The evolution of sexual reproduction is a great puzzle in modern evolutionary biology. Many groups of eukaryotic organisms, especially most animals and plants, reproduce sexually. The evolution of sex between two organisms of the same species contains two related but different themes: its origin and its maintenance. However, since hypotheses for the origin of sex are difficult to test experimentally, most of the current work has focused on the maintenance of sexual reproduction. Biologists, including W. D. Hamilton, Alexei Kondrashov, and George C. Williams, have proposed various explanations for how sexual reproduction is maintained in a large set of different living things.
Some bones develop within sheet like layers of connective tissue which are called intramembranous bones whereas the bones that are develop from a model of hyaline cartilage and are called endochondral bones.
<h3>Formation of
intramembranous bones and endochondral bones</h3>
Endochondral ossification involves the replacement of hyaline cartilage with bony tissue which leads to the formation of endochondral bones whereas, intramembranous ossification refers to the replacement of sheet-like connective tissue membranes with bony tissue which results in the formation of intramembranous bones.
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A) Crossing over is the mechanism of genetic variation that results from the exchange of gene segments between non-sister chomatids.
Answer:
D. Evolutionary relationships
Explanation:
phylogeny describes the relationships of organisms which evolved on most closely related species
