Index fossils (also known as guide
fossils, indicator fossils or zone
fossils) are fossils used to define
and identify geologic periods (or
faunal stages).
The correct answer is true
Answer:
(a)1. the replication of genetic materials at S-phase of interphase of both mitosis and meiosis prior to cell division.( This ensured required amount of genetic material are present in the daughter cells to produce, and enough food source as raw material fro the entire division process.
2.the manner in which the the chromosomes are aligned at the center of the cell before the chromosomes separates. (This ensured that required or exact copies of chromosomes are available in the new daughter cells as the chromosomes migrates to new daughter cells at Metaphase and Anaphase.
(b)Number of cell cycles or division and crossing over
This occurs because of the number of cell divisions that occurs, Mitosis occurs in one cycle of division which multiplied the number of cells formed, and therefore refereed to as multiplication division.(2n)The new daughter cells have exact number of chromosomes as the parent cells. While meiosis occurs in two cycles of Meiosis 1 and 11. This is a reduction division(n) in which the new daughter cells have haploid or half of the parent chromosome numbers.
Crossing over is another feature which increases the chances of variation from the mixing up of genetic materials of both parents in the new daughter cells at a point called chiasmata. This makes the new haploid daughter cells having new genetic composition slightly different from both parents.
Answer: pulmonary artery carries deoxygenated blood away from the heart
