<span>Too little is known about pre-Archean time, from the origin of Earth to 3.8 billion years ago, to divide that period into units.</span>
Discontinuous variation is when a trait is seen in a population in two or more different forms and there is no continuation along a gradient. A good example that Mendel studied is flower color. The flowers were either white or purple. There was no in between color. This is caused by an allele for purple or a lack of an allele for purple, which produces no pigment, or white.
Answer:
The grid method is best used in large crime scenes such as fields or woods.
Explanation:
Several searchers, or a line of them, move alongside each other from one end of the area to be searched to the other.
Each sieve tube element is normally associated with one or more nucleated companion cells, to which they are connected by plasnodesmata (channels between the cells). Each companion cell is derived from the same mother cell as its associated sieve tube member. Sieve tube members have no cell nucleus, ribosomes, or vacues. Thus, they depend on companion cells to provide proteins, ATP, and signalling molecules
