Test Question PoS

Hi I urgently need to know if Ethereum’s committee validators are still using the “solve the nonce” and Merkel trees to build and validate blocks.

My understanding was that PoS just delegated blocks so more processing can occur and less energy used up on everyone trying to solve the same nonce.

I am teaching the topic and have had a student challenge one of my test questions. My research isn’t turning up anything specific enough. I need to make sure I teach this right.

Appreciate the responses!