Q. Which one of the following pairs of items correctly belongs to the category of organs mentioned against it :
(a) Nephridia of earthworm and malpighian tubules of cockroach – Excretory organs
(b) Wings of honey bee and wings of crow – Homologous organs
(c) Thorn of Bougainvillea an tendrils of Cucurbita – Analogous organs
(d) Nictitating membrane and blind spot in human eye – Vestigial organs
Solution :
Correct option : A The structures, which are similar in their morphology, anatomy, genetics and embryology but dissimilar in their function are called as homologous organs. The thorn of bougainvillea and tendril in cucurbita are homologous organs. Both arise from an axillary bud. They perform different functions. Thorn provides protection and tendril provide support for climbing. They have anatomical similarity but they differ functionally hence they are called homologous organs. The nictitating membrane is a transparent or translucent third eyelid present in some animals that can be drawn across the eye for protection and to moisten it, while maintaining visibility. Some reptiles, birds, and sharks have full nictitating membrane. Blind spot is a small portion of the visual field of each eye that corresponds to the position of the optic disk (also known as the optic nerve head) within the retina. They are not vestigial organs. Wings of bee and wings of crow are examples of analogous organs because of having a similar function. Nephridia coiled tubular duct-like organs, filter and remove waste from an earthworm’s body. The excretory organ of cockroach is the malpighian tubules. It is found at the junction of the midgut and hind gut and are about 150 in number.