Lesson 4.3.1.1

4.3.1.1 Breadth-first and depth-first search Quiz: AQA Computer Science, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4.3.1.1, Breadth-first and depth-first search: 20 multiple choice questions for the AQA Computer Science (7517), Unit 3: Fundamentals of algorithms, written with Revision Ninja.

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The 20 questions

  1. Which graph traversal algorithm guarantees finding the shortest path in an unweighted graph?

    • Binary search
    • Breadth-first search
    • Linear search
    • Depth-first search

  2. Which data structure does breadth-first search typically use to hold nodes waiting to be explored?

    • A stack
    • A heap only
    • A queue
    • A binary search tree

  3. Which primary data structure is used to track unexplored nodes in depth-first search?

    • Array
    • Queue
    • Priority queue
    • Stack

  4. According to the AQA specification, what is a typical application of depth-first search?

    • Shortest path finding
    • Sorting array data
    • Infix conversion
    • Navigating a maze

  5. In what order does a breadth-first search explore nodes from the start node?

    • Random order
    • Highest value first
    • Level by level
    • Path by path

  6. Which search goes as deep as possible along one path before backtracking?

    • Binary search
    • Linear search
    • Depth-first search
    • Breadth-first search

  7. In a breadth-first search, which node is removed from the queue next?

    • Highest weight node
    • Deepest child node
    • Latest added node
    • Earliest added node

  8. Graph edges: A-B, A-C, B-D, C-D, D-E. Starting at A and taking neighbours in alphabetical order, what is the breadth-first visit order?

    • A, B, D, C, E
    • A, B, C, E, D
    • A, E, D, C, B
    • A, B, C, D, E

  9. Using the same graph (A-B, A-C, B-D, C-D, D-E), starting at A and taking neighbours alphabetically, what is the depth-first visit order?

    • A, C, B, D, E
    • A, B, E, D, C
    • A, B, C, D, E
    • A, B, D, C, E

  10. In the same graph, what is the shortest number of edges from A to E?

    • 1
    • 4
    • 3
    • 2

  11. What technique does depth-first search perform when reaching a dead end in a maze?

    • Level traversal
    • Linear looping
    • Shortest pathing
    • Backtracking

  12. If breadth-first search first discovers node T at edge distance 3, what is the shortest distance to T?

    • 4 edges
    • 2 edges
    • 1 edge
    • 3 edges

  13. Breadth-first search starts at S. S has neighbours X and Y, and X has neighbour Z. After S and then X are processed, which nodes are in the queue?

    • X and Y
    • S, X, Y and Z
    • Y and Z
    • Z only

  14. A depth-first search uses an explicit stack. S has neighbours X then Y pushed in that order. Which node is popped next?

    • X
    • Z
    • Y
    • S

  15. How many total nodes will a complete breadth-first search visit in a connected graph with 10 nodes?

    • 5
    • 10
    • 9
    • 1

  16. What structure in a graph makes tracking visited nodes necessary to prevent infinite loops?

    • Tree
    • Cycle
    • Leaf node
    • Edge weight

  17. What is the time complexity of breadth-first or depth-first search on a graph with V vertices and E edges, using adjacency lists?

    • O(V^2)
    • O(E log V) always
    • O(V + E)
    • O(2^V)

  18. Which search algorithm uses a queue to hold nodes waiting to be visited?

    • Depth-first search
    • Binary search
    • Linear search
    • Breadth-first search

  19. A search starts in a connected component with 4 nodes. How many nodes can it visit?

    • 0
    • 2
    • 6
    • 4

  20. Which algorithm finds the shortest path in a graph with positive edge weights?

    • Linear search
    • Dijkstra's algorithm
    • Depth-first search
    • Breadth-first search

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