Answer 1:
    Test cases:
        Are a set of procedures which is prepared by the 
testers. 
        (i.e)we no tht the entire testing of the 
application is not done by a single tester,the modules of 
the application is separated and given to different testers.
         So each tester wil prepare the test case for their 
own module.  
        After which the test cases are given to the test 
leader,who will check whether all the test cases for the 
specifications made in SRS are mentioned in the test case.
        And anything is missed the test case is given back 
to the corresponding tester,who has to include the testcase.
        So only after the test lead's approval,the tester 
can begin the testing...Got it..

Answer 3:
   Traceability matrix:
        It is a document tht is used to track the 
requirements in all the phases of the development.
  It includes:
        Based on the phase the traceability matrix will 
contain the columns.
         For eg: if its a reqiurement phase where the user 
requirements are obtained and converted into a 
specification document.Here the matrix is used to check 
whether all the requirements are mentioned in the 
specification.
         Here the columns will be:
User requirement:which contain user reqiurement ID
Description:Which contains the description abt the user    
reqiurement.
Specification:which contains the corresponding 
specification ID...
It wil be in the form of tabular column,so tht it wil be 
easy for us to track the defects

Hi Saranya good answers.SRS Document means client 
Requiremnet document.am i right?
if you know can you make answer for difference between 
error message and warning message?

Error message: After clicking the some button, the system 
does not allow the user to next screen.

Warning message: It will displayed in "Pop-up" states that 
this fields needs some specifcation or validation.

How you know test cases are cover;
That time we using Traceability matrix
Traceability matrix:-
It document that tarck the requirement against test case,
Following item comes under the traceability matrix.

Requirement ID- User requirements
Description : Requirement description.

Error:
Ex. Suppose u have test login functaionality,you enter
invalid user name & password & click on login button- It pop
up the error message for that wrong user id, This message is
called error message.

Warning Message:-

Suppose your password expired in few days
this message is called as warning message

if i am wrong plz comment me