Classification systems are essential to science; they act as the scaffolding that enables scientists to stand up close and get to know plants
Answer:
I think you're referring to the Metaphase...
Explanation:
During Cell Division (or, rather before!) the DNA needs to be replicated. This normally is done by DNA Polymerase, and results in two identical double strands (the "Sister Chromatids".
These chromatids are held together at the Centromere, which will be the heart of the "X"-shape. After that the DNA is packed into Chromosomes by winding it around proteins called Histones. If I remember correctly there are 5 different Histones.
This "Zipping Up" makes the chromosomes more visible.
As the two sister chromatids are still connected, the result is the X-shaped Metaphase Chromosome....
Explanation:
Pride is the social community of lions where they grow, mate, reproduce, communicate, hunt etc. When male lions gets control of a new territory or a pride, they most of the times kill the cubs of the pride because they are not biologically related and do not want to waste their energy by ensuring that the cubs genes are passed on.
They don't want to be stepfathers. Female lions also will not be responsive to mating during the time they are feeding, so killing the cubs allows the male lions to reproduce.
Answer:
tRNA and mRNA can leave the nucleus.
Explanation:
tRNA, when mature and correct, can leave the nucleus and enter the cytoplasm. mRNA can leave the nucleus through pores in the nuclear membrane. However, DNA cannot leave the nucleus, it has to be transcribed into RNA.