NCERT Solutions For Class 11 | Biology | Chapter 7 | Structural Organisation in Animals
1. Answer in one word or one line.
- (i) Give the common name of Periplanata americana.
- (ii) How many spermathecae are found in earthworm?
- (iii) What is the position of ovaries in cockroach?
- (iv) How many segments are present in the abdomen of cockroach?
- (v) Where do you find Malpighian tubules?
Answer –
- (i) The common name of Periplanata americana is american cockroach.
- (ii) There are four pairs of spermathecae in earthworm.
- (iii) They have a pair of ovaries lying laterally in the 2nd and 6th segments.
- (iv) They have 10 segments present in the abdomen of cockroach.
- (v) In the alimentary canals of the insects, Malphigian tubules are found in the junction of the midgut and the hindgut.
2. Answer the following:
- (i) What is the function of nephridia?
- (ii) How many types of nephridia are found in earthworm based on their location?
Answer –
- (i) They are the excretory organs that occur as segmentally arranged coiled tubules in earthworm. They regulate the volume and composition of body fluids, i.e. excretion and osmoregulation.
- (ii) There are three types of nephridia in earthworm based on their location. They are –
- Septal nephridia present on both sides of the intersegmental septa segment 15 to the last that opens in the intestine.
- Integumentary nephridia attached to the lining of the body wall of segment 3 to the last that opens on the body surface.
- Pharyngeal nephridia present as three paired tufts in the 4th, 5th and 6th segments.
3. Draw a labelled diagram of the reproductive organs of an earthworm.
Answer –
Credits – NCERT
4. Draw a labelled diagram of alimentary canal of a cockroach.
Answer –
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5. Distinguish between the following:
- (a) Prostomium and peristomium
- (b) Septal nephridium and pharyngeal nephridium
Answer –
(a) Prostomium and peristomium
| PROSTOMIUM | PERISTOMIUM |
| Small, fleshy lobe that serves as a opening of the mouth and wedge to open cracks in the soil for earthworm to crawl. | The cresentic aperture at the anterior end of the first segment of the earthworm that serves as the mouth. |
(b) Sepal Nephridium and Pharyngeal Nephridium
| SEPAL NEPHRIDIUM | PHARYNGEAL NEPHRIDIUM |
| Present on both anterior and posterior sides of the intersegmental septa of segment 15th to the last segment in the earthworm. | Present in the 4th, 5th and 6th segments as three paired tufts on either side of the elimentary canal |
| Excretion is discharged into the lumen of the alimentary canal. | Excretion is discharged into the lumen, but in pharynx or buccal cavity. |
6. What are the cellular components of blood?
Answer – The cellular components of blood are red blood cells (RBCs), white blood cells (WBCs), and platelets.
7. What are the following and where do you find them in animal body.
- (a) Chondriocytes
- (b) Axons
- (c) Ciliated epithelium
Answer –
- (a) Chondriocytes– They are the cells of cartilage which enclosed in small cavities within the matrixsecreted by them. The cartilage is present in the tip of the nose, outer ear joints, between adjacent bones of the vertebral column, limbs and hands.
- (b) Axons– Axons are the long, slender extension of the neuron in the nerve cells. They are found throughout the body. They start from cyton in the nerve cell and carry out the impulse throughout the body.
- (c) Ciliated epithelium– The cuboidal or Columnar epithelium with cilia are called as ciliated epithelium. They are present in the hollow organs like bronchioles and fallopian tubes. They move the particles or mucus in a specific direction.
8. Describe various types of epithelial tissues with the help of labelled diagrams.
Answer –
Epithelial tissues are present in the lining of the body surface. They are densely packed and have little intercellular matrix. They have either one surface free, which faces body fluid or the outer environment.
The two main types of epithelial tissues are
1. SIMPLE EPITHELIUM-
- They are composed of single layer of cells.
- They form the lining for body cavities, sucts and tubes.
- The four types of simple epithelium based on structural modification are –
- Squamous Epithelium– They are composed of single thin layer of flattened cells with irregular boundaries. They are located in the walls of blood vessels and air sacs of lungs. They function in excretion, protection, forming a diffusion boundaries, secretion, etc.
- Cuboidal Epithelium– They are composed of single layer of cuboidal cells. They are located in ducts of the glands and the proximal convoluted tubular parts of nephrons in kidneys with microvilli. There function is secretion and absorption.
- Columnar Epithelium– They are composed of single layer of tall and slender cells with their nuclei at the base. They are located in the lining of tomach and intestine to help in secretion and absorption.
- Ciliated Epithelium– When columnar or cuboidal epithelium has cilia present on the surface, it is called ciliated epithelium. They are mainly found in the inner wallf of bronchioles and fallopian tube. Their function is to move particles or mucus to a particular direction.
2. COMPOUND EPITHELIUM-
- They are multilayered, therefore have few roles in secretion and absorption.
- They cover the dry surface of the skin, the moist surface of the buccal cavity, pharynx, the inner linings of ducts of salivary glands and of pancreatic ducts.
- They provide protection against the mechanial or chemical stress.
9. Distinguish between
- (a) Simple epithelium and compound epithelium
- (b) Cardiac muscle and striated muscle
- (c) Dense regular and dense irregular connective tissues
- (d) Adipose and blood tissue
- (e) Simple gland and compound gland
Answer –
(a) Simple epithelium and compound epithelium
| SIMPLE EPITHELIUM | COMPOUND EPITHELIUM |
| Consists of a single layer of cells | Consists of many layers of cells. |
| They function in absorption and secretion | They function as a protective layer. |
| Present in the lining of body cavities, ducts and tubes like the inside of the stomach and intestine. | Present in the lining of the pharynx and the buccal cavity |
| Cells rest on the basement membrane. | The lowermost cells of the epithelium rest on the basement membrane |
(b) Cardiac muscle and striated muscle
| CARDIAC MUSCLE | STRIATED MUSCLE |
| It is the contractile tissue present in the heart only. | Found in the limbs, biceps and triceps of the body. |
| They are involuntary in function. | They are voluntary in function. |
| Branched fibres and uninucleated. | Unbranched and multinucleated. |
(c) Dense regular and dense irregular connective tissues
| DENSE REGULAR CONNECTIVE TISSUE | DENSE IRREGULAR CONNECTIVE TISSUE |
| The collagen fibres are arranged in rows between many parallel bundles of fibres. | Consists of fibroblasts and fibres which are arranged differently. |
| Tendons and ligaments have these tissues. | They are present in the skin. |
| Regular patterns of fibres | Irregular pattern of fibres |
(d) Adipose and blood tissue
| ADIPOSE TISSUE | BLOOD TISSUE |
| Loose connective tissue. | Fluid connective tissue. |
| Located beneath the skin. | Present in the blood vessels. |
| Consists of fibroblasts, collagen fibres, macrophages and adipocytes | Consisting of RBCs, WBCs, and platelets. |
| The excess nutrients which are not used immediately are converted into fats and stored in these tissues. | They transport oxygen, food, nutrients, water and hormones to different body parts |
(e) Simple gland and compound gland
| SIMPLE GLAND | COMPOUND GLAND |
| unicellular | multicellular |
| Consists of glandular cells | Consists of cluster of secretory cells |
| Example- goblet cells of alimentary canal | Example- salivary glands |
10. Mark the odd one in each series:
- (a) Areolar tissue; blood; neuron; tendon
- (b) RBC; WBC; platelets; cartilage
- (c) Exocrine; endocrine; salivary gland; ligament
- (d) Maxilla; mandible; labrum; antennae
- (e) Protonema; mesothorax; metathorax; coxa
Answer –
- (a) Areolar tissue; blood; neuron; tendon- It is not a connective tissue while others are.
- (b) RBC; WBC; platelets; cartilage– It is not a part of blood while others are.
- (c) Exocrine; endocrine; salivary gland; ligament– It is connective tissue while others are glands.
- (d) Maxilla; mandible; labrum; antennae– The rest are the parts of a cockroach’s stomach.
- (e) Protonema; mesothorax; metathorax; coxa– Others are the parts of segments in cockroaches while protonema is the filamentous stage in the moss life cycle.
11. Match the terms in column I with those in column II:
| Column I | Column II |
| (a) Compound epithelium | (i) Alimentary canal |
| (b) Compound eye | (ii) Cockroach |
| (c) Septal nephridia | (iii) Skin |
| (d) Open circulatory system | (iv) Mosaic vision |
| (e) Typhlosole | (v) Earthworm |
| (f) Osteocytes | (vi) Phallomere |
| (g) Genitalia | (vii) Bone |
Answer –
| Column I | Column II |
| (a) Compound epithelium | (iii) Skin |
| (b) Compound eye | (iv) Mosaic vision |
| (c) Septal nephridia | (v) Earthworm |
| (d) Open circulatory system | (ii) Cockroach |
| (e) Typhlosole | (i) Alimentary canal |
| (f) Osteocytes | (vii) Bone |
| (g) Genitalia | (vi) Phallomere |
12. Mention briefly about the circulatory system of earthworm.
Answer – The circulatory system of earthworm is explained as follows –
- They possess a closed type of blood vascular system which consist of vessels, capillaries and heart.
- Due to the closed type of circulatory system, the contractions help the blood to flow within the vessels and to the heart, in one particular direction.
- Smaller blood vessels supply blood to the gut, nerve cord, and the body wall.
- Blood glands present on the 4th, 5th and 6th segments produce blood cells and haemoglobin which dissolve in the blood plasma.
- Blood cells are phagocytic.
- Respiration occurs through moist body surface into directly their blood.
13. Draw a neat diagram of digestive system of frog.
Answer –
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14. Mention the function of the following
- (a) Ureters in frog
- (b) Malpighian tubules
- (c) Body wall in earthworm
Answer –
- (a) Uterers in frog– They act as a urinogenital duct which opens into the cloaca and carries perm and urine in the male frog. While in females, the ureters and oviduct open separately in the cloaca.
- (b) Malpighian tubules– They are the excretory organs in cockroaches.
- (c) Body wall in earthworm– the body wall helps in locomotion and burrowing.
