<span>The geologic time scale is divided into periods, which are then divided into epochs, which are further divided into ages. For example, the time of the dinosaurs lasted 3 periods (Triassic, Jurassic, Cretaceous), each period had 3 epochs (late, early, middle), and each age fit into one of those. Many epochs have more than 1 age associated with them.
As for the basis for differentiating the eras, I'm not so sure. The only one I can say for sure is the end of the Cretaceous, which is when the dinosaurs suddenly became extinct due to a meteor impact. I think the divisions are based on significant, global-scale events that changed the world.
Sorry its so long but that the answer i think >:) ur welcome
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Answer: Medication can be tested on the cancer culture before being injected into the patient.
A phylogeny is an evolutionary ”tree” of related
organisms that can be constructed by using
information obtained from the genetic material.
Genetic information is contained in all living cells,
in the form of long DNA molecules that take the
shape of connected double- stranded spirals
(DNA stands for deoxyribonucleic acid). DNA
spirals, or “helixes”, are tightly compressed in the
nucleus of every cell. Their information is
organized into a code made up of four small
molecules — the building blocks of DNA. The
molecules, called nucleotides, are labelled:
A (adenine), C (cytosine), G (guanine) and T
(thymine).
It is possible to draw conclusions about the
evolution of a group of plant or animal species,
and the relationships among them, by comparing
selected pieces of DNA.
Answer:
option B) The oxygen end of the molecule has a partial negative charge and the hydrogen end has a partial positive charge.
Justification:
The electronegativity of an element accounts for its relative ability to attract electrons.
Being oxygen more electronegative than hdyrogen (the electronegativity of oxygen is 3.44 while the electronegativity of the hydrogen is 2.20), the electron density will be displaced toward the oxygen, letting it with a partial negative charge and the hydrogen with a partial positive charge.
Finally, since the charge is not symmetrical distributed around a center of the molecule, the molecule ends being polar.
Answer: Possession of Valves
Explanation: Veins possess valves which ensures that blood flows in only one direction. Valves helps blood to flow back to the heart against gravitational force.
Arteries don't have valves because the pressure originating from the heart is capable of causing the blood to flow in one direction.
