blood vessels in the heart. This blockage causes necrosis and damages the portion of heart muscles. This condition is called heart attack or myocardial infarction.

The maintaining of the internal body conditions and to keep internal chemicals constant is called homeostasis.

Humoral immune response:
The response of B-lymphocytes by producing antibodies to destroy the macro-organisms or toxin is called humoral immune response.

The condition of high blood pressure is called hypertension. It may be due to stress, high uptake of sodium, etc.

The increase of volume of components of the cell wall especially cellulose, pectin and lignin without dissolving in water is called inhibitions.

The capability to recognize the foreign material in the body and mobilization of cells and cell products to help remove the particular sort of foreign material with great speed and effectiveness is called immunity. Body defense against foreign material is immunity.

The interferons are proteins which destroy the nucleic acid of the invading organism. Now days these are helpful for the treatment of viral disease because theses cut the viral nucleic acid and destroy it.

Interstitial fluid:
The fluid present in the space around the capillaries and tissues is called intestinal fluid. It helps in exchange of material between capillaries and cell.

The uncontrolled production of the white blood cells is called leukemia. It is also known as Cancer of white blood cells.

The colorless protenaceous fluid that flows in the lymphatic vessel is called lymph.

Lymph nodes:
Lymph nodes are masses of connective tissues present at certain points along the pathways of lymph vessels. These nodes help in filtration of lymph.

Lymphatic system:
The system which transports  and returns material from the tissues of the body to blood is called lymphatic system.

The presence of excessive fluid in the tissues of the body is called oedema.

Open circulatory system:
A circulatory system in which blood does not move in close blood vessels is called open circulatory system. It is present in arthropods.

The movement of water molecules form a region of higher concentration to the region of lower concentration through a partially permeable membrane is called osmosis.

Osmotic potential:
The change of water potential of a system due to presence of solute molecules is called osmotic potential.

Plasma is primarily water in which proteins, salts, nutrients and wastes are dissolved. It is a part of blood.

The plasmodesmata  are cytoplasmic strands that extend between adjacent cells. Or these are the cytoplasmic bridges that connect the adjacent plant cells.

Pressure flow theory:
It states that an osmotically generated pressure gradient between source and sink drives the solution through the sieve elements. According to this theory materials move from source to sink with the help of osmotically generated pressure.

Pressure potential:
The pressure exerted by the protoplast due to endosmosis of water is called plasmolysis.

Root pressure:
The osmotic pressure created in the root which forces water and dissolved ions up into the xylem is called root pressure.

Serum is the fluid part of blood after clotting.

Sieve tube members:
The sieve tube members are joined longitudinally in a series to form sieve tube.

Sieve areas:
The portions of the cell wall which interconnect the conducting cells are called sieves areas.

The areas of active metabolism or storage like root tubers, developing fruits and immature leaves are called sink. It is the part where food is stored.

Isobilateral leaves:
In these leaves, the stomata are present in both upper and lower epidermis. e.g., lily and maze leaves.

Dorsiventral leaves:
In these leaves, the stomata are present only in the lower epidermis.

Areas where food is prepared and transported to the sink are called areas of source e.g. leaf.

Symplast pathway:
The movement of minerals through the plasmodesmata of the cell is called symplast pathway.

The contract phase of heart is called systole.

It is genetically transmitted disease. The patient of thalassemia has abnormal haemoglobin. Instead of having normal haemoglobin the patient has foetal haemoglobin.

A solid mass of plug of blood constituents(clot) in a blood vessel is called thrombus.

The movement of material into the body, with in the body and out of the body of the organisms is called transport.

The evaporation of water from the aerial parts of the plants especially through stomata of the leaves is called transpiration.

Vascular pathway:
In this pathway water moves form vacuole to vacuole through neighboring cells.

The constriction of the wall of arterial blood vessels is called vasocontriction. This constriction is under the control of nervous system and hormones.

The relaxation of the arterial blood vessels is called vasodilation. This dilation is under the control of nervous system and hormones.

The blood vessels which transport the blood from body cells toward heart are called veins. All veins carry deoxygenated blood except pulmonary vein.

Water potential:
The total kinetic energy of the water molecules is called water potential. Pure water has maximum water potential which is zero.


Written by: Asad Hussain.

Sunday, 2 August 2015

FSc Notes Biology Part 1 Chapter 6 Kingdom Prokaryotae (Monera) Definitions

FSc Notes Biology Part 1 Chapter 6 Kingdom Prokaryotae (Monera) Definitions

Aerobic bacteria:
These bacteria require free oxygen for the respiration.

Akinetes are thick walled, enlarged vegetative cells.. These are the resting spores of cyanobacteria.

Antibody is a substance that protects the host against the infection due to attack of virulent organisms. These are produce in response of antigen.

Chemical substances used on living tissues that inhibit the growth of microorganism are called antiseptics.

Autotrophic bacteria:
The bacteria which can synthesize organic compounds from inorganic substances are called autotrophic bacteria.

Cell envelope:
The complexes of layers, extend to the cell protoplasm are collectively called cell envelope.

The transfer of genetic material form donor bacteria to recipient bacteria by cytoplasmic bridge is called conjugation.

Cyst are dormant, thick walled and desiccating resistant structure.

Cytoplasmic matrix:
The cytoplasmic matrix is a substance present between the plasma membrane and the nucleoid.

The chemical agent used on non-living material that inhibit the growth of vegetative cells of microorganism are called disinfectant.

Facultative bacteria:
They can grow in presence or absence of oxygen.

Generation time:
The interval of time until the completion of the next division is known as generation time.

Heterotrophic bacteria:
The bacteria which cannot synthesize their organic compounds from simple inorganic substances are heterotrophic bacteria.

The broken pieces of filament are called hormogonia.

Humus is a material formed as result of partial decay of plants and animals. It increases the fertility of soil.

The process of use of vaccine for producing resistance in the organism.

The cell membrane invaginates to form mesosomes.

Microaerophilic bacteria:
These bacteria require a low concentration of oxygen for respiration.

The nuclear material or DNA of bacteria aggregates to form irregular shaped body called nucleoid.

Pili are hollow non-helical and filamentous appendages use for attachment.

Plasmids are circular double stranded DNA molecules that can self replicate and contain same resistance genes on them.

Prokaryotes do not contain an organized nucleus and nuclear membrane is absent in them.

Some bacteria are covered with loose, soluble shield of macro-molecules called slime.

The metabolically dormant bodies with thick wall are called spores. These are resistant to high temperature.

The use of physical methods to control bacteria is known as sterilization.

A chemical the directly derived from the germ and produces resistance in the animal against the diseases is called vaccine.

Written by: Asad Hussain