APCSP - Unit 3

Question 1

Why is using a variable an example of abstraction?

Answer 1

This is because a variable does not have a specific value, it can be set to any number or value that the user chooses. It can represent lots of different values.

Question 2

By default, how are components laid out in App Inventor?

Answer 2

Vertically

Question 3

What does Fill parent do?

Answer 3

Let the button/UI component fill the area allotted on the screen. If it is width fill parent it will fit the width of the screen. If you do height fill parent it will fill the height of the screen.

Question 4

List 2 valid App Inventor variable names.

Answer 4

firstName, and lastName

Question 5

What does the following APCSP pseudocode display? Remember to trace through the code keeping track of the values in a and b after each line of code.
a ← 1 (Set a to 1)
b ← a (Set b to the current value of a)
b ← b + 1 (Add 1 to b)
a ← a + b (Set a to be the current value of a + b)
DISPLAY(a)
DISPLAY(b)

Answer 5

3
2

Question 6

What will happen if you ask for an index of 10 in a list that only has an index of 9?

Answer 6

The App Inventor server would crash because there is no item at that index.

Question 7

What is an event handler?

Answer 7

A block of code that reacts to an event.

Question 8

What type of data must a global destination variable be if it uses a ListPicker?

Answer 8

List

Question 9

What is true about data compression?

Answer 9

There are trade-offs involved in choosing a compression technique.

Question 10

When testing software, it is important to test critical values or boundary values–both valid and invalid values at the extremes of a range of legal values. In an app where the user enters a number for the month of the year, what would be appropriate boundary values to check?

Answer 10

0 and 1, also 12 and 13.

Question 11

Define refactoring

Answer 11

Restructuring a program to make it efficient without changing its basic behavior.

Question 12

RELEARN FLIPPED BITS

Answer 12

IN RUNESTONE

Question 13

How should you name a button? For example how would you name a button that is used to clear the screen?

Answer 13

ButtonRefresh
RefreshButton

Question 14

What is true about a TinyDb component?

Answer 14

Data stored in a TinyDb will persist between different uses of the app.

Question 15

A digital photo file contains data representing the level of red, green, and blue for each pixel in the photo. The file also contains metadata that describes the date and geographic location where the photo was taken. What goal would analyzing the metadata be more appropriate than analyzing the data?

Answer 15

Determining the likelihood that the photo was taken at a particular public event.

Question 16

Define algorithm

Answer 16

A formula or set of steps for solving a particular problem.

Question 17

Define analog

Answer 17

A device or system that represents changing values as continuously variable physical quantities.

Question 18

Define cloud computing

Answer 18

Relies on sharing resources rather than having a local server handle apps.

Question 19

Define cryptography

Answer 19

Art of protecting information by transforming it into an unreadable format.

Question 20

Define lossless comrpession

Answer 20

Data compression techniques in which data is not lost.

Question 21

Define lossy compression

Answer 21

Data compression technique in which some data is lost.

Question 22

Define megabyte

Answer 22

Used to describe data storage, 1,048,576 bytes.

Question 23

Define megapixel

Answer 23

One million picture elements used to reference the resolution of a graphics device.

Question 24

Define persistence

Answer 24

Ability to store data permanently like a Word document or your password.

Question 25

What is a pixel?

Answer 25

Short for a picture elements, a single point in a graphic image.