Bacteria: NCERT Class 11 Biology Concept Note For NEET 2023

National Eligibility cum Entrance Test or NEET is regarded as India’s most competitive entrance exam. NEET UG 2022 is expected to be conducted on 17 July. NTA released the NEET 2022 Application Form on 6 April for the aspirants. Moreover, the last day to fill up the NEET 2022 application form is 7 May. 

To score good marks in NEET 2022 Result, aspirants need to acquire in-depth knowledge of all the topics included in the NEET 2022 Syllabus. This article will provide information about the important NCERT class 11 Biology notes, the three-month revision strategy, and some expert tips to enhance your performance.

NEET 2022 Notification

In the official NEET 2022 notification, NTA has listed the information for NEET 2022 Exam Dates, NEET 2022 Registration Date, revised NEET 2022 Exam Pattern, and changes made for NEET 2022 Eligibility. NTA has made one major change to the eligibility criteria for NEET UG 2022. From 2022 onwards, the limitation for the maximum age limit of candidates has been removed.

NEET 2022 Exam Pattern and important dates

Apart from the changes made by NTA last year, there has been one more chance in the NEET 2022 Exam Pattern. This year medical aspirants will get an extra 20 minutes for answering the questions. The following table provides the information about NEET UG 2022 question pattern:

The total marks for NEET 2022 are 720. For each right answer, candidates are given four marks, and one mark is deducted as a negative marking for each wrong answer. NEET 2022 Cut-Off is determined according to the category of students. The following table shows the category-wise minimum marks required to qualify for NEET 2022:

Candidates who aim at taking NEET 2022 need to consider the following dates released by NTA:

NEET 2022 Syllabus of Biology

Biology is the most crucial section for NEET. Students need to have in-depth knowledge and understanding of each topic covered in the syllabus of classes 11 and 12 to qualify for NEET with good marks. The following table provides the information on the chapters included for NEET Biology:

Classification of Five Kingdoms

In 1969, R.H. Whittaker introduced a classification method of living organisms which was much more refined to remove all the demerits of Linnaeus’s classification. The new classification process grouped organisms according to their cellular structure, reproductive process, thallus organisation, mode of nutrition, and phylogenetic relationship. The organisms were classified into the following five groups:

• Monera
• Protista
• Fungi
• Plantae
• Animalia

What Is Meant By Bacteria?

Bacteria are single-celled organisms that belong to the prokaryotic group of living organisms. They are known to lack a nucleus and few organelles. Bacteria are the first living organisms that ever came on earth and evolved in different ways to form various microorganisms. 

A group of bacteria display exceptionally diverse metabolic capabilities. Moreover, they can use most of the organic compounds and a few inorganic compounds as a source of food. Therefore, they are essential to maintain the ecological balance. Functions like decaying of dead organisms, nitrogen fixation, etc., can get delayed with the absence of bacteria.

Structure of Bacteria

Although bacteria are tiny microscopic organisms, they have a well-structured shape which consists of the following parts:

• Capsule: It consists of polysaccharides which is a complex carbohydrate. Capsule performs multiple functions in a bacteria, but its most essential function is to protect the bacteria from drying and prevent larger organisms’ phagocytosis. It is the major virulence factor among serious disease-causing bacteria.
• Cell envelope: It consists of two to three layers. These layers are called the cell wall – the inner cytoplasmic membrane and the outer capsule. However, the outer capsule is found in very rare cases.
• Cell wall: All the bacteria have a rigid cell wall made of peptidoglycan and a protein-sugar molecule. The wall gives the cell a proper shape and surrounds the cytoplasmic membrane for protection from environmental factors. It also ensures adequate attachment of the flagella and pili, which originates from the cytoplasm membrane and extends through the wall to the outside environment. 
• Cytoplasm: The cytoplasm is the part where functions like replication, metabolism, and cell growth occur. It is a gel-like compound made up of enzymes, water, wastes, nutrients, and gases. Moreover, it contains cell structures, including a chromosome, ribosomes, and plasmids. 
• Cytoplasmic membrane: It is a layer of protein and phospholipids. It encloses the inner parts of the bacteria to regulate the flow of materials throughout the cell. This is the structural trait that bacteria share with other living cells. In addition, it acts as a barrier and allows only selective interaction with the outside environment. This membrane is very organised and has asymmetric sides. Both sides have different functions and surfaces. These membranes are highly dynamic and constantly adapt to various conditions.
• Flagella: They are hairlike structures that help in the movement of bacteria. Some bacteria have them on either end, while others are all over the surface. This part is crucial in the bacteria’s body because it keeps the bacteria away from toxic substances, promotes movement towards nutritional substances, and for photosynthetic cyanobacteria, flagella help in the movement towards the light.
• Nucleoid: It is a part of the cytoplasm which contains chromosomal DNA. It does not have a membrane; instead, it is just an area of cytoplasm. Most bacteria contain a single, circular chromosome that performs replication. However, some bacterial species are known to have more than two strands.
• Pili: Several bacterial species have this structure which looks like a hairlike projection. It images from the outer cell surface of bacteria. These tiny parts are responsible for clamping bacteria to other surfaces and cells like intestines, teeth, etc. without this part, illness-causing bacteria can hardly attach themselves to the host body. Special pili are also responsible for conjugation, which is when bacteria exchange the fragments of plasmid DNA.

How can we classify bacteria?

Bacteria are classified into different categories according to their characteristics and features. However, they are generally classified according to the following features:

• Composition of the cell wall

• Nutrition method

• Respiration method

• Shape 

• Number of flagella

• Temperature requirement

How do bacteria reproduce?

Most bacteria reproduce through a process known as binary fission. Conceptually it is considered a simple process where one cell grows to its double size and eventually gets divided into two parts. However, the bacteria must divide at the right time to remain competitive and viable. It is also important that the bacteria produce the exact copy of itself with all the important genetic information. The reproduction rate in bacteria depends on factors such as availability of nutrition and a favourable temperature. Some bacteria like Escherichia coli and E.coli reproduce around two million daughter cells every seven hours under favourable conditions.

Although most bacteria reproduce asexually, some rare ones follow a sexual reproduction method. Generally, sexual reproduction happens in bacteria for adaptation according to the change in the surrounding. Caenorhabditis elegans are one of the bacteria that reproduce asexually.

What are useful bacteria?

Generally, we think all the bacterias are harmful and cause disease. However, some healthy bacteria help human beings in numerous ways. Some of the benefits of useful bacteria are:

• They help produce antibiotics to fight various diseases caused by harmful bacteria.
• They enhance our immune system and aid in the digestion of food. Some examples of these bacterias are Bacteroidetes, Actinobacteria, etc.
• Bacteria like Lactobacillus help form curd, and Bacillus ferments the food for various purposes.