NCERT Book Class 11 Biology PDF

CBSE Class 11 NCERT Books for Biology PDF – Free Download

The NCERT textbooks are the most significant resource for students preparing for their class 9 to 12 exams. It is imperative that students use NCERT books per the syllabus and paper format that are recommended by the CBSE, regardless of whether they will be taking standard unit tests or final board exams. It has earned its credibility as the most trusted and best textbook distributor at the primary and secondary levels. NCERT books assist students in gaining a thorough understanding of all subjects.

Students who hope to pursue medical science should focus their academic efforts on being proficient in biology. Notwithstanding this, the NEET is the entrance exam that is taken to get admission to prestigious medical colleges in India. Both the NCERT books for Class 11 and 12 Biology are included in this examination scope and objectives.

It gives students a joyful learning experience and encourages them to be curious and look for answers themselves. Therefore, it would be beneficial for students to learn NCERT Biology Class 11 PDF because it covers the curriculum that the board and NEET require. In addition, subject matter experts and educators favour these NCERT books because they provide detailed and in-depth information regarding all subjects. It is the most reliable book for scoring maximum marks in competitive exams as most of the questions come from NCERT books.

Even the minutest doubt is resolved and the students develop an interest in learning and mastering the topic with ease. Therefore, the Biology Class 11 NCERT PDF book is useful because it allows students to save time and effort by only having to learn one book to prepare for various exams.

NCERT Book for Class 11 Biology PDF

Significance of Biology Class 11 NCERT

The study of life and living organisms focuses on the scientific discipline known as Biology. Because of this, it is also referred to as the science of life or life sciences. The Biology NCERT textbooks for Class 11 are the most reliable resource for learning the subject’s essential ideas. Reading this book is an excellent way for students to acquire significant information and prepare them for competitive exams.

In addition to this, the NCERT Biology book for Class 11 also assists students in enhancing their understanding of topics relevant to everyday life. This section covers the plant and animal kingdoms, which are critically significant for the board and NEET exams.

Students can strengthen their understanding of the material and their ability to perform well on both exams by downloading the NCERT Biology Class 11 PDF at their convenience.

NCERT Book for Biology Class 11 PDF Chapter Wise

The entire Biology syllabus required for the CBSE board examination is divided into four units, and each unit is further divided into numerous chapters. Let’s begin with the first unit, which is divided into four parts.

Unit 1: Diversity in the Living World

Chapter 1: The Living World

The NCERT biology textbooks for class 11 begin their first chapter with a discussion of the diverse kinds of living things that may be found in the environment. Along with providing an explanation of what it is for anything to be alive, this chapter also shows the ecological competition and cooperation that occurs among these individuals. Students get the opportunity to gain knowledge of the many physiological systems that assist living beings in maintaining themselves and passing on their species.

This chapter provides a more in-depth analysis of the pervasive diversity that can be seen in every region of the planet, despite differences in climate and other environmental factors. In addition, the taxonomic classifications and tools that apply to these live species are discussed in detail here.

1. Respiration:

In living things, the process of respiration is ongoing and continuous.. During this process, organisms take oxygen (O2) from the air and release carbon dioxide into the environment (CO2).

Fats and proteins undergo oxidation, which results in the liberation of stored energy. All of the various biological processes that take place in living things are driven by this form of free energy. One example of a catabolic reaction is respiration.

2. Reproduction :

Another trait that defines organisms is their capacity for reproduction. In multicellular creatures, the purpose of reproduction is to generate offspring with features that are very similar to those of their parents. These children are called offspring. Asexual reproduction can also occur in organisms. Fungi are capable of rapid reproduction due to the production of millions of asexual spores. In low-order creatures like yeasts and hydra, reproduction takes place through a process called budding. Planarian reproduction in its purest form (flatworms). It is possible for a fragmented organism to reclaim (live) the lost part of its body and so transform into an entirely new creature when true regeneration takes place. The fission (fragmentation) mechanism is used by fungi, fibrous algae, and the protonema of moss.

Chapter 2: Biological Classification

Since the dawn of civilization, human beings have endeavoured to classify the entirety of the known living population to exploit their resources, such as food, clothes, and shelter. Aristotle was the first person to attempt a scientific classification of them. Herbs, shrubs, and trees were the three categories that he used to classify plant life. In addition to this, he divided the kingdom of the animals into two distinct groups: those creatures that had red blood and those that did not have it.

This second chapter of the Class 11 NCERT Biology PDF explains the scientific classification process and five different classes, including Monera, Protista, Fungi, Plantae, and Animalia, as well as Viroid, Viruses, and Lichens. In addition, this chapter discusses the evolution of classification systems over time.

Protozoan Animal

These kingdoms are the most basic types of eukaryotic animals that are heterotrophic, tiny, and comprise the class Protista. They consist of a single cell. Inside of a cell is where all of the action happens in a living organism. They are serving as hosts. Some protozoa are parasitic.

(a) Amoebic Protozoa:

They are pristine in the aquatic or marine environment. Some of them can also be discovered in damp soil. On their exterior, certain species of amoeboid protozoa found in marine environments have a silica shell. They use pseudopodia to assist them in moving and to help them feed. Some amoebic protozoa such as entamoeba are parasitic. Entamoeba histolytica is the root cause in human populations

Amoebic dysentery is a disease.

(b) Flagellate Protozoa:

The members of this group are either completely self-sufficient or completely dependent on one another. The pellicle is the term used to describe the protective layer that is found on their bodies. Flagella contributes to healthy circulation as well as nutrition. Parasites such as Trypanosoma and leishmania are responsible for sleeping sickness and kala-azar, respectively.

(c) Ciliate Protozoa:

The organisms that belong to this clade live in water and possess many cilia. A stiff pellicle wraps around the body and protects it. They have cytostome and cytopyge that are always present. The food is transported to the cytoplasm through rhythmic movement in the ciliary.

Example:

Paramecium

(d) Sporozoa Protozoans:

They live inside their hosts and feed off of their tissues. They do not have adequate circulation. A covering is present. During the course of their life cycle, infectious spores are produced. A few decades ago, the human population was plagued by the malaria disease caused by the malaria parasite, Plasmodium.

Virus:

Ivanovsky was the one who found these for the first time (Ivanovsky, 1892). In addition, these go through the proof filtering process. M.W. Beijerinck discovered in 1898 that rubbing the sap of diseased plants on the leaves of healthy plants might likewise cause disease in healthy plants. This discovery was made by M.W. Beijerinck. 

Because of this fact, people referred to them as infectious living liquids or liquid poisons. W.M. Stanley was the first person to successfully isolate the virus in its crystalline form (W.M. Stanley, 1935). The fact that viruses are composed of nucleoproteins was first found by Dallington (Darlington, 1944). It is generally agreed that viruses serve as the transitional link between living and nonliving things.

Live Virus Symptoms

When they come into contact with living cells, they undergo a process of activation. The nucleic acid of the virus makes its way into the host cell, where it assumes control of the cell’s metabolic processes, initiates the process of self-multiplication, and produces the essential proteins for the virus’s continued survival. This results in a rise in the number of viruses, which may also be understood as reproduction.

Only in living cells can viruses continue their life cycle and spread.

Mutations in organisms are what cause changes in their genes.

Viruses are sensitive to various stimuli, including heat, chemical compounds, radiation, etc.

Chapter 3: Plant Kingdom

Students have gained information on the five classification systems of the plant kingdom from the prior topic. They will be able to learn about the Kingdom Plantae, sometimes known as the plant kingdom, and its subsequent classifications by reading this chapter of the Biology book for Class 11.

Algae, Bryophytes, Pteridophytes, Gymnosperms, and Angiosperms are the five divisions into which the entire kingdom of plants is divided for classification purposes. This chapter explains the usual traits of each plant class and helps understand the classification process. In addition, students have the opportunity to learn about plants’ many life cycles and generational shifts. Students will be able to get a solid foundation in the taxonomy of the plant kingdom as a result of this.

Economic Importance Of Algae 

1. Algae as Food: Algae are responsible for fifty per cent of all photosynthesis that occurs on Earth. Carbohydrates, minerals, and vitamins are all found in abundance in algae. The algae Porphyra, Alaria, Alva, Sargassum (Sargassum), and Laminaria, among others, were prepared as food items.

Chlorella contains a significant amount of protein. Vitamins can be discovered. It is widely acknowledged as the diet of the foreseeable future.

Because of this, there is a very good chance that we will be able to find a solution to the issue of how to feed our rising population.

2. The Industrial Use of Algae: The fossils and dead bodies of diatoms are what make diatomaceous earth, also known as Kieselguhr.. This dirt can withstand temperatures of up to 1500 degrees Celsius. It finds application in many businesses that manufacture metal coatings, varnishes, polishes, toothpaste, insulating surfaces, and other products.

Carrageenan is extracted from many species of algae, including Chondrus, Eucheuma, and others. It has several applications, including cosmetics, shampoo, etc.

The algae Alaria, Laminaria, and others can be used to produce algin. It plays a role in producing inflammable films, synthetic fibres, and other similar products. During surgical procedures, it can also be used to staunch blood flow.

Iodine, bromine, and other trace elements can be extracted from various seaweeds.

Chlorella is the source of the antibacterial compound known as chlorellin. It eliminates the microorganisms in the body. The presence of Chara and Nitella algae in the reservoir results in the death of mosquitoes in the area; hence, these algae contribute to the eradication of malaria.

It is possible to harvest agar-agar from red algae, and this substance is utilised in the production of artificial cultures.

Ornamental Plants: Ornamental plants include Soucis, Pinus, Arqucurid, Ginkgo, Thuja (Thuja ), and Cryptomeria, amongst others. Gymnosperms are economically important because of their role in producing these plants.

Plants with Nutritious Potential: Jamia is the source of sago. Cycas are the source. People consume the seeds of the Chilgoza tree (Pinus gerardiana). There is a culinary application for Gnetum, Ginkgo, and Cycas seeds.

The wood from pine (Pinus), cedar (Cedrus), cal (Pinus wallichiana), and fir (Abies) trees is commonly used for making furniture and timber.

Chapter 4: Animal Kingdom

The Kingdom Animalia and a systemic Classification procedure are discussed in the fourth chapter of the NCERT Class 11 Biology book PDF. This technique allows all known members to be allocated to a Class in a manner that is supported by scientific evidence. The foundation of this classification system is broken down in detail during the first part of this chapter. The organisation levels, symmetry, triploblastic and diploblastic organisations, coelom, segmentation, and notochord are all examples of taxonomic factors.

In addition, the second half of this topic discusses the classification of this kingdom according to essential physical characteristics shared throughout its members. These classifications are known as Phylum and include Porifera, Coelenterata, Ctenophora, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata, and Chordata respectively.

(A) Aestivation: “floret configuration” refers to the mutually related arrangement of the sepals and petals present in the bud stage. It is a type that is either corrosive, twisted, cortical or vexillary.

(b) Placementation: The term “ovary” refers to how ovules are arranged on the placenta in the ovary. These types of seedlings are known as the marginal type, the columnar type, the periphery type, the free columnar type, the base ascendant type, and the surface type.

(c) Actinomorphic is the property of a flower to be able to be sliced in two along any central perpendicular axis and remain intact as two separate flowers.

(d) Zygomorphy: This type of symmetry is referred to as monodia symmetry, and it occurs when the flower may be divided into two halves only by one central perpendicular axis.

(e) Superior Ovary: When additional flower elements emerge from the bottom of the ovary, this type of flower is referred to as an ovary, and the ovary itself is referred to as superior.

(f) Perigynous flowers are those in which the floral component of the flower emerges from the inflorescence at the same height as the ovary. This type of flower is known as a perigynous flower. Within this context, the ovary is only partially superior.

(g) Epipetalous Epipetalous is the term used to describe the state of the stamens in which they are connected to one another.

1. The rhizome is a storage organ that consists of underground stems that grow in a horizontal plane parallel to the surface of the earth. One can attend many festivals and celebrations at these locations. They branch out through orbital buds, which cause their length to rise, and their anterior buds cause their length to increase. Some buds. Produces pneumatic shoots when they are necessary; for example, ginger, banana, kelly, fern, turmeric, and other similar products.
2. Corm: Although they have symptoms similar to rhizomes, corms are underground stems that grow in a vertical direction. There are also festivals and celebrations of this kind included in this type of stem. This food is being kept in storage. There are developing buds. Orbital buds are developed from the anthers. Example- Arvi, Banda, Jimikand, etc.
3. Stem Tubers: These are produced due to the blossoming at the tips of underground branches. They have an asymmetrical shape. There are celebrations or festivals that take place on the hill, but it is difficult to see what is going on because of the accumulation of food in vast amounts. Potatoes have several eyeballs on the surface of their skin, which are covered by scales and buds, respectively. The buds eventually develop into new shoots that extend upward.
4. Bulbs: The bulb’s stem is short (briefly conical or flattened), as it is in this type of metamorphosis. The adventitious roots originate from the lowermost section of the plant. The multiple scale sheets that are present on this stem are used to store food. When environmental conditions are suitable, aerial shoots will develop from the bud that is located at the frontmost tip of the stem. In addition, orbital buds are generated in the cells that make up the scale sheets. To cite just a few examples: onion, garlic, lily, etc. Tubers of the scale.

Unit 2: Structural Organisation in Plants and Animals

The next section of the syllabus will begin right after this one. This section consists of three chapters that follow one another in sequence, chapters five through seven.

Chapter 5: Morphology of Flowering Plants

Morphology refers to the scientific study of the outward appearance of various organisms. This fifth chapter of the new edition of NCERT Biology for Class 11 presents the structure of the external parts of higher plants, as well as their importance and the process by which they function. Students have in the past gained knowledge regarding the classification of plants according to their morphological and various other distinguishable characteristics.

All of these morphological characteristics are outlined and discussed clearly and concisely in this section. In this chapter, students can learn about the plant’s root, stem, leaf, inflorescence, flower, fruit, and seed. In addition, it provides a description of some common flowering plants and an explanation of the characteristics typical of some important plant families.

Chapter 6: Anatomy of Flowering Plant

When observing a living organism, it is simple to spot the structural differences and similarities that exist within it. On the other hand, anatomy is the study of internal structures as well as the functions of those structures. This sixth chapter of Biology Class 11 NCERT PDF is available for download now. The functional organisation and internal structure of higher plants are dissected in excruciating detail in the Biology Class 11 NCERT PDF book, which can be downloaded here.

In a nutshell, this chapter aims to educate students on the various kinds of tissues found in plant bodies and the tissue systems that are organised differently depending on their location. This chapter goes into great detail about the anatomy of both monocotyledonous and dicotyledonous plants. Additionally, students can learn about plants’ primary and secondary growth stages. Primary growth occurs during the first few years of a plant’s life.

Chapter 7: Structural Organisation in Animal

Students can learn about multicellular and unicellular organisms that belong to the animal kingdom by reading the seventh chapter of the NCERT book for Class 11 Biology, which is available in PDF format. The single cell that makes up a unicellular organism is responsible for all of the organism’s vital functions, including respiration, reproduction, digestion, and so on. At the same time, multicellular organisms utilise a variety of organs, each of which was developed by a distinct set of cells, to carry out a specific set of functions.

This chapter is all about the various organs, tissues, and cells of animals, as well as their systems, functions, and other characteristics. For example, students can examine the morphological and anatomical structure of earthworms, cockroaches, and frogs to better understand these topics. Each of these three creatures is classified as vertebrates or invertebrates. Therefore, by learning about these animals, students can develop an understanding of the anatomy of animals.

Unit 3: Cell: Structure and Function

The student’s textbook for CBSE Class 11 Biology has reached another new unit at this point. This section is divided into three separate chapters, each discussing a different aspect of the structure and operation of a cell.

Chapter 8: The Unit of Life

The cell is introduced as the primary structural component of living things at the beginning of this chapter of Biology 11 NCERT PDF. There is no such thing as a single-celled or multi-celled organism; all living things are composed of cells. This topic begins by defining cells and then discusses cell theory. According to this hypothesis, all living things are made up of cells and products of cells, and new cells are generated from already existing cells.

It offers a comprehensive summary of the cell and the distinction between plant and animal cells. In addition, it can encase a wide variety of cell types, including but not limited to red blood cells, white blood cells, columnar epithelial cells, nerve cells, mesophyll cells, and so on. This chapter comes to a close by discussing the two primary categories of cells, prokaryotic and eukaryotic cells, and the characteristics, functions, and other aspects of each type.

Ultrastructure:

It is a structure with two distinct layers. Smooth on the outer layer and rough on the inner layer

Cristae are the name given to the inflorescences that look like fingers and can be found.

The peri mitochondrial space is the name given to the area that can be found between the two layers.

Within the cavity of the mitochondria is where you’ll discover the proteinaceous matrix. Exosomes and F1 particles are two names for the small particles that can be found on the surface of Christie.

It is speculated that exosomes play a role in forming ATP through their participation in the respiratory process of oxidative phosphatization. Electrons bidding at the Mitochondrion’s version of Christie’s

ATP is produced as a byproduct of the process of transduction, which takes place. DNA, ribosomes, water, salts, and wicks related to the Krebs cycle are some of the components that can be found in its matrix.

Chemical Composition: between 65 and 70 per cent protein, 25 per cent lipid, D.N.A., R.N.A., etc. All cytochromes that are associated with the chain in the inner phase of the respiratory system, such as Cyt b, Cyt c, Cyt a, Cyt a 3, quinone, NAD, FAD, FMN, etc.

Mitochondria’s Role in the Cell

The free energy that is produced is used to power the Krebs cycle, which is located in the matrix of the mitochondria, and the electron transport mechanism of the respiratory chain, which is located at the oxysome (F1 particle), to produce ATP. ATP supplies all of the kinetic energy that is required for biological processes.

The Lava’s Internal Structure

The receptacles have a double membrane surrounding them on all sides. These are unique to the eukaryotic plant cells and can be found nowhere else. Fungi do not contain these components. Heikel (1865) was the one who made the discovery, and Schimper was the one who gave it its name. There are three subtypes of leucoplasts: Chromoplast, Chloroplast, and Leucoplast.

1. Leucoplast:

The total number of lavers can be seen here. Because there is no pigment, they do not have any colour. There are three different kinds of amyloplasts: proteinoplasts, elaioplasts, and amyloplasts that accumulate bolls (accumulating protein).

2. Chromoplasts are fungi that have their own unique colouration. Typically located in things like flower petals, coloured fruits, coloured leaves, etc. Photosynthetic bacteria have chromatophores, while chloroplasts and chromoplasts are found in brown algae. Rhodoplasts are found in red algae.
3. Schimper was the one who first discovered the chloroplast, also known as the chloroplast (Schimper, 1864). They are composed of chlorophyll (chlorophyll). The green parts of the plant, specifically the leaves, are typically where these fungicides are found (mesophyll, columnar tissue, chlorenchyma). These range in size from small to large. The chloroplast structure is typically used as a diagnostic tool for identifying green algae. They are round, elliptical, flat, or elliptical in higher plants. In most cases, their length is between 2 and 5p, and their width is between 3 and 4 p. There could be anywhere between 20 and 40 of them inside the cell.

Chapter 9: Biomolecules

Every living thing in this biosphere comprises various chemical substances that can be broken down into either compounds or elements. The procedure for determining the chemical compositions of living things is detailed in chapter 9 of the NCERT 11 Biology book in PDF format. These substances, which are referred to as metabolites, can be identified with the assistance of biomolecules, which are responsible for their synthesis. This subject also provides in-depth knowledge regarding a variety of different metabolites.

As the lesson progresses, students learn about various biomolecules, such as proteins, polysaccharides, nucleic acids, etc. From this subject, one can derive, among other things, an in-depth concept of protein structure, the characteristics of bonds that link monomers in polymers, a concept of metabolism, and so on. This article also includes information on the significance of metabolism and numerous enzymes and the functions they serve.

Chapter 10: Cell Cycle and Cell Division

Students have come to the final chapter of this unit, during which they have learned about the cell in its entirety. This topic, which can be found in the NCERT books PDF for Class 11, The scientific discipline of Biology, describes a phenomenon known as cell division, which describes the process by which a single-celled organism can develop into a multicellular organism over time. This part explains a cell cycle and how the described process works.

Students also have the opportunity to learn about the various phases of the cell cycle, such as interphase, M phase, G1, S, and G2 phase, as well as prophase, metaphase, and anaphase. Students have the opportunity to prepare cell divisions and their classifications in the subsequent section of this chapter. It describes the two most important processes, mitosis and meiosis, as well as their significance and how they operate.

Unit 4: Plant Physiology

This is the beginning of the fourth unit, which has a total of five chapters. This lesson will cover everything there is to know about plant physiology and all of its different aspects.

Chapter 11: Transport in Plants

This eleventh chapter of the Class 11 NCERT Biology book PDF begins with an explanation of how water and other substances travel all the way to the very top of a tree and how different elements are transported from one cell to another. This exemplifies the transport system that plants have at their disposal. In addition, the eleventh chapter can glean information regarding the significance of the connection between plants and water. In addition, students can learn about water transportation over long distances and the elaboration of other nutrients and minerals.

An additional process known as transpiration is divided and illustrated here with an example. Students should have no trouble grasping the concept that trees use their phloem cells to carry out the functions of their transport system from the source.

Chapter 12: Mineral Nutrients

In this chapter of the NCERT Class 11 Biology book PDF, students can learn about the different approaches that can be taken to investigate which minerals are essential for the growth and survival of plants. They can gain knowledge about all of the necessary minerals that plants require as a result of this study. In addition, the mechanism that plants use to take in these essential elements is also broken down in this chapter.

Students gain an in-depth understanding of the process of solute translocation and the nitrogen metabolism system by studying this topic. Furthermore, it explains how the soil functions as a reservoir of these essential elements that plants absorb and transport to the various parts of their bodies to carry out the physiological processes necessary for their survival.

Chapter 13: Photosynthesis in Higher Plants

Photosynthesis is a biological process that enables plants to produce the food they need to sustain themselves, and all students who study Biology in Class 11 know this fact. On the other hand, the information presented in this chapter of the Class 11 NCERT Biology PDF gives more specifics about it.

Students can learn about the early experiments conducted on photosynthesis, the location at which it takes place, and the number of pigments involved in this process. In addition, information regarding the light reaction, electron transport, the applications of ATP and NADPH, as well as the C4 pathway are all thoroughly discussed in this Chapter. In conclusion, it is important for students to be aware of the factors that have the potential to affect this process.

Chapter 14: Respiration in Plants

The fourteenth chapter of the NCERT PDF Class 11 Biology textbook covers respiration, which is yet another significant and physically active process that plants engage in. In the field of Biology, the act of breathing is referred to as respiration. This chapter offers a variety of examples to demonstrate that it is necessary for all plants to breathe to survive. Additionally, the importance of glycolysis and fermentation concerning respiration is discussed in this chapter, as is their connection to respiration.

Students can learn about aerobic respiration, the balance sheet of respiration, a quotient of this process, and an amphibolic pathway as the unit of study progresses through this topic. When students have finished reading this chapter, they should have a comprehensive understanding of the respiratory system of plants.

Chapter 15: Plant Growth and Development

The growth process is one of the most universal and can be observed in all organisms still alive today. This chapter of the new NCERT Biology Class 11 PDF explains how various growth aspects relate to metabolism and how metabolism influences growth. Measurements of growth, its phases, rate of growth, and the condition of growth are all included in these aspects. Dedifferentiation, redifferentiation, and differentiation are all concepts that can be demonstrated with reliable examples and facts.

The development of plants is the topic that will be covered in the next section of this chapter. In addition to that, it illustrates the distinctions that exist between these two ideas as well. Students have the opportunity to learn about the various factors that control the processes of photoperiodism, vernalization, and plant growth.

The following are the primary internal factors that contribute to dormancy.

1. Impermeability: The seed coats of many plants are tough and water-resistant, meaning that the seeds cannot take in water and germinate even when they are in contact with water. This is because the seeds have a hard seed coat. These seeds do not emerge from the ground for a long time. Only after the seed coat has been sufficiently broken down and made more porous by the action of soil particles, bacteria, and fungi under natural conditions can the seed begin to germinate by taking in water. This process is known as scarification.
2. Seed Coat’s Impermeability to Oxygen: In some cases, dormancy in seeds can be caused by the seed coat’s impermeability to oxygen. The same factors or substances that make the seed coat impermeable to water also gradually make it impervious to oxygen. Xanthium, many different kinds of grass, and dormancy of a similar nature can be found in the seeds of some plants belonging to the Compositae family.
3. A Mechanically Resistant Seed Coat: In the seeds of some plants, water and oxygen are absorbed by the seed coat. However, the seed coat is so tough that the embryo does not develop completely, and its development is limited to the seed coat alone. For example, in the seed of Alisma Plantago, the embryo swells as a result of water and suppresses the seed coat by imbibition pressure; however, it is unable to break it, and germination stops as a result. The failure of the seed coat causes the seedling to stop growing as a result. Other plants that exhibit this form of dormancy include black mustard (Brassica nigra), Lepidium, Amaranthus, Retroflexus (Amaranthus retroflexus), and others.
4. Imperfectly Developed Embryo: In this type of dormancy, the embryonic development inside the seed does not even finish before the seed and its mother plant are separated. These types of seeds contain all stages of embryonic development, from the fertilised egg to the fully developed embryo. This includes all stages in between. Some seeds, like Erythronium, Ranunculus, Ilex, etc., undergo a slow embryonic development during the fall or winter months. This development is finished in the spring, just before the seedlings germinate.
5. Embryo Requirement after Ripening in Dry Storage: The embryo may be fully developed in some mature seeds. However, for these seeds to germinate, it is necessary to store them in a dry environment for a period of time before germination. If this requirement is not met, the seeds will not germinate. In the course of this process, the seeds undergo a number of the necessary metabolic changes to begin the germination process. This after-ripening process in Crataegus seeds can be finished anywhere from one to three months after it begins. During this process phase, the degree to which the embryo is acidic rises as later ripening progress. This speeds up the germination process and enhances the plant’s ability to absorb water.
6. The Presence of Germinating Inhibitors: Numerous plants contain substances that are either inhibitory or inhibitory, such as abscisic acid, coumarin, ferulic acid, and short-chain in the tissues of the embryo, endosperm, seed, and fruit, among other places. There are also other things like fatty acids.

Unit 5: Human Physiology

The NCERT books for Class 11 Biology come to a conclusion with this, the final unit, which covers human physiology. This section is divided into seven different chapters.

Chapter 16: Digestion and Absorption

All living things really need food as a basic necessity of life. Living things require carbs, lipids, protein, minerals, and vitamins for growth, development, and survival. All of these substances are ingested by living things through the digestive system.

The human digestive system, which consists of the alimentary canal, digestive glands, and the mechanism by which food is digested, is thoroughly described in this chapter. The process of absorbing digested food is highlighted. Additionally, this chapter covers all of the typical human illnesses, including jaundice, constipation, diarrhoea, etc.

Chapter 17: Breathing and Exchange of Gases

This chapter of the Class 11 NCERT Biology book contains information for biology students about the numerous respiratory organs, including the lungs and breathing systems. This subject explains how the human body regulates breathing, exchanges gases, and transports gases.

Last but not least, it displays diseases of the respiratory system in humans, such as asthma, emphysema, and occupational respiratory diseases.

Chapter 18: Body Fluid and Circulation

All the necessary ingredients are transported throughout the body through blood. Students studying Biology for Class 11 can learn about the components of blood, including plasma, fluid matrix, and formed elements, in this chapter of the NCERT Biology book. Additionally, it provides details on various blood types.

Here, lymph, another fluid that forms a tissue, is discussed. Additionally, students can learn about the cardiac cycle, the human circulatory system, and the circulation pathway. Additionally, this chapter provides numerous answers regarding cardiac functions, double circulation, and circulatory illnesses, including high blood pressure, angina, heart failure, etc.

Chapter 19: Excretory Products and Their Elimination

The human excretory system is discussed in chapter 19 of the Biology textbook for Class XI. This topic also covers the process of producing urine, various tubular functions, and the method of filtrate concentration.

Students can study the regulation of kidney function and the significance of other organs in excretion. Additionally, they can be informed about excretory conditions such as glomerulonephritis, renal failure, renal calculi, and uremia.

Chapter 20: Locomotion and Movement

A key aspect of all living things is mobility, which is explained in detail in this chapter of the NCERT Biology Class 11 PDF. Here, it also discusses how many muscles, including skeletal, visceral, and others, are involved in the movement.

In this chapter, specific details regarding the skeletal structure and joints are provided to assist students in understanding how the human skeleton supports movement and mobility. Additionally, this chapter provides a brief overview of muscular and skeletal conditions such as myasthenia, tetany, arthritis, osteoporosis, gout, etc.

Chapter 21: Neural Control and Coordination

A neurological system aids in coordinating the body’s many tasks, which are performed by human organs working together. Students may learn about the human brain system and its functional and structural elements in this chapter of the NCERT Biology books for Class 11 textbooks. The central nervous system of the human body and how it regulates most functions are also covered in this chapter.

Additionally, lessons on the reflex arc, action and the sensory transmission and reception process are available to students.

Chapter 22: Chemical Coordination and Integration

The final chapter of the NCERT Biology Class 11 PDF teaches students about various endocrine glands and hormones. Hormones serve as nutrient-free intercellular transmitters. The human endocrine system demonstrates the importance and uses of its hormones and secretions.

The hormones of the kidney, heart and gastrointestinal tract are also discussed in this chapter. Finally, the book’s conclusion explains how these hormones work.

Why NCERT Books Are Popular Among Both Students and Teachers?

The NCERT books for Class 11 Biology have always been a popular choice among students for both the CBSE board exam and the NEET exam. Teachers also suggest these books for many reasons.

Easy to Understand Language

The clear language of these books is the main reason why students prefer them. It facilitates their understanding of the chapter without requiring them to spend much time and effort. The clear writing style also aids students in efficiently completing this extensive subject within the constrained period and preparing for exams.

In-depth Explanation

The NCERT books also include a thorough explanation of each subject. As a result, students do not need to search through many reference materials to find the information they need. Its in-depth approach also helps students assess their knowledge while preparing for higher education. CBSE itself recommends NCERT books, which is the most reliable book for scoring maximum marks in competitive exams as most of the questions come from NCERT books.

Why Should Students Go for Extramarks?

Extramarks is one of the best educational platforms with the highest-quality e-learning tools. We have online classes where students may ask questions, get answers, and learn from the NCERT textbooks for Class 11 Biology more effectively. Our CBSE syllabus– and focused study tools might assist you in combining your preparation for the CBSE Exam and the NEET Exam. In addition, study the highlighted points carefully and work through the tasks to understand every concept and answer any question easily. This encourages the students to master the topic and increases their confidence in achieving a higher grade.