Mentors Comment:
The question is simple and straightforward. You have to discuss how Ac of 1919 or Montagu Chelmsford Reform (MCR) influenced our present-day constitution. Most of the discussion on constitution takes into the account GoI Act of 1935 and how it influenced provisions in our constitution. But if not more, then equally important was MCR with respect to our constitution. Most of the important provisions of our present-day political system are the result of MCR.

Features like the bicameral legislature, devolution of power to local self-governance, federal polity with state governments, state lists & union lists, public service commission, the practice of voting in choosing our representatives etc are some of the key features of MCR that got reflected in our constitution.

Before ending the answer, mention a few shortcomings of MCR but not in detail.

Answer:

The Government of India Act 1935 had introduced several features that form the nucleus of our Constitution. But equally important is the Montagu Chelmsford Reforms (MCR) which was also known as the Government of India Act 1919. The MCR stands out for proposing some of the most radical administrative changes and for giving provincial legislatures the mantle of self-governance.

How the GoI Act 1919 has shaped our constitution:
The report advocated the need to emancipate the local governments and legislatures from central control; and to advance, by successive stages, in the direction of conferring responsible government on the provinces.
MCR established the framework for devolution of powers and gave credence to the cry for self-governance.
The present idea of Council of Ministers being responsible to the parliament came from the MCR. It elucidated the principle of accountable governance by directing that the “Government of India must remain wholly responsible to Parliament.”
MCR provided for partial transfer of power to the electorate through the system of Dyarchy.
MCR also prepared the ground for the Indian federalism, as it identified the provinces as units of fiscal and general administration.
MCR made a provision for the classification of the central and provincial subjects. The provincial subjects were divided into two groups. One was reserved and another was transferred.
MCR also made the central legislature bicameral. The first house which was the central legislature was called central Legislative Assembly and second called was called Council of States.
The central legislature can be called a primitive model of today’s Lok Sabha & council of states can be called a primitive model of Today’s Rajya Sabha.
MCR provided for the establishment of a Public Service Commission in India for the first time.
MCR marked the end of the policy of benevolent despotism, and thus began the genesis of the responsible government in India.
It was for the first time, that elections to the legislatures were known to the people and this created political consciousness among the masses.
It was the GOI Act 1919, whereby, the Indians came in direct contact with administration for the first time. This was a very useful experience.
It was also for the first time that a number of Indian women got the right to franchise for the first time.

Some shortcomings of the Government of India Act 1919:
Absence of responsible government at the center
Separate electorates for different communities.
The introduction of diarchy in the province was too complicated to be smoothly worked.
Although the Mont-ford Report had declared that the separate electorate was a very serious hindrance to the development of the self-governing principles, yet separate electorate came to be a significant feature of Indian political life.

The key principles of responsible government, self-governance, and federal structure grew out of these reforms. Most scholars look at the Act as the first attempt by the British to introduce self-government in India albeit with significant restrictions. The MCR would go on to become the basis for the Government of India Act, 1935, and, ultimately, the Constitution.