There are all sorts of ways to reconstruct the history of life on Earth. Pinning down when specific events occurred is often tricky, though. For this, biologists depend mainly on dating the rocks in which fossils are found, and by looking at the “molecular clocks” in the DNA of living organisms.
There are problems with each of these methods. The fossil record is like a movie with most of the frames cut out. Because it is so incomplete, it can be difficult to establish exactly when particular evolutionary changes happened.
Modern genetics allows scientists to measure how different species are from each other at a molecular level, and thus to estimate how much time has passed since a single lineage split into different species. Confounding factors rack up for species that are very distantly related, making the earlier dates more uncertain.
These difficulties mean that the dates in the timeline should be taken as approximate. As a general rule, they become more uncertain the further back along the geological timescale we look. Dates that are very uncertain are marked with a question mark.
Answer:
Explanation:
Each of these types of scientists focus on different research studies and therefore needs different tools. Field Scientists' studies mainly revolve around observations which they, therefore, need only a pen and paper, this may sometimes change when they need bigger machinery to make a certain event occur, but this machinery is dependent on the type of research. On the other hand laboratory, scientists work with different specimens within the lab and tend to use tools such as Bunsen burner, beakers, reagent bottles, petri dishes, and microscopes.
Answer:
the physical distance between the two genes.
Explanation:
I’m not for sure but I believe it is A
i believe that the cell will expand because there is less sugar in the water. if you were to add more sugar into the water, then the cell will shrink in size because sugar and salt is the same thing if you add it in water.
