Question Discussion & Solution

OSI Model

• OSI stands for Open System Interconnection is a reference model that describes how information from a software application in one computer moves through a physical medium to the software application in another computer.
• OSI consists of seven layers, and each layer performs a particular network function.
• OSI model was developed by the International Organization for Standardization (ISO) in 1984, and it is now considered as an architectural model for inter-computer communications.

There are seven OSI layers. Each layer has different functions. A list of seven layers are given below:

1) Physical Layer: 

• The main functionality of the physical layer is to transmit the individual bits from one node to another node.
• It is the lowest layer of the OSI model.

2) Data-Link Layer: 

• This layer is responsible for the error-free transfer of data frames.
• It defines the format of the data on the network.
• It provides reliable and efficient communication between two or more devices.

3) Network Layer: 

• It is a layer 3 that manages device addressing, tracks the location of devices on the network.
• It determines the best path to move data from source to destination based on the network conditions, the priority of service, and other factors.
• Logical Addressing and Routing are functions of the Network Layer.

4) Transport Layer: 

• The Transport layer is a Layer 4 ensures that messages are transmitted in the order in which they are sent and there is no duplication of data.
• The main responsibility of the transport layer is to transfer the data completely.

5) Session Layer:

• The Session layer is used to establish, maintain, and synchronizes the interaction between communicating devices.

​6) Presentation Layer:

• It acts as a data translator for a network.
• This layer is a part of the operating system that converts the data from one presentation format to another format.

7) Application Layer: 

• An application layer serves as a window for users and application processes to access network service.
• This layer provides network services to the end-users.
• HTTP is an application layer protocol designed within the framework of the Internet protocol suite. Its definition presumes an underlying and reliable transport layer protocol, and Transmission Control Protocol (TCP) is commonly used.

​Thus, HTTP is an application layer in the OSI Model of Networking.

Explanation:

• Bacteria are the sole members of the Kingdom Monera. They are the most abundant micro-organisms.
• On the basis of origin, bacteria can be divided into two types - Archaebacteria & Eubacteria

Archaebacteria:

• These bacteria are special since they live in some of the harshest habitats such as extreme salty areas (halophiles), hot springs (thermoacidophiles) and marshy areas (methanogens).
• Archaebacteria differ from other bacteria in having a different cell wall structure and this feature is responsible for their survival in extreme conditions.
• For example - Methanogens are present in the gut of several ruminant animals such as cows and buffaloes and they are responsible for the production of methane (biogas) from the dung of these animals.

Additional Information 

Eubacteria:

• There are thousands of different eubacteria or ‘true bacteria’.
• They are characterised by the presence of a rigid cell wall, and if motile, a flagellum.
• The Eubacteria can be both autotrophic & heterotrophic.

Stack

• It is a Last In First Out (LIFO) data structure
• Piles is another name used for stack since data element are placed one above the other and last element on the pile is the first one to be removed (LIFO)

• Push-down list: A list in which the next item to be removed is the item most recently stored (LIFO); Stack is a LIFO data structure
• The stack is used in situations where data have to be stored and then retrieved in reverse order.
• Real-life implementation of the stack is shown:

The ball which is stored last (D) will be the first one to be taken out of the container

Important Points

• Stacks data structures are also called FILO (first in last out)
• push(), pop(), peek() are some of the functions of stack data structure

The Venn diagram that best represents the relationship between Uttar Pradesh, Jhansi, Goa is shown below:

Jhansi is a city of Uttar Pradesh.

Whereas, 

Uttar-Pradesh and Goa both are different States of India thus will come as a separate circle.

Hence, Option (4) is correct.

Additional InformationUttar-Pradesh:

• The Dudhwa National Park is located in Terai and is spread over an area of 490 sq.km. The national park also has the Dudhwa tiger reserve within its premises.
• National Chambal Sanctuary is also known as the National Gharial Wildlife Sanctuary that is home to the endangered gharial or small crocodile. The river Chambal follows through this sanctuary as the hills and ravines build many sandy beaches inside the park.
• Situated in the district of Pilibhit in Northern Uttar Pradesh, Pilibhit Tiger Reserve is one of the 41 Project Tiger reserves of the country. The forest cover here is dense which is why the tigers have a good eco-system to survive in with enough prey. The reserve is home to over 127 different kinds of animals and 556 kinds of birds.
• The Nawabganj bird sanctuary also popularly known as Shahid Chandra Shekhar Azad bird sanctuary is situated in the Unnao district of Uttar Pradesh. The sanctuary is famous for being the temporary home of more than 250 kinds of birds. The birds come all the way from former USSR countries.
• Chandraprabha Wildlife Sanctuary is located near the city of Varanasi, Uttar Pradesh. The sanctuary is not as famous as the other ones in the area but the place is rich in scenic landscapes and waterfalls. The two famous waterfalls are; Rajdari and Devadari. The variety of animals found here are the wild boar, Indian gazelle and blackbucks.

Goa:

• Spread over an area of 211 square kilometres, Netravali Wildlife Sanctuary is one of the newly established wildlife sanctuaries in Goa.
• With the number of Royal Bengal tigers that can be found at the Mhadei Wildlife Sanctuary, authorities are considering to promote the place as one of the Project Tiger Reserves. Among the very popular sanctuaries of Goa, it is located near Valpoi town in Sattari Taluka.
• The Bhagwan Mahaveer Sanctuary is the biggest wildlife sanctuary in Goa and is located in Sanguem taluka. It spreads over an area of 240 square kilometres. Along with the stunning landscapes of the Western Ghats, the sanctuary also encompasses the very famous Dudhsagar Falls and a number of temples from the era of the Kadamba Dynasty. You can also visit the famous Devil’s Canyon View Point, a perfect place to spot wildlife and birds.
• Set up in 1968 and spread over an area of 105 square kilometres, the Cotigao Wildlife Sanctuary is situated in the southern part of Goa, near Canacona Taluka.
• The core area of Bhagwan Mahaveer Sanctuary is known as the Molem Wildlife Sanctuary. It is located in the Sanguem region and is claimed to house up to 120 different species of birds such as drongo, golden oriole, the great Indian hornbill, three-toed kingfisher, wagtails, and fairy bluebird.

The correct answer is carbon.

Key Points

• A fullerene is an allotrope of carbon whose molecule consists of carbon atoms connected by single and double bonds so as to form a closed or partially closed mesh, with fused rings of five to seven atoms.
  • The molecule may be a hollow sphere, ellipsoid, tube, or many other shapes and sizes.
• Various allotropes of carbon are diamond, graphite, lonsdaleite, fullerene, C-540, C-70, amorphous carbon, carbon nanotube.
• Diamond and crystalline silicon are isomorphous because they both have a three-dimensional tetrahedral structure.
• Allotropy, the existence of a chemical element in two or more forms, which may differ in the arrangement of atoms in crystalline solids or in the occurrence of molecules that contain different numbers of atoms.

Additional Information

• When an element exists in more than one crystalline form, those forms are called allotropes; the two most common allotropes of carbon are diamond and graphite.
  • One of the allotropic form of a carbon is a fullerene in which “carbon atoms” are “arranged in a sphere”.
  • Each sphere has 60 carbon atoms and each carbon atom is linked by a single covalent.
  • The fullerene is considered as purest allotrope of “carbon” because they have “smooth structure” without having dangling bonds.