Answer:
Since a species' chromosome count doesn't change from generation to generation, meiosis requires that the number of chromosomes in germ cells be cut in half. Meiosis, unlike mitosis, achieves this accomplishment by requiring a single round of DNA replication followed by two rounds of cell division.
Antibiotics are, initially, molecules naturally synthesized by microorganisms to fight against bacteria competing with their environment. This created a pressure of selection on the bacterial populations, leading to the appearance of resistant strains. In fact, when an antibiotic is used, only bacteria with defense systems against this molecule survive (and reproduce).
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Answer:
mantle
Explanation:
A mantle is a layer inside a planetary body bounded below by a core and above by a crust. Mantles are made of rock or ices, and are generally the largest and most massive layer of the planetary body. Mantles are characteristic of planetary bodies that have undergone differentiation by density. All terrestrial planets (including Earth), a number of asteroids, and some planetary moons have mantles.
Correct answer - Tetrahedral, planar or flat.
Why? - When carbon forms single bonds with other atoms, the shape is tetrahedral. When two carbon atoms form a double bond, the shape is planar, or flat. Single bonds, like those found in ethane, are able to rotate.
