Internet programming

• PAM vs. BLOSUM Substitution Matrices:
• Statement (I): The PAM substitution matrices were derived using local multiple alignments. $\implies$ Incorrect.
• PAM (Point Accepted Mutation) matrices (Dayhoff et al., 1978) were derived from global alignments of closely related protein sequences with >85% identity.
• Statement (II): The BLOSUM matrices were derived using substitution frequencies derived from sets of closely related protein sequences. $\implies$ Incorrect.
• BLOSUM (Blocks Substitution Matrix) matrices (Henikoff & Henikoff, 1992) were derived from local multiple alignments of conserved ungapped blocks (BLOCKS database) representing moderately to distantly related proteins (e.g., BLOSUM62 clusters sequences sharing 62% identity or greater).
• Conclusion: Both Statement (I) and Statement (II) are incorrect (Option 2).

Correct option: (2) Both Statement (|) and Statement (II) are incorrect

• Queue as a FIFO Data Structure:
• Queue: A linear data structure operating under the FIFO (First-In, First-Out) principle, where elements are enqueued at the rear and dequeued from the front.
• Stack: Operates under the LIFO (Last-In, First-Out) principle (insertion and deletion at the same end/top).
• Linked List & Graph: Can support various access disciplines depending on pointer implementation.
• Conclusion: The FIFO data structure is Queues (Option 3).

Correct option: (3) Queues

• Combinatorics - Permutation vs. Combination:
• Permutation of a set of $n$ elements is an arrangement of the elements in a specific, definite order:

• Combination is a selection of elements where the order of arrangement does not matter:

• Conclusion: An arrangement in a given order is a Permutation (Option 2).

Correct option: (2) Permutation

• Search Complexity in Singly Linked Lists:
• In a singly linked list containing $n$ elements, random access is not supported because nodes must be traversed sequentially following pointers from the head.
• In the worst case (where the target element is located at the tail node or is not present in the list):
• The search algorithm must visit and compare every single node from 1 to $n$.
• Hence, the worst-case number of comparisons is exactly $n$ ($O(n)$ linear search time).
• Conclusion: The number of comparisons is n (Option 4).

Correct option: (4) n