Group IV of the Periodic Table of the Elements contains carbon (C), silicon (Si) and several heavy metals. Carbon, of course, is the building block of life as we know it. So is it possible that a planet exists in some other solar system where silicon substitutes for carbon? Several science fiction stories feature silicon-based life-forms--sentient crystals, gruesome golden grains of sand and even a creature whose spoor or scat was bricks of silica left behind. The novellas are good reading, but there are a few problems with the chemistry.
<span>
CRYSTALLINE CREATURES? Silicon can grow into a number of lifelike structures, but its chemistry makes it unlikely that it could be the basis for alien life-forms.</span>
Indeed, carbon and silicon share many characteristics. Each has a so-called valence of four--meaning that individual atoms make four bonds with other elements in forming chemical compounds. Each element bonds to oxygen. Each forms long chains, called polymers, in which it alternates with oxygen. In the simplest case, carbon yields a polymer called poly-acetal, a plastic used in synthetic fibers and equipment. Silicon yields polymeric silicones, which we use to waterproof cloth or lubricate metal and plastic parts.
Answer:
The correct answer would be "Myosin heads attach to sites on actin filaments".
The muscle cell or myofibril consists of two types of protein filaments namely; actin (thin filament) and myosin (thick filament).
The myosin heads attach to the binding sites on the actin filaments and pull it towards the M-line in order to produce contraction.
The hydrolysis of ATP provides energy for this contraction cycle.
Natural selection would cause speciation because the new advantageous traits introduced in the population would help species survive and adapt to the new environment they are in because of isolation. The ability to make best from available leads to speciation in isolation.
Explanation:
Natural selection is a an important element of evolution. The change in traits which are beneficial and heritable are transferred from one generation to other. These traits come from random mutations.
Speciation is a process in which an existing population diverge in to two distinct population or species due to geographic barrier or without it also. The speciation occurs when species from one group become reproductive isolated.
When a group of species become isolated on an island or some other geographic boundary.
The increase or introduction of new beneficial genes in a population is caused by natural selection process. The populations manage to survive and adapt the new environment and become a new species if left isolated.
B the bird could fly into the fan
