1: The nature of the cryptographically link chain ensures immutability and security, and reinforces the trustlessness and integrity of blockchain as a technology.
2: A Bitcoin block contains the hash from the previous block, its transactions and a nonce.
Why is it important that the blocks are cryptographically linked together?
Because if one block is changed, this block and all subsequent blocks will be invalidated and will need to be re-mined. This turns difficult for someone to change transactions on blockchain.
What does the block structure look like in bitcoin?
Itās like a linked list, each block is linked to the previous block. This is because the hash of each block is also based on the hash of the previous block. Each block has a set of transactions, a hash and the nounce found.
Why is it important that the blocks are cryptographically linked together?
to keep the system up
What does the block structure look like in bitcoin?
each block contain a link to the previous block, list of TXs, and nonce
If they were not, the blockchain wouldnāt be a chain anymore, only blocks.
It is composed of a nonce that has to be guessed, the transaction(s), and the hash key of the previous block, all of them making a new hash key for the new block.
Ton incentivize the miners to play by the rules. It makes it extremely difficult, actually impossible, for a miner to go and change a previous block without it creating a cascade of change in the rest of the blockchain; that way it makes more sense for a miner to mine according to the rules than to try to cheat, because thatās how heāll make money.
In each block, there is The previous blockās hash, the transaction list of the present block, and a nonce randomly chosen to obtain a hash that corresponds to certain target number.
Questions ( if they get answered further in the course, I can wait 
); how is the target number determined, is it by algorythm Iām assuming?
And what makes a miner good or netter than another, it seems like its more about computer power than anything else?
Why is it important that the blocks are cryptographically linked together?
Blocks permanently record data. Blocks can be described as individual sheets within a digital transaction ledger (en.bitoin.it, n.d.).
What does the block structure look like in bitcoin?
Blocks are chronologically organized sequentially. The terminology for chronologically sequential blocks is known as the block-chain.
Best Regards
References
En.Bitcoin.It, (n.d.), Block - Bitcoin Wiki; Retrieved From: https://en.bitcoin.it/wiki/Block
It is important that the blocks are cryptographically linked together so that it is hard or next to impossible for one miner to go back and change or alter a transaction in the blockchain.
The current block hash function consists of the following; transactions in the current block, hash from the previous block and the randomly guessed Nonce. Hash on the current block also has to guess the random number called Nonce then they hash this which is represented as a number and then compare this hash to a target ā target is a number that depends on the difficulty of the network ā meaning the more people are mining/the more miners there are on the network the lower the target number ā therefore making it more difficult for the miners to guess the nonce number. This is what consists of the puzzle each block has to solve.
It is important that the blocks are cryptographically linked together to make it impossible for miners to alter or delete any transactions in a block as doing so would completely change the hash functions of the block you are changing as well as the hash functions of all subsequent blocks. This would result in the links between the first altered block and each subsequent block being broken completely.
Each of these blocks that the miner changed would then have to be re-mined and then the miner would need to catch up and re-mine all of the new blocks that have been created during this time. This is totally impractical as the computational power required to do this would be so great that the cost could very well be hundreds of millions of dollars if not billions of dollars and it would take thousands of years to complete.
It is virtually impossible to alter or change a block due to the design of the blockchain.
The structure of a block in the blockchain consists of the hash function of that block which is based off of all of the transactions in that block as well as all of the transactions in the previous block plus the nonce that has been randomly chosen by the network.
Why is it important that the blocks are cryptographically linked together?
The blocks are cyptographically linked together so that it is impossible to change a previous block without invalidating and needing to rehash any subsequent blocks. This strongly discourages the motivation to alter the data within each block.
What does the block structure look like in bitcoin?
The block is comprised of the previous hash, the blockās list of transactions, the nonce and the hash of the current block.
It is important for blocks to be linked together so that no one can corrupt the past without making all future blocks useless. This allows us to have security and trustlessness
The block structure in bitcoin has a hash of previous block, transaction data, and a nonce
Because the hash from the next block contains the hash of the previous block.
The previous hash, the transaction list and the nonce
Linking blocks cryptographically protects transaction data from being altered afterwards. Because blocks are linked together, no one can add or remove transactions to already mined blocks, because that changes the blockās hash and corrupts the whole blockchain from that block on.
A bitcoin block consists of hash and transaction data. A new block to the chain is mined by using the hash of a previous block, transaction data of a new block, and a nonce, a random number that is needed to hit below the current hash target. Because the hash of previous block is included in mining the next block, blocks in the blockchain become cryptographically linked.
By having linked blocks, it becomes impossible to manipulate data
hash previous block, transactions, nonce
it is important for blocks to remain linked together for security and integrity
the block is made out of data which consists of the hash of the previous block , current target, nounce, block header