Welcome to the Chapter 7 - Structural Organisation in Animals, Class 11 Biology NCERT Solutions page. Here, we provide detailed question answers for Chapter 7 - Structural Organisation in Animals. The page is designed to help students gain a thorough understanding of the concepts related to natural resources, their classification, and sustainable development.
Our solutions explain each answer in a simple and comprehensive way, making it easier for students to grasp key topics Structural Organisation in Animals and excel in their exams. By going through these Structural Organisation in Animals question answers, you can strengthen your foundation and improve your performance in Class 11 Biology. Whether you’re revising or preparing for tests, this chapter-wise guide will serve as an invaluable resource.
(i) The common name of Periplaneta americana is the American cockroach.
(ii) Four pairs of spermathecae are present between sixth and the ninth segments. They help in receiving and storing the spermatozoa during copulation.
(iii) In a cockroach, the pair of ovaries is located between 12th and 13th abdominal segments.
(iv) In both sexes, the abdomen of a cockroach consists of ten segments.
(v) Malphigian tubules are excretory organs of cockroaches. They form a part of the alimentary canal.
(a) Areolar tissue, blood, and tendons are examples of connective tissues. Neuron is an example of neural tissue.
(b) RBCs, WBCs, and platelets are the three most important components of blood (fluid connective tissue) while Cartilage is skeletal connective tissue.
(c) Exocrine, endocrine, and salivary glands are examples of simple glandular epithelium. Ligament is a connective tissue.
(d) Maxilla, mandible, and labrum are mouthparts of a cockroach; white antennae are present in the head constituent of region of cockroaches.
(e) Prothorax, Mesothorax and metathorax are parts of thorax of cockroach and present in the legs of a cockroach.
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Column I |
Column II |
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(a) Compound epithelium (b) Compound eye (c) Septal nephridia (d) Open circulatory system (e) Typhlosole (f) Osteocytes (g) Genitalia |
(iii) Skin (iv) Mosaic vision (v) Earthworm (ii) Cockroach (i) Alimentary canal (vii) Bone (vi) Phallomere |
Earthworm (Pheretima) have closed blood vascular systems, which consists of the heart, blood vessels, and capillaries. The heart pumps blood for circulating it in one direction. Blood is supplied by smaller blood cells to the gut, nerve cord and the body wall. Blood glands are present in the 4th, 5th, and 6th segments, which produce blood cells and haemoglobin dissolved in blood plasma. Blood cells in earthworms are phagocytic in nature.
(a) Ureters in frogs: A ureter acts as a urinogenital duct, which carries sperms along with urine in male frogs.
(b) Malphigian tubules: Malphigian tubules are excretory organs in cockroaches.
(c) Body wall in earthworms: In earthworms, the body wall consists of muscle layers. It helps in movement and burrowing.
(i) Nephridia are segmentally arranged excretory organs present in earthworms.
(ii) On the basis of their location, three types of nephridia are found in earthworms. They are:
(a) Septal nephridia: These are present on both sides of the inter-segmental septa behind the 15th segment and they open into the intestine.
(b) Integumentary nephridia: These lie attached to the body wall from the third segment to the last segment, which opens on the body surface.
(c) Pharyngeal nephridia: These are present as three paired tufts in fourth, fifth, and sixth segments.
(a)
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Prostomium |
Peristomium |
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Prostomium is a small fleshy lobe, which overhangs the mouth of an earthworm. It helps the organism push into the soil and is sensory in function. |
The first body segment in the earthworm is called the peristomium. It surrounds the mouth opening. |
(b)
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Septal nephridium |
Pharyngeal nephridium |
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They are present on both sides of inter-segmental septa behind the 15thsegment and they open into the intestine. |
They are present as three paired tufts in the fourth, fifth, and sixth segments. |
Components of blood include erythrocytes (RBCs), leucocytes (WBCs), and thrombocytes (platelets). These components form 45% of blood. They are suspended in the remaining fluid portion, called plasma.
Mammalian erythrocytes are biconcave, coloured cells devoid of a nucleus. They help in transporting respiratory gases.
Leucocytes or white blood cells are nucleated cells. They can be divided into two types, granulocytes (neutrophils, eosinophils, and basophils) and agranulocytes (lymphocytes and monocytes). They help fight against various disease-causing agents entering the body.
Thrombocytes are cell fragments produced from megarkaryocytes of the bone. They play a major role during blood coagulation.
Chondriocytes:
They are cells of cartilages, and are present in small cavities within the matrix secreted by them.
Axons:
They are long, slender projections of neurons that help in carrying nerve impulses away from the neuron body. Axons aggregate in bundles which make up the nerves.
Ciliated epithelium:
It consists of simple columnar or cuboidal epithelium with cilia on their free surfaces. It is present on the inner surface of the oviducts and bronchioles. Where it helps in the movement of eggs or mucus in specific directions.
Epithelial tissue lines the surface of a body and forms a protective covering. Epithelium cells are packed tightly together with little intercellular matrix.
Epithelial tissue in the body is of two types.
(a) Simple epithelium: It consists of a single layer of cells where cells are in direct contact with the basement membrane. It is further sub-divided into the following types:
(i) Simple squamous epithelium: It consists of a single layer of flat cells with irregular boundaries. It is found in the walls of the blood vessels and in the lining of alveoli.
(ii) Simple cuboidal epithelium: It consists of a single layer of cube-like cells. It is present in regions where secretion and absorption of substances takes place such as the proximal convoluted tubule region of the nephron.
(iii) Simple columnar epithelium: It consists of a single layer of tall, slender cells with their nuclei present at the base of the cells. They may bear micro-villi on the free surfaces. Columnar epithelium forms the lining of the stomach and intestines, and is involved in the function of secretion and absorption.
(iv) 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.
(v) Glandular epithelium:It consists of 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) by the method through which they release enzymes.
.JPG "epithelial tissues")
(b)
Compound epithelium: It consists of many layers of cells. It is involved mainly in the function of providing protection and has a limited role in secretion and absorption.
Dry surface of the skin or moist inner lining of the buccal cavity, pharynx, pancreatic ducts, and the inner lining of ducts of salivary glands are some of the examples of compound epithelium
(a)
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Simple epithelium |
Compound epithelium |
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1. It is composed of only one layer of cells. 2. It is mainly involved in the function of absorption and secretion. 3. It is present in the lining of the stomach, intestine. |
1. It is composed of many layers of cells. 2. It is mainly involved in the function of protection 3. It is present in the lining of the pharynx and buccal cavity. |
(b)
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Cardiac muscles |
Striated muscles |
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1. They are involuntary in function. 2. They are multi-nucleated and branched. 3. They are found only in the heart. |
1. They are voluntary in function. 2. They are multi-nucleated and un branched. 3. They are found in triceps, biceps, and limbs. |
(c)
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Dense regular connective tissues |
Dense irregular connective tissues |
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1. In dense regular connective tissues, collagen fibres are present in rows between parallel bundles of fibres. 2. They are present in tendons and ligaments. |
1. In dense irregular connective tissues, fibres are arranged irregularly. 2. They are present in the skin. |
(d)
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Adipose tissue |
Blood tissue |
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1. It is composed of collagen fibres, elastin fibres, fibroblasts, macrophages, and adipociytes. 2. It helps in the synthesis, storage, and metabolism of fats. 3. It is present beneath the skin. |
1. It is composed of RBCs, WBCs, platelets, and plasma. 2. It helps in the transportation of food, wastes, gases, and hormones. 3. It is present in the blood vessels. |
(e)
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Simple glands |
Compound glands |
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1. They contain isolated glandular cells. 2. They are unicellular. 3. Examples include goblet cells of the alimentary canal. |
1. They contain a cluster of secretory cells. 2. They are multicellular. 3. Examples include salivary glands. |
There are three types of epithelial tissue on the basis of their structural modifications of cells:
The dorsal surface of the body of earthworm is marked by dark median dorsal line than ventral and ventral surface is distinguished by the presence of genital openings.
a. Wrong statement
In earthworms, there is the presence of a pair of the male genital pore.
b. Correct statement
c. Wrong statement
The muscular layer in the body wall of the earthworm is not only made up of circular muscles but it also has longitudinal muscles.
d. Correct statement
Nephridia in earthworms are defined as the organs that are for excretion and osmoregulation are tiny coiled tubules. And, are similar in structure that are classified into three types on the basis of their location. These are:
Features of eye in a cockroach are:
Frog is a Poikilotherm as it exhibits camouflage and undergoes aestivation and hibernation. These are beneficial for it as it sleeps and uses the stored energy in the body and emerges after the harsh environmental temperature has passes camouflage helps in its protection and catching prey.
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False body segmentation |
True body segmentation |
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It is the segmentation of the ectoderm. |
It is the segmentation of a body. |
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In this, different segments are independent of each other. |
In this, different segments are correlated to each other. |
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It does not have internal segmentation. Example: Tapeworm. |
It shows internal as well as external segmentation. Example: Earthworm. |
Some common features of connective tissues are:
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Bones |
Cartilage |
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Structure: Bones are hard, highly rigid, connective tissue that forms the skeleton of vertebrates. |
Cartilage is a thin fibrous, flexible connective tissue. |
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Bone cells are known as osteocytes. |
Cartilaginous cells are called chondrocytes. |
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Bone marrow is the site of production of blood cells. |
Cartilage forms models for growing bones. |
The involuntary tissue present in the hearth is known as cardiac tissue which have same characteristics like smooth muscles.
Gametic change in Earthworm during mating are:
There are three parts of alimentary canal:
MALE REPRODUCTIVE SYSTEM OF A FROG consists of a pair of yellowish, rod like testes which are joined to the anterior parts of the kidney by double folds of peritoneum, the mesorchia. 10-12 fine tubules, vasa efferentia arise from each testes, passes through the mesorchium and opens into the Bidder’s canal. It communicates with the ureter (carries urine and spermatozoa known as urinogenital duct in male frogs) which leaves the kidney near its hind end and opens into the cloaca and then cloaca opens out by cloacal apertures.
Gap junctions facilitate intercellular communication by allowing small signaling molecules to pass from cell to cell.
Blood, bone and cartilage are known as connective tissue because they have role in the binding and connection of different tissues and organs. And, all contains tissue that is mesoderm in origin.
Neurons are known as excitable cells because they possess electrical potential difference and their membranes are found in a polarized state. Due to this state, ions interact with the membrane and change the state of polarization. Because of this neurons get excited and transfer nerve impulse.
Earthworms help farmers by moving through the soil which helps in the aeration of the soil. Excreta released by them increase fertility of soil. The worms reduce the acidity and the alkalinity of the soil and creates optimum conditions for the plant growth and increases the soil fertility by earthworms. That’s why they are known as friend of farmer. And, many more reasons are there to prove that earthworms are very useful.
