(i) Blood consists of 60% of plasma and 40% of blood cells.

(ii) Red blood cells are nucleated containing haemoglobin (red pigment) and these are oval shaped.
(iii) Leucocytes are nucleated and circular in shape.

(i) The head is small, triangular and lies at right angle to the longitudinal axis of the body.
(ii) The mouth parts are directed downwards so it is hypognathous.

(a) Clitellum Location: 14^th to 17^th segments appears as unsegmented externally
(b) Spermathecal openings: Location 6/7, 7/8 and 8/9 segments.

(i) Ommatidia are the visual units of compound eyes of cockroach.
(ii) Each ommatidium is functional as an eye unit.
(iii) Photoreceptors are dorsally found.
(iv) Each compound eye consists of 2000 simple eyes called ommatidia.
(v) All the visual images captured by ommatidia are made into a single coherent picture by supra oesophageal ganglion (brain).

(i) The dried solid excreta rich in urea released by pygidium of earthworms are earthworm casts or worm castings or worm pellets
(ii) They are released by anus due to the function of nephridia
(iii) Released worm castings increase the fertility of soil for plant growth
(iv) Worm castings are less released during rainy season

(i) On drying the skin it dies.
(ii) Dorsal blood vessel is exhibited as mid dorsal line
(iii) Body is divisible into pre-clitellar region, clitellar region and post-clitellar region
(iv) Regeneration is noticed if it is transversely cut.
(v) Presence of earthworms in the soil increases the fertility
(vi) Metamere appear as rings or annulus (Annelida) so earthworms are called ringworms

(i) The process of elimination of nitrogenous wastes, salt and water balance from the body is called excretion.
(ii) This system consists of a paired kidneys, ureters, urinary bladder and cloaca.
(iii) Kidneys are dark red, long, flat organs situated on either sides of the vertebral column.
(iv) Kidneys are mesonephric type.
(v) The functional excretory units of kidneys are nephrons.
(vi) Nephrons separate nitrogenous wastes from the blood and excrete urea so frogs are ureotelic.
(vii) A paired long ureter emerges from the kidneys and opens into the cloaca.
(viii) A thin walled unpaired urinary bladder is present ventral to the rectum.
(ix) Rectum opens into the cloaca.