4.1.1.13 Local and global variables Quiz: AQA Computer Science, Unit 1

The 20 questions

1. Which term describes a variable accessible only within its declaring subroutine?

   • Pointer
   • Constant
   • Local variable
   • Global variable

2. How does the scope of a local variable affect memory usage during program execution?

   • Memory remains allocated
   • Memory is doubled
   • Memory becomes static
   • Memory is released

3. Where is a global variable declared?

   • Inside functions
   • Outside subroutines
   • Inside loops
   • Local stack

4. What main risk is reduced by using local variables instead of global variables?

   • Stack overflow
   • Side effects
   • Syntax errors
   • Memory leaks

5. Two subroutines declare a local variable named count. How do these variables interact?

   • Second overwrites first
   • They are independent
   • They share values
   • Syntax error occurs

6. Which property primarily distinguishes a local variable from a global variable?

   • Scope
   • Memory size
   • Identifier length
   • Data type

7. What happens to a local variable when its subroutine finishes executing?

   • It is destroyed
   • Made global
   • Moved to heap
   • Saved to disk

8. What major issue can arise from updating global variables in multiple subroutines?

   • Increased compilation time
   • Difficult debugging
   • Syntax errors
   • Stack overflow

9. Why should intermediate calculations inside a subroutine use local variables?

   • Makes variables global
   • Speeds up compilation
   • Frees memory automatically
   • Prevents parameter passing

10. A function has a local variable x. A global x also exists. Which is accessed inside the function?

    • The local variable
    • Both variables
    • Neither variable
    • The global variable

11. What error occurs if a subroutine tries to access another subroutine's local variable?

    • Scope error
    • Stack overflow
    • Type mismatch
    • Syntax error

12. What key feature prevents local variables from colliding across different subroutines?

    • Global registry
    • Static linking
    • Heap sorting
    • Stack allocation

13. What is achieved by passing data via parameters rather than using global variables?

    • Modular code design
    • Automatic data compression
    • Faster instruction cycles
    • Reduced stack memory

14. A subroutine modifies a local variable sharing a name with a global variable. The global variable:

    • Is overwritten
    • Remains unchanged
    • Resets to zero
    • Is deleted

15. What is the most appropriate use of a global variable?

    • Loop counter
    • Temporary result
    • Application-wide setting
    • Subroutine parameter

16. What type of value might an uninitialised local variable hold?

    • Constant value
    • Unpredictable value
    • Null reference
    • Always zero

17. Which term describes a variable accessible only within the subroutine declaring it?

    • Local scope
    • Global scope
    • Dynamic scope
    • Universal scope

18. How should values be passed into a subroutine to avoid using global variables?

    • As return values
    • As global flags
    • As constants
    • As parameters

19. Where is memory allocated for local variables when a subroutine is called?

    • On hard drive
    • On call stack
    • In heap memory
    • In global memory

20. A local variable is initialised to 0 in a subroutine. What is its value at the start of a second call?

    • 1
    • 2
    • 0
    • Undefined

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