NCERT Solutions for Class 11 Biology
NCERT Solutions for Class 11 Biology in PDF format for CBSE & UP Board for academic session 2020-21 are available to download free with latest NCERT Textbooks. NCERT solutions of other subjects are also available to download.Download updated solutions, study material issued by CBSE, for the coming session based on latest CBSE Syllabus. Join the Discussion Forum to ask questions or reply the others.
NCERT Solutions for Class 11 Biology
NCERT Solutions for Class 11 Biology in English
NCERT Solutions for Class 11 Biology in English Medium updated for new academic session 2020-21 in PDF format free. NCERT books and answers, study material for final exams and other online study books for revision are available to free download. NCERT Solutions 2020-21 based on latest CBSE Syllabus are available to free download. Join the discussion forum to ask your doubts and reply to other’s questions.
Select the Chapter for 11th Biology Solutions
- Chapter 1: The Living World
- Chapter 2: Biological Classification
- Chapter 3: Plant Kingdom
- Chapter 4: Animal Kingdom
- Chapter 5: Morphology of Flowering Plants
- Chapter 6: Anatomy of Flowering Plants
- Chapter 7: Structural Organisation in Animals
- Chapter 8: Cell: The Unit of Life
- Chapter 9: Biomolecules
- Chapter 10: Cell Cycle and Cell Division
- Chapter 11: Transport in Plants
- Chapter 12: Mineral Nutrition
- Chapter 13: Photosynthesis in Higher Plants
- Chapter 14: Respiration in Plants
- Chapter 15: Plant Growth and Development
- Chapter 16: Digestion and Absorption
- Chapter 17: Breathing and Exchange of Gases
- Chapter 18: Body Fluids and Circulation
- Chapter 19: Excretory Products and their Elimination
- Chapter 20: Locomotion and Movement
- Chapter 21: Neural Control and Coordination
- Chapter 22: Chemical Coordination and Integration
What is meant by Anatomy?
It is the study of gross internal structure of organs and different parts. It ascertains the identification and similarities of one organism with other organism in the course of studies. Some organism have considerable similarities in external and internal features, where as in some organisms, there is close resemblance in external features but they differ in internal structure. For example – Man, Monkey and Dog have analogy in internal organ system but externally all of them differ from one another.
What is Cell Biology?
The body of living beings is composed of one or many cells. The structure, function and division of the cell directly determines the life activities of living beings. All researches or studies related to cell are included under the branch known as Cell Biology. It involves the studies of all kinds of cells and their behaviour.
What do you know about Molecular Biology?
The cell consists of large number of micro and macro molecules such as nucleic acids, proteins, lipids etc. The interaction between these bio-chemical molecules results into life and all these studies of cells at molecular level are included under the branch known as Molecular Biology. It involves the studies of composition and mechanism of synthesis of the biomolecules of cells.
What is Morphology?
It is the study of external features of organisms. It essentially includes the understanding and interpretation of structure both external and internal.
Branches of Biology – Taxonomy
Man has always tried to name and classify the things present in the surrounding according to their utility. This led to extensive collection of knowledge about plants and animals. At present about 1200000 species of animals and about 7 to 8 lakh species of plants are known to us. The branch of biology which deals with the identification and classification of organisms is called Taxonomy.
Branches of Biology – Physiology
Plants and animals perform life processes in a similar fashion. For example digestion, respiration, excretion etc. In addition, plants also perform photosynthesis. All these life activities are the consequences of bio-chemical reactions that occur inside the cell. The detailed study of these reactions is known as Physiology. The study of life processes and functions of plants is called Plant-Physiology. Whereas study related to animals is defined as Animal Physiology.
Branches of Biology – Histology
The body of various plants and animals are composed of different kinds of organs and organ systems. These organs are formed by special structures called tissues. The tissues are the groups of such cells which are similar in structure, function and origin. Thus the tissues are microscopic structures and can be studied only with the help of microscope. Substantially the microscopic study of internal structure of living organism is called as Histology.
Important Questions on Class 11 Biology
Each of these two groups can be further classified on the basis of the names of the students falling in these groups.
Since it is possible that more than one student can have a particular name, these names can be further divided based on the surnames.
Since there is still some chance that more than one student can have the same surname, the final level of classification will be based on the roll numbers of each student.
Algal bloom refers to an increase in the population of algae or blue-green algae in water, resulting in discoloration of the water body. This causes an increase in the biological oxygen demand (BOD), resulting in the death of fishes and other aquatic animals.
Red tides are caused by red dinoflagellates (Gonyaulax) that multiply rapidly. Due to their large numbers, the sea appears red in colour. They release large amounts of toxins in water that can cause death of a large number of fishes.
Euglenoids (such as Euglena) are unicellular protists commonly found in fresh water.
Instead of cell wall, a protein-rich cell membrane known as pellicle is present.
They bear two flagella on the anterior end of the body.
A small light sensitive eye spot is present.
They contain photosynthetic pigments such as chlorophyll and can thus prepare their own food. However, in absence of light, they behave similar to heterotrophs by capturing other small aquatic organisms.
They have both plant and animal-like features, which makes them difficult to classify.
(b) Primary endosperm nucleus in a dicot – Triploid
(c) Leaf cell of a moss – Haploid
(d) Prothallus of a fern – Haploid
(e) Gemma cell in Marchantia – Haploid
(f) Meristem cell of a monocot – Diploid
(g) Ovum of a liverwort – Haploid
(h) Zygote of a fern – Diploid
Jointed legs that allow more mobility on land
Hard exoskeleton made of chitin that protects the body
The hard exoskeleton also reduces water loss from the body of arthropods making them more adapted to terrestrial conditions.
In alternate phyllotaxy, a single leaf arises from the node of a branch. This type of phyllotaxy is observed in the sunflower, mustard, and peepal. Plants with opposite phyllotaxy have two leaves arising from the node in opposite directions. It is found in guava and jamun plants. Plants with whorled phyllotaxy have three or more leaves arising from the node. It is found in Alstonia.
The secondary growth in plants increases the girth of plants, increases the amount of water and nutrients to support the growing number of leaves, and also provides support to plants.
The characteristics of prokaryotic cells are as follows:
Most of them are unicellular.
They are generally small in size. The size of a prokaryotic cell varies from 0.5 – 5 µm.
The nuclear region of a prokaryotic cell is poorly-defined because of the absence of a nuclear membrane. Hence, a prokaryotic cell lacks a true nucleus.
The genetic materials of prokaryotic cells are naked. They contain single, circular chromosomes. In addition to the genomic DNA, they have a small, circular plasmid DNA.
They have specialised membranous structures called mesosomes. Mesosomes are formed by the invagination of the cell membrane. These extensions help in the synthesis of the cell wall, replication of DNA. They also help in the equal distribution of chromosomes into the daughter cells.
Membrane-bound cell organelles such as mitochondria, plastids, and endoplasmic reticulum are absent from a prokaryotic cell.
Most prokaryotic cells contain a three-layered structure – outermost glycocalyx, middle cell wall, and the innermost plasma membrane. This structure acts as a protective unit.
Examples of prokaryotic cells include blue green algae, bacteria, etc.
Thrombin and fibrinogen – They help in blood clotting.
Antigen (antibody) – It helps in blood transfusion.
Insulin – It helps in maintaining blood glucose level in the body.
Renin – It helps in osmoregulation.
Proteins are also commonly used in the manufacture of cosmetics, toxins, and as biological buffers.
Water potential (Ψw) is expressed as the sum of solute potential (Ψs) and pressure potential (Ψp).
Ψw = Ψs + Ψp
When some solute is dissolved in water, the water potential of pure water decreases. This is termed as solute potential (Ψs), which is always negative. For a solution at atmospheric pressure, Ψw = Ψs.
The water potential of pure water or a solution increases on the application of pressure values more than atmospheric pressure. It is termed as pressure potential. It is denoted by Ψp and has a positive value, although a negative pressure potential is present in the xylem. This pressure potential plays a major role in the ascent of water through the stem.
Micronutrients: They are also called trace elements and are present in plant bodies in very small amounts, i.e., amounts less than 10 m mole kg– 1 of dry matter. Examples include cobalt, manganese, zinc, etc.
Beneficial nutrients: They are plant nutrients that may not be essential, but are beneficial to plants. Sodium, silicon, cobalt and selenium are beneficial to higher plants.
Toxic elements: Micronutrients are required by plants in small quantities. An excess of these nutrients may induce toxicity in plants. For example, when manganese is present in large amounts, it induces deficiencies of iron, magnesium, and calcium by interfering with their metabolism.
Essential elements: These elements are absolutely necessary for plant growth and reproduction. The requirement of these elements is specific and non-replaceable.
They are further classified as macro and micro-nutrients.
During synthesis of fatty acids, acetyl CoA is withdrawn from respiratory pathway. Also, in the synthesis of proteins, respiratory substrates get withdrawn. Thus, respiration is also involved in anabolism. Therefore, respiration can be termed as amphibolic pathway as it involves both anabolism and catabolism.
(ii) Gibberellic acid
(v) Abscisic acid
The chemosensitive region present near the respiratory centre is sensitive to carbon dioxide and hydrogen ions. This region then signals to change the rate of expiration for eliminating the compounds.
The receptors present in the carotid artery and aorta detect the levels of carbon dioxide and hydrogen ions in blood. As the level of carbon dioxide increases, the respiratory centre sends nerve impulses for the necessary changes.
Like the other connective tissues, blood is mesodermal in origin.
It connects the body systems, transports oxygen and nutrients to all the parts of the body, and removes the waste products. Blood has an extra-cellular matrix called plasma, with red blood cells, white blood cells, and platelets floating in it.
An adult human excretes about 1 – 1.5 litres of urine per day.
Glands that do not discharge their secretions into ducts are known as endocrine glands. Instead, these glands discharge their secretions directly into the blood. Pituitary gland, thyroid gland, adrenal gland, etc. are examples of endocrine glands.