Question

Tendril of Cucurbita and thorns of Bougainvillea are
A. Vestigial organ
B. Analogous organ
C. Homologous organ
D. None of the above

Answer 1

Hint: Thorns in Bougainvillea are modifications of the stem. They act generally as protection against grazing animals. And also the tendrils of the Cucurbita is the stem modification. So we have to think about the different structural and functional behaviour of these two plant modifications.

Complete answer:
Homologous organ-
The homologous organs are similar (or are embryological same), however, perform different functions in different organisms. These offer strong proof within the favour of evolution. Example: The bone structure ascertained in wings of birds, wings of bats, flippers of dolphins, and arms of people at large tally with one another, though they appear strikingly totally different on the skin and though they vary in performance however they're similar in anatomical structure.

Analogous organ-
Analogous structures measure physically (but not genetically) similar structures that weren't present in the last common relative. Bat wings and bird wings evolved severally and are thought-about analogous structures. Genetically, a batwing and a bird wing have little or no in common; the last common relative of daft and birds didn't have wings like either bats or birds.

Vestigial organ-
These 'useless' body-parts, otherwise referred to as undeveloped organs, are remnants of lost functions that our ancestors possessed. They once depicted a performance that evolved out of a necessity for survival, however over time that performance became non-existent. As an example vermiform appendix.

Thorns of bougainvillaea and tendrils of Cucurbita square measure examples for homologous organs. They arise from the axillary buds. They perform different kinds of functions. The thorn is for protecting the grazing animals. The tendrils help in providing support whereas ascension. They're anatomically similar. However, the functions are different.

Hence, the correct answer is option (C).

Note: Thorns of vine and tendrils of Cucurbita are homologous organs. These are changed branches and are axillary in position. It means that axillary branches in the vine are changed into thorns for cover from burrowing animals and in Cucurbita into tendrils for mounting.