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The first fossilized evidence of sexual reproduction in eukaryotes is from the Stenian period, about 1.05 billion years old. [19] [20]Biologists studying evolution propose several explanations for the development of sexual reproduction and its maintenance.
The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction.Many non-living substances such as fluids, hormones, and pheromones are also important accessories to the reproductive system. [1]
In population ecology and demography, the net reproduction rate, R 0, is the average number of offspring (often specifically daughters) that would be born to a female if she passed through her lifetime conforming to the age-specific fertility and mortality rates of a given year.
Uterus didelphys seen on ultrasonography. Besides a physical examination, the physician will need imaging techniques to determine the character of the malformation: gynecologic ultrasonography, pelvic MRI, or hysterosalpingography.
Holmberg IX is a dwarf irregular galaxy and a satellite galaxy of M81, located in the constellation of Ursa Major. It is of the Magellanic type of Galaxy as it is similar to the Small Magellanic Cloud , neighbour galaxy to Milky Way Galaxy. [ 3 ]
9 to 5: The Musical is a musical based on the 1980 film of the same name, with music and lyrics by Dolly Parton. It features a book by Patricia Resnick , based on the screenplay by Resnick and Colin Higgins .
Estimates of world population by their nature are an aspect of modernity, possible only since the Age of Discovery.Early estimates for the population of the world [10] date to the 17th century: William Petty, in 1682, estimated the world population at 320 million (current estimates ranging close to twice this number); by the late 18th century, estimates ranged close to one billion (consistent ...