Blockchain Developer Core Blockchain Data Structures 3

Question 1

What does the Merkle root in a block header summarize?

Accepted Answer

All transactions in the block

Answer

The Merkle root is a single hash representing every transaction included in that block.

Question 2

Which field is NOT typically part of a Bitcoin block header?

Accepted Answer

The full list of transactions

Answer

Transactions are stored in the block body, while the header holds only summary metadata like the Merkle root.

Question 3

What is a Patricia Merkle Trie used for in Ethereum?

Accepted Answer

Storing account state and enabling efficient state proofs

Answer

Ethereum uses Patricia Merkle Tries to store and prove account state, storage, and transaction data efficiently.

Question 4

What makes a hash function suitable as a blockchain building block?

Accepted Answer

It is one-way and collision-resistant

Answer

Blockchain hash functions must be one-way and collision-resistant so outputs cannot be forged or reversed.

Question 5

In a Merkle tree, how many hashes must an SPV client receive to prove inclusion in a tree of N transactions?

Accepted Answer

Approximately log2(N)

Answer

A Merkle proof requires only about log2(N) sibling hashes to reconstruct the root path.

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