E, D, and C I believe. It has been a while since I took this class.
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:
Two rounds
Explanation:
Meiosis is characterized by one round of DNA replication followed by two rounds of cell division, resulting in haploid germ cells. Crossing-over of DNA results in genetic exchange of genes between maternal and paternal DNA.
Answer:
The high yielding property of a plant species would be most useful for meeting the scientists’ goal.
Explanation:
In selective breeding, we develop a new variety by crossing a wild specie with the domestic growing variety in order to achieve the characteristic which is present only in wild specie. So with the help of selective breeding, this characteristics is transferred to the offspring. The main goal of scientist is to produce such variety which produces maximum yield and also good quality seeds.
Answer:
The diagram is attached below.
Explanation:
when sodium and chlorine comes close together they form anion and cation. The compound formed is called sodium chloride.
Both atoms bonded together through ionic bond.
Ionic bond:
It is the bond which is formed by the transfer of electron from one atom to the atom of another element.
Both bonded atoms have very large electronegativity difference. The atom with large electronegativity value accept the electron from other with smaller value of electronegativity.
For example:
Sodium chloride is ionic compound. The electronegativity of chlorine is 3.16 and for sodium is 0.93. There is large difference is present. That's why electron from sodium is transfer to the chlorine. Sodium becomes positive and chlorine becomes negative ion.
