Simplify the following text for a Grade 9 native English-speaking person.
Original: Medawar was awarded his Nobel Prize in 1960 with Burnet for their work in tissue grafting which is the basis of organ transplants , and their discovery of acquired immunological tolerance .
Simplified: Medawar was awarded his Nobel Prize in 1960 for work in tissue grafting , which is the basis of organ transplants . He and his team discovered acquired immunological tolerance .