Union executive is part of parliament, and later controls the former through in several ways like through Financial control, Administrative control, legislative control, collective and individual Responsibility, Representative control, control through inform control by suggestions.
The Government is required to pass budget and financial bill in both the houses. Parliament does not allow the Government to expense unnecessarily. The Government cannot withdraw any amount of money from the consolidates fund without Parliamentary authority.
Generally, Parliament does not interfere in Administrative matters but if any policy is formed in wrong way, parliament may ask for explanations.
While enacting any law in Parliament, the Government needs to explain its all provisions and answer questions asked by the members of a parliament. Thus, it does not allow the executive to enact any arbitrary acts.
Collective and Individual Responsibility:
The whole council of ministers is answerable to lok Sabha for any step taken by any of the minister of the council of ministers. Even the minister is answerable individually to the Lok Sabha for steps taken by his officials of his department. If Lok Sabha does not approve the act of the minister. The whole cabinet has to resign, because of collective responsibility.
Members of Parliament represents different sections of people. They ask questions to the executive as representatives.