System and Software Design Concepts (Structured Analysis (DFD, Decision Table, Decision Tree, Data Dictionary) & Design Principles, Cohesion and Coupling) : MCQs & PYQs with Explanation

Option C

The architectural design provides a high-level view of system components and their interactions.

Option B

Cohesion refers to how closely the elements within a single module of a program are related to one another. The higher the cohesion, the better the design, as the module performs a single, well-defined task. Different types of cohesion describe different levels of relationship among module elements.

• Best Type : Functional Cohesion.
• Worst Type : Co-incidental Cohesion.

QUALITY ORDER FROM WORST TO BEST:

Co-incidental → Logical → Temporal → Procedural → Communicational → Sequential → Functional.

Option D

A Decision Table is a tabular method for representing logical relationships between conditions and actions in a system. It is widely used in software testing, system design, and decision-making.

Option C

A Data Dictionary is a centralized, structured repository that contains metadata, information about the data used in a system, such as:

• Names of data elements.
• Data types and formats.
• Relationships between data items.
• Default values or constraints.

Option A

When a big program becomes too large to understand, we divide it into small manageable modules. To show how these modules are arranged and how they communicate, we use a special tool called a Structure Chart.
It looks like a Tree Diagram where the top represents the main module and the bottom branches represent submodules.

• So, a Structure Chart is the program development tool that graphically shows how a program is divided into modules, their hierarchy, organization, and communication.

Option B

An ACD (Architectural Context Diagram) provides a high-level view of the system and shows how it fits into its environment. It illustrates the system boundary and depicts all external interfaces through which the system communicates with other entities.

This helps designers and stakeholders understand what lies inside and outside the system’s scope, ensuring that all necessary interactions are properly identified and managed.

Option C

Coupling refers to the degree of interdependence between modules in a system, means, coupling measures how tightly connected different modules are. Lower coupling is always preferred because it makes the system easier to maintain and modify.

• Loose Coupling is good: modules are independent, easier to test, modify, and reuse.
• Tight Coupling is bad: modules depend heavily on each other, so changes ripple through the system.

Data Coupling (Most desirable):

• Modules interact by passing only the necessary data as parameters. This is the best type because modules remain independent.

Content Coupling (Least desirable):

• One module directly accesses or modifies the internal data or code of another module. This is the worst type because it creates strong dependency and makes maintenance very difficult.

Option A

Data Flow Diagrams (DFDs) are used to represent how data moves through a system. A Context Diagram is the highest-level view of a DFD, which provides an overview of the entire system as a single process.
Because it gives this top-level, overall picture without showing internal details, the Context Diagram is also called a Level 0 DFD.

Lower-level DFDs such as Level 1, Level 2, and so on, break this single process into smaller sub-processes, showing more internal details of how the system functions.

Option B

Cohesion refers to the degree of relatedness and functional strength of the elements within a single module. It indicates how well the parts of a module work together to achieve a specific purpose.
High cohesion means that all parts of the module are closely related and focused on a single task, which leads to more maintainable, understandable, and reliable software.

• Cohesion tells how strongly the parts of a module are related to each other.
• Higher cohesion means stronger, better, and more focused module.

Option A

A Data Flow Diagram (DFD) is a visual representation that depicts the flow of information and the transformations applied to data as it moves from input to output in a system. It graphically shows how data enters the system, the processes that act on the data, where the data is stored, and how it exits the system.

Option B

The Open-Closed Principle (OCP) is one of the key object-oriented design principles. It states that a software component such as a class, module, or function should be open for extension but closed for modification. This means that the behavior of a component can be extended without altering its existing source code.

Option A

In software engineering, especially in modular design and structured programming, fan-in and fan-out are used to measure module interactions.

• Fan-in refers to the number of modules that call or use a particular module.
• Fan-out refers to the number of modules that are called by a particular module.
• High fan-in : Module is reusable and widely used.
• High fan-out : Module depends on many other modules.

Option B

The low coupling and high cohesion make modules independent and maintainable, improving overall software design quality.

Option C

In computer systems, coupling refers to the degree of connection and dependency between processors or computers.
Distributed Processing is a loosely coupled system because multiple computers work independently and communicate through a network. Each computer has its own memory and resources.
E.g.:

• Internet Systems.
• Distributed Databases.

Parallel Processing is a tightly coupled system because multiple processors work together closely on the same task and usually share memory and resources.
E.g.:

• Multi-Core Processors.
• Supercomputers.

Option D

The Activity Diagrams model the dynamic behavior of a system and represent workflows of actions and activities.