NCERT Solutions for Class 11 Biology Chapter 7 Structural Organisation In Animal

Ans : (i) The common name of Periplaneta americana is the American cockroach. 
(ii) Four pairs of spermathecae are present in earthworms. They are located between sixth and the ninth segments. They help in receiving and storing the spermatozoa during copulation. 
(iii) In a cockroach, the pair of ovaries is located between 12th and 13th abdominal segments. 
(iv) In both sexes, the abdomen of a cockroach consists of ten segments.
(v) Malpighian tubules are main excretory organs of cockroaches. They form a part of the alimentary canal. 

Ans : (i) Nephridia are segmentally arranged excretory organs present in earthworms. 
(ii) On the basis of their location, three types of nephridia are found in earthworms. 
They are: 
(a) Septal nephridia: These are present on both sides of the intersegmental septa behind the 15th segment. They open into the intestines. 
(b) Integumentary nephridia: These lie attached to the body wall from the third segment to the last segment, which opens on the body surface. 
(c) Pharyngeal nephridia: These are present as three paired tufts in fourth, fifth. and sixth segments. 

Ans : (a) 

(b) 
 

Ans : Components of blood include erythrocytes (RBCs), leucocytes (WBCs), and thrombocytes (platelets). These components form 45% of blood. They are suspended in the remaining fluid portion, called plasma Mammalian erythrocytes are biconcave, coloured cells devoid of a nucleus. They help in transporting respiratory gases. 
Leukocytes or white blood cells are nucleated cells. They can be divided into two types, granulocytes (neutrophils, eosinophils, and basophils) and agranulocytes (lymphocytes and monocytes). They help fight against various disease-causing germs entering the body. Thrombocytes are cell fragments produced from megakaryocytes of the bone. They play a major role during blood coagulation. 

Ans : Chondrocytes: They are cells of cartilages, and are present in small cavities within the matrix secreted by them. 
Axons:They are long, slender projections of neurons that help in carrying nerve impulses from the neuron body. Axons aggregate in bundles which make up the nerves. 
Ciliated epithelium: It consists of simple columnar or cuboidal epithelium with cilia on their free surfaces. It is present on the inner surface of the oviducts and bronchioles. It helps in the movement of eggs or mucus in specific directions.