Each party gets a number of seats on a committee in proportion to how many representatives they have in Parliament
Main job of committees
1. Supervise the work of the government
2. Hear evidence from experts, members of the public and others
3. Write reports with recommendations for the Government
Committees

Education Committee
Health Committee
The Energy and Climate Change committee announced in 2016 that the government are failing to meet its renewable energy targets, having discussed this with energy experts
MPs' influence on committees
Limited, as the reports they introduce are only suggestions and the Government can entirely ignore them if they wish
The actual membership of each committee is based on how many MPs each party has, so the governing party usually has the largest number of representatives