Mempool is a list of unconfirmed transactions, not UTXOs.
Why do you think that? A mempool will decrease every 10 minutes because transactions will move from the mempool into a newly mined block. Mempool grows in size as new unconfirmed txs get broadcasted. 
I thought a growing mempool, would mean bigger bytes addded in a rate faster than the 10 min decrease, therefore fees increase as miners would need to mine faster (more power, more fees).
1.) The mempool is a data structure of incomplete transactions stored on each node. In other word a list of unconfirmed transaction data.
2.) If the miners can’t keep with the rate of new transactions the fees get higher due to the level of difficulty rising. The backlog or mempool of unconfirmed transactions will continue to grow until processed.
3.) A growing mempool increases transaction fees because it will be more difficult and take longer to confirm transactions. Therefore the fee goes up to compensate miners for the time and energy required to do the work.
The mempool consists of all the Tx’s that make sense in the nodes but are still unconfirmed until a miner confirms it and adds it to a new block.
The mempool gets larger as they try to keep up
The larger the mempool, the longer it takes to confirm the transaction as the miners will choose the ones with the higher transaction fees.
It is not much more difficult for miners to mine when the mempool is congested, it is because the blockspace becomes more valuable because of all the transactions that want to get confirmed, driving the price up.
A mempool is a list of all unfonfirmed transactions.
There will be more and more unconfirmed transactions piling up, increasing the fee.
When the mempool piles up with unconfirmed transactions the fees will go up.
1. What is the mempool?
A mempool is a place where all unconfirmed transactions are kept. Unconfirmed transactions are transactions that have been verified by nodes in the network but are still waiting to be confirmed or added to a block by the miner.
2. What happens if the miners can’t keep up with the rate of the new transaction?
The mempool gets larger and have longer transaction times
3. How does a growing mempool effect transaction fees?
Transaction fees become higher because miners will choose transactions with the higher fees.
Higher demand (for transactions to be mined or put in a block) means increase in mining fees.
mempool is where unconfirmed transactions wait for a miner to pick them and add to next block
if miners cant keep up with the rate mempool will get bigger and longer transaction times.
when transaction fees increase due to larger mempool which causes competition amongst miners the larger fees are offered to get transaction threw faster
What is the mempool?
Is a collection of unconfirmed transactions that are held into every node including the miner’s
What happens if the miners can’t keep up with the rate of the new transaction?
The difficulty level to solve puzzles will be lower so they can process quicker.
How does a growing mempool effect transaction fees?
if the mempool is too big users can bid a higher fee to get their transactions through
The difficulty level is not influenced by a larger mempool. The transaction times would increase and potentially fees.
Mempool is a pool of pending transactions and each node has its own mempool.
Mempool gets bigger.
Transactions with higher fees get added to the block while lower fee transactions are queued. Wallets will automatically increase transaction fees for your TXs to get through resulting in higher fees across all participants.
You could manually choose a low fee but it would result in your TX not chosen to be in the block for a really long time. So it’s a sacrifice between time and price.
A mempool is a collection of unconfirmed but accepted transactions on a specific node. As transactions are broadcast from node to node and accepted it will be added to the respected mempool. Therefore each mempool may be different as transactions take time to broadcast across the whole network.
WRT Bitcoin Each mining node will select near 1MB of the transactions in the mempool with the highest paying fees determined by satoshis/byte. These transactions are then hashed and concatenated with a nonce before being rehashed and compared to the difficulty level. If lower than the difficulty level the transactions are added to the new block and removed from the mempool.
If the miners cant keep up with the amount of transactions the mempool grows in size. There are both benefits and downfalls to a growing mempool.
A growing mempool will force an increase in transaction fees as competition to get their transaction confirmed as part of the next block increases. While this poses downsides to the transaction based user, a growing mempool with increasing fees is added incentive for a miner to keep maintaining the network even after block rewards have been cut. If there is near zero block reward but a staggering amount of unconfirmed transactions in the mempool there is still money to be made.
1. What is the mempool?
Mempool is the list of unconfirmed transactions that each node has.
2. What happens if the miners can’t keep up with the rate of the new transaction?
The number of unconfirmed transactions will increase. Transactions with lower fees might stay in mempool for long time.
3. How does a growing mempool effect transaction fees?
Transactions with the higher fees will be picked up first, therefore, the bigger the mempool the higher the fee would have to be to include the transaction in block.