QA Life Cycle is nothing but the SDLC models and the 
requriments of the client,Design,Testing and production of 
the product with respective to cost is the Life cycle of QA.

QA Life cycle is 

Risk Analysis
Test plan
Test design
Test excution
Defect tracking
Reporting

QA Life cycle starts from the project Intiaton to the 
Project deployment.There are different stages such as:
1)Assesing the development plan.
2)Preparing the Test plan.
3)Reqirement phase testing .
4)Designe phase testing .
5)Program phase testing .
6)Analyzing the test results.
7)Black box or functional testing.
8)Analyzing the functional test results.
9)Instalation testing
10)Testing the Test effectiveness of the process.

The QA life cycle starts from project initiation to project 
windup if its a development project otherwise QA life cycle 
for maintenance will have to take care of every change 
requests.For the new change same procedure like 
estimation,resourcea,efforts etc are to be taken care of.
the phases of life cycle of Software as per  qa activities 
are:

1. project Initiation -It includes following:
-Statement of work(SOW)or contract
-Kick-off Minutes of meeting
-Project initiation note
-Resorce tracking sheet
-Estimation
2. Project Planning
-Project Management Plan
-MPP (project plan )
-Risk logs and Issue logs
3. Project Monitoring and control
-Check for Requirement Traceability matrix preperation and 
updations
-Reviews of the following-
Requirement documents (SRS)
Design documents 
Testplan,test cases 
Code
-Baselining of the documnents
-Collection of all Documents in a repository
-Time lines constraint and schedule tracking
-Deliveries and Releases time constraints
4. Configuration Management
-Tracking tool for CM
-Tracking and managing the change requests
-Impact analysis
-logs of change requests
5  Risk Management
-Tracking of Risk logs and issue logs
-Root cause analysis
-alternative solutions
-Mitigation and Contingency plans
6.Project windup
-Prepare windup plan 
-Lesson learnt in central repository
-windup report