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.
B causes all vegetation to freeze
Answer:
It looks like a chinchilla
Explanation:
looking at the size, shape and tail it must be a chinchilla but i could be wrong but im pretty sure.
Answer:
Enzyme- Peptidase/protease
Explanation:
According to this question, a student is conducting an experiment to determine the roles of molecules in metabolic processes such as digestion. Based on what she found out that the molecule, which itself can be broken down into amino acids, can also break down proteins into amino acids, this suggests that the molecule being described is a PROTEOLYTIC ENZYME.
This is because an enzyme is made up of proteins which can be denatured or broken down into its simplest unit (amino acids) and also, a substance that breaks down amino acid is said to be PROTEOLYTIC.
However, another observation that the molecule is found in high concentrations in the small intestine was made, hence, the enzyme is a PEPTIDASE OR PROTEASE, which are secreted into the small intestine by the pancreas to aid digestion of proteins.
