CBSE Class 11 Biology Revision Notes Chapter 7

CBSE Class 11 Biology Revision Notes Chapter 7 – Structural Organisation in Animals

Chapter 7 of Class 11 Biology introduces students to many interesting facts about how Animal bodies function and their structural organisation with them. Students will learn about how similar cells in the Animal body along with intercellular substances come together to form tissues that perform specific functions. And how these tissues come together to further form organs.

In order to make their preparation easier, Students can access Revision Notes for this chapter prepared by Extramarks. These notes summarise all the important information in this chapter in a simple and easy-to-understand language. Students can access these from the Extramarks’ website.

Access Class 12 Biology Chapter 7 – Structural Organisation in Animals

Some of the important concepts that students will learn in this chapter include:

• Multicellular organisms’ cells are grouped into tissues to execute varied functions
• Tissue: A group of cells and intercellular molecules that come together to achieve specific bodily functions
• There are only four basic tissue types in all complex animals
• Similar tissues come together to form organs
• Organ System: A group of organs that operate together to accomplish a particular goal. Each is made of unique tissues and serves a specific role in the body.

7.1 Animal Tissues

As the structure of cells varies according to their functions, tissues can broadly be classified into the following:

7.1.1: Epithelial Tissues:

• It comprises densely packed cells with little intercellular matrix, with one surface exposed to air or internal fluid.
• It provides a surface for molecular absorption, excretion, and transport while also acting against mechanical injury, infections, and dehydration.

The two types of epithelium are simple epithelium and stratified epithelium.

• Epithelium simple: It is an end-to-end arrangement of a single layer of cells. It is mostly found as a lining for body cavities, ducts, and tubes.

• Compound or stratified epithelium: The compound epithelium is a protective layer in our skin of two or more cell layers.
• Squamous, cuboidal, and columnar epithelium are the three forms of simple epithelium based on their structure.

1. Squamous Epithelium:

Flattened cells with irregular borders are arranged to form a thin layer that appears polygonal when viewed from the top.

• Because of their compact form, which resembles floor tiles, also called pavement epithelium.
• It is responsible for the delicate lining of cavities such as the mouth, oesophagus, nose, pericardium, alveoli, and other organs and the lining of blood vessels.
• They have a role in the diffusion boundaries and the coating of the tongue and skin.
• Squamous epithelium is organised in many layers in the skin to avoid wear and tear.

2. Cuboidal Epithelium:

A layer of cube-like cells with square sections but hexagonal free surfaces

• It is found in the tubules of the kidneys, thyroid vesicles, and glands.
• In the gonads, it is responsible for the germinal epithelium.
• Absorption, excretion, and secretion, as well as mechanical support, are all aided by it.
• Microvilli are seen in a kidney’s nephron’s proximal convoluted tubule epithelium. Microvilli are finger-like projections on the surface of epithelial cells. They assist in the absorption of nutrients.

3. Columnar Epithelium:

• A thin layer of tall, narrow cells.
• The nuclei are at the bottom of the pyramid.
• On the free surface, microvilli may be present.
• They help with secretion and absorption and are located in the lining of the stomach and intestines.

4. Ciliated Epithelium:

• On the surface, cuboidal or columnar epithelium with fine, hair-like protoplasmic outgrowths.
• Is found in the nephrons, trachea, and fallopian tubes.
• Cilia drive particles or mucus in a direction through the epithelium.

5. Glandular Epithelium:

• It is modified cells with the ability to secrete. They can be columnar or cuboidal in shape.
• Unicellular: They’re single, isolated gland cells that look like goblet cells in the gastrointestinal tract.

• Multicellular: They are gland cells identical to those found in the salivary gland.
• Exocrine glands produce chemicals that are secreted through ducts or tubes. These glands secrete saliva, mucus, earwax, oil, milk, digestive enzymes, and other cell products.
• Endocrine: There are no ducts in them (ductless glands). Hormones are their byproducts, which are immediately secreted into the fluid surrounding the gland.

6. Stratified or Compound Epithelium:

• They are multi-layered, with multiple layers of cells, and only play a minor part in secretion and absorption.
• They are generally used to safeguard against mechanical and chemical stressors.
• The dry surface of the skin, the pharynx, the wet surface of the buccal cavity, the inner lining of salivary gland ducts, and pancreatic ducts are all places where they can be found.

Junctions: They are specialised structures that physically and functionally connect individual cells. Tight, adherent, and gap junctions are the three types.

• Tight intersections: These specialised structures keep chemicals from seeping through a tissue’s surface.

• Junctions that adhere: A specialised structure that unites cells nearby
• Junctions with Gaps: These specific structures enable cell communication. They connect the cytoplasm of nearby cells, allowing ions, tiny molecules, and large molecules to be transferred quickly.

7.1.2: Connective Tissue:

• In the body of sophisticated animals, the connective tissue of various forms is the most plentiful of all tissues. 
• They’re termed such because they help connect and support human tissues and organs.
• They might be soft or specialised.
• Connective tissue is made of a matrix of cells that are widely spaced.
• The matrix determines the function of the tissue.
• Collagen and elastin are structural proteins secreted by cells in connective tissues that save blood, strength, elasticity, and flexibility.
• The collection of modified polysaccharides released by cells forms the matrix or ground substance.
• Connective tissue can be loose, thick, or specialised.
• The three types of connective tissue are loose, dense and specialised connective tissue.

Loose Connective Tissue:

• Areolar, adipose, and reticular tissue is semi-fluid ground substances with loosely distributed cells and fibres.

Areolar Tissue:

• It is the most frequent form of connective tissue in the human body.
• Inside organs, between skin and organs, around blood vessels and nerves, this tissue can be found in the bone marrow.
• It is widely employed as an epithelial support structure.
• Fibroblasts, macrophages, and mast cells make up this cell type.
• Fibroblasts produce two fibres: elastic yellow fibres and inelastic white fibres.
• It connects the organ’s numerous tissues.
• It helps the body’s tissues heal after an injury.
• Allergies to mast cells are a concern.

Adipose Tissue:

• The majority of these tissues is situated beneath the skin.
• Fat storage is built into the cells.
• Adipocytes, oval and circular cells loaded with fat globules, make up the tissue.
• It prevents heat loss from the body and functions as insulation.
• It helps to store excess energy in the form of fats.
• It produces a shock-absorbing cushion around essential organs like the heart, kidneys, and eyes.

Reticular Tissue:

• The cells of this tissue are structured like stars and create a network-like structure.
• The fibres are made up of the protein reticulin.
• The spleen, lymph nodes, tonsils, and other organs contain it.
• It is in charge of the development of lymphoid tissues in the body.
• In the bone marrow, reticular tissue aids in the production of blood cells.

Dense Connective Tissue:

• Cells, fibres, and fibroblasts are grouped compactly with the matrix.
• The terms dense regular and dense irregular tissues refer to tissue orientation that is either regular or irregular.
• Collagen fibres are sandwiched between multiple parallel fibre bundles. Collagen fibres can be observed in rows. Ligaments and tendons are two examples.

• Tendons: These are white fibrous tissues. The fibroblasts are arranged continuously. It is rigid and inflexible. A skeletal muscle is connected to a bone by a ligament.

• Ligaments: Ligaments are formed of yellow elastic tissue. The fibroblasts are all over the place. The tissue is robust but malleable. It joins two bones together.
• Dense, erratic connective tissues: In this case, the fibroblasts and fibres (mostly collagen) are oriented differently. The skin’s tissues are made of these.

Specialised Connective Tissue:

• Connective tissue that has been trained to serve a purpose is referred to as specialised connective tissue.
• Bone, cartilage, and lymph make up this structure.
• Bone is a skeletal tissue type.
• It provides structural support to the body.
• In addition to collagen, it is built of a rigid, non-pliable matrix of calcium phosphate, calcium carbonate, and a protein (ossein).
• The matrix is made of Haversian canals, which are long.
• The matrix is organised into layers called lamellae. The lamellae appear as crescentic rings around Haversian channels.
• Lacunae are fluid-filled gaps found between the lamellae’s rings.
• Bone cells, or osteocytes, are found in the cavities.
• Bones provide support and protection for soft tissues and organs.
• The weight is supported by limb bones, such as the long bones of the legs. To move, they also interact with the skeletal muscles linked to them.
• The bone marrow in some bones is the site of blood cell production.

Cartilage:

• In addition, it is a form of skeletal tissue.
• This tissue is tough and supple, although it’s not as hard as bone.
• The matrix is both rigid and malleable, having the ability to tolerate compression.
• Chondrocytes, or cartilage cells, are contained in microscopic cavities within the matrix.
• Elasticity is due to the presence of the protein chondrin.
• Fibres reinforce the matrix, and the cells are widely separated.
• It is in charge of the vertebrate embryonic skeleton. Bones eventually replace the majority of the cartilage.
• Cartilage can be found in the tip of the nose, adult limbs and hands, outer ear joints, and other places. It can also be present in the spinal column between adjacent bones.

Blood:

• It’s a fluid connective tissue made up of plasma and blood cells that acts as the body’s circulating fluid and aids in the movement of numerous substances.
• It’s the most sensitive connective tissue in the body.
• Plasma, which is roughly 90% water, is the fluid component. Proteins, salts, hormones, and other materials to digest food, gases, excretory products, and other parts make up the remaining 10%.
• Blood cells include RBCs, WBCs, and platelets.

7.1.3: Muscle Tissue:

• Muscle tissue can contract and relax, allowing it to do mechanical work.
• Muscle fibres are long cylindrical fibres placed in parallel arrays.
• Myofibrils are a type of tiny fibril that makes up the fibres.
• When muscle fibres are activated, they contract. They then uncoordinatedly relax and return to their original uncontracted state.
• Their actions cause the body or sections of the body to move to react to changes in the environment and keep the various body parts in their proper places.
• Skeletal, smooth, and cardiac muscle cells are the three types of muscle cells.
• Muscles of the Skeletal System:

1. It has a strong bond with the skeletal bones.
2. They’re striated and arranged in a parallel manner.
3. A connective tissue sheath surrounds several bundles of muscle fibres.
4. Because they are under conscious control, they are also known as voluntary muscles.
5. Cells are unbranched and have numerous nuclei.
6. The cells of smooth muscle taper at both ends to form a spindle or fusiform shape.
7. They have no striae.
8. They are held together by cell junctions, covered in a connective tissue sheath.
9. Nuclei are missing from cells.
10. Because the conscious mind does not direct its function, they are sometimes known as involuntary muscles.

Cardiac Muscle:

• Only the heart has this type of contractile muscle tissue.
• Cell junctions allow heart muscle cells to stick together by connecting their plasma membranes.
• Communication crossroads
• Intercalated discs at some fusion points allow cells to contract as a single unit. When one cell receives a signal, the surrounding cells are stimulated to contract.
• Muscles that can’t be controlled.
• They’re uninucleate and branching.
• Throughout life, these muscles contract and relax in a rhythmic pattern.

7.1.4: Neural Tissue

• Neural tissue with densely packed cells called neurons is specialised nerve impulse conduction.
• Neurons can be found across the brain, spinal cord, and nerves.
• Neuroglial cells protect and nourish neurons.
• More than half of the volume of neural tissue in our bodies is made of neuroglia.
• The cyton, dendrites, and axons are the three components of a neuron.
• Cyton: Nissl’s granules are highly pigmented particles found in the cell body, nucleus, and cytoplasm.

• Dendrites: It is a single or more short branching cytoplasmic process. They transport impulses to the cyton from receptors or other neurons.

• Axon: A procedure that transports impulses from one neuron to the next. Myelinated or unmyelinated nerve fibres exist.
• An electrical impulse travels swiftly through the plasma membrane when a neuron fires. When this impulse reaches the neuron’s terminals, it triggers events that stimulate or inhibit neighbouring neurons.

7.2: Organ and Organ System

• Basic tissue types in the body organise in ways to form organs. Many similar organs will then create organ systems in multicellular creatures.
• The body must be organised into tissues, organs, and organ systems. It also helps to coordinate the activity of an organism’s millions of cells. One or more types of tissues make up each organ in our bodies. Our heart, for example, is made up of epithelial, connective, muscular, and neurological components. The complexity of organs and organ systems follows an evolutionary tendency.

7.3: Earthworm

• It is a reddish-brown terrestrial invertebrate that lives in the upper layer of damp sand.
• Worm casting, or faecal deposits, can be used to identify them.

7.3.1: Morphology:

• An earthworm’s body is long and cylindrical. Metamers are over a hundred small segments that are similar to one another that make up the human body (metameres about 100-120 in number).
• A dark median mid-dorsal line represents the dorsal blood vessel on the body’s dorsal surface.
• The presence of genital apertures distinguishes the ventral surface (pores).
• At the front, the mouth and the prostomium are placed. The prostomium is a lobe that protects the mouth.
• The prostomium has a sensory role and is utilised like a wedge to force open dirt fissures so the earthworm can crawl through them.
• The prostomium is used for sensory purposes.
• The mouth is found in the peristomium, the initial part of the body (buccal cavity).
• The segments 14-16 of a mature worm are covered by the clitellum, a conspicuous dark ring of glandular tissue.
• Preclitellar, clitellar, and postclitellar are the three regions of the body.
• The ventrolateral sides of the intersegmental grooves have four pairs of spermathecal apertures. In other words, they’re present between the 5th and 9th segments.
• A solitary female genital pore can be found on the 14th segment’s mid-ventral line.
• There are two male genital apertures on the ventrolateral sides of the 18th segment.
• Nephridiopores are pores on the body’s surface that open.
• Nephridiopores: Many creatures, including flatworms and annelids, have a nephridiopore’s excretory organ.
• There are rows of S-shaped seats on each body segment. The first, final, and clitellum segments are devoid of setae. They can be detected at the epidermal pits in the centre of each sector. Setae can expand and contract. Locomotion is their principal function.

7.3.2: Anatomy

• A thin non-cellular cuticle protects the earthworm’s body wall from the outside, followed by the epidermis, two muscle layers (circular and longitudinal), and an innermost coelomic epithelium.

Digestive System:

• The alimentary canal is a long, straight tube that extends from the mouth to the stomach.
• The tube’s end has a mouth into the buccal cavity (1-3 segments).
• The muscular pharynx comes next. There is a little oesophagus between the 5th and 7th segments. It eventually develops into a muscular gizzard (8-9 sectors).
• Between segments 9 and 14, the stomach is placed. The earthworm feeds on decaying leaves and organic debris mixed with the soil. Calciferous glands are found in the stomach. They work by neutralising humic acid in humus.
• The gut runs from the 15th segment to the last sector. A pair of short and conical intestinal caeca protrude from the colon on the 26th segment.
• After the 26th segment, an internal median fold of the dorsal wall, known as typhlosole, is a defining feature of the intestine (except for the last 23rd-25th sectors). The effective absorption area in the gut is increased.
• A spherical opening known as the anus connects the alimentary canal to the outer world. The ingested dirt is rich in organic stuff. It passes through the gastrointestinal tract.
• Digestive enzymes break down complex foods into smaller absorbable pieces in the digestive tract. Through intestinal membranes, these simpler molecules are absorbed and utilised.

Circulatory System:

• Blood veins, capillaries, and the heart makeup Pheretima’s closed blood vascular system.
• It depicts a closed circulatory system to restrict the blood to the heart and arteries.
• Blood only flows in one way during contractions.
• Smaller blood arteries serve the gut, nerve cord, and body wall to transport oxygen and nutrients.
• The fourth, fifth, and sixth segments all have blood glands. They are in charge of making red blood cells and haemoglobin. Haemoglobin, which is dissolved in blood plasma, is present.
• Blood cells are phagocytic by nature.
• Earthworms lack specific breathing equipment. The wet body surface allows for respiratory exchange. Through the skin, gases are exchanged directly into the bloodstream.

Excretory System:

• Nephridia are earthworms’ excretory organs (sing.: nephridium). Coiled tubules are organised in segments. The three forms of nephridia are septal, integumentary, and pharyngeal.
• Nephridia regulate and adjust body fluid volume and composition.

Nervous System:

• It is made of segments of ganglia located on the ventral paired nerve cord. In the anterior region, the nerve cord separates (3rd and 4th segments). The pharynx is wrapped around it. Finally, it forms a nerve ring by connecting the dorsal cerebral ganglia.

Reproduction:

• The earthworm is bisexual, having both testes and ovaries.
• In the tenth and eleventh segments, two pairs of testes are detected. Their vasa deferentia reach the prostatic duct in the 18th segment.
• Auxiliary glands are separated into two kinds. They’ll be found in the 17th and 19th sections.

7.4: Cockroach:

• They are brown or black-bodied organisms belonging to the Phylum Arthropoda’s Class Insecta.
• Cockroaches with bright colours like red, yellow, and green have been seen in tropical areas.
• They are 0.-7-6 cm in length.
• Their antennae, legs, and a flat extension of the upper body wall that hides their head are all long.
• They’re nocturnal omnivores who enjoy moist conditions.
• They infest homes and transmit diseases.

7.4.1: Morphology

• The most prevalent cockroach species is Periplaneta americana, which reaches 33-54mm in length.
• Males’ wings extend past the abdomen.
• The head, thorax, and abdomen make up their body.
• An exoskeleton guards the entire body. It is constructed of chitin and is complex.

7.4.2: Anatomy

• Digestive System/Alimentary Canal: The foregut, midgut, and hindgut are the three portions of the alimentary canal.

Alimentary Canal of Cockroach

• Circulatory System/Blood Vascular System: The cockroach’s circulatory system is open.
• A set of poorly developed blood arteries that open into the central cavity is known as the hemocoel. Visceral organs are found in the hemocoel. They are surrounded by and in direct contact with the hemolymph.
• The hemolymph is colourless. Plasma and haemoglobin make up this substance. Haemoglobin and plasma are both colourless.

Respiratory System:

• It’s a network of tubes that looks like the trachea and ends in 10 pairs of pores called spiracles. Laterally, these spiracles can be found.

Excretory System:

• Malpighian tubules, lined by glandular and ciliated cells, are responsible for excretion.
• They take in nitrogenous waste and convert it to uric acid, expelled through the hindgut. As a result, uricotelic is the name given to this bug.
• The Malpighian tubules are excreted with the help of the fat body, nephrocytes, and urecose glands.

Nervous System:

• The neurological system of a cockroach is divided between the head and the ventral (belly-side) section of the body, and it is dispersed throughout the body. As a result, a cockroach with its head severed can live for up to a week.

Reproduction:

• Cockroaches come in two genders.
• Both sexes have fully developed reproductive organs.

7.5: Frog

• Frogs are amphibian vertebrates that belong to the Phylum Chordata’s class Amphibia and can live in both freshwaters and on land.
• The Rana tigrina is the most prevalent species in India.
• Cold-blooded creatures are known as poikilotherms.

7.5.1: Morphology:

• The skin is smooth and slippery as of the presence of mucus. That keeps the skin moisturised all the time.
• It is olive green with dark irregular markings on the dorsal side of the body. The ventral side is yellow.
• The frog consumes no water. Instead, the skin absorbs it.
• The head and the trunk are two separate portions of a frog’s body.

7.5.2: Anatomy

Frogs have well-developed systems in their bodies that aid them in their physiological operations. The digestive, respiratory, circulatory, excretory, nervous, and reproductive systems are all housed in the body cavity, and their activities are nearly identical to those of human body systems.

Digestive System:

• It has both an alimentary canal and digestive glands.
• Frogs have a short alimentary canal and a short intestine because they are carnivores.
• The pharynx connects the mouth to the buccal cavity, which leads to the oesophagus.
• The oesophagus is a tube with a tiny opening. It is linked to the stomach. The intestine comes after the stomach. The intestine enters the rectum and exits through the cloaca into the outside world.
• Cloaca: It is a shared chamber after the digestive tract. It is to release excretory and genital secretions from vertebrates (excluding most mammals) and certain invertebrates.

• Pancreas: A digestive gland that produces digestive enzyme-rich pancreatic juice

• Tongue bilobed: It assists in the capture of food.

• Stomach: This organ secretes gastric juice and HCl. That helps with food digestion.

• Chyme: Food that is half-digested and forming in the stomach.

• Chyme moves from the stomach to the duodenum.
• The first segment of the intestine is the duodenum. It gets bile from the gallbladder and pancreatic juice from the pancreas via a single bile duct. Bile emulsifies fats, and pancreatic juice digests proteins and carbs.
• The gut is the final stop for digestion.
• The many villi and microvilli absorb food that has been digested.
• Microvilli: These are the many finger-like extensions that protrude from the intestine’s inner wall. They increase the absorption surface area available.
• Solid waste enters the rectum and exits the cloaca undigested.

Respiration in Water:

• They use cutaneous respiration in water, in which the skin acts as an aquatic respiratory organ.
• Through the skin, diffusion exchanges dissolved oxygen in the water.

Respiration on Land:

• They breathe through their lungs.
• The buccal cavity, skin, and lungs are all respiratory organs.
• The lungs are a pair of pink sac-like organs found in the upper section of the trunk (thorax).
• Air can enter the buccal cavity through the nose. It subsequently makes its way to the lungs.
• During aestivation and hibernation, breathing is done through the skin.

Circulatory System:

• It has a well-developed circulatory system and lymphatic system.
• The heart, arteries, and blood make up the blood vascular system.
• The lymphatic system consists of lymph, lymph tubes, and lymph nodes.
• The heart is a muscular structure in the body’s upper chamber. There are three chambers in it: two atria and one ventricle. A membrane that surrounds the heart is known as the pericardium.
• The sinus venosus connects the right and left atriums.
• The vena cava, or veins, are responsible for supplying blood to the heart.
• The conus arteriosus takes over from the ventricle. It is a sac-like structure on the ventral side of the heart.
• The heart circulates blood throughout the body via arteries (arterial system). Veins transport blood from various regions to the heart (venous system).
• Hepatic portal: This vein connects the liver and the stomach.

• Renal Portals Management System: A vein that connects the kidney with the rest of the body

• Blood: The blood is made of plasma and cells. Red blood cells, erythrocytes (white blood cells), and platelets are the different types of blood cells (white blood cells).
• RBCs include nuclei and the red pigment haemoglobin.
• Blood is not the same as lymph. It has no RBCs and only a few proteins.
• The blood carries nutrients, gases, and water to its proper locations during circulation.
• The pumping activity of the muscular heart is responsible for blood circulation.

Excretory System:

• It is in charge of the body’s nitrogen waste removal.
• The system has two kidneys, ureters, a cloaca, and a urine bladder.
• Kidneys are red, bean-like structures in the back of the body located on either side of the spinal column.
• The nephron is a kidney’s structural and functional unit. There are numerous nephrons, or uriniferous tubules, in each kidney.
• The ureters are tubular structures that arise from the kidney. The cloaca is reached through the urogenital ducts.
• The oviduct and ureters open into the cloaca separately in females.
• Bladder urinary: It is placed ventral to the rectum and has thin walls. The rectum also links to the cloaca.
• Ureotelic: It is Animals that emit urea as nitrogenous waste. Frogs are ureotelic animals.

Control and Coordination:

• It encompasses both the brain system and the endocrine glands in frogs.
• Glands of the endocrine system: Secretory tissues secrete hormones, which cause chemical coordination in animals. The most significant endocrine glands are the pituitary, thyroid, parathyroid, thymus, pineal body, pancreatic islets, adrenals, and gonads.

• The central nervous system, peripheral nervous system, and autonomic nervous system make up the nervous system.
• The brain produces ten pairs of cranial nerves.
• The brain box protects the brain.
• The forebrain, midbrain, and hindbrain are the three parts of the brain.
• The forebrain is made of the olfactory lobes, paired cerebral hemispheres, and an unpaired diencephalon.
• Two optic lobes distinguish the midbrain.
• The cerebellum and the medulla oblongata make up the hindbrain. The medulla oblongata exits from the foramen magnum and enters the spinal cord. The vertebral column protects the spinal cord.
• Papillae sensory
• The taste organs are taste buds.
• The nasal epithelium is a scent organ.
• The eyes are the visual organs.
• Tympanum (hearing organ)
• Internal ear and eye structures are well-organised.
• The remaining cellular aggregations (sensory papillae, taste buds, and nasal epithelium) develop around nerve ends.
• Eyes: The orbit of the skull contains a pair of structures. They are simple eyes with only one unit.
• Ears: External ears are not present. The tympanum is visible from the outside. It is both a hearing organ and a balancing or equilibrium organ.

Reproduction:

• Male and female reproductive systems are both well-organised.
• A pair of yellowish ovoid testes are present in the male reproductive system.
• They are connected to the top area of the kidney by the mesorchium, a double fold of the peritoneum.
• The peritoneum is a serous membrane that lines the abdominal cavity and protects the abdominal organs.
• Mesorchium: The peritoneum fold is the connection between the testis and the top section of the kidney.

• Efferentia of the Vasa: They come from the testes and numbers 10-12. They enter the kidneys by Bidder’s canal and escape through the side.

• Canal for bidders: The frog’s kidney contains the Bidder’s canal. Several vasa efferentia get sperm from the testes. It enters the cloaca after connecting to the urinogenital duct.

• Cloaca: Feces, urine, and sperms are transported to the outside through a small median chamber.

• System of Female Reproduction: It consists of two ovaries that are placed near the kidneys.

• There is no functional link between the ovaries and the kidneys.
• Oviduct: The ovary and the cloaca are connected by this tube. It opens into the cloaca on its own.
• A mature female can lay between 2500 and 3000 eggs at any given time.
• Fertilisation takes place in the water.
• A frog’s life cycle includes a larva stage.
• Tadpole: The frog’s larval stage After metamorphosis, it matures into an adult.

Humans benefit from frogs because they consume insects and protect crops. Frogs contribute to the ecosystem’s balance by serving as a vital link in the food chain and web. Man also consumes the muscular legs of frogs in some areas.

CBSE Class 11 Biology Revision Notes Chapter 7 – Structural Organisation in Animals

Class 11 Biology Chapter 7 notes are available on Extramarks’ official website. These notes will help students to grab the concepts of this chapter easily. These notes are easily accessible to. 

Revision Notes For Chapter 7 Biology Class 11

Extramarks Biology chapter 7 notes for Class 11 cover the following topics:

• Multicellular organisms’ cells
• Organ, Tissue, and Organ Systems
• Tissues of epithelia, junctions, tight junctions, adherens junctions, gap junctions, squamous epithelium, cuboidal epithelium, columnar epithelium, ciliated epithelium, glandular epithelium, stratified or compound epithelium
• Areolar tissue, adipose tissue, reticular tissue, dense connective tissue, dense regular connective tissue, dense irregular connective tissue, and specialised connective tissue are all examples of connective tissue.
• Muscle tissue includes bone, cartilage, blood, skeletal muscle, smooth muscle, and cardiac muscle.
• Biology chapter 7 for Class 11 The notes include information regarding neural tissue, organs, and organ systems.
• The circulatory, excretory, neurological, and reproductive systems of earthworms
• Cockroach anatomy (blood vascular system, circulatory system, respiratory system, excretory system, neurological system), and reproduction (head, thorax, abdomen) (male and female reproductive systems)

Importance of Notes of Chapter 7 Biology Class 11

No one has the time to go through the entire chapter right before their exams. At that time, what you need are summarised and accurate notes that can help refresh your memory regarding all the important topics covered in the chapter. This is exactly what Revision Notes by Extramarks will do for you. These notes cover all the important information included in the chapter and present it in a concise manner so that you don’t have to prepare your own notes.