Buy BOOKS at Discounted Price

Structural Organisation In Animals

Class 11th Biology CBSE Solution

Ncert Questions
Question 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) Cockroach (ii) Four pairs (iii) Ovaries in cockroach lie in the 4th, 5th and 6th segments (iv) Ten segments(v) Malphigian tubules are found in insects.
Question 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) Nephredia is the excretory organ present in earthworm. (ii) Three types of nephridia are found in earthworms:(a) Septal nephridia: Present on both sides of the intersegmental septa.(b) Integumentary nephridia: Attached to the lining of the body wall.(c) Pharnygeal nephridia: Found in the 4th ,5th and 6th segments.
Question 3.

Distinguish between the followings(a) Prostomium and peristomium(b) Septal nephridium and pharyngeal nephridium


Answer:
Question 4.

What are the cellular components of blood?


Answer: The cells found in blood are called blood corpuscles. These are of three types,(i) Red blood corpuscles(ii) White blood corpuscles and(iii) Platelets.(i) Red blood corpuscles: Red blood corpuscles are also called erythrocytes. The red colour of erythrocytes is due to the presence of haemoglobin, a red coloured pigment with high affinity for oxygen. The shape and size of RBC’s vary in different animals. The cells may be nucleated or non-nucleated. Actually, the nucleus is present in the RBCs of mammals initially, but when these cells finally differentiate and mature, the nucleus, mitochondria and endoplasmic reticulum degenerate. Such cells accommodate more haemoglobin for transportation of oxygen. About 4.8± 1.0 million RBCs per cubic millimetre of blood are found in adult women and 5.5± 1.0 million per cubic millimetre in adult men.Haemoglobin is a conjugated protein made up of globin and Fe2+ containing a tetrapyrrole prophyrin ring called haeme. One molecule of haemoglobin binds to four molecules of oxygen. Erythrocytes also participate in transporting carbon dioxide from tissues to lungs. Carbon dioxide is mainly carried in both plasma and RBCs as bicarbonate. Carbon dioxide is also partly carried in combination with globin of haemoglobin. Erythrocytes have an average life span of about 120 days.(ii) White blood corpuscles: White blood corpuscles are also called leukocytes, as these are colourless. These are devoid of haemoglobin. Leukocytes are nucleated blood cells. The number of WBCs in adult humans is 7.5 ± 3.5 x103 per cubic millimeter of blood. WBCs are of two types - granulocytes and agranulocytes. On the basis of staining characteristics of cytoplasmic granules and shape of nucleus, granulocytes are of three types (a) neutrophils, (b) eosinophils and (c) basophils. Granules are in abundance in the cytoplasm. These are phagocytic in action. Eosinophils are larger in size and with bi-lobed nucleus and abundant coarse granules. Basophils release heparin and histamines in the blood. Heparin is a natural anticoagulant. Agranulocytes are non-granular white blood cells. The nucleus is non-lobulated. These are of two types, (a) lympocytes and (b) monocytes. Lymphocytes have a large and rounded nucleus. Due to this reason, cytoplasm forms a thin peripheral film. These are formed in the bone marrow and are differentiated in the same place or in the thymus. The primary function of lymphocytes is to produce antibodies against antigens or to kill the invading pathogens directly in the body.(iii) Blood platelets: Blood platelets are also called thrombocytes because they secrete thromboplastin. These are the smallest blood corpuscles. Blood platelets are non-nucleated, round or oval, biconvex disc-like bodies. Their number normally varies from 0.15 to 0.40 million per cubic millimetre of blood. They bud-off from the cytoplasm of very large megakaryocyte cells of the bone marrow. When a blood vessel is injured, platelets get clumped at the injured spot and release certain chemicals called platelet factors. The thromboplastin, a protein-phospholipid complex, released from the platelets at the site of injury is an important clotting factor in blood coagulation. The oozed out transparent fluid after coagulation of blood is called serum. It means, serum is blood without corpuscles and fibrin protein.
Question 5.

What are the following and where do you find them in animal body. (a) Chondriocytes(b) Axons(c) Ciliated epithelium


Answer: (a) The intercellular material of cartilage consist of cells called Chondriocytes, they are enclosed in small cavities within the matrix secreted by them. (b) The neuron consist of a long fiber which originates from the cell body of the neuron and this is called axon. The distal ends of these are branched to synaptic junction. (c) Ciliated epithelium: These are columnar or cuboidal cells which bear cilia on their free surface. They are mainly present in the inner surface of hollow organs like bronchioles and fallopian tube.
Question 6.

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
(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

Question 7.

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) neuron(b) cartilage(c) ligament(d) antennae(e) coxa.
Question 8.

Mention briefly about the circulatory system of earthworm


Answer: Earthworm exhibits a closed type of blood vascular system. This type of blood vascular system consists of blood vessels, capillaries and heart. Due to closed circulatory system, blood is confined to the heart and blood vessels. Contractions of the body keep blood circulating in one direction. Smaller blood vessels supply the gut, nerve cord, and the body wall. Blood glands are present on the4th, 5th and 6th segments. They produce blood cells and haemoglobin, which is dissolved in blood plasma. Blood cells are phagocytic in nature. Earthworms lack specialised breathing devices. Respiratory exchange occurs through the moist body surface directly into the blood stream.
Question 9.

Mention the function of the following(a) Ureters in frog(b)Malpighian tubules(c) Body wall in earthworm


Answer: (a) Ureters in FrogIn frogs two ureters emerge from the kidneys. In male frog the ureters act as urinogenital duct which opens into the cloaca. It helps in passing the urine as well as the sperm to the exterior. In females the ureters and oviduct open seperately in the cloaca. The ureters excrete only the urine. (b) Malpighian tubulesThe malpighian tubules help in the removal of excretory products present in the haemolymph of the cockroach. (c) Body wall in the earthwormThe moist body wall helps in respiration. The circular and the longitudinal muscles present below the cuticle along with the setae, which is embedded in the epidermal pits, help in the locomotion of the earthworm.