Question

Which type of homology exists between the arm and leg of man and horse?
A. Phylogenetic
B. Sexual
C. Serial
D. None of the above

Answer 1

Hint: Homology, in genetics, structural resemblance, pathology, or creation based on their descent from a single ancestral ancestor among various species of organisms.

Complete Answer:
- In genetics, homology is a resemblance between a pair of structures or genes in different taxa due to common ancestors.
- The forelimbs of vertebrates are a typical example of homologous structures, where the wings of bats and birds, the bodies of humans, the front flippers of whales and the forelegs of four-legged vertebrates including dogs and crocodiles are all formed from the same system of ancestral tetrapods.
- As a result of descent with alteration from a single ancestor, evolutionary biology clarifies homologous systems suited to various purposes.
- In developmental biology, there are serially homologous organs that have formed in the embryo in the same way and from identical sources, such as matching primordia in successive segments of the same animal.
Examples include the legs of a centipede, the insect's maxillary palp and labial palp, and the spinous processes in a vertebral column of successive vertebrae.

- Male and female reproductive organs, including the ovaries and testicles in animals, like humans, are homologous as they mature from the same embryonic tissue.
Examples of homologous organs include the arm and leg of a man and a horse. An example of an organ or bone that exists in various animals is a homologous structure, underlining anatomical commonalities that demonstrate descent from a similar ancestor.

- In other words, there are bones that appear very similar in shape or function and tend to be related while very different animals have them.

So the answer is”Phylogenetic”.

Note: In terms of common heritage, sequence homology between protein or DNA sequences is similarly defined. Due to either a speciation event (orthologs) or a replication event (paralogs), two segments of DNA may have a common ancestry. From their sequence similarity, homology among proteins or DNA is inferred. An important similarity is a clear proof that through divergent evolution from a single ancestor, two sequences are related.
Multi-sequence alignments are used to discover the homologous regions.