NCERT Class 11 Biology Chapter 7 Notes Structural Organisation In Animals- Download PDF Notes

The NCERT chapter 7 structural organisation in animals discusses animal tissues, organs and organ system. The NCERT Class 11 Biology chapter 7 notes cover a brief outline of the chapter Structural Organization in Animals. The main topics covered in NCERT Class 11 Biology Notes are definitions and types of animal tissues and their detailing, earthworm and cockroach anatomy, and morphology. Class 11 Biology chapter 7 notes cover all the important concepts of this chapter in easy and simple language. Having revision notes and NCERT Solutions for Class 11 Biology Chapter 7 handy is beneficial to save you time. The NCERT Class 11 Biology chapter 7 notes PDF can be downloaded through the link given below.

Structural organisation in animals Class 11 notes Biology Chapter 7 also covers all the important headings of NCERT that are useful in various competitive exams. Chapter 7 Structural Organization in Animals Notes help you revise these major concepts given in the NCERT Book in a short period of time during CBSE Board exam preparation. Download the CBSE Notes for Class 11 Biology Chapter 7 PDF to use offline anywhere. It can be downloaded through the link. Students must go through each topic in Structural Organisation In Animals in Class 11 Notes Biology in the easiest and most effective way possible with the help of NCERT Notes for Class 11. Check the given Class 11 Biology Notes Chapter 7 Structural Organisation In Animals PDF for quick revision.

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NCERT Class 11 Biology Chapter 7 Notes

Animal Tissues:

A cell is the structural and functional unit of all living organisms. The group of cells is called tissues. There are mainly two types of tissues: plant and animal tissues. Each has its own specific functions. Animal tissues can be divided into four subtypes:

1. Epithelial tissue

2. Connective tissue

3. Muscular tissue

4. Neural tissue

Epithelial Tissue

Epithelial tissues act as a protective covering for the surfaces exposed to the environment and lining for the inner body cavities and internal organs. The cells are arranged in a dense manner with fewer intercellular spaces. This is again classified into two:

Simple Epithelial Tissue

The simple epithelium consists of single-layered cells. It protects the body cavities, internal organs, and ducts by acting as their lining. So the cells differ in their structure and therefore it is again divided into three types:

1. Squamous epithelium is flattened single-layered cells which protect the alveolar sac of the lungs and the walls of blood vessels and promote the diffusion of gases.

2. Cuboidal epithelium is cube-like single-layered cells that are found in the kidney tubules and ducted glands and are mainly concerned with absorption and secretion.

3. The columnar epithelium is tall single-layered cells that are found in the intestine and stomach and promote secretion and absorption.

If the columnar or cuboidal cells have cilia (helps in the movement of particles) on their surface, it is ciliated epithelium which is found in the oviduct (fallopian tube) and bronchioles.

If the cuboidal and the columnar epithelial cells are meant for secretion, they are called the glandular epithelium.

Compound Epithelial Tissue

Compound epithelial tissues consist of more than one layer of cells and provide protection to the body from any kind of stress.

All the cells are arranged in such a manner that they have intercellular space in between them. There are three types of cell junctions:

1. Tight junction prevents the entry of materials from one tissue to another.

2. Gap junction allows the entry of certain ions and molecules across tissues.

3. Adhering junction act as an intermediate to hold the tissues together.

Connective Tissue

Connective tissue acts as a connecting link between the other tissues present in the body. It contains collagen or elastin fibers. It is mainly divided into:

Loose Connective Tissue

In this, the cells and fibers are loosely arranged. It contains areolar tissue which is found under the skin acting as a support for epithelial tissues and adipose tissues which are found under the skin and function to store fats.

Dense Connective Tissue

In this, fibers are densely arranged. It contains tendons that connect the muscles and bones together and ligaments which connect one bone to another.

Specialised Connective Tissue

It contains bones, cartilages, and blood.

1. Cartilage is a solid, flexible connective tissue that contains cells called chondrocytes. It prevents friction between the joints.

2. Bone is a solid connective tissue that contains cells called osteocytes. It provides structure, movement, and support due to the presence of calcium salts and collagen fibres.

3. Blood is a fluid that contains red blood cells, white blood cells, platelets, plasma and facilitates the transport of gases and nutrients throughout the body.

Muscle Tissue

Muscle tissue consists of fibres containing myofibrils arranged in a parallel manner. It is further divided into three :

1. Skeletal muscle tissues contain elongated fibres found closer to the skeletal bones and are responsible for movement.

2. Smooth muscle tissues are found closer to the internal organs.

3. Cardiac muscle tissues are found in the heart.

Neural Tissue

Neural tissues are found in the nerves, the brain, and the spinal cord. This is mainly associated with control and coordination.

Organ and Organ System

The tissues are organized to form organs to perform certain functions. All these organs constitute an organ system. This is very essential for an organism to function.

Cells Form Tissues Form Organs Form Organ System

This means that every organ is composed of many tissues.

The external and internal features of the three organisms are mentioned.

NCERT Class 11 Biology Chapter 7 Notes: Earthworm

An earthworm is a terrestrial invertebrate that is responsible for decomposing litter. It finds its shelter in the upper layer of the moist soils. Its scientific name is Pheretima Posthuma.

Morphology

The body of the earthworm is cylindrical in shape and is divided into 100-120 segments. There is a dark band of glandular tissue found in 14-16 segments and is called clitellum. Hence, the segments can be divided into three:

1. Preclitellar segments

2. Clitellar segments

3. Post clitellar segments

The first segment is called peristomium composed of mouth and prostomium which serve as a covering for the mouth. In 5-9 segments, four pairs of spermathecal apertures are there. There is a female genital pore in the 14th segment and a pair of male genital pores in the 18th segment. Nephridiopores are fine pores present on the body surface. There are setae in each segment without the first, clitellum, and the last segment which is concerned with locomotion. The posterior end consists of genital pores.

Anatomy

The external surface of an earthworm consists of a non-cellular cuticle, epidermis, two muscle layers, and inner coelomic epithelium. The alimentary canal extends from the first segment till the last segment. The mouth and the buccal cavity lie in 1st-3rd segments. The oesophagus lies in the 5th-7th segments and gizzard which helps in grinding food particles in 8-9 segments. The stomach with calciferous glands (to neutralise the humic acid) extends from 9-14 segments which are followed by the intestine which extends from 15 to the last segment.

There is an intestinal caecae present in the 26th segment and a typhlosole is present after this segment except at the last 23-25th segments. It has a closed vascular system having the heart, blood vessels, and capillaries. There are blood glands in segments 4, 5, and 6 which produce blood cells and haemoglobin. Blood circulation takes place in one direction. The respiration of earthworms occurs through their body surface. The excretory organ of earthworms is nephridia which helps in the removal of wastes. This is of three types but identical in their structure:

1. Septal nephridia (15 to the last segment)

2. Integumentary nephridia (3 to the last segment)

3. Pharyngeal nephridia (4-6 segments)

The sense organs are present on the anterior part. It does not have eyes but has touch and light receptors and can feel the ground vibrations. Both the testes and ovaries are present in it. Two pairs of testes are present in the 10-11 segments, vasa deferentia in the 18th segment, one pair of each accessory gland in the 17th and 19th segment, male genital pores in the 18th segment, and one pair of each spermathecae which store sperms during copulation in 6th-9th segments. Meanwhile, the ovaries are present in the 12th and 13th segments and female genital pores on the 14th segment. During copulation, a mutual exchange of sperm takes place between the earthworms. Development is direct in them. Fertilisation and development take place in the cocoons which in turn are deposited in the soil. Baby worms are produced after 3 weeks.

Cockroach

Cockroaches are omnivores and nocturnal in nature. They are found in the houses of human beings. They are the causative agents for certain diseases too. Its scientific name is Periplanata Americana. The morphology and anatomy of a cockroach are described in NCERT Class 11 biology Chapter 7 Notes.

Morphology

The external part of the body of a cockroach is composed of a hard chitinous exoskeleton containing sclerites and an arthrodial membrane. The body can be distinguished into three main regions: head, thorax, and abdomen. The triangular head is formed by joining six segments and has a flexible neck promoting mobility in all directions. It has a pair of compound eyes, a pair of antennae, and mouthparts (labrum, labium, mandibles, hypopharynx, and maxilla) in it. The head is joined to the thorax through the neck and wings are attached here. Thorax has three parts- prothorax, mesothorax, and metathorax. The next part is the abdomen having ten segments.

Anatomy

The alimentary canal is classified into foregut, midgut, and hindgut. The foregut is covered by cuticles and contains the mouth, pharynx, oesophagus, crop, and gizzard. There is a hepatic caecae present at the junction between the foregut and midgut which helps in the secretion of digestive juice. The malpighian tubules present at the junction between the midgut and hindgut help in the removal of wastes. The hindgut contains the ileum, colon and rectum, and anus. The cockroach has an open blood circulation system. Blood transporting from the sinuses enters the heart and then returns to the sinuses again. Internal organs are located in haemolymph (blood). The respiratory system contains a trachea and spiracles.

The gaseous exchange takes place through diffusion. The excretion is done by the Malpighian tubules, urecose glands, nephrocytes, and fat bodies. The nitrogenous wastes are converted into uric acid (uricotelic) and then removed through the hindgut. The nervous system spreads throughout the entire body of the cockroach and consists of fused ganglia, three in the thorax and six in the abdominal region. Cockroaches are unisexual in nature. The male reproductive system consists of a pair of testes, vas deferens, ejaculatory duct, seminal vesicle, and male gonopore.

There is an accessory reproductive gland present in it which is a mushroom-shaped gland. Seminal vesicles store sperm and release it during mating. The female reproductive system contains a pair of ovaries having ovarian tubules (stores ova), oviduct, spermatheca, and genital chamber. The fertilised eggs are kept in oothecae.

FROG

The frog is a carnivore and an amphibian. The common type found is Rana tigrina. They are poikilotherms which means they have no fixed body temperature. They can withstand extreme hot and cold climates and can hide from enemies by camouflage (color-changing). The morphology and anatomy of frogs are described in NCERT Class 11 biology Chapter 7 Notes.

Morphology

The body of the frog is divisible into the head and trunk. It has a mouth, a pair of nostrils, eyes covered with a nictitating membrane helping to prevent the entry of water, tympanum, hindlimbs, forelimbs. Male frogs have a vocal sac that makes sounds and a copulatory pad.

Anatomy

The digestive system consists of a short alimentary canal, digestive glands, mouth, tongue, buccal cavity, oesophagus, pharynx, stomach, intestine, rectum, cloaca, and respiratory, circulatory, nervous excretory, and reproductive system. The gallbladder stores bile which is a secretion of the liver. The stomach produces HCl and gastric juices that are responsible for digestion. The digested food is absorbed by villi and microvilli in the intestine. The undigested food is removed through cloaca. Frog respires in the land with the help of the buccal cavity, lungs, and the skin and in water with the help of skin only.

The frog has a closed blood vascular system involving heart, blood, and blood vessels. Blood from the heart is transported to the body parts through arteries and blood from the different body parts is transported to the heart through the veins. The excretory system consists of kidneys containing nephrons, urinary bladder, ureter, and cloaca. The endocrine glands contain the pituitary gland, thyroid gland, parathyroid gland, gonads, adrenals, islets of Langerhans, thymus, and pineal gland.

The nervous system consists of the brain, spinal cord, cranial and spinal nerves. The sensory organs include the organs of touch, hearing, smell, vision, and taste. The male reproductive system consists of a pair of testes above the kidneys, vasa efferentia, and Bidder’s canal. The female reproductive system includes ovaries and oviducts. It undergoes external fertilization and indirect development.

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NCERT Class 11 Biology Chapter 7 notes contain an easily understandable and brief overview of chapter 7 Biology. These Notes for Class 11 Biology chapter 7 are also beneficial for covering the core concepts of the CBSE Biology Syllabus in Class 11 as well as for competitive exams such as AIPMT, AIIMS, NEET, and other similar exams. Class 11 Biology chapter 7 notes pdf download can be utilised for offline preparation.

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