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

The NCERT Class 11 Biology Chapter 7, Structural Organisation in Animals, discusses the types of animal tissues, organs, and organ systems in an easy and simple manner. The chapter introduces the students to how different tissues are involved in performing a specific function and where they are found in the animal body. The principles are simplified using flowcharts and diagrams in the NCERT Class 11 Biology Notes, which can be easily read and remembered for exams.

This Story also Contains

1. Detailed Notes for Chapter 7: Structural Organisation in Animals
2. Approach to Solve Questions of Class 11 Biology Chapter 7
3. Important Topics from Class 11 Biology Chapter 7: Structural Organisation in Animals
4. Most Important Questions Class 11 Biology Chapter 7 Structural Organisation In Animals
5. Chapter-Wise NCERT Class 11 Notes Biology

The chapter "Structural Organisation in Animals" is also discussed in terms of the anatomy and morphology of animals such as frogs, earthworms, and cockroaches, with labelled diagrams. The chapter describes how these animals perform basic life activities like respiration, reproduction, and excretion. The NCERT Notes for Class 11 are an easy and convenient means of revising these important topics while preparing for CBSE board exams. Quick access to these notes and NCERT Solutions saves time and guarantees that students perform well in board exams and competitive exams in the future.

Also, students can refer to:

• NCERT Solutions for Class 11 Biology Structural Organisation in Animals
• NCERT Exemplar Class 11 Biology Solutions: Structural Organisation in Animals

Detailed Notes for Chapter 7: Structural Organisation in Animals

Provided below are the notes of this chapter that help to give a clear understanding of how animals are structurally made and the components present.

Animal Tissues

In unicellular organisms, the single-celled body performs all functions. But in multicellular organisms, the body is made up of many types of cells, and the cell is the structural and functional unit of life. A group of structurally similar cells of common origin performing the same function is known as tissue. There are mainly two types of tissues: plant and animal tissue. Animal tissue is divided into four major classes based on their functions:

• Epithelial tissue

• Connective tissue

• Muscle tissue

• Nervous tissue

Epithelial Tissue

Epithelial tissues are sheets of cells that cover body surfaces. They perform many functions, such as protection, secretion, absorption, excretion, conduction, and sensation. Based on cell shape and number of cell layers, epithelial tissues are classified into two categories:

Simple Epithelial Tissue

It consists of a single layer of cells resting on a basement membrane. It protects the body cavities, internal organs, and ducts by acting as their lining. It is further divided into three types:

1- Squamous epithelium- It consists of a layer of thin, flat, scale-like cells with a nucleus. This epithelium easily exchanges materials by diffusion. It occurs in the alveoli of lungs, Bowman’s capsule and in the lining of blood and lymph vessels.

2- Cuboidal epithelium- The cuboidal epithelium consists of cells that appear in vertical sections. These cells are usually rounded and participate in secretion, excretion, and absorption.

3- Columnar epithelium- The cells of columnar epithelium appear rectangular in vertical section. Columnar epithelium is present in the large and small intestines with a border in the gall bladder.

Ciliated epithelium is columnar cells that have cilia on their free surfaces. The function of the cilia is to move particles or mucus in a specific direction over the epithelial surface.

Compound Epithelial Tissue

A compound epithelium consists of more than one layer of cells. Being a multilayered compound epithelium has little role in secretion or absorption but it provides protection to the underlying tissues.

All the cells are arranged in such a manner that they have an intercellular space 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 junctions act as an intermediate to hold the tissues together.

Connective Tissue

Connective tissues are the most abundant and widely distributed in the body. They are named connective tissues because of their special functions of linking and supporting other tissues/organs of the body. In all connective tissues except blood, the cells secrete fibres of structural proteins called collagen or elastin.

• Loose Connective Tissue - This tissue has cells and fibres that are loosely arranged in a semi-fluid ground substance. Adipose tissue is an example of loose connective tissue.
• Dense Connective Tissue -In this, the fibres and fibroblasts are compactly packed. The pattern of these fibres is an irregular one, and collagen fibres are present in rows. Tendons and ligaments are examples of dense connective tissue.
• Specialised Connective Tissue- It consists of blood, bone, and cartilage.

1. Cartilage- It is a solid but semi-rigid and flexible connective tissue. The cells of cartilage are known as chondrocytes. They are oval and often lie in groups of 2 or 3 in spaces present within the matrix.
2. Bone- Bone is a highly hard and rigid connective tissue. It is very strong and can withstand severe stress such as bending, twisting etc.
3. Blood- Blood is a transport medium of the body. It is an extremely complex substance carrying a wide variety of cells and substances to all areas of the body.

Muscle Tissue

Muscle tissue contracts and relaxes to provide movement of limbs and internal organs, and is also helpful in the locomotion of the organism. Based on structure, location, and functions, muscles are classified into three types:

• Skeletal muscles- These types of muscles mainly occur in association with bones and about body wall. These muscles, normally made to contract according to our will, are also known as voluntary muscles.
• Smooth muscles- These muscles are found in the walls of hollow tubes of the stomach, small intestine and large intestine, urinary bladder, and blood vessels. These are also known as visceral muscles.
• Cardiac muscles- These muscles are only present in the heart. They resemble smooth muscles in being involuntary.

Neural Tissue

The nervous system is mainly made up of these types of tissues and has the special property of being able to conduct impulses rapidly from one part of the body to another.

Organ and Organ System

The tissue of two or more types combine to form an organ. An organ is an organised part of the body that performs one or more special functions. Several organs combine for a common function to constitute an organ system.

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

Earthworm

Earthworms are soft-bodied, segmented worms that live in soil and play an important role in maintaining soil fertility. Its scientific name is Pheretima Posthuma.

Morphology

The morphology of earthworms includes their long, cylindrical, and segmented bodies, which are usually brown or reddish. The body is divided into 100-120 segments. Hence, the segments can be divided into three:

1-Preclitellar segments

2-Clitellar segments

3-Post-clitellar segments

The first segment contains the mouth and last segment consist of anus. There is a female genital pore in the 14th segment and a pair of male genital pores in the 18th segment. Their moist skin allows them to breathe by absorbing oxygen directly from their surroundings.

Anatomy

The digestive system of earthworms is a straight, tubular structure extending from the mouth to the anus. Food is ingested through the mouth and passes into the pharynx, where it is lubricated with mucus. The mouth and the buccal cavity lie in the 1st- 3rd segments, and the oesophagus lies in the 5th- 7th segments. The stomach with calciferous glands (to neutralise the humic acid) extends from 9-14 segments, which are followed by the intestines, which extend from 15 to the last segment. Earthworms have a closed circulatory system that transports nutrients and oxygen throughout the body. Oxygen and carbon dioxide exchange occur directly through the moist skin.

The nervous system is relatively simple but well-organised. A pair of cerebral ganglia is located near the anterior end. A ventral nerve cord runs along the length of the body, coordinating movement and responding to external stimuli. Earthworms do not have specialised respiratory organs. Instead, they breathe through their skin. Oxygen diffuses directly across the skin into the bloodstream, while carbon dioxide is released in the same manner. Earthworms are hermaphrodites, meaning they possess both male and female reproductive organs. However, cross-fertilisation occurs during copulation. Fertilisation and development take place in the cocoons, which in turn are deposited in the soil.

Cockroach

The cockroach, Periplaneta americana, is a common natural, omnivorous, household pest which is commonly found in warm, damp places. The morphology and anatomy of a cockroach are described in the NCERT Class 11 biology Chapter 7 Notes.

Morphology

1. Body Shape and Size:

• The cockroach has a flat, oval-shaped body..
• It is usually brown or reddish-brown.
• An adult cockroach is about 2-4 cm long.

2. Body Division: The cockroach’s body is divided into three parts:

-Head, which is small and triangular.

• It has a pair of long antennae that help detect smells.

• The head has compound eyes for detecting movement and light.

• It has mouth parts which is used for chewing.

- The thorax is the middle part with three segments.

• Each segment has a pair of legs (a total of 6 legs), which help in fast movement.

• The second and third segments have a pair of wings (forewings and hindwings), which help in flying.

- Abdomen: The largest part, made up of 10 segments.

• It has small holes for breathing and the anus at the end.

Anatomy

The anatomy of a cockroach includes different systems that help it survive and function efficiently. The digestive system starts from the mouth, which leads to a long, tube-like structure. Food is stored in the crop and then crushed in the gizzard before digestion and absorption take place in the intestine. The respiratory system consists of small openings called spiracles present on the sides of the body, which connect to a network of tubes called the trachea. The cockroach has an open blood circulation system. Blood transported from the sinuses enters the heart and then returns to the sinuses again. Internal organs are located in the haemolymph (blood).

The nervous system spreads throughout the entire body of the cockroach and consists of fused ganglia. The excretory system removes waste with the help of Malpighian tubules, which filter out waste from the blood. The reproductive system is well-developed, and cockroaches reproduce sexually. Female cockroaches produce egg cases called oothecae, each containing several eggs. All these systems work together to ensure the survival and adaptability of the cockroach in various environments.

Frog

Frogs are amphibians that live both on land and in water. They have smooth and moist skin. These are cold-blooded animals and undergo metamorphosis. The morphology and anatomy of frogs are described in the NCERT Class 11 biology Chapter 7 Notes.

Morphology

The morphology of a frog includes its external structure and body shape. A frog has smooth, moist skin that is usually green or brown, allowing it to blend with its surroundings. Its body is divided into the head and trunk. Frogs have large eyes and a pair of nostrils. Frogs have strong hind limbs that are longer than the front limbs, which help them jump long distances and swim effectively.

Anatomy

The anatomy of a frog includes various systems that help it survive in both land and water. The digestive system consists of a short alimentary canal, digestive glands, mouth, tongue, buccal cavity, oesophagus, pharynx, stomach, intestine, rectum, and cloaca. The respiratory system allows frogs to breathe through their lungs on land and through their moist skin in water.

The circulatory system is well-developed, with a three-chambered heart that pumps blood to the body and lungs. The nervous system includes the brain and spinal cord, as well as cranial and spinal nerves, which control movement and responses. The sensory organs include the organs of touch, hearing, smell, vision, and taste.

Frogs also have a well-developed excretory system, with kidneys that filter waste from the blood. The male reproductive system consists of a pair of testes above the kidneys, vasa efferentia, and the Bidder’s canal. The female reproductive system includes the ovaries and oviducts. It undergoes external fertilisation and indirect development.

Digestive System of the Frog

Approach to Solve Questions of Class 11 Biology Chapter 7

To answer Structural Organisation In Animals questions well, adopt this easy-to-follow approach:

1. Read and learn the four major animal tissues: epithelial, connective, muscular, and neural, their structure, location, and functions.
2. Learn the fundamentals of organ and organ system organization-how tissues become organs and organs become systems, using examples such as the heart with all four tissue types.
3. Study the morphology (external features) and anatomy (internal structure) of the earthworm, cockroach, and frog, using diagrams and major identifying features.
4. Practice diagram drawing and labelling diagrams of the tissues, organs, and body parts of the earthworm, cockroach, and frog, since they are frequently asked in exams.
5. Rework NCERT textbook questions and previous years' papers to become familiarised with the kind of questions being asked, particularly application-based and diagram-based questions

Subject-Wise NCERT Exemplar Solutions

• NCERT Exemplar Class 11 Solutions
• NCERT Exemplar Class 11 Maths
• NCERT Exemplar Class 11 Physics
• NCERT Exemplar Class 11 Chemistry
• NCERT Exemplar Class 11 Biology

Important Topics from Class 11 Biology Chapter 7: Structural Organisation in Animals

This chapter is important because it explains how animals are built from cells to tissues, organs, and organ systems, showing the complexity and coordination that sustain life. Understanding these topics helps learn how different body parts work together efficiently, which is essential for studying animal physiology and anatomy.

These topics cover the basic building blocks of animal structure and their functional integration, which are essential for understanding animal biology completely.

Subject-Wise NCERT Solutions

• NCERT Solutions for Class 11 Mathematics
• NCERT Solutions for Class 11 Chemistry
• NCERT Solutions for Class 11 Physics

• NCERT Solutions for Class 11 Biology

Most Important Questions Class 11 Biology Chapter 7 Structural Organisation In Animals

Biomolecules are essential organic compounds such as carbohydrates, proteins, lipids, and nucleic acids, which form the basis of structure and function in all living organisms. Understanding their types, structure, and functions is crucial for mastering this chapter.

Q1. Which of the following is a reducing sugar?
A. Galactose
B. Gluconic acid
C. Sucrose
D. β-methyl galactosidase

Answer:
Galactose is a reducing sugar because it has a free aldehyde group or a potential aldehyde group that can reduce other substances.
Hence, the correct option is A. Galactose.

Chapter-Wise NCERT Class 11 Notes Biology

The chapterwise notes are given below: