its like a twisted ladder or a double helix
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C the earth because that is the only planet around so he thought that the sun and everything else rotated around us.
Answer:
At the microscopic level of a visceral muscle cell are actin and myosin filaments. They slide past each other in an antiparallel manner to shorten the distances between their ends. In a smooth muscle cell, the ends of chains of these functional units are attached to the cell membrane. They are several in a cell arranged in an elaborate framework. They contract together and deferentially to enable the muscle to contract as needed.
When we talk about evolution we come across the process of natural selection. Genetic variation is always required for the natural selection. A change or variation in the genes may help the individuals in a population to better adapt to the environment. Such changes may be brought by mutations or random mating in the population. Such variations help in the survival of the population by allowing them to adapt to changing environmental conditions.