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NCERT Solutions for Class 11 Biology Chapter 7 - Structural Organization in Animals

The 'Structural Organization in Animals' chapter discusses unicellular and multicellular organisms of the animal kingdom. The chapter talks about all the functions, such as respiration, digestion, and reproduction in unicellular organisms that are performed only by a single cell. Different groups of cells perform all the above basic functions inside the complex body of multicellular animals in an orderly manner.

All those animals who have complex body structures are made up of four basic types of tissues. These four tissues are placed in specific locations inside the body to develop organs, like the stomach, heart, kidney, and lungs. The topics of this chapter have been explained below.

  • Animal Tissue
  • Organ and Organ System
  • Earthworm
  • Cockroach
  • Frogs

This chapter concentrates on the specific set of functions that in multicellular organisms are performed by similar cells. Hence, this group of similar cells that carries out a particular function is called a tissue. In animals, tissues can be segregated into four different types: Connective, Epithelial, Nural, and Muscular. The arrangement of these complex animal tissues in a particular pattern and proportion helps in the formation of an organ in them.

When formed, these organs provide functionality through their chemical and physical interaction that comprises the organ system. Tissues, cells, organs, and organ systems in animals divide their operation in such a manner that clear division of labour and their contribution towards the survival of the body is visible. All these different animal bodies are very nicely portrayed in the chapter using animals, such as frogs, earthworms, and cockroaches, as examples.

NCERT Solutions for Class 11 Biology Chapter 7 Structural Organisation in Animals

Q1. Answer in one word or one line

(i). Give the common name of Periplaneta americana.


The common name of Periplaneta americana is the cockroach.

(ii) How many spermathecae are found in earthworms?


  • Four pairs of spermathecae are found in the earthworm.
  • These are found to be located between the sixth and the ninth segments. 
  • The function of spermathecae is to receive and store the spermatozoa during copulation.


(iii) What is the position of ovaries in cockroaches?


  • The pair of ovaries is located between the 12th and 13th abdominal segments in the cockroach.

(iv) How many segments are present in the abdomen of the cockroach?


  • In total, 10 segments are present in the abdomen of the cockroach whether male or female.


(v) Where do you find Malpighian tubules?


  • Malpighian tubules are the major excretory organs of cockroaches.
  • These form a part of the alimentary canal.

Q2. Answer the following

(i) What is the function of nephridia?


  • Nephridia are the excretory organs of earthworms. They are involved in the functions of excretion and osmoregulation in the earthworm.


(ii) How many types of nephridia are found in earthworms based on their location?


  • On the basis of location, nephridia can be of three types i.e. septal nephridia, integumentary nephridia, and pharyngeal nephridia.
  1. Septal nephridia: These nephridia are found to be present on both sides of the intersegmental septa behind the 15th segment. They open into the intestines.
  2. Integumentary nephridia: These nephridia lie attached to the body wall from the third segment to the last segment, which opens on the body surface.
  3. Pharyngeal nephridia: These nephridia are found to be are present in the fourth, fifth. and sixth segments.


Q3. Draw a labeled diagram of the reproductive organs of an earthworm.



  • Reproductive organs of an earthworm

Reproductive organs of an earthworm

Q4. Draw a labeled diagram of alimentary canal of a cockroach.



  • The alimentary canal of a cockroach


Alimentary canal


Q5. Distinguish between the following


  1. Prostomium and peristomium







The prostomium is the fleshy lobe that overhangs the mouth of an earthworm.


Peristomium is the first segment of the body of the earthworm.


It helps the earthworm push into the soil and is sensory in function.


It surrounds the opening of the mouth.


  1. Septal nephridium and pharyngeal nephridium



Septal nephridium


Pharyngeal nephridium


These nephridia are found in the 15th segment attached to the septa.


Pharyngeal nephridia are found to be present in the 4th, 5th, and 6th segments lying on the sides of the gut.


These remove metabolic wastes from the blood and coelomic fluid.


These remove metabolic wastes from the blood only.


Q6. What are the cellular components of blood?


  • Blood is the fluid connective tissue. It consists of blood plasma and cellular components. The cellular components of blood are of the following types.
  1. Erythrocytes- These are red blood cells. Erythrocytes are red due to the presence of hemoglobin. Erythrocytes are biconcave, colored cells devoid of a nucleus. These mainly help in transporting respiratory gases.
  2. Leucocytes- These are white blood cells. There are 5 types of leucocytes i.e. neutrophils, eosinophils, basophils, lymphocytes, and monocytes. Leucocytes are mainly involved in fighting infections and providing immunity.
  3. Thrombocytes- These are blood platelets involved in the coagulation of blood.


Q7. What are the following and where do you find them in the animal bodies.

  1. Chondrocyte


  • Chondrocytes- These are cells of cartilages. They are found to be present in the small cavities within the matrix secreted by them.




  • Axons- An axon is the long, slender projection found in the neuron. It helps in carrying nerve impulses from the neuron body.


(c)Ciliated epithelium


  • Ciliated epithelium- The ciliated epithelium consists of cells that bear fine, vibratile cytoplasmic processes called cilia on its free surface. It is found in the inner lining of bronchioles, urinary tubules of kidneys, nasal passage, oviducts, and ventricles of the brain.


Q8. Describe various types of epithelial tissues with the help of labelled diagrams?


  • Epithelial tissue provides covering or lining for some parts of the body. It consists of a layer of cells and a basement membrane. The cells of the epithelium are compactly packed without intercellular space.

(a)Simple epithelium: It is the single layer of cells that are in direct contact with the basement membrane. Simple epithelium is further subdivided into the following types:

(b)Simple squamous epithelium: It consists of a single layer of flat cells with irregular boundaries. Simple squamous epithelium is mostly found in the walls of the blood vessels and in the lining of alveoli.

(c)Simple cuboidal epithelium: It consists of a single layer of cube-like cells and is present in regions where secretion and absorption of substances take place such as the proximal convoluted tubule region of the nephron.

(d)Simple columnar epithelium: This epithelium is formed by a single layer of tall, slender cells with their nuclei present at the base of the cells. These generally possess microvilli on the free surfaces. Columnar epithelium forms the lining of the stomach and intestines. The major function of simple columnar epithelium is secretion and absorption.

(e)Ciliated epithelium: It consists of columnar or cuboidal cells with cilia on their free surfaces. They are present in bronchioles and oviducts from where they direct mucus and eggs in specific directions.



(f)Glandular epithelium: These are columnar or cuboidal cells involved in the secretion of substances. Glands are of two types, unicellular glands (goblet cells of the alimentary canal) and multicellular glands (salivary glands). They can be classified as exocrine (ductless glands) and endocrine glands (duct glands) based on the method through which they release enzymes.



(g)Compound epithelium: When the simple epithelium is consists of many layers of cells, it is called the compound epithelium. The compound epithelium is involved mainly in the function of providing protection and has a limited role in secretion and absorption. Examples of compound epithelium include the dry surface of the skin or moist inner lining of the buccal cavity, pharynx, pancreatic ducts, and the inner lining of ducts of salivary 





Q9. Distinguish between


  1.  Simple epithelium and compound epithelium



Simple epithelium


Compound epithelium


It consists of one layer of epithelial cells


It consists of several layers of epithelial cells


The function of simple epithelium is absorption and secretion


The major function of compound epithelium is protection


  1. Cardiac muscle and striated muscle



Cardiac muscle


Striated muscle


Cardiac muscles are multinucleate and branched


Striated muscles are multinucleate and unbranched


These are involuntary


These are voluntary


These are found in the heart


These are found in limbs


  1. Dense regular and dense irregular connective tissue



Dense regular connective tissue


Dense irregular connective tissue


In this tissue, collagen fibers are present in a regular manner


In this tissue, collagen fibers are found irregularly


These are found in tendons and ligaments


These are found in the skin.


  1. Adipose and blood tissue



Adipose tissue




It is present beneath the skin


It is present in the blood vessels


It helps in the synthesis, storage, and metabolism of fats


It helps in the transportation of food, water, gases, and hormones


It is composed of collagen, elastin, fibroblasts, macrophages, etc.


It consists of RBCs, WBCs, platelets and blood plasma


  1. Simple gland and compound gland



Simple gland


Compound gland


These are unicellular.


These are multicellular.


These possess isolated glandular cells.


These type of glands are composed of secretory cells.


Q10. Mark the odd one in each series:

  1. Areolar tissue; blood; neuron; tendon


  • Areolar tissue, blood, and tendons are types of connective tissue whereas neuron is nervous tissue. Thus, neuron is odd one out.


  1.  RBC; WBC; platelets; cartilage


  • RBS, WBC, and platelets are cellular components of blood while cartilage is specialized connective tissue. Thus, cartilage is the odd one out in the series.


  1.  Exocrine; endocrine; salivary gland; ligament


  • Exocrine, endocrine and salivary glands are simple glandular epithelium. However, ligaments represent connective tissue. Thus, the ligament is the odd one out in the series.


(d)Maxilla; mandible; labrum; antennae


  • Maxilla, mandible, and labrum are the names of mouthparts of a cockroach. On the other hand, antennae, are regions present in the head. Hence, antennae are the odd one out.


(e)Protonema; mesothorax; metathorax; coxa


  • Protonema is the young stage in the life cycle of moss. On the other hand, mesothorax, metathorax, and coxa are parts or segments present in the legs of a cockroach. Thus, protonema is the odd one out.

Q11. Match the terms in column I with those in column II:



Column I

Column II


Compound epithelium

  1. Alimentary canal


Compound eye

  1. Cockroach


Septal nephridia



Open circulatory system

(iv)Mosaic vision






(vi) Phallomere



(vii) Bone


  1. iii, b-iv, c-v, d-ii, e-i, f-vii, g-v


Column I - Column II

  1. Compound epithelium (i) Skin
  2. Compound eye           (ii) Mosaic vision
  3. Septal nephridia           (iii) Earthworm
  4.  Open circulatory system (iv) Cockroach
  5. Typhlosole                       (v) Alimentary canal
  6. Osteocytes                       (vi) Bone
  7. Genitalia                              (vii) Phallomere

Q12. Mention briefly the circulatory system of earthworms.


  • The circulatory system of the earthworm is closed type as the blood flows in fine closed blood vessels. It includes blood, blood vessels, heart and anterior loops, and blood glands.

1. Blood- A colored respiratory pigment hemoglobin is found to be present in the plasma. Due to this, the color of the plasma is red. In the blood, only one type of blood corpuscles, the leucocytes are present in the blood of the earthworm.

2. Blood vessels- The blood vessels found in earthworms are as follows:

Dorsal blood vessels- These extend from one end of  the body to the other. The blood flows in this vessel from behind to forward on the dorsal side of the alimentary canal. The dorsal blood vessel has valves that prevent the backward flow of blood.

Ventral blood vessels- These extend from one end to the other end of the body. It does not have any valves and the flow of the blood is from the anterior to the posterior end of the body. It is the major distributing vessel.

Sub-neural blood vessel- It runs from the posterior end of the body up to the 14th segment in front. It collects blood from the body wall and nerve cord. This blood is then sent to the dorsal blood vessel through commissural vessels.

Lateral oesophageal vessel- These are the paired blood vessels lying one on either ventrolateral side of the alimentary canal between the body wall and the alimentary canal in the first 14th segment.

Supra-oesophageal blood vessel- It is a single vessel that lies on the dorsal side of the alimentary canal between the 9th and 13th segments. It receives blood from the lateral oesophageal through two pairs of anterior loops and pours into two pairs of latero- oesophageal hearts present in the 12th and 13th segments.

Hearts and anterior loops- In earthworms, four pairs of tubular hearts are provided with valves. The anterior two pairs of the heart are known as the lateral heart and they lie in the 7th and 9th segments. They receive blood from the dorsal blood vessel and convey it to the ventral blood vessel. The posterior two pairs of hearts are situated in the 12th and 13th segments. These carry blood from the dorsal blood vessel and supra oesophageal vessel to the ventral blood vessel. Two pairs of anterior loops are present in the 10th and 11th segments.

3. Blood glands- These are situated in the 4th, 5th, and 6th segments and produce blood corpuscles and hemoglobin.


Q13. Draw a neat diagram of the digestive system of a frog.


  • The digestive system of the frog



Q14. Mention the function of the following

a)Ureters in frog


  • Ureters in frog- A ureter acts as a urinogenital duct, which carries sperms along with urine in male frogs.


(b)Malpighian tubule


  • Malpighian tubules- These are the excretory organs in the earthworm.


(c)Body wall in earthworm


  • Body wall in earthworm- Body wall helps the earthworm in movement and burrowing.



Also See



NCERT Solutions for Class 11 Biology Chapter 1 - The Living World

NCERT Solutions for Class 11 Biology Chapter 2 - Biological Classification

NCERT Solutions for Class 11 Biology Chapter 3 - Plant Kingdom

NCERT Solutions for Class 11 Biology Chapter 4 - Animal Kingdom

NCERT Solutions for Class 11 Biology Chapter 5 - Morphology of Flowering Plants

NCERT Solutions for Class 11 Biology Chapter 6 - Anatomy of Flowering Plants

NCERT Solutions for Class 11 Biology Chapter 8 - Cells: The Unit of Life

NCERT Solutions for Class 11 Biology Chapter 9 - Biomolecules

NCERT Solutions for Class 11 Biology Chapter 10 - Cell Cycle and Division

NCERT Solutions for Class 11 Biology Chapter 11 - Transport in Plants

NCERT Solutions for Class 11 Biology Chapter 12 - Mineral Nutrition

NCERT Solutions for Class 11 Biology Chapter 13 - Photosynthesis in Higher Plants

NCERT Solutions for Class 11 Biology Chapter 14 - Respiration in Plants

NCERT Solutions for Class 11 Biology Chapter 15 - Plant Growth and Development

NCERT Solutions for Class 11 Biology Chapter 16 - Digestion and Absorption

NCERT Solutions for Class 11 Biology Chapter 17 - Breathing and Exchange of Gases

NCERT Solutions for Class 11 Biology Chapter 18 - Body Fluids and Circulation

NCERT Solutions for Class 11 Biology Chapter 19 - Excretory Products and their Elimination

NCERT Solutions for Class 11 Biology Chapter 20 - Locomotion and Movement

NCERT Solutions for Class 11 Biology Chapter 21 - Neural Control and Coordination

NCERT Solutions for Class 11 Biology Chapter 22 - Chemical Coordination and Integration

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