In addition to Frances Arnold, Maria Zuber will co-chair the President’s Council of Advisors on Science and Technology.

This will be her fourth time serving in a White House administration.

"I look forward to continuing to advocate for science and a nonpartisan manner in this new role," said Zuber, who is Massachusetts Institute of Technology’s vice president for research and E. A. Griswold professor of geophysics. "I am thrilled with the challenge and the opportunity to work together with the scientific leadership of this administration to restore trust in science and pursue breakthroughs that benefit all people."

Zuber said that the work is critical "as the pandemic continues to rage."

Beyond the pandemic, she highlighted other areas of focus for the team, including the "transition to a zero-carbon energy system, our need to create good-paying jobs of the future and other aspects of our existential fight against climate change."

Zuber grew up in Carbon County, Pennsylvania, which she described as once being coal country. Both of her grandparents mined and died of black lung, she said, while noting that communities like hers still haven't recovered long after mining jobs have left.

"I could not be more excited for the efforts of this administration to deploy science to help breathe new life into these places, into so many communities large and small that are hurting today," she said. "Bold scientific leadership will be a critical component of building back better, guarding our health and safety, helping spark new, clean industries, and keeping America competitive in the race for those well-paying jobs of the future."

Zuber was the first woman to lead a NASA spacecraft mission and the first woman to lead a science department at MIT.

In 2004, former President George W. Bush appointed her to the Presidential Commission on the Implementation of United States Space Exploration Policy. In 2013, former President Barack Obama appointed her to the National Science Board, and President Trump reappointed her in 2018.

During remarks on Saturday, Biden introduced Francis Arnold as co-chair of the President's Council of Advisors on Science and Technology and part of the first all-women team to lead the council. Arnold is the first woman in American history to receive a Nobel Prize in Chemistry and is currently the Linus Pauling professor of chemical engineering, bioengineering, and biochemistry and director of the Rosen Bioengineering Center at the California Institute of Technology. Arnold has been inducted into the National Inventors Hall of Fame.

Known for her contributions to renewable energy, Arnold co-founded three biotechnology companies in sustainable chemistry and agriculture.

"My belief has grown that our highest responsibility in each generation is to preserve our fragile planet, prepare our economy and our workforce for the future and pass on a better world," Arnold said in her remarks Saturday.

"When we put science back to work for the benefit of all people, revitalizing our economy, fueling our climate response, broadening our perspective as we rebuild around greater equity and opportunity, we are making a society that is worth passing on to our children and our grandchildren. It is an act of love. I am honored by the opportunity to help nurture this effort," Arnold said.

As deputy director for science and society for the Office of Science and Technology Policy, Alondra Nelson said she wants to promote scientific research that is "honest and inclusive."

"As a Black woman researcher, I am keenly aware of those who are missing from these rooms," Nelson said Saturday during a press briefing introducing key members of the Biden administration's science team. "I believe we have a responsibility to work together to make sure that our science and technology reflects us and when it does, that it reflects all of us. That it reflects who we are together."

Nelson, president of the Social Science Research Council and a Princeton University professor, is known for her research at the intersection of science, politics and social inequality.

"There has never been a more important moment for scientific development -- to get scientific development right or to situate that development in our values of equality, accountability, justice, and trustworthiness," Nelson said.

Eric Lander is Biden's nominee for presidential science adviser, a position Biden announced Saturday he is elevating to a Cabinet-level position for the first time in U.S. history.

Lander served as the co-chair of the President’s Council of Advisors on Science and Technology (PCAST) during the Obama-Biden administration. He currently serves as president and the founding director of the Broad Institute of MIT and Harvard. Landon is also one of the principal leaders of the Human Genome Project.

"It's not hyperbole to suggest that Dr. Lander's work has changed the course of human history. His role in helping us map the genome, pull back the curtain on human disease, allowing scientists ever since and for generations to come to explore the molecular basis for some of the most devastating illnesses affecting our world," Biden said.

In his remarks Saturday, Lander said, "The President-Elect knows that science and technology will be crucial in meeting this moment," adding that "America's greatest asset, I think, is our unrivaled diversity. After all, scientific progress is about seeing something that no one’s ever seen before. Because they bring a different lens, different experiences, different questions, different passions. No one can top America in that regard. But we have to ensure that everyone not only has a seat at the table, but a place at the lab bench."

Late Friday, Health and Human Services Secretary Alex Azar refuted several media reports that he was resigning early, but did share his resignation letter -- effective Jan. 20 at noon -- on Twitter.

While Azar wrote on Twitter that it was his "duty to help ensure a smooth transition to President-elect Biden’s team during the pandemic" through Inauguration Day, he did criticize President Donald Trump and called on him to more strongly condemn the violence at the Capitol last week.

"Unfortunately, the actions and rhetoric following the election, especially during this past week, threaten to tarnish these and other historic legacies of this Administration," Azar wrote in the resignation letter. "The attacks on the Capitol were an assault on our democracy and on the tradition of peaceful transitions of power that the United States of America first brought to the world. I implore you to continue to condemn unequivocally any form of violence, to demand that no one attempt to disrupt the inaugural activities in Washington or elsewhere, and to continue to support unreservedly the peaceful and orderly transition of power on January 20, 2021."

Azar clarified he handed in the letter, dated Jan. 12, last week "along with every other political appointee."

The two-page letter, in which he calls serving as HHS secretary "the greatest professional privilege and honor of my life," details the administration's response to the coronavirus pandemic. Azar paints an entirely rosy picture, referring to it as a "remarkable response," despite skyrocketing deaths and case rates across most of the nation.

"While we mourn every lost life, our early, aggressive, and comprehensive efforts saved hundreds of thousands or even millions of American lives," he wrote, echoing a refrain from the president. There have been over 391,000 deaths in the U.S., nearly twice the number of the second-highest country (208,000 in Brazil).

He also highlighted the agency's efforts to combat the opioid crisis, electronic cigarettes and the HIV epidemic, and made special mention of "protect[ing] the sanctity of human life from conception to natural death."

Azar has served as HHS secretary since January 2018. President-elect Joe Biden has nominated Xavier Becerra, California's attorney general, to serve as his HHS chief.

ABC News' Ben Siu contributed to this report.