D avid Cameron said his new ministerial team "reflects modern Britain" and insisted the newly promoted women in his administration deserved their jobs as he faced a backlash over the reshuffle.
The decision not to make the new Leader of the House of Lords Baroness Stowell a full Cabinet minister was labelled a "constitutional outrage" by furious peers and Mr Cameron faced further questions over the decision to demote Michael Gove.
The claim by one of his new senior ministers that it was now a "Eurosceptic Cabinet" also risked straining relations with Mr Cameron's Liberal Democrat coalition partners.
At Prime Minister's Questions, Mr Cameron said: "I have appointed more women to the front bench, more women to our Cabinet, on the basis that they deserve those jobs, and I want a team that reflects modern Britain and can be everything that modern Britain needs it to be."
Lady Stowell replaced Lord Hill of Oareford as Leader of the Lords, but unlike him will not be a full member of the Cabinet although she will attend the high-level meetings.
The Conservative Party will top up her salary to the same rate that Lord Hill was on, but peers claimed the Upper Chamber was at risk of losing its authority because of her status.
Senior Tory Lord Forsyth claimed it was the first time in the history of the Lords that there was no Cabinet minister in the House and asked: "W hat sort of signal does that send to the Civil Service and others about the authority of this place in its important duty in revising legislation?"
Labour former attorney general Baroness Scotland of Asthal said Mr Cameron's decision was a "constitutional outrage".
Downing Street refused to comment on a London Evening Standard report that some of the male ministers who stood down in the reshuffle were in line for honours, but Mr Cameron told MPs he would not apologise for recognising people who have "contributed to our government".
The newspaper said f ormer ministers Alan Duncan and Hugh Robertson were in line to be made Knights Commander of the Order of St Michael and St George, f ormer solicitor general Oliver Heald would get a knighthood and Tory veteran Ken Clarke was set to become a Companion of Honour.
Challenged by Labour's Jonathan Reynolds that he had "given more knighthoods to men that he has sacked than he has given Cabinet jobs to women", Mr Cameron said: "I make no apology for saying that I think in public life we should recognise public service, people who have worked hard, people who have contributed to our nation, contributed to our government.
"I think that is a good thing to do."
T he extensive changes to his Cabinet included shifting key ally Michael Gove from Education Secretary to chief whip - ordering him to act as "minister for TV".
Mr Cameron defended the decision during clashes with Ed Miliband in the Commons, saying Mr Gove was the "very best candidate" for the job and praised his record in the Department for Education.
Despite Mr Gove's insistence that it was his choice to move in the reshuffle, his wife Sarah Vine appeared to indicate that she was not so happy with the move.
Ms Vine, a columnist with the Daily Mail, tweeted a link to an article from the paper by Max Hastings under the headline: "A shabby day's work which Cameron will live to regret."
In the article, Mr Hastings described the former education secretary as "the undisputed Tory hero of the past four years", adding: "What was Cameron thinking of to sack Gove?"
Defence Secretary Michael Fallon said the new Cabinet, including Foreign Secretary Philip Hammond who has said he would vote to leave the EU unless powers were clawed back, was certainly Eurosceptic, but claimed that matched the mood of the country.
Asked if the reshuffle contained a message aimed at Ukip supporters, Mr Fallon told BBC Radio 4's Today programme: "W e certainly want people who may have flirted with Ukip at the recent European election to understand how we can get change in Europe and understand that the Conservative Party is the only party that can deliver that change."
He also signalled a tougher line on the European Convention on Human Rights, saying: "Many people have been extremely frustrated by the process by which we are able to deport people who have no connection with this country, weren't born here, aren't citizens of this country, want to commit terrorist acts against this country, and we have not been able to get rid of them."
But Deputy Prime Minister Nick Clegg said: "If the Conservatives want to constantly change their own policy or their own stance or the way they talk about Europe, that is up to them.
"This Government, a coalition Government because of the Liberal Democrats in it, will remain anchored in the centre ground with Britain anchored firmly in the heart of the European Union."
The extensive reshuffle saw a series of established figures culled in favour of women, with the highest-profile casualty Owen Paterson losing his environment brief to Liz Truss.
Nicky Morgan, 41, who replaced Mr Gove, and new Environment Secretary Ms Truss, 38, are the first mothers in the Cabinet since the resignation of Maria Miller in April.
But the Electoral Reform Society said that Mr Cameron has failed to meet his own pledge that by the end of this parliament in 2015 a third of his ministers would be female.
With only a few junior posts remaining to be allocated, the ERS analysis found that 24% of Tory ministers - or 28% if whips are included - are women. Female representation in Cabinet was better at 30%, or 31% including those who attend meetings without being full members.
Katie Ghose, chief executive of the Electoral Reform Society, said: "While it is heartening to see more women taking a seat at the top table of politics, the fact that the Prime Minister has failed to hit his own relatively unambitious target shows how much more effort needs to be made."
The Prime Minister announced a series of junior ministerial appointments, with South West Bedfordshire MP Andrew Selous being appointed a junior minister at the Ministry of Justice.
Lord Ahmad of Wimbledon was been promoted to Parliamentary Under Secretary of State at the Department of Communities and Local Government, Anne Milton promoted within the Whips Office, and Lord Ashton of Hyde becoming a whip in the Lords.
Mr Paterson told the Prime Minister he was "disappointed" not to be able to continue in the role.
In an exchange of letters with Mr Cameron, released by Downing Street, the prominent eurosceptic made clear that he held "clear ideas on the future of the UK and its place in the world" and intended to "continue to serve my country and constituents from the backbenches".
And the minister, whose handling of the highly-controversial badger cull is thought to have played a part in his departure, said it was a "national scandal" that the UK had not managed to get control of the threat of the threat of TB to cattle herds.
"In order to improve the environment, we must manage not only our landscapes but also the species that live in them. This is particularly true when it comes to safeguarding our animal and plant health," he wrote.
"It is a national scandal that the future of our cattle industry is under threat as a result of the failure to control bovine TB. We have overseen the first pilot cull of badgers giving hope to our farmers and demonstrating that we are prepared to bear down on the disease in wildlife as well as cattle."
An independent expert concluded that pilot badger culls were inhumane and failed to deliver the level of deaths needed to bring about a reduction in TB in cattle and that too many badgers took more than five minutes to die.
Its conclusions prompted renewed calls from opponents of the cull to abandon the controversial policy, but the Government said it would go ahead with a second year of culling while implementing recommendations from the panel.
Mr Cameron welcomed Mr Paterson's " outstanding contribution" in his last role and as Northern Ireland secretary.
"Over a period of five years in both Opposition and in Government you contributed hugely to a period of stability across Northern Ireland's public institutions," he said.
"Your tenacity, hard work and unfailing good humour went a long way to building trust across the community as you developed strong relationships with local leaders that still exist today.
He also said he had given " clear direction" to the clear-up operation after last winter's severe floods.
"You have been a steadfast and reliable colleague, and for that I remain hugely grateful. I know that you have much more to give in terms of public service - not least in continuing to represent your constituents in North Shropshire," he concluded.