Answer:
The Miller and Urey experiment is a well-known classic experiment in which hypothetical conditions of the early Earth's evolution were simulated to test the possibility of chemical evolution. In fact, this was an experimental test of the hypothesis previously expressed by Alexander Oparin and John Haldane that the conditions that existed on primitive Earth promoted chemical reactions that could lead to the synthesis of organic molecules from inorganic ones. It was held in 1953 by Stanley Miller and Harold Urey. The apparatus designed for the experiment included a mixture of gases corresponding to the notion of the composition of the atmosphere of the early Earth in the 1950s, and electric discharges passing through it (simulating lightning strikes on the ground). The Miller and Urey experiment is considered one of the most important experiments in the study of the origin of life on Earth.
All evolutionary changes that allow a species to change in response to the environment, are originally a result of beneficial DNA mutations.
Beneficial genetic (DNA) mutations are result in individuals with special characteristics that allow them to survive better in the environment so they pass their genes to the next generation.
Here's a fictional example I made just for you!: Lets say you have an alien species called Hibas. They are jelly blobs that float around, don't move, and open their mouths to capture neon shrimps that happen to swim into their mouths. But one day a certain Hiba developed some muscles through a genetic mutation. It was able to "wiggle" through the water and steer itself instead of floating around. This allowed it to eat more neon shrimp than the other Hibas, so it grew faster and was able to reproduce faster. It's kids also had muscles and had an advantage so they reproduced faster then the other Hibas. Eventually the whole Hiba species started to have muscles because the ones that didn't weren't able to compete and did not survive as well.
The reason that most of the Hibas developed muscles was because one of them had a mutation that allowed it to have muscles. This was a BENEFICIAL mutation that allowed it to SURVIVE BETTER.
Answer: I don't really understand what you're asking, but arthropods have 8 legs.
Answer:
if your on a mountian it colder
Explanation:
In humans, the yolk sac is the
site of origin for blood cells and primordial germ cells. The human yolk sac is
a membrane located outside the embryo and it is connected by a tube through the
umbilical opening to the embryo's midgut. The yolk sac serves as an early site
for the formation of blood and in time, is incorporated into the primitive gut
of the embryo.
