Note the relationship between the first two words and suggest the suitable word/words for the fourth place.

(a) Cones: Iodopsin:: Rods: ………….

(b) Sound: Eardrum :: Dynamic balance : …………………..

(a) Cones: Iodopsin:: Rods: Rhodopsin

Explanation: The membranous photoreceptor protein opsin contains a pigment molecule called retinal. In rod cells, these together are called rhodopsin. In cone cells, there are different types of opsins that combine with retinal to form pigments called iodopsin or photopsins.

(b) Sound: Eardrum:: Dynamic balance: Semi-circular canals

Explanation: The major task of the ear is to detect, transmit and transduce sound. Another very important function of the ear is to maintain our sense of balance. The sound waves travel from the outer ear and in through the auditory canal, causing the eardrum, or tympanic membrane, to vibrate whereas the semi-circular canals are responsible for maintaining balance.