By going through these CBSE Class 11 Biology Notes Chapter 7 Structural Organisation in Animals, students can recall all the concepts quickly.

Structural Organisation in Animals Notes Class 11 Biology Chapter 7

→ Cells, tissues, organs and organ systems split up the work in a way that ensures the survival of the body as a whole and exhibit division of labour.

→ A tissue is defined as a group of cells along with intercellular substances performing one or more functions in the

→ Epithelia are sheet-like tissues lining the body’s surface and its cavities, ducts and tubes. Epithelia have one free surface facing a body fluid or the outside environment. Their cells are structurally and functionally connected at junctions.

→ Diverse types of connective tissues bind together, support, strengthen, protect and insulate other tissue in the body. Soft connective tissues consist of protein fibres as well as a variety of cells arranged in a ground ‘ substance.

→ Cartilage, bone, blood, and adipose tissue are specialised connective tissues. Cartilage and bone are both structural materials.

→ Blood is a fluid tissue with transport functions.

→ Adipose tissue is a reservoir of stored energy. Muscle tissue, which can contract (shorten) in response to stimulation, helps in the movement of the body and specific body parts.

→ Skeletal muscle is the muscle tissue attached to bones. Smooth muscle is a component of internal organs. The cardiac muscle makes up the contractile walls of the heart. Connective tissue covers all three types of tissues. Nervous tissue exerts the greatest control over the response of the body. Neurons are the basic units of nervous tissue.

→ Earthworm, cockroach and frog show characteristic features in body organisation. In Pheretima Posthuma (earthworm), the body is covered by a cuticle.

→ All segments of its body are alike except the 14th, 15th and 16th segment, which are thick and dark and glandular, forming clitellum.

→ A ring of S-shaped chitinous setae is found in each segment. These setae help In locomotion. On the ventral side, spermathecal openings are present in between the grooves of 5 and 6, 6 and 7, 7 and 8 and 9 segments.

→ Female genital pores are present in the 14th segment and male genital pores in the 18th segment.

→ The alimentary canal is a narrow tube made of the mouth, buccal cavity, pharynx, gizzard, stomach, intestine and anus. The blood vascular system is of closed type with heart and valves. The nervous system is represented by the ventral nerve cord.

→ The earthworm is hermaphrodite. Two pairs of testes occur in the 10th and 11th segment, respectively. A pair of ovaries are present on the 12 and 1.3th intersegmental septum. It is a protandrous animal with cross-fertilisation. Fertilisation and development take place in the cocoon secreted by the glands of the clitellum.

→ The body of the cockroach (Periplaneta americana) is covered by a chitinous exoskeleton. It is divided into head, thorax and abdomen. Segments bear jointed appendages. There are three segments of thorax, each bearing a pair of walking legs. Two pairs of wings are present, one pair each on the 2nd and 3rd segment. There are ten segments in the abdomen.

→ The alimentary canal is well developed with a mouth surrounded by mouthparts, a pharynx, oesophagus, crop, gizzard, midgut, hindgut and anus. Hepatic cancer is present at the junction of the foregut and midgut.

→ Malpighian tubules are present at the junction of the midgut and hindgut and help in excretion. A pair of the salivary gland is present near 1 crop. The blood vascular system is of open type. Respiration takes place by a network of tracheae.

→ The trachea opens outside with spiracles. The nervous system is represented by segmentally arranged ganglia and ventral nerve cord.

→ A pair of testes are present in the 4th and 5th segments and ovaries in the 4th, 5th and 6th segment. Fertilisation is internal. Female produces 10-40 ootheca bearing developing embryos. After rupturing of single ootheca, ‘ sixteen young ones, called nymphs come out.

→ The Indian bullfrog, Rana Tigrina, is the common frog in the Indian Body that is covered by skin. Mucous glands are present in the skin which is highly vascularized and helps in respiration in water and on land.

→ The body is divisible into the head and hunk. A muscular tongue is present, which is bilobed at the tip and is used in capturing the prey. The alimentary canal consists of the oesophagus, stomach, intestine and rectum, which open into the cloaca. The main digestive glands are the liver and pancreas. It can respire in water through the skin and through lungs on land.

→ The circulatory system is closed with a single circulation. RBC, are nucleated. The nervous system is organised into central, peripheral and autonomic. The organs of the urinogenital system are kidneys and urinogenital ducts, which open into the cloaca.

→ The male reproductive organ is a pair of testes. The female reproductive organ is a pair of ovaries. A female lays 2500-3000 ova at a time. The fertilisation and development are external. The eggs hatch into tadpoles, which metamorphose into frogs.

→ Tadpole: Development involves a larval stage called tadpole. Tadpole undergoes metamorphosis to form the adult.

→ BrainBox: The brain is enclosed in a bony structure called brain box (cranium)

→ Vena-cava: Right atrium receives blood through the major veins called vena cava.

→ Sinus venous: A triangular structure called sinus Venosus joins the right atrium.

→ Pericardium: The heart has three chambers, two atria and one ventricle and is covered by a membrane called the pericardium.

→ Pulmonary respiration: The respiration by the lungs is called pulmonary respiration.

→ Summer sleep and winter sleep: The frogs are not seen during peak summer and winter. During this period they take shelter in deep burrows to protect them from extreme heat and cold. This is called summer sleep (aestivation) and winter sleep (hibernation).

→ Mimicry: Frogs have the ability to change the colour to hide from their enemies (camouflage).

→ Poikilotherms: Frogs do not have constant body temperature i.e., their body temperature varies with the temperature of the environment. Such animals are called cold-blooded or poikilotherms.

→ Oothecae: Cockroaches fertilised eggs are encased in capsules called oothecae. The ootheca is a dark reddish to the blackish-brown capsule, about 3/8″ (8mm) long.

→ Spermatophores: The sperms are stored in the seminal vesicles and are glued together in the form of bundles called spermatophores which are discharged during copulation.

→ Spiracles: The respiratory system consists of a network of the trachea, that open through 10 pairs of small holes called spiracles present on the lateral side of the body.

→ Hepatic or gastric: A ring of 6-8 blind tubules called hepatic or gastric cancer is present at the junction of foregut and midgut, which secreted digestive juice.

→ Vermicomposting: The process of increasing the fertility of the soil by the earthworms is called vermicomposting.

→ Anus: The alimentary canal opens to the exterior by a small rounded
aperture called the anus.

→ typhlosole: The characteristic feature of the intestine between 26-35 segments is the presence of an internal median fold of the dorsal wall called typhlosole.

→ Glandular epithelium: Some of the columnar or cuboidal cells get specialised for secretion and are called the glandular epithelium.