2.1.1

Question 1

Define the term abstraction

Answer 1

Abstraction is the process of separating ideas from particular instances. It is a means of hiding detail. It is a representation of reality using symbols to show real life features.

Question 2

Why is abstraction needed

Answer 2

Reduces processing requirements

Simplifies programming

Reduces memory requirements

Question 3

Reusable components

Answer 3

Components that have already been written debugged and tested. They can be transplanted into new systems to save development time

Question 4

Name the three programming constructs

Answer 4

Sequence, branching and iteration

Question 5

Which two categories of loop is iteration split up into

Answer 5

• Count-controlled

- Condition-controlled

Question 6

Describe how the branching programming construct works

Answer 6

A certain block of code is run if a specific condition is met, using IF statements

Question 7

What is recursion

Answer 7

A programming construct in which a subroutine calls itself during its execution until the stopping condition is met

Question 8

What is the base case in recursion

Answer 8

A condition that must be met in order for the recursion to end

Question 9

State two advantages of recursion

Answer 9

Can be represented in fewer lines of code

Easier to express some functions recursively than using iteration

Question 10

State a disadvantage of recursion

Answer 10

Inefficient use of memory
Danger of stack overflow
Difficult to trace

Question 11

Give two pieces of information that are stored on the call stack

Answer 11

Parameters
Return addresses
Local variables

Question 12

Define scope

Answer 12

The section of the program in which a variable is accessible

Question 13

Give advantages of using local variables over global variables

Answer 13

Less memory is used

Self-contained so unaffected by code outside the subroutine

Take precedence over global variables with the same name

Question 14

What is top-down design

Answer 14

A technique used to modularise programs in which the problem is continually broken down into sub-problems, until each can represented as an individual, self-contained module which performs a certain task

Question 15

State two advantages of modular design

Answer 15

Makes a problem easier to understand and approach

Simpler to divide tasks between a team

Easier to manage project

Self-contained modules simplify testing and maintenance

Greater reusability

Question 16

Give another name for top-down design

Answer 16

Stepwise refinement

Question 17

What is the difference between procedures and functions

Answer 17

Functions must always return a single value while a procedure does not always have to return a value

Question 18

What does it mean to pass a parameter to a subroutine by reference

Answer 18

The address in memory of the parameter is passed to the subroutine so its value outside of the subroutine will be updated

Question 19

Features of IDEs

Answer 19

Stepping (whats stepping)

Variable watch

Breakpoints

Source code editor

Debugging tools

Question 20

What is encapsulation in OOP

Answer 20

When attributes are declared as private so can only be accessed and edited by public methods

Question 21

Describe the purpose of encapsulation

Answer 21

Program complexity is reduced by protecting data from being accidentally edited by other parts of the program

Question 22

Define the term parameter

Answer 22

(A description of) an item of data That is used as a variable within the subroutine

Question 23

What does it mean to pass a parameter to a subroutine by value

Answer 23

A local copy is stored, used and then discarded. The value of the original data is unchanged

Question 24

Global variables (features)

Answer 24

Global variables are defined at the start of the program

Exists throughout the program

Allows data to be shared by modules