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

NCERT Solutions for Class 11 Biology Chapter 7 – Structural Organisation in Animals, provides a crisp and coherent explanation of every topic of the chapter. Biology experts at Instasolv have crafted this solution to make it comprehensive for you. As we are going deep into the study, the complexity of each topic is increasing. This chapter of NCERT Solutions deals with the intricate organisation of animal structure. It highlights the structure of animal tissue, their organ system, and the morphology as well as the anatomy of various animals. 

The NCERT Solutions for Class 11 Biology Chapter 7 has 14 questions that are based on various concepts introduced in the chapter. We help you to understand the answers to all these questions so that you can prepare well for CBSE exams. This chapter will also help you in NEET and other entrance tests. We have ensured that all the answers are as per the latest CBSE class 11 biology syllabus and are well-structured. 

Important Topics for NCERT Solutions for Chapter 7- Structural Organisation in Animals

Animal Tissues

The cell structure varies with respect to their structure. Tissues are grouped into four types: Epithelial, Connective, Muscular, and Neural.

  1. Epithelial Tissue or the epithelial tissues have a free surface and provide covering or lining to the body parts. These are closely packed cells with a very small intercellular matrix. Epithelial Tissues are of two types: Simple and compound. 
  • Simple epithelium is made of a single layer of cells and provides lining for body cavities, ducts, and tubes. It is further divided into three types: Squamous, Cuboidal and Columnar.
  • Compound epitheliums are the multi-layered cells having the function of secretion and absorption. Structural and functional linkages between individual cells in animal tissue are provided by junctions. In epithelium, there are three types of cell junctions: tight, adhering and gap.
  1. Connective Tissue in the body of complex animals, these tissues are found in abundance. They provide support and links to the tissues and organs of the body. Connective tissues are of three types: loose, dense, and specialised. 
  • Loose connective tissues – in semi-solid ground substance cells and fibres are loosely placed. E.g. areolar tissue beneath the skin. 
  • Dense connective tissues- fibres and fibroblasts are packed compactly. These can show a regular and irregular pattern. E.g. tendons. 
  • Specialised connective tissues- its various types are the cartilage, bones, and blood.  
  • Muscle tissue is made up of long cylindrical fibres placed in parallel arrays. Its fibre is called the myofibrils, which is made of numerous fine fibrils. Muscle helps in the movement of the body. A muscle can be: skeletal, smooth, and cardiac.

iii. Neural Tissue provides control over the body’s responsiveness to changing conditions. The unit of the neural system is the excitable cells called the neurons. The neuroglial cell protects and supports the neurons.

Organ and Organ system

In multicellular organisms, the tissues organize to form different organs that together form the organ system. The study of the form and the externally visible features is called the morphology. The study of the morphology of internal organs in animals is known as anatomy. Now, let’s discuss morphology and the anatomy of a few animals:

Ø Earthworm

It is a terrestrial invertebrate that is reddish-brown. It lives on the upper layer of the moist soil. Pheretima and Lumbricus are the common Indian earthworms.

  • Morphology

The body is long cylindrical. It is divided into hundreds of similar segments. A dark median mid-dorsal line along the longitudinal axis is present. A genital opening on the ventral surface and the mouth is on the anterior end. 

Prostomium acts as a covering on the mouth and also serves as a wedge to enter in soil. The buccal segment or the periosteum is the first segment of the body. Clitellum in mature earthworms is covered by a dark band of glandular tissue. The whole body is divided into three segments: pre-clitellar, clitellar, and post-clitellar. On the ventrolateral sides of the intersegmental grooves (5th – 9th) are the four pairs of spermathecal apertures found. 

On the 14th segment of mind ventral female genital pore is there and on the 18th segment of the ventrolateral are the male genital pores. Nephridiopores on the surface and in each body segment there are S-shaped setae (except the first, last, and the clitellum) which help in locomotion. 

  • Anatomy

The body wall has a thin non-cellular cuticle and epidermis is below it. The epidermis contains secretory gland cells. The alimentary canal which runs between the first and last segments is a straight tube. The mouth opens in the buccal cavity (1-3 segments) and to the muscular pharynx. Oesophagus (5-7 segments) leads to the muscular gizzard (8-9 segments). 

On the 9-14 segments is the stomach and it has calciferous glands. From the 15th segment till last is the intestine and on the 26th is the intestinal caeca. From 26-35 segments in the intestine is the internal median fold of the dorsal wall called the typhlosole is found. A small rounded aperture called the anus is present in the exterior. 

The blood vascular system is closed type, so the blood remains in the heart and the blood vessels. On the 4th, 5th, and 6th segment blood glands are present. Respiration is carried by a moist body surface. Nephridia are the coiled tubules excretory organs and are of three types: septal, integumentary, and pharyngeal. 

On the ventral paired nerve cord segment-wise ganglia are present, which constitutes the nervous system. No eyes are there but in the sensory system, they have light and touch organs. Earthworms are hermaphrodite. On 10th and 11th segment two pairs of testes and on 17th and 19th segments two pairs of accessory glands are present. They are called the ‘friends of farmers’ as they help in vermicomposting.

  • Cockroaches belong to the class insect of phylum Arthropoda and are nocturnal omnivores. They can be of 1- 3 inches in size and have an antenna, legs and upper body wall that conceal the head. 
  • Morphology

Common is the Periplaneta Americana species in cockroach; it is about 34-53 mm long. The body has 3 segments: head, thorax, and the abdomen and it is covered by a hard chitinous exoskeleton. The Head is a triangle and has six segments. Pair of compound eyes and antennae is present. Mouthparts are- labrum, a pair of mandibles, a pair of maxillae and a labium. Thorax has three parts- prothorax, mesothorax, and metathorax. Tegmina are the forewings. Both the male and the female abdomen have 10 segments. 

  • Anatomy

The body cavity lies in the alimentary canal. It is divided into three parts- foregut, midgut, and the hindgut. Oesophagus opens into a sac-like structure called the crop. After the crop lies the gizzard or the proventriculus. Malpighian tubules are present at the juncture of mid and hindgut.

Open type blood vascular systems with poorly developed blood vessels are present. The respiratory system has a network of trachea and spiracles. 

Malpighian tubules carry out excretion. Cockroaches are also called uricotelic. There is a series of fused segmentally placed ganglia that form the nervous system. Throughout the body lies the nervous system. Antennae, eyes, maxillary palps, labial palps, anal cerci, etc. are the sensory organs. 

Ø Frogs

Belong to the class Amphibia of the phylum Chordata and can live both on land and water. They are poikilotherms. Rana tigrina is the common species found in India. 

  • Morphology

Due to the presence of mucus, the skin is smooth and slippery. It never drinks water but absorbs through the skin. It has a head, trunk, mouth, bulging eyes, and membranous tympanum ears. Feet are webbed. They are sexual dimorphisms. 

  • Anatomy

Alimentary canal and digestive glands form the digestive system. They are omnivores and have a short alimentary canal. In the buccal cavity, the mouth is there which leads then to the oesophagus. It has a short oesophagus. The bilobed tongue captures the food. Intestine consists of villi and microvilli. 

They respire through the skin in water and buccal cavity, skin, and lungs on land. It has a closed vascular and a lymphatic system. Kidneys, ureters, cloaca, and the urinary bladder form the excretory system. Frog is a ureotelic animal, as it excretes urea. The nervous system has 3 parts- central, peripheral, and autonomic. 

Discussion of Exercises of NCERT Solutions for Class 11 Biology Chapter 7- Structural Organisation in Animals

  • The first question is a very short answer type question and deals with the structure of earthworm and cockroaches; 
  • Comparative questions relating to various structures in animals are asked; 
  • Questions on the circulatory and digestive systems of earthworm and frog are asked.
  • Compiled in an easy language and detailed elucidation, our NCERT solutions for class 11 chapter 7 of class 11 biology will facilitate your best preparation avenue of your examination.