A Level Computer Science OCR Practice Exam

How does Bubble Sort function in sorting a list?

1. It sorts by inserting elements into their correct position

2. It moves through the list comparing pairs and potentially swapping them

3. It divides the array into smaller parts to sort

4. It uses a tree structure to organize the elements

The correct answer is: It moves through the list comparing pairs and potentially swapping them

Bubble Sort functions by moving through the list and comparing adjacent pairs of elements to determine their order. During each pass through the list, it checks each pair of elements and swaps them if they are in the wrong order. This process continues, gradually pushing larger elements to the end of the list, much like bubbles rising to the surface, hence the name "Bubble Sort." This method is straightforward and intuitive, though it is not the most efficient sorting algorithm. The comparisons and potential swaps are repeated until the entire list is sorted, which is why the answer accurately describes the function of Bubble Sort. The other choices describe different sorting mechanisms that do not align with the Bubble Sort method. For instance, the first option refers to insertion sort, the third option pertains to divide-and-conquer algorithms like quicksort or mergesort, and the last option suggests tree-based sorting methods like heapsort. These approaches differ significantly from how Bubble Sort operates.